Global satellite validation of SCIAMACHY O<sub>3</sub> columns with GOME WFDOAS

Abstract

Abstract. Global stratospheric ozone columns measured by SCIAMACHY (Scanning Imaging Spectrometer for Atmospheric Chartography; data versions 5.01 and 5.04) aboard the recently launched Environmental Satellite (ENVISAT) from January to June 2003 were compared to collocated total ozone data from GOME (Global Ozone Monitoring Experiment on ERS-2) retrieved using the weighting function DOAS algorithm (WFDOAS; Version 1.0) in order to assess the level-2 data (trace gas data) retrieval accuracy from SCIAMACHY. The large number of collocated total ozone data from the two instruments which are flying in the same orbit were spatially binned into regular 2.5° and 2.5° grids and then compared. This binning method shows similar results than direct comparisons but is about thousand times faster. Results of these satellite comparisons show that SCIAMACHY O3 vertical columns (version 5.01/5.04) are on average 1% (±2%) lower than GOME WFDOAS and scatter increases at solar zenith angles above 85° and at low total ozone values. Results show dependencies on the seasonal cycle, latitudes, and total ozone amounts which are explained by the implementation of an old GOME algorithm based on GOME Data Processor (GDP) version 2.4 algorithm for the SCIAMACHY operational product. A reprocessing with an algorithm equivalent to GOME GDP version 4.0 and/or GOME WFDOAS V1.0 will improve significantly the quality of the SCIAMACHY ozone product. Since GOME lost its global coverage in July 2003 due to data rate limitation, continuation of the total ozone time series with SCIAMACHY is of highest importance for long-term trend monitoring.

Overview of SCIAMACHY validation: 2002–2004

“…It is expected that the OL SCIAMACHY processor will be upgraded in 2005 to a GDP 4-like version, including a better treatment of RRS, of the cross-sections temperature dependence and of the air mass factor, and therefore significant improvements are anticipated. Comparisons with GOME retrievals from IFE/IUP-Bremen (WF-DOAS 1.0) confirm these results and additionally show that the dependencies of the deviations on solar zenith angle, latitude, and total ozone disappear when SCIAMACHY total ozone is retrieved with an algorithm equivalent to GOME WF-DOAS 1.0 (Bracher et al, 2005a). SCIAMACHY O 3 column data sets have also been produced by scientific processors developed at BIRA-IASB, IUP/Bremen and KNMI.…”

Investigation of SO2Effect on TOMS O3Retrieval from OMI Measurement in China

“…DOAS 알고리즘 또한 위성측정을 통한 오존 산출에 사 용되어 왔다 (Bracher et al, 2005;Kroon et al, 2008;Loyola et al, 2011). 1995년 4월 Second Europe Remote Sensing satellite (ERS-2)의 Global Ozone Monitoring Experiment (GOME)센서, 2002년 3월의 European ENVIronmental SATellite (ENVISAT) 위성의 SCanning Imaging Absorption spectro Meter for Atmospheric CHartogaphY (SCIAMACHY) 센서가 측정한 원시자료로부터 DOAS 알고리즘을 사 용하여 오존전량을 산출하였다 (Bracher et al, 2005;Loyola et al, 2011). 현재는 2006년 10월과 2012년 9월에…”

SO<sub>2</sub> Retrieval from SCIAMACHY using the Weighting Function DOAS (WFDOAS) technique: comparison with Standard DOAS retrieval

“…The WFDOAS method has been first demonstrated to be applicable to retrievals of trace gas columns in the near infrared region of SCIAMACHY (Buchwitz et al, 2000). It is also being used for direct retrieval of vertical O 3 amounts Weber et al, 2005;Bracher et al, 2005). It is distinct from the SDOAS by the use of wavelength-dependent weighting functions, which describe the relative radiance change due to a vertical profile change.…”