Data Resources: Sign conventions NCEP Reanalyses Fluxes
Radiative FluxesWhere the direction of the radiative flux is included, the convention is that the flux is always positive because it is defined that way.
- Downward longwave: always positive
- Upward longwave: always positive
- Downward shortwave: positive or zero (never negative)
- Upward shortwave: positive or zero (never negative)