21-25 June 2004 2nd International Conference on Volcanic Ash and Aviation Safety Alexandria, VA.

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Atmospheric Research, Australia

Detection of upper level SO2 via the GOES Sounder

Fred Prata1, Anthony Schreiner2,Gary Ellrod3 and Timothy Schmit4

1CSIRO Atmospheric Research, Australia2Cooperative Institute for Meteorological Satellite Studies (CIMSS)

University of Wisconsin-MadisonMadison, WI 53706, U.S.A.

3NOAA/NESDIS, Office of Research and ApplicationsCamp Springs, Maryland

4NOAA/NESDIS, Office of Research and ApplicationsMadison, WI 53706, U.S.A.

21-25 June 2004 2nd International Conference on Volcanic Ash and Aviation Safety Alexandria, VA. 2

Atmospheric Research, Australia

The GOES Sounder

21-25 June 2004 2nd International Conference on Volcanic Ash and Aviation Safety Alexandria, VA. 3

Atmospheric Research, Australia

The GOES Sounder

21-25 June 2004 2nd International Conference on Volcanic Ash and Aviation Safety Alexandria, VA. 4

Atmospheric Research, Australia

SO2 from GOES

•Infrared channel near 7.3 µm SO2 absorption (channel 11)

•Reference channel (channel 9)

•Upper-level SO2 only (>3 km)

•Example – Montserrat

21-25 June 2004 2nd International Conference on Volcanic Ash and Aviation Safety Alexandria, VA. 5

Atmospheric Research, Australia

SO2 Retrieval from Sounder Data

• Absorption measurement. GOES channel 11 brightness temperatures are colder than expected, because of the presence of SO2.

• Reference channel. A second channel is used to eliminate background effects. The O3 channel was used (channel 9).

• Brightness temperature difference (BT). The BT is related to transmittance and then to absorber amount through radiative transfer modelling.

21-25 June 2004 2nd International Conference on Volcanic Ash and Aviation Safety Alexandria, VA. 6

Atmospheric Research, Australia

GOES-12

SO2 retrieval using the ozone channel as reference

QuickTime™ and aCinepak decompressor

are needed to see this picture.

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Atmospheric Research, Australia

Montserrat

GOES

AIRS

TOMS

HYSPLIT

JULY 13, 2002

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Atmospheric Research, Australia

Conclusions• It appears that the GOES sounder is capable of

detecting Upper Troposphere Lower Stratosphere SO2.• Unprecedented temporal resolution heralds new

possibilities for monitoring SO2 and ash.• Changes to the ABI will permit purposeful SO2

detection using the 7.3 µm channel.• More work is required to validate the SO2 retrievals

and to find the ‘optimum’ reference channels.