# Presentation: 099895

## Quantitative analysis of volcanic plumes with the GOES Sounder

- S. A. Ackerman, T. Schmit, H. Woolf, T. Schreiner, M. Gunshor, and J. Li
- University of Wisconsin-MadisonCooperative Institute for Meteorological Satellite Studies
- NOAA/NESDIS Advanced Satellite Products Team

## Motivation

- Plumes of SO2, along with other gases,  and ash, are expelled from the erupting volcanoes.
- Climatic impacts SO2 -> H2SO4
- Aviation safety
- Detection of these SO2 plumes has been accomplished via the AHVRR, HIRS, MODIS, AIRS, OMI, TOMS, etc.
- GEO provides complete temporal coverage

## Volcanic Ash

- 	Passive IR detection based on variouscombinations of:
- 			3.9, 8.5 10.7, and 12.0 m

## Volcanic Gases

- Gases include: : water vapor, sulfur dioxide (SO2), chlorine, hydrogen sulfide, nitrogen 	oxides...
- One of many processes: oxidation and hydration of SO2 -> H2SO4 (sulfuric acid)
- The resulting ash/acid mix is highly corrosive and can cause damage to jet engines and external parts of the aircraft, and there are climate implications.

## SO2 detection

- Strong SO2 absorption at 7.3 μm  and weak SO2 absorption at 8.5 μm
- Detection accomplished via various combinations of observations at
- 6.7, 7.3, 8.5, and 11 μm

## GOES Sounder Channels

- The Sounder has a 10 km IFOV; once per hour temporal coverage over USA. (Coverage over Caribbean is less.)

- 13.4

- 7.4

- SO2 plume detection is a “band difference” image based on the 7.4 μm (sensitive to Sulfur Dioxide) and a CO2 absorption band (Band 5, 13.3 μm and not sensitive to SO2). Band 5 is chosen because the weighting function (i.e. the region or vertical layer of the atmosphere these spectral bands are most sensitive to changes) for both bands peak around the same region of the atmosphere.

## After Schmit et al. 2005, BAMS

- SO2 calculations from F. Prata

**Notes:**
7.4 um (7.3 to 7.5 um) to a 7.34 um  (7.24 to 7.44 um)7.0 um (6.8 to 7.2 um) to a 6.95 um  (6.75 to 7.15 um)

## Retrieval

## Simulations

- Sensitive to SO2 altitude and atmospheric profile.

## First case: July 2003

- Soufriere Hills Volcano, Montserrat  on 12 July 2003 (around 0230 UTC, 13 July 2003), triggered by a major collapse of the lava dome

- Photo by

## GOES-12 Sounder

**GOES-12 Sounder**
- Band 10 (7.4 μm) – Band 5 (13.3μm)

- 13 July 2003 13:20 UTC

- 13 July 2003 19:20 UTC

- 14 July 2003 01:20 UTC

- ?

## AIRS Retrieval (F. Prata)

## GOES BT 7.4-BT 13.4

## GOES SO2 Retrieval

## May 21-22, 2006Prata retrieval from AIRS

## MAY 20, 2006 0720 UTC

## MAY 20, 2006 1320 UTC

## MAY 20, 2006 1920 UTC

## MAY 21, 2006 0120 UTC

## MAY 21, 2006 0720 UTC

## MAY 21, 2006 0920 UTC

## MAY 21, 2006 1020 UTC

## MAY 21, 2006 1120 UTC

## MAY 21, 2006 1520 UTC

## MAY 21, 2006 1620 UTC

## MAY 21, 2006 1720 UTC

## MAY 21, 2006 2120 UTC

## MAY 21, 2006 2220 UTC

## MAY 21, 2006 2320 UTC

## MAY 22, 2006 0320 UTC

## MAY 22, 2006 0420 UTC

## MAY 22, 2006 0520 UTC

## MAY 22, 2006 0620 UTC

## MAY 22, 2006 0920 UTC

## MAY 22, 2006 1020 UTC

## MAY 20, 2006 1320 UTC

- CO2 slicing can estimate ash heights.

## MAY 20, 2006 1920 UTC

## MAY 21, 2006 0120 UTC

## SO2 GOES Sounder 

- SO2 GOES Sounder

- Ash cloud

## SO2 GOES Sounder 

- SO2 GOES Sounder

- Ash cloud

## SO2 GOES Sounder 

- SO2

## SO2 GOES Sounder 

- SO2

## SO2 GOES Sounder 

## SO2 GOES Sounder 

## Next Generation GOES

- After Schmit et al. 2005, BAMS: Slightly shifted, toward larger wavenumbers, the two narrow ABI water vapor bands to better discriminate the SO2 peak.

- ABI – Advanced Baseline Imager

## Next Generation GOES

- ABI Wavelength (micron)

- BT difference (K)

- Current GOES imager doesn’t have capability.

**Notes:**
The ABI volcanic ash detection will depend on 12 m data (Schmit et al. 2001), plus 7.34 and 8.5 m data. The ABI water vapor bands have been shifted to detect upper-level SO2, as well as the mid-level water vapor. Forward calculations with the LBLRTM (left panel, Figure 3) show the sensitivity of the 7.34 and 8.5 m bands to SO2 for the U.S. standard atmosphere. If the vertical and spatial extents of the plume are sufficient, the ABI should be able to detect medium to large SO2 amounts (greater than 100 Dobson Units (DU)), but not small amounts (less than 50 DU). High-spectral resolution measurements (HES), if they include the 7 m region, should have more sensitivity than broadband radiometers for detecting SO2 because individual absorption features can be used. ABI bands, simulated from AIRS data, show the potential for depicting upper-level SO2 (right panel, Figure 3). This case is from July 13, 2003.

## Summary

- Current GOES Sounder can track SO2 plumes from volcanoes.
- The temporal resolution delineates the evolution of the plume.
- Estimates of total loading require profile and altitude: profile from sounder.
- Estimates of 20-22 May 2006 and July 2003 eruptions of Montserrat are consistent with AIRS retrieval by Prata (GOES a bit too high).
- Next generation GOES imager will be better suited for detection and retrieval.