SO2 and HCHO data from satellite & MAXDOAS instrument in Beijing Jos van Geffen Michel Van Roozendael, Isabelle De Smedt BIRA-IASB 1st AMFIC progress meeting – May 2008 LAP-AUTH, Thessaloniki, Greece

SO2 from satellite & SACS SO2 enters the atmosphere as a result of anthropogenic activities and natural phenomena, such as volcanic eruptions. It is not possible to distinguish between these two sources without additional information, e.g. on the elevation of the SO2 layer. SO2 retrieval and monitoring at BIRA-IASB primarily within the Support to Aviation Control Service (SACS) of GSE-PROMOTE. The SO2 data is also used for air quality records and for validation activities in projects such as AMFIC.

Aim and users of the service The aim of the Support to Aviation Control Service (SACS) is to deliver in near-real time data derived from satellite measurements regarding SO2 and aerosol emissions possibly related to volcanic eruptions, and where possible to track volcanic plumes. The Volcanic Ash Advisory Centres (VAACs) are the official organisations to gather information on volcanic ash clouds and on the basis of that issue advice and alerts to air line and air traffic control organisations on the possible danger of volcanic clouds for aviation. Notifications of “exceptional SO2 concentrations” (or: “SO2 event”) and data from SACS can assist the VAACs with their task: to assess volcanic activity and if necessary to issue alerts to air traffic control and airline organisations. Key users: the Toulouse and London VAACs.

Pre-defined plot regions Default maps of SO2 and cloud cover made for: 42 volcano regions of 30 by 30 degrees 11 air quality regions of 40 by 40 degrees China region

SO2 retrieval Retrieval of SO2 with DOAS in 315 – 326 nm window, also fitting for ozone, as well as Ring effect, polarisation effect, etc. Due to the interference of the SO2 and O3 absorption signals, which is strogest at high solar zenith angle and large O3 concentrations, a background correction needs to be applied. Conversion to a total (vertical) column with an AMF from look-up tables, assuming a certain elevation of a 1 km thick SO2 layer. For the data files three levels are used: 1 km above ground level 6 km [or 1 km above ground level if that is higher] 14 km The first case is suitable for studying SO2 in the boundary layer, i.e. the validation task within AMFIC. The “6 km” case is used for the plots on the website.

Status of the SO2 data products SCIAMACHYOMIGOME-2 archive period (maps + data) 09/2004 – 04/2008[to come] *[to come] NRT period: maps data available operational since 08/2007 – today yes 09/ /2007 – today no * 10/ /2008 – today not yet ** 02/2008 notification operational since yes *** 02/2007 [to come] Archive of GOME-1 data ( ) is to come too. *) OMI NRT data is not made public, since off-line data usually 3-7 days later available from the NASA/UMBC website; SACS will just host maps **) Currenly applying a preliminary background correction that should work for low and mid latitudes ***) Number of subscribers: 31

Tungurahua (Ecuador) – 6 Feb On 6 Feb the Tungurahua volcano in Ecuador erupted. Ash emissions reached 15 km altitude south of the volcano, and 9 km altitude 225 km NW of the volcano. Tungurahua (summit: 5 km) lies some 130 km south of the town Quito. The eruptions killed five people and made about hectare of agricultural ground infertile. Several thousand people were evacuated. Tungurahua has been active since 1999, when it erupted for the first time in 80 years. On 6 Feb.SACS sent out an alert of an “exceptional SO2 concentration” based on SCIAMACHY data. AFP, 15/07/2006

Tungurahua (Ecuador) – 6 Feb max.GOME2SCIAOMI VCD1.90 DU4.98 DU5.30 DU long lat time15:0115:2519:04 Tungurahua volcano, Ecuador: long = , lat = -1.47

Anthropogenic SO2 over China

Antrophogenic SO2 over China Best to use “1 km above ground level” SO2 total column value Extracted overpass data from SCIA orbit data files, i.e. all ground pixels within 50 km, for validation → MariLiza Archive also provides monthly averaged data on a lat-lon grid: can provide overpass data from this too, either a single point or an average over a given lat-lon region → Xingying Zhang Dedicated plots for “1 km” case with optimised colour scale of monthly averages (images and movie) and yearly averages:

Antrophogenic SO2 over China

HCHO from satellite Impact on oxidation capacity of the troposphere NMVOCs Non-methane hydrocarbons Oxygenated non-methane hydrocarbons Short-lived species Production of organic aerosols 85% 3% 12%

HCHO retrieval Retrieval of HCHO with DOAS in – 346 nm window, including fitting for ozone, NO2, O4, OClO, Ring effect, and polarisation effect. Reference sector correction and normalisation of background HCHO (due to CH4 oxidation) using IMAGES model AMFs based on IMAGES monthly profiles Cloud correction: FRESCO+

Status of the HCHO data products GOMESCIAMACHY Product version *G Fv5S Fv5 Archive period03/1996 – 12/200301/2003 – 12/2007 Resolution320 x 40 km 2 60 x 30 km 2 * Algorithm documented in De Smedt et al., 2008 (submitted to ACP)

NMVOC emissions from inverse modeling Pyrogenic & biogenic emissions worldwide (in 10^10 molec / cm^2 sec) Prior emission inventory from MEGAN_ECMWF (Muller et al, 2008) – left Optimisation using IMAGES (v2) model, using monthly HCHO columns (Jenny Stavrakou) – right Currently rather course resolution – would be nice to get high(er) resolution emission estimates over China → input to VITO, with NOx from KNMI

MAXDOAS in Beijing New 2-channels MAXDOAS with direct-sun pointing capability developed and tested at BIRA Instrument funded by Belspo as part of bilateral research agreement for DRAGON-AMFIC Installation at IAP/CAS (Beijing) scheduled for late May early June Target products: O3, NO2, BrO, HCHO, CHOCHO, SO2, OClO, aerosol extinction profiles, H2O column Operation at IAP during 6 months (first phase) followed by permanent installation in background site North of Beijing Will provide complementary measurements of AQ-related gases and contribute to satellite validation