https://rapidrefresh.noaa.gov/hrrr/
In this dataset's GRIB format files, there are two variables representing an atomspheric pressure forecast: (output as opened with pygrib)
41:MSLP (MAPS System Reduction):Pa (instant):lambert:meanSea:level 0:fcst time 0 hrs:from 202111241700
62:Surface pressure:Pa (instant):lambert:surface:level 0:fcst time 0 hrs:from 202111241700
I'm trying to understand how can I convert the pressure values between the two using barometric formula so that I only need to store 1 copy of the pressure grid, preferably only the MSLP pressure because they are aligned to MSL=0.
According to the MAPS algorithm used for HRRR's sea level correction (page 2100), the sea level pressure is calculated from computing the temperature at sea level using the 700 hPa level temperature, but I tried regenerating the surface pressure values from sea level pressure and they don't match up so well (averaging > 2 hPa difference).
I'm wondering could someone help shed light on how the MSLP grid and the SP grid in HRRR are created and whether there exists a conversion formula between the two?
First question on this site. Thanks a lot in advance for your help!
