| Accumulated precipitation (over 24 h) | 3 - high | Poor time sampling.. Time sampling to be interpolated by GEO. | MW channels around 19, 23, 37 and 90 GHz, and in 54 and 183 GHz bands |
| Atmospheric temperature | 2 - very high | Coarse vertical resolution. | Many MW channels in the 54 GHz band. Nearly all-weather sounding |
| Cloud drop effective radius | 5 - marginal | Highly indirect. | MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz |
| Cloud ice | 3 - high | No specific limitation. | MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz |
| Cloud ice Total Column | 3 - high | No specific limitation. | MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz |
| Cloud ice effective radius | 2 - very high | No specific limitation. | MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz |
| Cloud liquid water (CLW) | 2 - very high | No specific limitation. | MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz |
| Cloud liquid water (CLW) total column | 2 - very high | No specific limitation. | MW channels around 37 and 90 GHz, and in bands 54 and 183 GHz |
| Downward long-wave irradiance at Earth surface | 5 - marginal | Highly indirect. | MW channels in bands 54 and 183 GHz to account for downward cloud radiation |
| Freezing level height in clouds | 3 - high | No specific limitation. | MW channels in the 54 GHz band. Inference from the temperature profile |
| Long-wave Earth surface emissivity | 5 - marginal | Long time series needed. | MW channels around 19, 37 and 90 GHz. Emissivity across this MW range inferred by statistical analysis |
| Melting layer depth in clouds | 3 - high | No specific limitation. | MW channels in the 54 GHz band. Inference from the temperature profile |
| Precipitation intensity at surface (liquid or solid)* | 3 - high | No specific limitation. | MW channels around 19, 23, 37 and 90 GHz; and in bands 54 and 183 GHz, insensitive to surface emissivity and providing information on atmospheric structure |
| Snow cover | 3 - high | Coarse spatial resolution. | MW channels around 19, 37 and 90 GHz. Higher frequencies less sensitive to emissivity from ground under snow |
| Snow status (wet/dry) | 2 - very high | Coarse spatial resolution. | MW channels around 19, 37 and 90 GHz. Higher frequencies less sensitive to emissivity from ground under snow |
| Snow water equivalent | 2 - very high | Coarse spatial resolution.. Ground stations network needed. | MW channels around 19, 37 and 90 GHz. Higher frequencies less sensitive to emissivity from ground under snow |
| Specific humidity | 2 - very high | Coarse vertical resolution. | MW channels in the 183 GHz band, and 54 GHz for temperature and liquid water corrections |
| Integrated Water Vapour (IWV) | 1 - primary | No specific limitation. | MW channel(s) in the water vapour bands around 23 and 183 GHz |
| Upward long-wave irradiance at Earth surface | 5 - marginal | Highly indirect. | MW channels is the 54 and 183 GHz bands to infer the impact of clouds on the upward LW radiation |
| Wind speed (near surface)* | 4 - fair | Over sea only. | MW channels around 19 and 37 GHz |
| Sea-ice cover* | 3 - high | No specific limitation. | MW channels around 19, 37 and 90 GHz |
| Sea-ice type | 4 - fair | No specific limitation. | MW channels around 19, 37 and 90 GHz. Type interpreted as age/roughness |
Instrument: SSMIS