Overview of SCIAMACHY validation: 2002–2004

Abstract

Abstract. SCIAMACHY, on board Envisat, is now in operation for almost three years. This UV/visible/NIR spectrometer measures the solar irradiance, the earthshine radiance scattered at nadir and from the limb, and the attenuation of solar radiation by the atmosphere during sunrise and sunset, from 240 to 2380 nm and at moderate spectral resolution. Vertical columns and profiles of a variety of atmospheric constituents are inferred from the SCIAMACHY radiometric measurements by dedicated retrieval algorithms. With the support of ESA and several international partners, a methodical SCIAMACHY validation programme has been developed jointly by Germany, the Netherlands and Belgium (the three instrument providing countries) to face complex requirements in terms of measured species, altitude range, spatial and temporal scales, geophysical states and intended scientific applications. This summary paper describes the approach adopted to address those requirements. The actual validation of the operational SCIAMACHY processors established at DLR on behalf of ESA has been hampered by data distribution and processor problems. Since first data releases in summer 2002, operational processors were upgraded regularly and some data products – level-1b spectra, level-2 O3, NO2, BrO and clouds data – have improved significantly. Validation results summarised in this paper conclude that for limited periods and geographical domains they can already be used for atmospheric research. Nevertheless, remaining processor problems cause major errors preventing from scientific usability in other periods and domains. Untied to the constraints of operational processing, seven scientific institutes (BIRA-IASB, IFE, IUP-Heidelberg, KNMI, MPI, SAO and SRON) have developed their own retrieval algorithms and generated SCIAMACHY data products, together addressing nearly all targeted constituents. Most of the UV-visible data products (both columns and profiles) already have acceptable, if not excellent, quality. Several near-infrared column products are still in development but they have already demonstrated their potential for a variety of applications. In any case, scientific users are advised to read carefully validation reports before using the data. It is required and anticipated that SCIAMACHY validation will continue throughout instrument lifetime and beyond. The actual amount of work will obviously depend on funding considerations.

Validation of Ozone Monitoring Instrument nitrogen dioxide columns

“…Only the instruments at the Observatoire Haute‐Provence (OHP), France, and Bauru, Brazil, are in any proximity to presumed anthropogenic sources of NO 2 . Measurements from the SAOZ instruments have been previously used to compare with NO 2 measurements by the space‐borne Global Ozone Monitoring Experiment (GOME) [ Burrows et al , 1999b] and Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) [ Bovensmann et al , 1999] instruments [ Ionov et al , 2006a, 2006b, 2007; Piters et al , 2006; Lambert et al , 2001].…”

Ground‐based validation of EOS‐Aura OMI NO2 vertical column data in the midlatitude mountain ranges of Tien Shan (Kyrgyzstan) and Alps (France)

“…It was launched on 15 July 2004, onboard NASA's EOS Aura platform, into sun‐synchronous near polar orbit [ Levelt et al , 2006]. According to numerous validation studies, the overall accuracy of operational GOME and SCIAMACHY NO 2 vertical column data is estimated to fall within ∼0.3 × 10 15 molecules/cm 2 in the areas of low tropospheric NO 2 [ Lambert and Balis , 2004; Piters et al , 2006]. The scientific requirements for the OMI data products call for an accuracy of ∼0.2 × 10 15 molecules/cm 2 , for the same conditions [ Brinksma et al , 2003].…”

Validation of atmospheric chemistry measurements from MIPAS, SCIAMACHY, GOMOS onboard ENVISAT by observations of balloon-borne MIPAS-B

“…SCIAMACHY is a scan imaging absorption spectrometer [17,18]. It observes the transmitted, backscattered, and reflected radiations from the atmosphere.…”