Verbesserungen des troposphärischen NO:sub:2:/sub:-Retrievals aus GOME- und SCIAMACHY-Daten

Abstract

The retrieval of tropospheric NO:sub:2:/sub: from measurements taken by the satellite born instruments GOME and SCIAMACHY takes three steps: (1) Determination of the slant column (SC) by applying the method of the Differential Optical Absorption Spectroscopy (DOAS), (2) separation of the stratospheric amount of NO:sub:2:/sub:, and (3) conversion of the tropospheric SC to the tropospheric vertical column (VC) by applying an Air Mass Factor (AMF), which is determined by a simulation of the radiative transport (RT) by the RT model SCIATRAN.The essence of this thesis is the implementation of a new concept for the determination of the AMF. It leads to a substantial improvement in the retrieval by providing individual AMF for each observation.The sensitivity of the measurement is strongly dependant on the height. Therefore the shape of the NO:sub:2:/sub: profile must be known in order to calculate the AMF. This a priori information is taken from simulations of the chemistry and transport models (CTM) IMAGES, MOZART2 and TOMCAT.Since the explicit calculation of the AMF is rather time consuming, the approximation method block AMF was implemented. It is based on a look-up table of AMF for single atmospheric layers. The lookup table contains a total of 11,618,100 values, for the different combination of 13 albedo values, 6 aerosol types, 91 possible ground heights above sea level