1. Monitoring of sulphur dioxide emissions from satellite as part of GSE PROMOTE Jos van Geffen, Michel Van Roozendael, Isabelle De Smedt, Caroline Fayt (BIRA-IASB) Pieter Valks (DLR) Ronald van der A (KNMI) SO2 workshop -- 22 June 2006 KNMI, De Bilt

2. Contents Introduction Support to Aviation Control Service of GSE PROMOTE stage 2 SO2 retrieval from SCIAMACHY Some examples

3. Introduction Sulphur dioxide (SO2) enters the atmosphere as a results of both natural phenomena and anthropogenic activities. In view of the main sources of SO2, the monitoring is divided in two: Volcanic SO2 Service Concentrates on regions with volcanoes known to have erupted after 1800 Air Quality SO2 Service Concentrates on industrialised areas Near-real-time and archive data of both for the “Support to Aviation Control” and “Air Quality Record” Services of PROMOTE stage 2. Part of the services also falls under the TEMIS project.

4. Support to Aviation Control Service (1) One of the baseline services in GSE PROMOTE stage 2. Objective Provision in near-real-time of SO2 and aerosol data related to volcanic emissions to assist air line companies in the planning of routes. Core users Volcanic Ash Advisory Centres of London and Toulouse, who cover Europe and Africa.

5. Support to Aviation Control Service (2) Parameters to be delivered SO2 slant column densities from SCIAMACHY and GOME-2 SO2 index from OMI Volcanic aerosol indicator from SEVIRI Trajectories of the motion of plumes E-mail warning of exceptional SO2 emissions Service partners BIRA-IASB (Belgium) DLR (Germany) KNMI (Netherlands) CGS (Italy)

6. SO2 retrieval from SCIAMACHY (1) For the monitoring services, SO2 slant columns are retrieved from SCIAMACHY measurements with a DOAS technique in the range 315 – 326 nm. For a given month the reference spectrum is an earthshine spectrum from around the middle of the month, taken near 65º East, 5º South (that is south-west of India). SO2 vertical columns will be computed using AMFs from radiative transfer calculations → presentation Pieter Valks. A correction for the background SO2 level and the “interference” with the ozone absorption signal at high SZA is applied on the basis of a monthly average over the SO2 slant columns (omitting strong events with strong emissions) as function of SZA.

7. SO2 retrieval from SCIAMACHY (2) → Different correction for the two hemispheres needed.

8. SO2 retrieval from SCIAMACHY (3) SCDcorr = SCDretr – f(SZA) f(SZA) = fit [ SO2aver + SO2sigma*(SZA/90)^4 ]

9. SO2 retrieval from SCIAMACHY (4) Ongoing development: direct-fitting of SO2 vertical column using GODFIT  Preliminary results indicate that the ozone related bias at large SZA can be avoided

10. SO2 retrieval from SCIAMACHY (5) Delivery of data and images Data files cover the whole world: – ASCII at orbit coordinates – HDF at lat-lon grid of 0.25 by 0.25 degrees: daily data, 3-day composites, monthly averages Images are made for all regions of the two data Services. Daily and 3-day data: SO2 slant column and (if available) SO2 vertical column in DU and FRESCO cloud cover fraction. Examples on following sheets Eruption of the Sierra Negra volcano (22 Oct. 2005), with slant columns well over 100 DU → presentation Andreas Richter. SO2 around the Nyamuragira and Nyiragongo volcanoes. SO2 from the Grímsvötn eruption (1 Nov. 2004) can be followed across Europe SO2 from air pollution & the South Atlantic Anomaly

11. Eruption of the Sierra Negra volcano (1)

12. Eruption of the Sierra Negra volcano (2)

13. SO2 around Nyamuragira & Nyiragongo volcanoes

14. SO2 from Grímsvötn eruption across Europe

15. SO2 from air pollution & the South Atlantic Anomaly