SO2 and HCHO data from satellite& MAXDOAS instrument in Beijing

Jos van GeffenMichel Van Roozendael, Isabelle De Smedt

BIRA-IASB

1st AMFIC progress meeting – 13-14 May 2008LAP-AUTH, Thessaloniki, Greece

SO2 from satellite & SACS

SO2 enters the atmosphere as a result of anthropogenic activitiesand natural phenomena, such as volcanic eruptions.

It is not possible to distinguish between these two sources withoutadditional information, e.g. on the elevation of the SO2 layer.

SO2 retrieval and monitoring at BIRA-IASB primarily within theSupport to Aviation Control Service (SACS) of GSE-PROMOTE.

The SO2 data is also used for air quality records and for validationactivities in projects such as AMFIC.

Aim and users of the service

The aim of the Support to Aviation Control Service (SACS) is todeliver in near-real time data derived from satellite measurementsregarding SO2 and aerosol emissions possibly related to volcaniceruptions, 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 andcloud 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, whichis strogest at high solar zenith angle and large O3 concentrations, abackground correction needs to be applied.

Conversion to a total (vertical) column with an AMF from look-uptables, 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 kmThe 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

SCIAMACHY OMI GOME-2

archive period (maps + data)

09/2004 – 04/2008 [to come] * [to come]

NRT period: maps

data available

operational since

08/2007 – today

yes

09/2006

10/2007 – today

no *

10/2007

02/2008 – today

not yet **

02/2008

email notification

operational since

yes ***

02/2007

[to come] [to come]

Archive of GOME-1 data (1996-2003) 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. 2008

On 6 Feb. 2008 the Tungurahua volcano in Ecuador erupted. Ashemissions reached 15 km altitude south of the volcano, and 9 kmaltitude 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 20.000 hectare ofagricultural ground infertile. Several thousand people were evacuated.

Tungurahua has been activesince 1999, when it eruptedfor the first time in 80 years.

On 6 Feb.SACS sent out analert of an “exceptional SO2concentration” based onSCIAMACHY data.

AFP, 15/07/2006

Tungurahua (Ecuador) – 6 Feb. 2008

max. GOME2 SCIA OMI

VCD 1.90 DU 4.98 DU 5.30 DU

long. -79.18 -79.18 -78.31

lat. -2.57 -2.40 -2.51

time 15:01 15:25 19:04

Tungurahua volcano, Ecuador:long = -78.44 , 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:

http://www.oma.be/BIRA-IASB/Molecules/SO2archive/cases/china.php

Antrophogenic SO2 over China

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 328.5 – 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

GOME SCIAMACHY

Product version * G-200804-Fv5 S-200804-Fv5

Archive period 03/1996 – 12/2003 01/2003 – 12/2007

Resolution 320 x 40 km2 60 x 30 km2

* 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) – rightCurrently rather course resolution – would be nice to get high(er) resolutionemission 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