Earthdata Forum

I am trying to calculate potential evapotranspiration and I am needing to ensure the radiation budget is correct. I see that surface net downward longwave (LWGNET) flux is the difference between upwelling and downwelling longwave (LWGNET = LWGDWN - LWGUP).

The documentation is not as specific about surface shortwave net downward longwave flux (SWGNET). The documentation doesn't say anything about how SWGNET = SWGDWN - SWGUP. I think that I am getting too low of potential evapotranspiration values when I apply albedo to calculate net surface radiation, but I am usure.

Am I correct in assuming that albedo has already been applied to surface shortwave net downward longwave flux (SWGNET)?

Yes, the upward component of the shortwave flux accounts for the albedo. Surface net downward shortwave flux is defined in the same manner as longwave, so your equation for that is correct (SWGNET = SWGDWN - SWGUP). If you would like to know the albedo used in the flux calculation, you can divide the upward component by the downward. (Albedo = SWGUP/SWGDWN)

As a caution however, the shortwave and longwave flux models may or may not arise from the same flux algorithm, depending on source and year. There may not be a closed radiation budget.