Three years of global carbon monoxide from SCIAMACHY: comparison with MOPITT and first results related to the detection of enhanced CO over cities

[摘要] Carbon monoxide (CO) is an important atmospheric constituentaffecting air quality and climate.SCIAMACHY on ENVISAT is currently the only satellite instrumentthat can measure the vertical column of CO with nearlyequal sensitivity at all altitudesdown to the Earth's surface becauseof its near-infrared nadir observations of reflected solar radiation.Here we present three years' (2003–2005)of SCIAMACHY CO columns consistently retrieved with the latest versionof our retrieval algorithm (WFMDv0.6). We describe the retrievalmethod and discuss the multi-year global CO data set focusing on acomparison with the operational CO column data product of MOPITT.We found reasonable to good agreement (~20%) with MOPITT,with the best agreement for 2004. We present detailed results for various regions (Europe, Middle East, India, China) and discuss to what extent enhanced levels of CO can be detected over populated areas including individual cities.The expected CO signal from cities is close to or even belowthe detection limit of individual measurements. We showthat cities can be identified when averaging long time series.

[学科分类] 大气科学