| Aerosol column burden | 2 - very high | Cloud sensitive.. Daylight only. | UV (for absorbing aerosol) and VIS spectrometry | 
	
	| Aerosol effective radius | 2 - very high | Cloud sensitive.. Daylight only. | UV (for absorbing aerosol) and VIS spectrometry | 
	
	| Aerosol mass mixing ratio | 2 - very high | Cloud sensitive.. Daylight only. | UV (for absorbing aerosol) and VIS spectrometry | 
	
	| Aerosol Optical Depth | 2 - very high | Cloud sensitive.. Daylight only. | UV (for absorbing aerosol) and VIS spectrometry | 
	
	| Aerosol type | 2 - very high | Cloud sensitive.. Daylight only. | UV (for absorbing aerosol) and VIS spectrometry | 
	
	| BrO* | 1 - primary | Cloud sensitive.. Daylight only. | UV spectrometry.  BrO lines around 300 nm | 
	
	| HCHO* | 2 - very high | Cloud sensitive.. Coarse vertical resolution.. Daylight only. | UV spectrometry.  HCHO lines around 350 nm | 
	
	| HCHO Total Column* | 2 - very high | Cloud sensitive.. Daylight only. | UV spectrometry.  HCHO lines around 350 nm | 
	
	| ClO* | 1 - primary | Cloud sensitive.. Daylight only. | UV Spectrometry.  ClO lines around 300 nm | 
	
	| Cloud cover | 5 - marginal | Daylight only. | VIS spectroscopy | 
	
	| Cloud optical depth | 5 - marginal | Low-density cloud only.. Daylight only. | VIS spectrometry | 
	
	| H2O* | 3 - high | Cloud sensitive.. Daylight only. | UV and VIS spectrometry.  Several weak bands | 
	
	| NO* | 2 - very high | Cloud sensitive.. Coarse vertical resolution.. Daylight only. | UV spectrometry.  NO lines around 250 nm | 
	
	| NO2* | 2 - very high | Cloud sensitive.. Coarse vertical resolution.. Daylight only. | UV and VIS spectrometry.  Several lines in the ranges around 220 nm and 400 nm | 
	
	| NO2  Total Column* | 2 - very high | Cloud sensitive.. Daylight only. | UV and VIS spectrometry.  Several NO2 lines | 
	
	| O3* | 2 - very high | Cloud sensitive.. Daylight only. | UV and VIS spectrometry.  Ozone lines in the bands around 260 nm (Hartley) and/or 340 nm (Huggins) and 600 nm (Chappuis) | 
	
	| O3 Total Column* | 2 - very high | Cloud sensitive.. Daylight only. | UV and VIS spectrometry.  Ozone lines in the bands around 260 nm (Hartley) and/or 340 nm (Huggins) and 600 nm (Chappuis) | 
	
	| PSC occurrence | 2 - very high | Coarse vertical resolution.. Daylight only. | UV and VIS spectrometry | 
	
	| SO2* | 2 - very high | Cloud sensitive.. Coarse vertical resolution.. Daylight only. | UV spectrometry.  SO2 lines around 350 nm | 
	
	| SO2 Total Column* | 3 - high | Cloud sensitive.. Daylight only. | UV spectrometry.  SO2 lines around 350 nm | 
	
	| Upward short-wave irradiance at TOA | 3 - high | Spectral interpolation needed.. Information on BRDF needed. | UV and VIS spectrometry | 
	
	| Upward spectral radiance at TOA | 5 - marginal | Missing NIR, SWIR and all Long-waves. | UV and VIS spectrometry | 
	
	| Aerosol volcanic ash | 2 - very high | Cloud sensitive.. Daylight only. | UV (specifically sensitive to ash) and VIS spectrometry | 
	
	| Aerosol volcanic ash  Total Column | 2 - very high | Cloud sensitive.. Daylight only. | UV (specifically sensitive to ash) and VIS spectrometry |