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Variational assimilation of combined satellite retrieved and in situ aerosol data in an advanced chemistry transport model

Lars Peter Nieradzik(1) and Hendrik Elbern(1)

(1) RIU - University of Cologne, Aachener Str 201-209, 50931 Koeln, Germany


The advent of satellite retrieved aerosol information allows for the preparation of assimilation based analysis maps. In combination with aerosol in situ measurements an avenue is opened for verification or complementary estimates of aerosol burden.

ENVISAT aerosol retrievals along with in situ data is assimilated in the RIU at University of Cologne Chemistry-Transport-Model EURAD-CTM (EURopean Air Dispersion and pollution CTM). A three-dimensional (3Dvar) type of data assimilation scheme has been developped and applied using PM10 and PM2.5 data from SYNAER (SYNergetic Aerosol Retrieval of DLR - DFD) aerosol retrievals of ENVISAT-SCIAMACHY-AATSR measurement data. SYNAER produces PM10 and PM2.5 information from Aerosol Optical Thickness (AOT) measurements. As background (or first guess) PM10 and PM2.5 data is delievered by the aerosol model MADE (Modal Aerosol Dynamics model for Europe) in combination with the Secondary Organic Aerosol Module (SORGAM), both implemented as integral part of the EURAD model. The presentation includes a description of the formulation of the variational approach, namely the design of the non-factorized 3D-background error covariance matrix with related formulation of anisotropic and inhomogeneous influence radii, to account for regional differences. As satellite retrievals are available in near real time, this approach aims at the applicability of PM10 and PM2.5 assimilation in an operational forecast model. This is of considerable value adding, as retrievals offer the opportunity to include irregular aerosol emission processes like biomass burning, volcanic eruptions and desert dust outbreaks in future operational products.


Workshop presentation

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry