Table 1. Key UV and IR satellite sensors with SO2 detection limits (Nimbus-7 TOMS for comparison)

Instrument (footprint size1, noise level2)

Tons of SO2 in cloud3

Data coverage dates4

TOVS-HIRS/2: IR, d = 18.5 km; NET = 0.5K

3800 strat

Oct 1978 ­

Nimbus 7 TOMS: UV, 50´50 km; 1s = 4 DU

7000 strat

14000 trop BL

Nov 1978 ­ May 1993

Earth Probe TOMS: UV, 39´39 km; 1s = 3.5 DU

3700 strat

7400 trop BL

Aug 1996 ­

GOME: UV, 40´320 km; 1s = 0.2 DU

3600 strat

7100 trop BL

Jan 1996 ­ Jun 2003

MODIS: IR, 1´1 km; NET = 0.25K

6 strat

174 trop BL

Terra: Feb 2000 ­

Aqua: Sep 2002 ­

ASTER: IR, 0.09´0.09 km; NET < 0.3K

0.05 strat

1.4 trop BL

Feb 2000 ­

AIRS: IR, d = 13.5 km; NET = 0.2K

100 strat

2986 trop BL

Sep 2002 ­

SCIAMACHY: UV, 30´60 km; 1s = 0.2 DU

125 strat

251 trop BL

Sep 2002 ­

MSG/SEVIRI: IR, 4.8´4.8 km; NET ~ 0.35K

140 strat

4010 trop BL

Jan 2004 ­

OMI: UV, 13´24 km; 1s = 0.2 DU

43 strat

87 trop BL

From late 2004

1. Given as dimensions of a rectangular footprint except for TOVS-HIRS/2 and AIRS, which have circular footprints with the given diameter.

2. Noise levels are given at the 1-sigma level for UV sensors (DU = Dobson Units or milli atm cm), and as Œnoise equivalent change in temperatureš or NET for IR sensors.

3. Calculated for a cluster of 5 nadir pixels at 5s in the stratosphere (strat) and the lower tropospheric boundary layer (trop BL); off-nadir values will be higher.

4. All sensors provide global coverage except SEVIRI, which is in geostationary orbit over Europe/Africa.

 

Acronyms

 

AIRS - Atmospheric Infrared Sounder

ASTER - Advanced Spaceborne Thermal Emission and Reflection Radiometer

GOME - Global Ozone Monitoring Experiment

HIRS/2 - High Resolution Infrared Radiation Sounder

MODIS - Moderate Resolution Imaging Spectroradiometer

MSG - Meteosat Second Generation

OMI - Ozone Monitoring Instrument

SCIAMACHY - Scanning Imaging Absorption Spectrometer for Atmospheric Cartography       

SEVIRI - Spinning Enhanced Visible and Infrared Imager

TOMS - Total Ozone Mapping Spectrometer

TOVS - TIROS Operational Vertical Sounder