| Atmospheric temperature* | 1 - primary | Cloud sensitive. | MWIR and TIR spectrometry in the CO2 4.3 and 15 micrometer bands. Frequent sampling (GEO) enables monitoring instability onset |
| C2H2 | 3 - high | Cloud sensitive.. Coarse vertical resolution. | TIR spectrometry. C2H2 lines around 7.5 and 13.7 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| C2H6 | 3 - high | Cloud sensitive.. Coarse vertical resolution. | TIR spectrometry. C2H6 lines around 12 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| CFC-11 | 3 - high | Cloud sensitive.. Coarse vertical resolution. | TIR spectrometry. CFC-11 lines around 9.2 and 11.7 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| CFC-12 | 3 - high | Cloud sensitive.. Coarse vertical resolution. | TIR spectrometry. CFC-12 lines around 8.8 and 10.8 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| CH4 mole fraction | 2 - very high | Cloud sensitive.. Coarse vertical resolution. | MWIR and TIR spectrometry. CH4 lines around 4.3 and 7.7 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| ClONO2 | 2 - very high | Cloud sensitive.. Coarse vertical resolution. | MWIR and TIR spectrometry. ClONO2 lines around 5.7, 7.7 and 12.5 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| Cloud cover | 3 - high | Discontinuous coverage. | MWIR and TIR spectrometry |
| Cloud top height | 2 - very high | Discontinuous coverage. | MWIR and TIR spectrometry in window and water vapour band (for emissivity) to estimate cloud top height from its temperature |
| Cloud top temperature | 1 - primary | Discontinuous coverage. | TIR spectrometry in window and water vapour band (for emissivity) |
| Cloud type | 4 - fair | Discontinuous coverage. | MWIR and TIR spectrometry |
| CO | 3 - high | Cloud sensitive.. Coarse vertical resolution. | MWIR spectrometry. CO lines around 4.6. Frequent sampling (GEO) enables monitoring diurnal variations |
| CO2 mole fraction | 3 - high | Cloud sensitive.. Coarse vertical resolution. | TIR spectrometry. CO2 lines around 15 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| COS | 3 - high | Cloud sensitive.. Coarse vertical resolution. | TIR spectrometry. COS lines around 11.6 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| Downward long-wave irradiance at Earth surface | 1 - primary | Cloud sensitive.. Highly indirect. | MWIR and TIR spectrometry including water vapour and CO2 bands |
| H2O | 2 - very high | Cloud sensitive.. Coarse vertical resolution. | MWIR/TIR spectrometry in a range centred on 6.3 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| Height of the top of PBL | 4 - fair | Cloud sensitive. | MWIR and TIR spectrometry. Height of PBL top from temperature profile. Frequent sampling (GEO) enables monitoring the PBL evolution |
| Height of the tropopause | 4 - fair | Cloud sensitive. | TIR spectrometry. Height of tropopause from temperature profile. Frequent sampling (GEO) enables monitoring the tropopause evolution |
| HNO3 | 3 - high | Cloud sensitive.. Coarse vertical resolution. | MWIR and TIR spectrometry. HNO3 lines around 5.9, 7.6 and 11.3 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| Land surface temperature | 2 - very high | Cloud sensitive.. Coarse spatial resolution. | MWIR and TIR spectrometry (inclusive of several narrow-bandwidth windows and absorption bands for atmospheric corrections) |
| Long-wave Earth surface emissivity | 1 - primary | Cloud sensitive.. Long time series needed. | MWIR and TIR spectrometry measuring land temperature in many windows. Emissivity inferred by statistical analysis |
| N2O mole fraction | 2 - very high | Cloud sensitive.. Coarse vertical resolution. | MWIR and TIR spectrometry. N2O lines around 4.5 and 7.7 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| N2O5 | 3 - high | Cloud sensitive.. Coarse vertical resolution. | MWIR and TIR spectrometry. N2O5 lines around 5.8 and 8 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| NO | 3 - high | Cloud sensitive.. Coarse vertical resolution. | MWIR spectrometry. NO lines around 5.3 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| NO2 | 3 - high | Cloud sensitive.. Coarse vertical resolution. | TIR spectrometry. NO2 lines around 6.1 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| NO2 Total Column | 4 - fair | Cloud sensitive. | TIR spectrometry. NO2 lines around 6.1 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| O3 | 3 - high | Cloud sensitive.. Coarse vertical resolution. | TIR spectrometry. Ozone band around 9.7 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| O3 Total Column* | 3 - high | Cloud sensitive. | TIR channel(s). Ozone lines in band around 9.7 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| PAN | 3 - high | Cloud sensitive.. Coarse spatial resolution. | MWIR and TIR spectrometry. PAN lines around 5.7, 8.6 and 12.5 micrometers. Frequent sampling (GEO) enables monitoring diurnal variations |
| PSC occurrence | 2 - very high | Marginal view from GEO.. Coarse vertical resolution. | MWIR and TIR spectroscopy |
| Sea surface temperature | 1 - primary | Cloud sensitive. | MWIR and TIR spectrometry (inclusive of several narrow-bandwidth windows and absorption bands for atmospheric corrections) |
| SF6 | 3 - high | Cloud sensitive.. Coarse vertical resolution. | TIR spectrometry. SF6 lines around 10.5 micrometers. Frequent sampling (GEO) for diurnal variations |
| SO2 | 2 - very high | Cloud sensitive.. Coarse vertical resolution. | TIR spectrometry. SO2 lines around 7.3 and 8.6 micrometers. Frequent sampling (GEO) for sources monitoring |
| SO2 Total Column | 2 - very high | Cloud sensitive. | TIR spectrometry. SO2 lines around 7.3 and 8.6 micrometers. Frequent sampling (GEO) for sources monitoring |
| Specific humidity* | 1 - primary | Cloud sensitive. | TIR spectrometry in the water vapour band around 6.3 micrometers. Frequent sampling (GEO) enables monitoring instability onset |
| Integrated Water Vapour (IWV) | 2 - very high | Cloud sensitive. | TIR spectrometry in the bands around 6.3 and above 11 micrometers. Frequent sampling (GEO) enables monitoring instability onset |
| Temperature of the tropopause | 3 - high | Cloud sensitive. | TIR spectrometry. Tropopause temperature from temperature profile. Frequent sampling (GEO) enables monitoring the tropopause evolution |
| Upward spectral radiance at TOA | 2 - very high | Missing all Short-waves. | MWIR and TIR spectrometry resolving water vapour lines in the bands around 6.3 micrometers and 11 to 15 micrometers; and other greenhouse gases |
| Upward long-wave irradiance at TOA | 3 - high | Spectral interpolation needed. | MWIR and TIR spectrometry in the windows regions around 3.7 and 11 micrometers, and in water vapour and CO2 bands around 4,3, 6.3 and 15 micrometers |
| Upward long-wave irradiance at Earth surface | 1 - primary | Cloud sensitive.. Highly indirect. | MWIR and TIR channels in windows around 3.7 and 11 micrometers, and in water vapour and CO2 bands around 4,3, 6.3 and 15 micrometers |
| Wind (horizontal)* | 2 - very high | Cloud sensitive.. Water vapour tracers needed. | TIR spectrometry in the 6.3 micrometers band. Wind profile in clear air by tracking water vapour patches in the humidity profile |
Instrument: GXS