Navy Operational Global Atmospheric Prediction System (NOGAPS) forcing products. We provide access to three products: nogaps0.5a, nogaps0.5c, and nogaps1.0a. Where,
|0.5||=||0.5 degree output|
|1.0||=||1.0 degree output|
|c||=||computational grid (i.e. gaussian)|
|a||=||application grid (i.e. constant lat-lon)|
Note: The existing HYCOM interpolation code can transparently handle the gaussian grid.
Within these directories there are files like: nogaps0.5a-std, nogaps0.5a-sea, and nogaps0.5a-sec. The 'std' means standard and nothing has been done to them but put them in a format that the HYCOM interpolation code can read. The 'sea' means sea-only where we have used the atmospheric model land-sea mask and extrapolated ocean values onto land; this is done to avoid using an atmospheric model land flux over an ocean model water gridpoint. The 'sec' only applies to the stresses (strblk), wind components (uv-10m) and wind speed (wndspd). Here we took the 'sea' version of these fields and applied a QuikSCAT correction to them.
The files in nogaps0.5c come from the GODAE server and they start in 2003. They do not contain any forecasts. These are continually updated (about once per week). When we process forcing products, we'll put all variables into their own files, and additionally we'll merge certain variables because that is what the interpolation code expects. For a specific year, we have these fields like:
TaqaQrQp: a merged file of temp2m (air temp at 2m), spchum (specific humidity), radiative fluxes that is composed of solrad (net surface shortwave) minus longwv (net surface longwave) and penetrating radiation (solrad). This field is the input thermal forcing file for a HYCOM simulation. The fields in this file have a daily filter applied to them.
Taqa_day-QrQp: These are like the TaqaQrQp daily filtered files, but Ta and qa are NOT daily filtered whereas QrQp ARE daily filtered.
TaqaQlQg: These files are used by CICE when running coupled HYCOM/CICE. Taqa are the same as in the TaqaQrQp files, but Ql is net surface longwave radiation and Qg is downward surface shortwave radiation (glbrad).
dwpt2m: dewpoint temperature at 2 m (Kelvins)
lndsea: the atmospheric model's land/sea mask
longwv: net surface longwave (W/m^2)
mslprs: mean sea level pressure (hPa/100 - 1000)
soiltm: surface (land and ocean) temperature (Kelvins)
solrad: net surface shortwave (W/m^2)
spchum: specific humidity (kg/kg)
strblk: bulk-derived wind stress (N/m^2)
strpbl: planetary boundary layer wind stress (N/m^2)
temp2m: air temperature at 2 m (Kelvins)
uv-10m: zonal and meridional wind components (m/s)
wndspd: wind speed (m/s)
The lndsea files is actually dynamic for nogaps0.5c with: 0 = OCEAN, 1 = LAND, 2 = ICE, 3 = SNOW.
Often the wind stress curl field associated with the strpbl file is very noisy so traditionally we have always used the strblk stresses to force HYCOM. Nonetheless, we keep both sets of stresses.
For the set of files listed above, there are nogaps0.5c-sea versions. For the QuikSCAT corrected winds and stresses, these are the 'sec' files. Note there are secC and secD versions. For uv-10m and wndspd, the secC are the appropriate files to use but for strblk the secD file is appropriate. For simplicity, we simply call them sec (without the C or D).
The files in nogaps0.5a start in 2007. All filenaming conventions are the same as for nogaps0.5c. These files are updated daily and pushed to the Navy DSRC. The tail end of these files contain forecasts typically out to tau=120 hrs. When the forcing is processed the following day, the previous day's forecasts get throw away and are overwritten with the appropriate analysis fields and the forecasts out to tau=120 for that day.
The only field *at this resolution* that we typically force HYCOM with is the total precipitation (ttlpcp). The reason for doing this is because we don't have it at finer resolution until it started for 0.5a sometime in 2008. (We never got ttlpcp for nogaps0.5c.) We suggest you only use the ttlpcp files in the nogaps1.0a/3hourly directory. Grab the finer resolution 0.5a or 0.5c output for the other forcing fields. For precip, only the 'std' files are needed.
We stopped processing nogaps1.0a ttlpcp a while ago because we were getting it on the 0.5a grid, thus the 2009 file above is very small and may only contain a few time points.