Last Revised: February 2016

Map Information

This nowCOAST™ time-enabled map service provides maps depicting the latest global forecast guidance of water currents, water temperature, and salinity at forecast projections: 0, 12, 24, 36, 48, 60, 72, 84, and 96-hours from the NWS/NCEP Global Real-Time Ocean Forecast System (GRTOFS). The surface water currents velocity maps display the direction using white or black streaklets. The magnitude of the current is indicated by the length and width of the streaklet. The maps of the GRTOFS surface forecast guidance are updated on the nowCOAST™ map service once per day. For more detailed information about layer update frequency and timing, please reference the
nowCOAST™ Dataset Update Schedule.

Background Information

GRTOFS is based on the Hybrid Coordinates Ocean Model (HYCOM), an eddy resolving, hybrid coordinate numerical ocean prediction model. GRTOFS has global coverge and a horizontal resolution of 1/12 degree and 32 hybrid vertical layers. It has one forecast cycle per day (i.e. 0000 UTC) which generates forecast guidance out to 144 hours (6 days). However, nowCOAST™ only provides guidance out to 96 hours (4 days). The forecast cycle uses 3-hourly momentum and radiation fluxes along with precipitation predictions from the NCEP Global Forecast System (GFS). Each forecast cycle is preceded with a 48-hr long nowcast cycle. The nowcast cycle uses daily initial 3-D fields from the NAVOCEANO operational HYCOM-based forecast system which assimilates situ profiles of temperature and salinity from a variety of sources and remotely sensed SST, SSH and sea-ice concentrations. GRTOFS was developed by NCEP/EMC/Marine Modeling and Analysis Branch. GRTOFS is run once per day (0000 UTC forecast cycle) on the NOAA Weather and Climate Operational Supercomputer System (WCOSS) operated by NWS/NCEP Central Operations.

The maps are generated using a visualization technique developed by the Data Visualization Research Lab at The University of New Hampshire's Center for Coastal and Ocean Mapping (http://www.ccom.unh.edu/vislab/). The method combines two techniques. First, equally spaced streamlines are computed in the flow field using Jobard and Lefer's (1977) algorithm. Second, a series of "streaklets" are rendered head to tail along each streamline to show the direction of flow. Each of these varies along its length in size, color and transparency using a method developed by Fowler and Ware (1989), and later refined by Mr. Pete Mitchell and Dr. Colin Ware (Mitchell, 2007).

Time Information

This map service is time-enabled, meaning that each individual layer contains time-varying data and can be utilized by clients capable of making map requests that include a time component.

In addition to ArcGIS Server REST access, time-enabled OGC WMS 1.3.0 access is also provided by this service.

This particular service can be queried with or without the use of a time component. If the time parameter is specified in a request, the data or imagery most relevant to the provided time value, if any, will be returned. If the time parameter is not specified in a request, the latest data or imagery valid for the present system time will be returned to the client. If the time parameter is not specified and no data or imagery is available for the present time, no data will be returned.

This service is configured with time coverage support, meaning that the service will always return the most relevant available data, if any, to the specified time value. For example, if the service contains data valid today at 12:00 and 12:10 UTC, but a map request specifies a time value of today at 12:07 UTC, the data valid at 12:10 UTC will be returned to the user. This behavior allows more flexibility for users, especially when displaying multiple time-enabled layers together despite slight differences in temporal resolution or update frequency.

When interacting with this time-enabled service, only a single instantaneous time value should be specified in each request. If instead a time range is specified in a request (i.e. separate start time and end time values are given), the data returned may be different than what was intended.

Care must be taken to ensure the time value specified in each request falls within the current time coverage of the service. Because this service is frequently updated as new data becomes available, the user must periodically determine the service's time extent. However, due to software limitations, the time extent of the service and map layers as advertised by ArcGIS Server does not always provide the most up-to-date start and end times of available data. Instead, users have three options for determining the latest time extent of the service:

  Issue a returnUpdates=true request (ArcGIS REST protocol only)
  for an individual layer or for the service itself, which will return
  the current start and end times of available data, in epoch time format
  (milliseconds since 00:00 January 1, 1970). To see an example, click on
  the "Return Updates" link at the bottom of the REST Service page under
  "Supported Operations". Refer to the
  ArcGIS REST API Map Service Documentation
  for more information.


  Issue an Identify (ArcGIS REST) or GetFeatureInfo (WMS) request against
  the proper layer corresponding with the target dataset. For raster
  data, this would be the "Image Footprints with Time Attributes" layer
  in the same group as the target "Image" layer being displayed. For
  vector (point, line, or polygon) data, the target layer can be queried
  directly. In either case, the attributes returned for the matching
  raster(s) or vector feature(s) will include the following:


      validtime: Valid timestamp.


      starttime: Display start time.


      endtime: Display end time.


      reftime: Reference time (sometimes referred to as
      issuance time, cycle time, or initialization time).


      projmins: Number of minutes from reference time to valid
      time.


      desigreftime: Designated reference time; used as a
      common reference time for all items when individual reference
      times do not match.


      desigprojmins: Number of minutes from designated
      reference time to valid time.




  Query the nowCOAST™ LayerInfo web service, which has been created to
  provide additional information about each data layer in a service,
  including a list of all available "time stops" (i.e. "valid times"),
  individual timestamps, or the valid time of a layer's latest available
  data (i.e. "Product Time"). For more information about the LayerInfo
  web service, including examples of various types of requests, refer to
  the 
  nowCOAST™ LayerInfo Help Documentation

References

Fowler, D. and C. Ware, 1989: Strokes for Representing Vector Field Maps. Proceedings: Graphics Interface '98 249-253. Jobard, B and W. Lefer,1977: Creating evenly spaced streamlines of arbitrary density. Proceedings: Eurographics workshop on Visualization in Scientific Computing. 43-55. Mitchell, P.W., 2007: The Perceptual optimization of 2D Flow Visualizations Using Human in the Loop Local Hill Climbing. University of New Hampshire Masters Thesis. Department of Computer Science. NWS, 2013: About Global RTOFS, NCEP/EMC/MMAB, College Park, MD (Available at http://polar.ncep.noaa.gov/global/about/). Chassignet, E.P., H.E. Hurlburt, E.J. Metzger, O.M. Smedstad, J. Cummings, G.R. Halliwell, R. Bleck, R. Baraille, A.J. Wallcraft, C. Lozano, H.L. Tolman, A. Srinivasan, S. Hankin, P. Cornillon, R. Weisberg, A. Barth, R. He, F. Werner, and J. Wilkin, 2009: U.S. GODAE: Global Ocean Prediction with the HYbrid Coordinate Ocean Model (HYCOM). Oceanography, 22(2), 64-75. Mehra, A, I. Rivin, H. Tolman, T. Spindler, and B. Balasubramaniyan, 2011: A Real-Time Operational Global Ocean Forecast System, Poster, GODAE OceanView –GSOP-CLIVAR Workshop in Observing System Evaluation and Intercomparisons, Santa Cruz, CA.

Last Revised: February 2016 Map InformationThis nowCOAST™ time-enabled map service provides maps depicting the latest surface weather and marine weather observations at observing sites using the international station model. The station model is a method for representing information collected at an observing station using symbols and numbers. The station model depicts current weather conditions, cloud cover, wind speed, wind direction, visibility, air temperature, dew point temperature, sea surface water temperature, significant wave height, air pressure adjusted to mean sea level, and the change in air pressure over the last 3 hours. The circle in the model is centered over the latitude and longitude coordinates of the station. The total cloud cover is expressed as a fraction of cloud covering the sky and is indicated by the amount of circle filled in; however, all cloud cover values are presently displayed using the "Missing" symbol due to a problem with the source data. Present weather information is also not available for display at this time. Wind speed and direction are represented by a wind barb whose line extends from the cover cloud circle towards the direction from which the wind is blowing. The short lines or flags coming off the end of the long line are called barbs, which indicate wind speed in knots. Each normal barb represents 10 knots, while short barbs indicate 5 knots. A flag represents 50 knots. If there is no wind barb depicted, an outer circle around the cloud cover symbol indicates calm winds.Due to software limitations, the observations included in this map service are organized into three separate group layers: 1) Wind velocity (wind barb) observations, 2) Cloud Cover observations, and 3) All other observations, which are displayed as numerical values (e.g. Air Temperature, Wind Gust, Visibility, Sea Surface Temperature, etc.).Additionally, due to the density of weather/ocean observations in this map service, each of these group data layers has been split into ten individual "Scale Band" layers, with each one visible for a certain range of map scales. Thus, to ensure observations are displayed at any scale, users should make sure to always specify all ten corresponding scale band layers in every map request. This will result in the scale band most appropriate for your present zoom level being shown, resulting in a clean, uncluttered display. As you zoom in, additional observations will appear.The observations in this nowCOAST™ map service are updated approximately every 10 minutes. However, since the reporting frequency varies by network or station, the observations for a particular station may update only once per hour. For more detailed information about layer update frequency and timing, please reference the nowCOAST™ Dataset Update Schedule.Background InformationThe maps of near-real-time surface weather and ocean observations are based on non-restricted data obtained from the NWS Family of Services courtesy of NESDIS/OPSD and also the NWS Meteorological Assimilation Data Ingest System (MADIS). The data includes observations from terrestrial and maritime observing stations from the U.S.A. and other countries. For terrestrial networks, the platforms include but are not limited to ASOS, AWOS, RAWS, non-automated stations, U.S. Climate Reference Networks, many U.S. Geological Survey Stations via NWS HADS, several state DOT Road Weather Information Systems, and U.S. Historical Climatology Network-Modernization. For maritime areas, the platforms include NOS/CO-OPS National Water Level Observation Network (NWLON), NOS/CO-OPS Physical Oceanographic Real-Time System (PORTS), NWS/NDBC Fixed Buoys, NDBC Coastal-Marine Automated Network (C-MAN), drifting buoys, ferries, Regional Ocean Observing System (ROOS) coastal stations and buoys, and ships participating in the Voluntary Ship Observing (VOS) Program. Observations from MADIS are updated approximately every 10 minutes in the map service and those from NESDIS are updated every hour. However, not all stations report that frequently. Many stations only report once per hour sometime between 15 minutes before the hour and 30 minutes past the hour. For these stations, new observations will not appear until approximately 23 minutes past top of the hour for land-based stations and 33 minutes past the top of the hour for maritime stations.Time InformationThis map service is time-enabled, meaning that each individual layer contains time-varying data and can be utilized by clients capable of making map requests that include a time component.In addition to ArcGIS Server REST access, time-enabled OGC WMS 1.3.0 access is also provided by this service.This particular service can be queried with or without the use of a time component. If the time parameter is specified in a request, the data or imagery most relevant to the provided time value, if any, will be returned. If the time parameter is not specified in a request, the latest data or imagery valid for the present system time will be returned to the client. If the time parameter is not specified and no data or imagery is available for the present time, no data will be returned.This service is configured with time coverage support, meaning that the service will always return the most relevant available data, if any, to the specified time value. For example, if the service contains data valid today at 12:00 and 12:10 UTC, but a map request specifies a time value of today at 12:07 UTC, the data valid at 12:10 UTC will be returned to the user. This behavior allows more flexibility for users, especially when displaying multiple time-enabled layers together despite slight differences in temporal resolution or update frequency.When interacting with this time-enabled service, only a single instantaneous time value should be specified in each request. If instead a time range is specified in a request (i.e. separate start time and end time values are given), the data returned may be different than what was intended.Care must be taken to ensure the time value specified in each request falls within the current time coverage of the service. Because this service is frequently updated as new data becomes available, the user must periodically determine the service's time extent. However, due to software limitations, the time extent of the service and map layers as advertised by ArcGIS Server does not always provide the most up-to-date start and end times of available data. Instead, users have three options for determining the latest time extent of the service:Issue a returnUpdates=true request (ArcGIS REST protocol only) for an individual layer or for the service itself, which will return the current start and end times of available data, in epoch time format (milliseconds since 00:00 January 1, 1970). To see an example, click on the "Return Updates" link at the bottom of the REST Service page under "Supported Operations". Refer to the ArcGIS REST API Map Service Documentation for more information.Issue an Identify (ArcGIS REST) or GetFeatureInfo (WMS) request against the proper layer corresponding with the target dataset. For raster data, this would be the "Image Footprints with Time Attributes" layer in the same group as the target "Image" layer being displayed. For vector (point, line, or polygon) data, the target layer can be queried directly. In either case, the attributes returned for the matching raster(s) or vector feature(s) will include the following:validtime: Valid timestamp.starttime: Display start time.endtime: Display end time.reftime: Reference time (sometimes referred to as issuance time, cycle time, or initialization time).projmins: Number of minutes from reference time to valid time.desigreftime: Designated reference time; used as a common reference time for all items when individual reference times do not match.desigprojmins: Number of minutes from designated reference time to valid time.Query the nowCOAST™ LayerInfo web service, which has been created to provide additional information about each data layer in a service, including a list of all available "time stops" (i.e. "valid times"), individual timestamps, or the valid time of a layer's latest available data (i.e. "Product Time"). For more information about the LayerInfo web service, including examples of various types of requests, refer to the nowCOAST™ LayerInfo Help DocumentationReferencesNWS, 2013: Sample Station Plot, NWS/NCEP/WPC, College Park, MD (Available at http://www.wpc.ncep.noaa.gov/html/stationplot.shtml).NWS, 2013: Terminology and Weather Symbols, NWS/NCEP/OPC, College Park, MD (Available at http://www.opc.ncep.noaa.gov/product_description/keyterm.shtml).NWS, 2013: How to read Surface weather maps, JetStream an Online School for Weather (Available at http://www.srh.noaa.gov/jetstream/synoptic/wxmaps.htm).

Map Information

This nowCOAST time-enabled map service provides maps depicting NWS gridded forecasts of the following selected sensible surface weather variables or elements: air temperature (including daily maximum and minimum), apparent air temperature, dew point temperature, relative humidity, wind velocity, wind speed, wind gust, total sky cover, and significant wave height for the next 6-7 days. Additional forecast maps are available for 6-hr quantitative precipitation (QPF), 6-hr quantitative snowfall, and 12-hr probability of precipitation. These NWS forecasts are from the National Digital Forecast Database (NDFD) at a 2.5 km horizontal spatial resolution. Surface is defined as 10 m (33 feet) above ground level (AGL) for wind variables and 2 m (5.5 ft) AGL for air temperature, dew point temperature, and relative humidity variables. The forecasts extend out to 7 days from 0000 UTC on Day 1 (current day). The forecasts are updated in the nowCOAST map service four times per day. For more detailed information about the update schedule, please see: https://new.nowcoast.noaa.gov/help/#section=updateschedule The forecast projection availability times listed below are generally accurate, however forecast interval and forecast horizon vary by region and variable. For the most up-to-date information, please see https://graphical.weather.gov/docs/datamanagement.php.

The forecasts of the air, apparent, and dew point temperatures are displayed using different colors at 2 degree Fahrenheit increments from -30 to 130 degrees F in order to use the same color legend throughout the year for the United States. This is the same color scale used for displaying the NDFD maximum and minimum air temperature forecasts.
Air and dew point temperature forecasts are available every hour out to +36 hours from forecast issuance time, at 3-hour intervals from +36 to +72 hours, and at 6-hour intervals from +72 to +168 hours (7 days). Maximum and minimum air temperature forecasts are each available every 24 hours out to +168 hours (7 days) from 0000 UTC on Day 1 (current day).

The relative humidity (RH) forecasts are depicted using different colors for every 5-percent interval. The increment and color scale used to display the RH forecasts were developed to highlight NWS local fire weather watch/red flag warning RH criteria at the low end (e.g. 15, 25, & 35% thresholds) and important high end RH thresholds for other users (e.g. agricultural producers) such as 95%. The RH forecasts are available every hour out to +36 hours from 0000 UTC on Day 1 (current day), at 3-hour intervals from +36 to +72 hours, and at 6-hour intervals from +72 to +168 hours (7 days).

The 6-hr total precipitation amount forecasts or QPFs are symbolized using different colors at 0.01, 0.10, 0.25 inch intervals, at 1/4 inch intervals up to 4.0 (e.g. 0.50, 0.75, 1.00, 1.25, etc.), at 1-inch intervals from 4 to 10 inches and then at 2-inch intervals up to 14 inches. The increments from 0.01 to 1.00 or 2.00 inches are similar to what are used on NCEP/Weather Prediction Center's QPF products and the NWS River Forecast Center (RFC) daily precipitation analysis. Precipitation forecasts are available for each 6-hour period out to +72 hours (3 days) from 0000 UTC on Day 1 (current day).

The 6-hr total snowfall amount forecasts are depicted using different colors at 1-inch intervals for snowfall greater than 0.01 inches. Snowfall forecasts are available for each 6-hour period out to +48 hours (2 days) from 0000 UTC on Day 1 (current day).

The 12-hr probability of precipitation (PoP) forecasts are displayed for probabilities over 10 percent using different colors at 10, 20, 30, 60, and 85+ percent. The probability of precipitation forecasts are available for each 12-hour period out to +72 hours (3 days) from 0000 UTC on Day 1 (current day).

The wind speed and wind gust forecasts are depicted using different colors at 5 knots increment up to 115 knots. The legend includes tick marks for both knots and miles per hour. The same color scale is used for displaying the RTMA surface wind speed forecasts. The wind velocity is depicted by curved wind barbs along streamlines. The direction of the wind is indicated with an arrowhead on the wind barb. The flags on the wind barb are the standard meteorological convention in units of knots. The wind speed and wind velocity forecasts are available hourly out to +36 hours from 00:00 UTC on Day 1 (current day), at 3-hour intervals out to +72 hours, and at 6-hour intervals from +72 to +168 hours (7 days). The wind gust forecasts are available hourly out to +36 hours from 0000 UTC on Day 1 (current day) and at 3-hour intervals out to +72 hours (3 days).

The total sky cover forecasts are displayed using progressively darker shades of gray for 10, 30, 60, and 80+ percentage values. Sky cover values under 10 percent are shown as transparent. The sky cover forecasts are available for each hour out to +36 hours from 0000 UTC on Day 1 (current day), every 3 hours from +36 to +72 hours, and every 6 hours from +72 to +168 hours (7 days).

The significant wave height forecasts are symbolized with different colors at 1-foot intervals up to 20 feet and at 5-foot intervals from 20 feet to 35+ feet. The significant wave height forecasts are available for each hour out to +36 hours from 0000 UTC on Day 1 (current day), every 3 hours from +36 to +72 hours, and every 6 hours from +72 to +144 hours (6 days).

Background Information The NDFD is a seamless composite or mosaic of gridded forecasts from individual NWS Weather Forecast Offices (WFOs) from around the U.S. as well as the NCEP/Ocean Prediction Center and National Hurricane Center/TAFB. NDFD has a spatial resolution of 2.5 km. The 2.5km resolution NDFD forecasts are presently experimental, but are scheduled to become operational in May/June 2014. The time resolution of forecast projections varies by variable (element) based on user needs, forecast skill, and forecaster workload. Each WFO prepares gridded NDFD forecasts for their specific geographic area of responsibility. When these locally generated forecasts are merged into a national mosaic, occasionally areas of discontinuity will be evident. Staff at NWS forecast offices attempt to resolve discontinuities along the boundaries of the forecasts by coordinating with forecasters at surrounding WFOs and using workstation forecast tools that identify and resolve some of these differences. The NWS is making progress in this area, and recognizes that this is a significant issue in which improvements are still needed. The NDFD was developed by NWS Meteorological Development Laboratory.

As mentioned above, a curved wind barb with an arrow head is used to display the wind velocity forecasts instead of the traditional wind barb. The curved wind barb was developed and evaluated at the Data Visualization Laboratory of the NOAA-UNH Joint Hydrographic Center/Center for Coastal and Ocean Mapping (Ware et al., 2014). The curved wind barb combines the best features of the wind barb, that it displays speed in a readable form, with the best features of the streamlines which shows wind patterns. The arrow head helps to convey the flow direction.

Time Information

This map is time-enabled, meaning that each individual layer contains time-varying data and can be utilized by clients capable of making map requests that include a time component.

This particular service can be queried with or without the use of a time component. If the time parameter is specified in a request, the data or imagery most relevant to the provided time value, if any, will be returned. If the time parameter is not specified in a request, the latest data or imagery valid for the present system time will be returned to the client. If the time parameter is not specified and no data or imagery is available for the present time, no data will be returned.

In addition to ArcGIS Server REST access, time-enabled OGC WMS 1.3.0 access is also provided by this service.

Due to software limitations, the time extent of the service and map layers displayed below does not provide the most up-to-date start and end times of available data. Instead, users have three options for determining the latest time information about the service:

Issue a returnUpdates=true request for an individual layer or for
the service itself, which will return the current start and end times of
available data, in epoch time format (milliseconds since 00:00 January 1,
1970). To see an example, click on the "Return Updates" link at the bottom of
this page under "Supported Operations". Refer to the ArcGIS REST API Map Service Documentation for more information.


  Issue an Identify (ArcGIS REST) or GetFeatureInfo (WMS) request against
  the proper layer corresponding with the target dataset. For raster
  data, this would be the "Image Footprints with Time Attributes" layer
  in the same group as the target "Image" layer being displayed. For
  vector (point, line, or polygon) data, the target layer can be queried
  directly. In either case, the attributes returned for the matching
  raster(s) or vector feature(s) will include the following:


      validtime: Valid timestamp.


      starttime: Display start time.


      endtime: Display end time.


      reftime: Reference time (sometimes reffered to as
      issuance time, cycle time, or initialization time).


      projmins: Number of minutes from reference time to valid
      time.


      desigreftime: Designated reference time; used as a
      common reference time for all items when individual reference
      times do not match.


      desigprojmins: Number of minutes from designated
      reference time to valid time.




  Query the nowCOAST LayerInfo web service, which has been created to
  provide additional information about

Last Revised: February 2016

Map Information

This nowCOAST™ time-enabled map service provides a map depicting the latest daily sea surface temperature analyses from both the NOAA/NWS/NCEP operational Real-Time Global SST Analysis System, commonly referred to as RTG_SST, and the NASA/SPoRT experimental Sea Surface Temperature Composite.

The RTG_SST has a 1/12 degree (~9 km) grid resolution and covers the globe including the Great Lakes. SSTs are indicated by different colors at 2 degrees F intervals. NCEP generates the analysis once per day and it is updated on the nowCOAST™ map service around 0400 UTC (11 PM EST).

The experimental SPoRT SST analysis has a 2 km grid resolution and covers the North Atlantic Ocean and the Eastern North Pacific Ocean, the Great Lakes, and occasionally other large lakes. SSTs are displayed by the same color scale used for the RTG_SST analysis. NASA generates the analysis twice per day and it is updated on the nowCOAST™ map service around 0330 UTC (2230 EST) and 1530 UTC (1030 EST). For more detailed information about layer update frequency and timing, please reference the nowCOAST™ Dataset Update Schedule.

Background Information

The NWS/NCEP daily SST (1/12 deg) analysis is generated by the NCEP RTG_SST Analysis System using a two-dimensional variational interpolation scheme. The interpolation scheme uses the most recent 24-hours buoy and ship data and U.S. Navy SEATEMP (SST) retrievals derived from AVHRR data from the NOAA polar orbiting satellites. The first guess for the interpolation scheme is provided by the un-smoothed analysis from the previous day with a one-day climate adjustment. The analysis system was developed by the NWS/NCEP/Environmental Modeling Center/Marine Modeling and Analysis Branch.

The NASA/SPoRT experimental SST Composite is a blend of the MODIS and NESDIS SST products except over the Great Lakes, where it is a blend of the MODIS and the United Kingdom Met Office (UKMO) Operational Sea Surface Temperature and Sea Ice Analysis (OSTIAS2). The NESDIS and OSTIAS2 products have spatial resolutions of 9 and 6 km, respectively. The compositing algorithm uses a seven-day collection of MODIS level-2B data and the most recent NESDIS GOES/POES SST Composite and OSTIAS2 daily products. Two types of weighting are used in the compositing process. One weight is for the data latency and the other for the product type. The MODIS data with a 1-km resolution is given the most weight. All available confidence flags and bias information are incorporated in the compositing process. The SST Composite is computed twice-daily (nighttime and daytime). The MODIS and OSTIA products are obtained in near-real-time from the GHRSST archive at NASA/JPL. The compositing system was developed by NASA Short-Term Prediction Research and Transition Center (SPoRT) Team.

Time Information

This map service is time-enabled, meaning that each individual layer contains time-varying data and can be utilized by clients capable of making map requests that include a time component.

In addition to ArcGIS Server REST access, time-enabled OGC WMS 1.3.0 access is also provided by this service.

This particular service can be queried with or without the use of a time component. If the time parameter is specified in a request, the data or imagery most relevant to the provided time value, if any, will be returned. If the time parameter is not specified in a request, the latest data or imagery valid for the present system time will be returned to the client. If the time parameter is not specified and no data or imagery is available for the present time, no data will be returned.

This service is configured with time coverage support, meaning that the service will always return the most relevant available data, if any, to the specified time value. For example, if the service contains data valid today at 12:00 and 12:10 UTC, but a map request specifies a time value of today at 12:07 UTC, the data valid at 12:10 UTC will be returned to the user. This behavior allows more flexibility for users, especially when displaying multiple time-enabled layers together despite slight differences in temporal resolution or update frequency.

When interacting with this time-enabled service, only a single instantaneous time value should be specified in each request. If instead a time range is specified in a request (i.e. separate start time and end time values are given), the data returned may be different than what was intended.

Care must be taken to ensure the time value specified in each request falls within the current time coverage of the service. Because this service is frequently updated as new data becomes available, the user must periodically determine the service's time extent. However, due to software limitations, the time extent of the service and map layers as advertised by ArcGIS Server does not always provide the most up-to-date start and end times of available data. Instead, users have three options for determining the latest time extent of the service:

  Issue a returnUpdates=true request (ArcGIS REST protocol only)
  for an individual layer or for the service itself, which will return
  the current start and end times of available data, in epoch time format
  (milliseconds since 00:00 January 1, 1970). To see an example, click on
  the "Return Updates" link at the bottom of the REST Service page under
  "Supported Operations". Refer to the
  ArcGIS REST API Map Service Documentation
  for more information.


  Issue an Identify (ArcGIS REST) or GetFeatureInfo (WMS) request against
  the proper layer corresponding with the target dataset. For raster
  data, this would be the "Image Footprints with Time Attributes" layer
  in the same group as the target "Image" layer being displayed. For
  vector (point, line, or polygon) data, the target layer can be queried
  directly. In either case, the attributes returned for the matching
  raster(s) or vector feature(s) will include the following:


      validtime: Valid timestamp.


      starttime: Display start time.


      endtime: Display end time.


      reftime: Reference time (sometimes referred to as
      issuance time, cycle time, or initialization time).


      projmins: Number of minutes from reference time to valid
      time.


      desigreftime: Designated reference time; used as a
      common reference time for all items when individual reference
      times do not match.


      desigprojmins: Number of minutes from designated
      reference time to valid time.




  Query the nowCOAST™ LayerInfo web service, which has been created to
  provide additional information about each data layer in a service,
  including a list of all available "time stops" (i.e. "valid times"),
  individual timestamps, or the valid time of a layer's latest available
  data (i.e. "Product Time"). For more information about the LayerInfo
  web service, including examples of various types of requests, refer to
  the 
  nowCOAST™ LayerInfo Help Documentation

References

  Jedlovec, G.J., F. LaFontaine, J. Shafer, J. Vazquez, E. Armstrong, and M. Chin, 2009:
  An Enhanced MODIS / AMSR-E SST Composite Product, GHRSST User Symposium, Santa Rosa, CA.


  NASA, 2014: Sea Surface Temperature (SST) Product Details (Available at http://weather.msfc.nasa.gov/sport/sst/descriptions.html)


  NWS, 2001: The Real-Time Global Sea Surface Temperature Analysis: RTG_SST, NWS Technical Procedures Bulletin Series No. 477, NWS, Silver Spring, MD
  (Available at http://www.nws.noaa.gov/om/tpb/477.pdf)

Last Updated: January 2015

Map Information

This nowCOAST time-enabled map service provides map depicting the latest surface weather and marine weather observations at observing sites using the international station model. The station model is method for representing information collected at an observing station using symbols and numbers. The station model depicts current weather conditions, cloud cover, wind speed, wind direction, visibility, air temperature, dew point temperature, sea surface water temperature, significant wave height, air pressure adjusted to mean sea level, and the change in air pressure over the last 3 hours. The circle in the model is centered over the latitude and longitude coordinates of the station. The total cloud cover is expressed as a fraction of cloud covering the sky and is indicated by the amount of circle filled in. (Cloud cover is not presently displayed due to a problem with the source data. Present weather information is also not available for display at this time.) Wind speed and direction are represented by a wind barb whose line extends from the cover cloud circle towards the direction from which the wind is blowing. The short lines or flags coming off the end of the long line are called barbs. The barb indicates the wind speed in knots. Each normal barb represents 10 knots, while short barbs indicate 5 knots. A flag represents 50 knots. If there is no wind barb depicted, an outer circle around the cloud cover symbol indicates calm winds. The map of observations are updated in the nowCOAST map service approximately every 10 minutes. However, since the reporting frequency varies by network or station, the observation at a particular station may have not updated and may not update until after the next hour. For more detailed information about the update schedule, please see: http://new.nowcoast.noaa.gov/help/#section=updateschedule

Background Information The maps of near-real-time surface weather and ocean observations are based on non-restricted data obtained from the NWS Family of Services courtesy of NESDIS/OPSD and also the NWS Meteorological Assimilation Data Ingest System (MADIS). The data includes observations from terrestrial and maritime observing from the U.S.A. and other countries. For terrestrial networks, the platforms including but not limited to ASOS, AWOS, RAWS, non-automated stations, U.S. Climate Reference Networks, many U.S. Geological Survey Stations via NWS HADS, several state DOT Road Weather Information Systems, and U.S. Historical Climatology Network-Modernization. For over maritime areas, the platforms include NOS/CO-OPS National Water Level Observation Network (NWLON), NOS/CO-OPS Physical Oceanographic Observing Network (PORTS), NWS/NDBC Fixed Buoys, NDBC Coastal-Marine Automated Network (C-MAN), drifting buoys, ferries, Regional Ocean Observing System (ROOS) coastal stations and buoys, and ships participating in the Voluntary Ship Observing (VOS) Program. Observations from MADIS are updated approximately every 10 minutes in the map service and those from NESDIS are updated every hour. However, not all stations report that frequently. Many stations only report once per hour sometime between 15 minutes before the hour and 30 minutes past the hour. For these stations, new observations will not appear until 22 minutes past top of the hour for land-based stations and 32 minutes past the top of the hour for maritime stations.

Time Information

This map is time-enabled, meaning that each individual layer contains time-varying data and can be utilized by clients capable of making map requests that include a time component.

This particular service can be queried with or without the use of a time component. If the time parameter is specified in a request, the data or imagery most relevant to the provided time value, if any, will be returned. If the time parameter is not specified in a request, the latest data or imagery valid for the present system time will be returned to the client. If the time parameter is not specified and no data or imagery is available for the present time, no data will be returned.

In addition to ArcGIS Server REST access, time-enabled OGC WMS 1.3.0 access is also provided by this service.

Due to software limitations, the time extent of the service and map layers displayed below does not provide the most up-to-date start and end times of available data. Instead, users have three options for determining the latest time information about the service:

Issue a returnUpdates=true request for an individual layer or for
the service itself, which will return the current start and end times of
available data, in epoch time format (milliseconds since 00:00 January 1,
1970). To see an example, click on the "Return Updates" link at the bottom of
this page under "Supported Operations". Refer to the
ArcGIS REST API Map Service Documentation
for more information.


  Issue an Identify (ArcGIS REST) or GetFeatureInfo (WMS) request against
  the proper layer corresponding with the target dataset. For raster
  data, this would be the "Image Footprints with Time Attributes" layer
  in the same group as the target "Image" layer being displayed. For
  vector (point, line, or polygon) data, the target layer can be queried
  directly. In either case, the attributes returned for the matching
  raster(s) or vector feature(s) will include the following:


      validtime: Valid timestamp.


      starttime: Display start time.


      endtime: Display end time.


      reftime: Reference time (sometimes reffered to as
      issuance time, cycle time, or initialization time).


      projmins: Number of minutes from reference time to valid
      time.


      desigreftime: Designated reference time; used as a
      common reference time for all items when individual reference
      times do not match.


      desigprojmins: Number of minutes from designated
      reference time to valid time.




  Query the nowCOAST LayerInfo web service, which has been created to
  provide additional information about each data layer in a service,
  including a list of all available "time stops" (i.e. "valid times"),
  individual timestamps, or the valid time of a layer's latest available
  data (i.e. "Product Time"). For more information about the LayerInfo
  web service, including examples of various types of requests, refer to
  the nowCOAST help documentation at:
  http://new.nowcoast.noaa.gov/help/#section=layerinfo

References

NWS, 2013: Sample Station Plot, NWS/NCEP/WPC, College Park, MD (Available at http://www.hpc.ncep.noaa.gov/html/stationplot.shtml). NWS, 2013: Terminology and Weather Symbols, NWS/NCEP/OPC, College Park, MD (Available at http://www.opc.ncep.noaa.gov/product_description/keyterm.shtml). NWS, 2013: How to read Surface weather maps, JetStream an Online School for Weather (Available at http://www.srh.noaa.gov/jetstream/synoptic/wxmaps.htm).

The Japanese 25-year Reanalysis (JRA-25) represents the first long-term global atmospheric reanalysis undertaken in Asia. Covering the period 1979-2004, it was completed using the Japan Meteorological Agency (JMA) numerical assimilation and forecast system and specially collected and prepared observational and satellite data from many sources including the European Center for Medium-Range Weather Forecasts (ECMWF), the National Climatic Data Center (NCDC), and the Meteorological Research Institute (MRI) of JMA. A primary goal of JRA-25 is to provide a consistent and high-quality reanalysis dataset for climate research, monitoring, and operational forecasts, especially by improving the coverage and quality of analysis in the Asian region. In JRA-25, three-dimensional variational (3D-Var) data assimilation and a global spectral model were employed to produce 6-hourly atmospheric analysis and forecast cycles. The global spectral model was based on a 320 by 160 (~1.125 degree) Gaussian grid with T106 truncation. Vertical discretization employed a hybrid sigma-pressure coordinate utilizing 40 levels where 0.4 hPa represents the model top level. A predictive mass-flux Arakawa-Schubert scheme was utilized for cumulus parameterization, and Simple Biosphere (SiB) parameterizations for land-surface processes. Assimilated variables include temperature, relative humidity, and surface pressure from conventional observations, and also winds retrieved from geostationary satellites, radiative brightness temperature from TIROS Operational Vertical Sounder (TOVS), and precipitable water from Special Sensor Microwave/Imager (SSM/I). Variables not directly assimilated include daily sea surface temperature (SST) and sea ice based on Centennial in-situ Observation-Based Estimates (COBE), and ozone profiles based on chemical transport models constrained by observations from Total Ozone Mapping Spectrometer (TOMS).

The JRA-25 shows marked improvement over previous reanalyses in several notable areas, especially predicted (both 6-hourly and long term) precipitation, with more realistic variability and fewer spurious trends due to contamination of satellite data by volcanic eruptions. JRA-25 is also the first reanalysis to assimilate wind profiles around tropical cyclones deduced from best-track data, resulting in improved tropical cyclone analysis in a global context. In addition, low-level (stratus) cloud decks along the western subtropical coasts of continents are also better simulated, improving radiation budgets in these regions. In 2006, JMA started real-time operation of the JMA Climate Data Assimilation System (JCDAS). JCDAS employs the same system as JRA-25 and the data assimilation cycle is extended to the present time. JRA-25 and JCDAS products will enable users to conduct climate diagnostics with a long-term, and current, homogeneous reanalysis dataset. The JMA has also engaged in ongoing cooperation with ECMWF (European Center for Medium-Range Weather Forecasts) on reanalysis, including the ECMWF CDAS (ECDAS), more commonly known as ERA-Interim.

Last Updated: January 2015

Map Information

This nowCOAST time-enabled map service provides map depicting the latest surface weather and marine weather observations at observing sites using the international station model. The station model is method for representing information collected at an observing station using symbols and numbers. The station model depicts current weather conditions, cloud cover, wind speed, wind direction, visibility, air temperature, dew point temperature, sea surface water temperature, significant wave height, air pressure adjusted to mean sea level, and the change in air pressure over the last 3 hours. The circle in the model is centered over the latitude and longitude coordinates of the station. The total cloud cover is expressed as a fraction of cloud covering the sky and is indicated by the amount of circle filled in. (Cloud cover is not presently displayed due to a problem with the source data. Present weather information is also not available for display at this time.) Wind speed and direction are represented by a wind barb whose line extends from the cover cloud circle towards the direction from which the wind is blowing. The short lines or flags coming off the end of the long line are called barbs. The barb indicates the wind speed in knots. Each normal barb represents 10 knots, while short barbs indicate 5 knots. A flag represents 50 knots. If there is no wind barb depicted, an outer circle around the cloud cover symbol indicates calm winds. The map of observations are updated in the nowCOAST map service approximately every 10 minutes. However, since the reporting frequency varies by network or station, the observation at a particular station may have not updated and may not update until after the next hour. For more detailed information about the update schedule, please see: http://new.nowcoast.noaa.gov/help/#section=updateschedule

Background Information The maps of near-real-time surface weather and ocean observations are based on non-restricted data obtained from the NWS Family of Services courtesy of NESDIS/OPSD and also the NWS Meteorological Assimilation Data Ingest System (MADIS). The data includes observations from terrestrial and maritime observing from the U.S.A. and other countries. For terrestrial networks, the platforms including but not limited to ASOS, AWOS, RAWS, non-automated stations, U.S. Climate Reference Networks, many U.S. Geological Survey Stations via NWS HADS, several state DOT Road Weather Information Systems, and U.S. Historical Climatology Network-Modernization. For over maritime areas, the platforms include NOS/CO-OPS National Water Level Observation Network (NWLON), NOS/CO-OPS Physical Oceanographic Observing Network (PORTS), NWS/NDBC Fixed Buoys, NDBC Coastal-Marine Automated Network (C-MAN), drifting buoys, ferries, Regional Ocean Observing System (ROOS) coastal stations and buoys, and ships participating in the Voluntary Ship Observing (VOS) Program. Observations from MADIS are updated approximately every 10 minutes in the map service and those from NESDIS are updated every hour. However, not all stations report that frequently. Many stations only report once per hour sometime between 15 minutes before the hour and 30 minutes past the hour. For these stations, new observations will not appear until 22 minutes past top of the hour for land-based stations and 32 minutes past the top of the hour for maritime stations.

Time Information

This map is time-enabled, meaning that each individual layer contains time-varying data and can be utilized by clients capable of making map requests that include a time component.

This particular service can be queried with or without the use of a time component. If the time parameter is specified in a request, the data or imagery most relevant to the provided time value, if any, will be returned. If the time parameter is not specified in a request, the latest data or imagery valid for the present system time will be returned to the client. If the time parameter is not specified and no data or imagery is available for the present time, no data will be returned.

In addition to ArcGIS Server REST access, time-enabled OGC WMS 1.3.0 access is also provided by this service.

Due to software limitations, the time extent of the service and map layers displayed below does not provide the most up-to-date start and end times of available data. Instead, users have three options for determining the latest time information about the service:

Issue a returnUpdates=true request for an individual layer or for
the service itself, which will return the current start and end times of
available data, in epoch time format (milliseconds since 00:00 January 1,
1970). To see an example, click on the "Return Updates" link at the bottom of
this page under "Supported Operations". Refer to the
ArcGIS REST API Map Service Documentation
for more information.


  Issue an Identify (ArcGIS REST) or GetFeatureInfo (WMS) request against
  the proper layer corresponding with the target dataset. For raster
  data, this would be the "Image Footprints with Time Attributes" layer
  in the same group as the target "Image" layer being displayed. For
  vector (point, line, or polygon) data, the target layer can be queried
  directly. In either case, the attributes returned for the matching
  raster(s) or vector feature(s) will include the following:


      validtime: Valid timestamp.


      starttime: Display start time.


      endtime: Display end time.


      reftime: Reference time (sometimes reffered to as
      issuance time, cycle time, or initialization time).


      projmins: Number of minutes from reference time to valid
      time.


      desigreftime: Designated reference time; used as a
      common reference time for all items when individual reference
      times do not match.


      desigprojmins: Number of minutes from designated
      reference time to valid time.




  Query the nowCOAST LayerInfo web service, which has been created to
  provide additional information about each data layer in a service,
  including a list of all available "time stops" (i.e. "valid times"),
  individual timestamps, or the valid time of a layer's latest available
  data (i.e. "Product Time"). For more information about the LayerInfo
  web service, including examples of various types of requests, refer to
  the nowCOAST help documentation at:
  http://new.nowcoast.noaa.gov/help/#section=layerinfo

References

NWS, 2013: Sample Station Plot, NWS/NCEP/WPC, College Park, MD (Available at http://www.hpc.ncep.noaa.gov/html/stationplot.shtml). NWS, 2013: Terminology and Weather Symbols, NWS/NCEP/OPC, College Park, MD (Available at http://www.opc.ncep.noaa.gov/product_description/keyterm.shtml). NWS, 2013: How to read Surface weather maps, JetStream an Online School for Weather (Available at http://www.srh.noaa.gov/jetstream/synoptic/wxmaps.htm).

NDFD temperature, max and min temperature, apparent temperature and relative humidity forecastsLink to graphical web page: https://digital.weather.govLink to data download (grib2): https://tgftp.nws.noaa.gov/SL.us008001/ST.opnl/DF.gr2/DC.ndfd/Link to metadataQuestions/Concerns about the service, please contact the DISS GIS teamTime Information:This map is time-enabled, meaning that each individual layer contains time-varying data and can be utilized by clients capable of making map requests that include a time component.This particular service can be queried with or without the use of a time component. If the time parameter is specified in a request, the data or imagery most relevant to the provided time value, if any, will be returned. If the time parameter is not specified in a request, the latest data or imagery valid for the present system time will be returned to the client. If the time parameter is not specified and no data or imagery is available for the present time, no data will be returned.In addition to ArcGIS Server REST access, time-enabled OGC WMS 1.3.0 access is also provided by this service.Due to software limitations, the time extent of the service and map layers displayed below does not provide the most up-to-date start and end times of available data. Instead, users have two options for determining the latest time information about the service:Issue a returnUpdates=truerequest for an individual layer or for the service itself, which will return the current start and end times of available data, in epoch time format (milliseconds since 00:00 January 1, 1970). To see an example, click on the "Return Updates" link at the bottom of this page under "Supported Operations". Refer to the ArcGIS REST API Map Service Documentation for more information.Issue an Identify (ArcGIS REST) or GetFeatureInfo (WMS) request against the proper layer corresponding with the target dataset. For raster data, this would be the "Image Footprints with Time Attributes" layer in the same group as the target "Image" layer being displayed. For vector (point, line, or polygon) data, the target layer can be queried directly. In either case, the attributes returned for the matching raster(s) or vector feature(s) will include the following relevant fields returned:idp_validtime - valid time of forecastidp_validendtime - end time of forecastidp_fcst_hour - start time of number of hours from current time forecast is validIn ArcGIS.com this option can be turned on by clicking the three dots under "NDFD Temp" heading and choosing "Enable Time Animation".

Sea Surface Temperature Imagery Overview:

The University of Rhode Island (URI) Oceanographic Remote Sensing Laboratory maintains an archive of processed, geographically rectified and atmospherically corrected (for 5 channel AVHRR sensors) images of sea surface temperature (SST) for selected areas of the eastern seaboard and offshore of the United States. The images are classified by region and are created from all available Level 1b AVHRR at URI. Since data from all of the NOAA Series AVHRR Platforms (TIROS-N, NOAA-6, NOAA-7, NOAA-8, NOAA-9, and NOAA-10) are compiled in these data sets a generic term, NOAAXX, is used to specify the source platform.

URI generates 512x512x1 byte images of 6 regions from Level 1b -data. The names of the geographic regions, the latitude and longitude range of the regions and the pixel resolution defined for their processing are:

Region Lat/Lon Resolution

Gulf of Maine 40-45N 64-72W 1.1km New York Bight 37-42N 69-76W 1.1km Cape Hatteras 34-39N 70-76W 1.1km Northeast Area 34-44N 63-76W 2.0km Sargasso Sea 30-38N 64-74W 1.7km Sub-Tropical Convergence 22-33N 61-73W 2.0km

All images are generated under a standardized processing procedure described below.

SST Image Processing

The image display and processing system used at URI is DSP, a system developed by the University of Miami Rosenstiel School of Marine and Atmospheric Sciences. The procedure described is followed for processing Level 1b data to a 512x512 rectified and corrected image format.

1/ Ingesting of Level 1b data from magnetic tape to magnetic hard disk. In the case of TIROS-N, NOAA-6, NOAA-8 and NOAA-10 channel 4 is ingested. For NOAA-7 and NOAA-9 both channels 4 and 5 are ingested.

2/ Precision renavigation and update of separate navigation database records. Operators correct spacecraft position errors resulting from inaccurate ephemeris information stored with the Level 1b data records by the platform software. Through changes in time and platform orientation parameters the operator corrects the spacecraft ephemeris using the known position of landmarks visible in the satellite passes. This procedure provides consistent navigational accuracy to within 1km of true. Corrected values for ephemeris and platform orientation are permanently stored, on-line, in the DSP processing system navigation database. This database is referenced by the processing system when it creates a corrected version of the Level 1b data at full resolution.

3/ Processing of data to produce corrected temperature or sensor radiances. For NOAA-7 and NOAA-9 accurate values of SST which have have been corrected for atmospheric attenuation can be obtained using two channel split window method with channels 4 and 5. (McClain et al 1983, McMillin and Crosby 1984). The form of the equation for SST is,

Tss = A0 + A1*T1 + A2*(T2 - T1)

where Tss is the desired SST value, T1 is the channel 5 brightness temperature and T2 is the channel 4 brightness temperature. A0, A1 and A2 are the regression coefficients for the equation. The following coefficients have been derived from comparison with in situ measurements obtained from drifting buoys (NOAA/NESDIS 1982, 1985)and were used to generate SSTs from the NOAA-7 and NOAA-9 digital data.

NOAA-7 A0 A1 A2 DAY -283.93 1.0351 -3.046 NIGHT -288.23 1.0527 -2.627

NOAA-9 A0 A1 A2 DAY -268.92 .9864 -2.670 NIGHT -268.41 .9855 -2.668

For TIROS-N, NOAA-6, NOAA-8 and NOAA-10 sensors radiances are computed directly from channel 4 of the the Level 1b data. While it is not possible to remove the atmospheric attenuation from single channel data, images generated using sensor radiance values contain detailed information on the thermal structure the surface waters and features.

The processing to SST values and sensor radiances produces an intermediate full resolution version of the data that is used to generate the final data product, the standardized remapped images.

4/ Geographically rectify and remap 512x512 standard images. The end data product is the rectified image. These images are generated from the corrected version of the Level 1b data at a specified resolution and location. A pseudo-mercator projection is used with the pixel scaling defined by LATSIZ = R, and LONSIZ = R/cos(LAT). R is the specified resolution. Navigation and processing information are stored along with the remapped image as an image header at the time of creation.

URI SST Archive

Over 1800 separate images for each of the six regions are presently stored on magnetic tape. The archive is constantly being updated with new as well as historical data.

URI SST Satellite Image Archive available on the World Wide Web (WWW)

The URI Graduate School of Oceanography has provided access to the AVHRR sea surface temperature satellite image archive through the World Wide Web. Each image covers the area from latitude 60.575N longitude 96.222W to latitude 9.399N longitude 33.768W and contains 1024 x 1024 pixels. The resolution is 5 km/pixel in equirectangular projection. The archive consists of over 20,000 images.

There are two ways to browse the images using a web browser or XBrowse.

To view the images using a forms-based WWW browser, just use the forms to get the desired image. XBrowse is an interactive tool for satellite image browse and retrieval and must be built onto the user's workstation.

Related Data Sets:

URI NOAA-6 Level 1b URI NOAA-7 Level 1b URI NOAA-8 Level 1b URI NOAA-9 Level 1b URI NOAA-10 Level 1b

Last Revised: February 2016

Map Information

This nowCOAST™ time-enabled map service provides maps depicting the latest global forecast guidance of water currents, water temperature, and salinity at forecast projections: 0, 12, 24, 36, 48, 60, 72, 84, and 96-hours from the NWS/NCEP Global Real-Time Ocean Forecast System (GRTOFS). The surface water currents velocity maps display the direction using white or black streaklets. The magnitude of the current is indicated by the length and width of the streaklet. The maps of the GRTOFS surface forecast guidance are updated on the nowCOAST™ map service once per day. For more detailed information about layer update frequency and timing, please reference the
nowCOAST™ Dataset Update Schedule.

Background Information

GRTOFS is based on the Hybrid Coordinates Ocean Model (HYCOM), an eddy resolving, hybrid coordinate numerical ocean prediction model. GRTOFS has global coverge and a horizontal resolution of 1/12 degree and 32 hybrid vertical layers. It has one forecast cycle per day (i.e. 0000 UTC) which generates forecast guidance out to 144 hours (6 days). However, nowCOAST™ only provides guidance out to 96 hours (4 days). The forecast cycle uses 3-hourly momentum and radiation fluxes along with precipitation predictions from the NCEP Global Forecast System (GFS). Each forecast cycle is preceded with a 48-hr long nowcast cycle. The nowcast cycle uses daily initial 3-D fields from the NAVOCEANO operational HYCOM-based forecast system which assimilates situ profiles of temperature and salinity from a variety of sources and remotely sensed SST, SSH and sea-ice concentrations. GRTOFS was developed by NCEP/EMC/Marine Modeling and Analysis Branch. GRTOFS is run once per day (0000 UTC forecast cycle) on the NOAA Weather and Climate Operational Supercomputer System (WCOSS) operated by NWS/NCEP Central Operations.

The maps are generated using a visualization technique developed by the Data Visualization Research Lab at The University of New Hampshire's Center for Coastal and Ocean Mapping (http://www.ccom.unh.edu/vislab/). The method combines two techniques. First, equally spaced streamlines are computed in the flow field using Jobard and Lefer's (1977) algorithm. Second, a series of "streaklets" are rendered head to tail along each streamline to show the direction of flow. Each of these varies along its length in size, color and transparency using a method developed by Fowler and Ware (1989), and later refined by Mr. Pete Mitchell and Dr. Colin Ware (Mitchell, 2007).

Time Information

This map service is time-enabled, meaning that each individual layer contains time-varying data and can be utilized by clients capable of making map requests that include a time component.

In addition to ArcGIS Server REST access, time-enabled OGC WMS 1.3.0 access is also provided by this service.

This particular service can be queried with or without the use of a time component. If the time parameter is specified in a request, the data or imagery most relevant to the provided time value, if any, will be returned. If the time parameter is not specified in a request, the latest data or imagery valid for the present system time will be returned to the client. If the time parameter is not specified and no data or imagery is available for the present time, no data will be returned.

This service is configured with time coverage support, meaning that the service will always return the most relevant available data, if any, to the specified time value. For example, if the service contains data valid today at 12:00 and 12:10 UTC, but a map request specifies a time value of today at 12:07 UTC, the data valid at 12:10 UTC will be returned to the user. This behavior allows more flexibility for users, especially when displaying multiple time-enabled layers together despite slight differences in temporal resolution or update frequency.

When interacting with this time-enabled service, only a single instantaneous time value should be specified in each request. If instead a time range is specified in a request (i.e. separate start time and end time values are given), the data returned may be different than what was intended.

Care must be taken to ensure the time value specified in each request falls within the current time coverage of the service. Because this service is frequently updated as new data becomes available, the user must periodically determine the service's time extent. However, due to software limitations, the time extent of the service and map layers as advertised by ArcGIS Server does not always provide the most up-to-date start and end times of available data. Instead, users have three options for determining the latest time extent of the service:

  Issue a returnUpdates=true request (ArcGIS REST protocol only)
  for an individual layer or for the service itself, which will return
  the current start and end times of available data, in epoch time format
  (milliseconds since 00:00 January 1, 1970). To see an example, click on
  the "Return Updates" link at the bottom of the REST Service page under
  "Supported Operations". Refer to the
  ArcGIS REST API Map Service Documentation
  for more information.


  Issue an Identify (ArcGIS REST) or GetFeatureInfo (WMS) request against
  the proper layer corresponding with the target dataset. For raster
  data, this would be the "Image Footprints with Time Attributes" layer
  in the same group as the target "Image" layer being displayed. For
  vector (point, line, or polygon) data, the target layer can be queried
  directly. In either case, the attributes returned for the matching
  raster(s) or vector feature(s) will include the following:


      validtime: Valid timestamp.


      starttime: Display start time.


      endtime: Display end time.


      reftime: Reference time (sometimes referred to as
      issuance time, cycle time, or initialization time).


      projmins: Number of minutes from reference time to valid
      time.


      desigreftime: Designated reference time; used as a
      common reference time for all items when individual reference
      times do not match.


      desigprojmins: Number of minutes from designated
      reference time to valid time.




  Query the nowCOAST™ LayerInfo web service, which has been created to
  provide additional information about each data layer in a service,
  including a list of all available "time stops" (i.e. "valid times"),
  individual timestamps, or the valid time of a layer's latest available
  data (i.e. "Product Time"). For more information about the LayerInfo
  web service, including examples of various types of requests, refer to
  the 
  nowCOAST™ LayerInfo Help Documentation

References

Fowler, D. and C. Ware, 1989: Strokes for Representing Vector Field Maps. Proceedings: Graphics Interface '98 249-253. Jobard, B and W. Lefer,1977: Creating evenly spaced streamlines of arbitrary density. Proceedings: Eurographics workshop on Visualization in Scientific Computing. 43-55. Mitchell, P.W., 2007: The Perceptual optimization of 2D Flow Visualizations Using Human in the Loop Local Hill Climbing. University of New Hampshire Masters Thesis. Department of Computer Science. NWS, 2013: About Global RTOFS, NCEP/EMC/MMAB, College Park, MD (Available at http://polar.ncep.noaa.gov/global/about/). Chassignet, E.P., H.E. Hurlburt, E.J. Metzger, O.M. Smedstad, J. Cummings, G.R. Halliwell, R. Bleck, R. Baraille, A.J. Wallcraft, C. Lozano, H.L. Tolman, A. Srinivasan, S. Hankin, P. Cornillon, R. Weisberg, A. Barth, R. He, F. Werner, and J. Wilkin, 2009: U.S. GODAE: Global Ocean Prediction with the HYbrid Coordinate Ocean Model (HYCOM). Oceanography, 22(2), 64-75. Mehra, A, I. Rivin, H. Tolman, T. Spindler, and B. Balasubramaniyan, 2011: A Real-Time Operational Global Ocean Forecast System, Poster, GODAE OceanView –GSOP-CLIVAR Workshop in Observing System Evaluation and Intercomparisons, Santa Cruz, CA.

Last Updated: January 2015

Map Information

This nowCOAST time-enabled map service provides map depicting the latest surface weather and marine weather observations at observing sites using the international station model. The station model is method for representing information collected at an observing station using symbols and numbers. The station model depicts current weather conditions, cloud cover, wind speed, wind direction, visibility, air temperature, dew point temperature, sea surface water temperature, significant wave height, air pressure adjusted to mean sea level, and the change in air pressure over the last 3 hours. The circle in the model is centered over the latitude and longitude coordinates of the station. The total cloud cover is expressed as a fraction of cloud covering the sky and is indicated by the amount of circle filled in. (Cloud cover is not presently displayed due to a problem with the source data. Present weather information is also not available for display at this time.) Wind speed and direction are represented by a wind barb whose line extends from the cover cloud circle towards the direction from which the wind is blowing. The short lines or flags coming off the end of the long line are called barbs. The barb indicates the wind speed in knots. Each normal barb represents 10 knots, while short barbs indicate 5 knots. A flag represents 50 knots. If there is no wind barb depicted, an outer circle around the cloud cover symbol indicates calm winds. The map of observations are updated in the nowCOAST map service approximately every 10 minutes. However, since the reporting frequency varies by network or station, the observation at a particular station may have not updated and may not update until after the next hour. For more detailed information about the update schedule, please see: http://new.nowcoast.noaa.gov/help/#section=updateschedule

Background Information The maps of near-real-time surface weather and ocean observations are based on non-restricted data obtained from the NWS Family of Services courtesy of NESDIS/OPSD and also the NWS Meteorological Assimilation Data Ingest System (MADIS). The data includes observations from terrestrial and maritime observing from the U.S.A. and other countries. For terrestrial networks, the platforms including but not limited to ASOS, AWOS, RAWS, non-automated stations, U.S. Climate Reference Networks, many U.S. Geological Survey Stations via NWS HADS, several state DOT Road Weather Information Systems, and U.S. Historical Climatology Network-Modernization. For over maritime areas, the platforms include NOS/CO-OPS National Water Level Observation Network (NWLON), NOS/CO-OPS Physical Oceanographic Observing Network (PORTS), NWS/NDBC Fixed Buoys, NDBC Coastal-Marine Automated Network (C-MAN), drifting buoys, ferries, Regional Ocean Observing System (ROOS) coastal stations and buoys, and ships participating in the Voluntary Ship Observing (VOS) Program. Observations from MADIS are updated approximately every 10 minutes in the map service and those from NESDIS are updated every hour. However, not all stations report that frequently. Many stations only report once per hour sometime between 15 minutes before the hour and 30 minutes past the hour. For these stations, new observations will not appear until 22 minutes past top of the hour for land-based stations and 32 minutes past the top of the hour for maritime stations.

Time Information

This map is time-enabled, meaning that each individual layer contains time-varying data and can be utilized by clients capable of making map requests that include a time component.

This particular service can be queried with or without the use of a time component. If the time parameter is specified in a request, the data or imagery most relevant to the provided time value, if any, will be returned. If the time parameter is not specified in a request, the latest data or imagery valid for the present system time will be returned to the client. If the time parameter is not specified and no data or imagery is available for the present time, no data will be returned.

In addition to ArcGIS Server REST access, time-enabled OGC WMS 1.3.0 access is also provided by this service.

Due to software limitations, the time extent of the service and map layers displayed below does not provide the most up-to-date start and end times of available data. Instead, users have three options for determining the latest time information about the service:

Issue a returnUpdates=true request for an individual layer or for
the service itself, which will return the current start and end times of
available data, in epoch time format (milliseconds since 00:00 January 1,
1970). To see an example, click on the "Return Updates" link at the bottom of
this page under "Supported Operations". Refer to the
ArcGIS REST API Map Service Documentation
for more information.


  Issue an Identify (ArcGIS REST) or GetFeatureInfo (WMS) request against
  the proper layer corresponding with the target dataset. For raster
  data, this would be the "Image Footprints with Time Attributes" layer
  in the same group as the target "Image" layer being displayed. For
  vector (point, line, or polygon) data, the target layer can be queried
  directly. In either case, the attributes returned for the matching
  raster(s) or vector feature(s) will include the following:


      validtime: Valid timestamp.


      starttime: Display start time.


      endtime: Display end time.


      reftime: Reference time (sometimes reffered to as
      issuance time, cycle time, or initialization time).


      projmins: Number of minutes from reference time to valid
      time.


      desigreftime: Designated reference time; used as a
      common reference time for all items when individual reference
      times do not match.


      desigprojmins: Number of minutes from designated
      reference time to valid time.




  Query the nowCOAST LayerInfo web service, which has been created to
  provide additional information about each data layer in a service,
  including a list of all available "time stops" (i.e. "valid times"),
  individual timestamps, or the valid time of a layer's latest available
  data (i.e. "Product Time"). For more information about the LayerInfo
  web service, including examples of various types of requests, refer to
  the nowCOAST help documentation at:
  http://new.nowcoast.noaa.gov/help/#section=layerinfo

References

NWS, 2013: Sample Station Plot, NWS/NCEP/WPC, College Park, MD (Available at http://www.hpc.ncep.noaa.gov/html/stationplot.shtml). NWS, 2013: Terminology and Weather Symbols, NWS/NCEP/OPC, College Park, MD (Available at http://www.opc.ncep.noaa.gov/product_description/keyterm.shtml). NWS, 2013: How to read Surface weather maps, JetStream an Online School for Weather (Available at http://www.srh.noaa.gov/jetstream/synoptic/wxmaps.htm).