Available Saildocs grib models (November 18, 2010)


The primary source for Saildocs grib-data is NOAA's "GFS" global model, requested by using the code "GFS:" (or "Grib:") in a grib-request. Data from other models is also available. Here are the details for the available models:

GFS: The most-often used model is NOAA/NCEP's global "GFS" model. Data is generally available on a 0.5 x 0.5-deg grid every 3 hours out to 192 hours, and then on a 2.5-deg grid out to 384 hours (16 days). The request-code is "gfs:" as used in the examples above. The code "grib:" can also be used, the difference is that for "grib:" the forecast-times are always adjusted to provide forecast-times relative to 00z. Available parameters are PRMSL,WIND,HGT500,AIRTEMP,SEATMP. Data is always available by HH+05:00 hours ("HH" being the synoptic-time).

COAMPS: This is a meso-scale (i.e. more detailed) regional model provided by the US Navy. Data is available for three regions: eastern Pacific, west Atlantic, and Carib/Central America. The syntax is the same as for a basic grib, except the request-code "coamps:" is used in place of "gfs:" or "grib:". Forecast data is available on a 0.2 x 0.2-deg grid at 6-hour intervals out to 48 hours (72 for west-Atlantic). For best results, use a grid of 0.2-deg or multiples of that to avoid interpolation. Available (and default) parameters are PRMSL,WIND.

The areas for the available coamps areas are:
East-Pacific: 29n,60n,160w,114w
West-Altantic: 20n,55n,093w,055w
Cent-Am and Carib: 00n,32n,120w,060w
The same "coamps:" code is used for all regions, and Saildocs chooses the correct region based on the requested lat-lon area. Requests which fall partially outside the selected region will be trimmed at the edge of the region, and a zero-length file will result if the request is completely outside any of the regions. It is not possible to span multiple regions because data from different files does not match at the region edges, apparently a boundary-condition issue with the model.

WW3: This is NOAA's WW3 wave model, data is available on a 1 x 1.25 grid (lat x lon), forecasts every 3 hours out to 180, updated every 6 hours usually by HH+06:00. All of the WW3 data is available, the default parameter is "HTSGW" (height of sig waves) or "WAVES", other WW3 parameters are defined here:
http://polar.ncep.noaa.gov/waves/products.html
Also, the "WAVES" parameter can be added to a GFS request and Saildocs will combine the files, adding the WW3 sig-wave data layer to the same grib file (on the 1x1.25 grid if coarser than the user-specified grid). One issue is that WW3 data sometimes shows up late with the 00z data arriving at the NOAA server at 06:30 or thereabouts so it may not always be available.

NOGAPS: "Nogaps" is a US Navy model and data is available on a 1-deg grid with forecasts every every 3 hours to 24, then 6 hours to 96, then 12 hours to 144, and updated every 12 hours by HH+07:00. Available parameters are PRMSL,WIND,HGT (the default is PRMSL,WIND). The server is sometimes late which results in missing valid-times, as Saildocs terminates the download task at HH+07:00. There is no particular advantage to Nogaps over GFS, it is simply being made available as a 'second opnion".

RTOFS: This is Atlantic ocean currents from NOAA's RTOFS system, based on the HYCOM model (see http://polar.ncep.noaa.gov/ofs/ for more details). There are two regions, the smaller-area gulf-stream dataset covers 25N-48N, 083W-052W. That file has higher resolution of 0.05 deg (approx) and goes out to 120 hours at 24-hour increments. The larger-area Atlantic file also goes out 120 hours but at a 12-hour increment, 0.25-deg grid, and covers roughly 20S to 70N, North America to Africa/Europe. Saildocs selects whichever file best covers your request. Available parameters are CUR (or CURRENT), WTMP (or WATER_TEMP), DSL_M (sea-level deviation), and SALTY (salinity). The default (if parameters are omitted) is current.

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Thanks for using Saildocs and Good Sailing!
--Jim