Global air pollution map produced by Envisat's SCIAMACHY

October 12, 2004

Paris, 11 Oct 2004

The image shows the global mean tropospheric nitrogen dioxide (NO2) vertical column density (VCD) between January 2003 and June 2004, as measured by the SCIAMACHY instrument on ESA's Envisat. The scale is in 1015 molecules/cm-2. Image produced by S. Beirle, U. Platt and T. Wagner of the University of Heidelberg's Institute for Environmental Physics.

Comparing the spatial resolution of GOME and SCIAMACHY. The two images show mean tropospheric nitrogen dioxide (NO2) vertical column density (VCD) for August 2002, as resolved by the two sensors. SCIAMACHY has superior resolution, with a typical pixel size of 60 x 30 km compared to an elongated 320 x 40 km for GOME. The result is that individual city sources can be seen. For SCIAMACHY all available raw data for August 2002 are used. For GOME only pixels with corresponding SCIAMACHY measurements are shown. The units measured are 1015 molecules/cm-2. Images from the University of Bremen.

11 October 2004
The Differential Optical Absorption Spectroscopy (DOAS) method enables the detection of very weak absorption structures in the spectra of backscattered sun light measured by the satellite instrument. In the centre a spectrum of sunlight scattered back from the earth's atmosphere is shown. From such spectra the absorption structures of various atmospheric trace gases can be retrieved simultaneously. Graphic from T. Wagner, University of Heidelberg's Institute for Environmental Physics.

SCIAMACHY is an imaging spectrometer whose primary mission objective is to perform global measurements of trace gases in the troposphere and in the stratosphere. The solar radiation transmitted, backscattered and reflected from the atmosphere is recorded at relatively high resolution (0.2 nm to 0.5 nm) over the range 240 nm to 1700 nm, and in selected regions between 2.0 µm and 2.4 µm.

European Space Agency ml

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