Overview of SCIAMACHY validation: 2002–2004

Abstract

Abstract. SCIAMACHY, on board Envisat, has been in operation now 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.Since provisional releases of limited data sets in summer 2002, operational SCIAMACHY processors established at DLR on behalf of ESA were upgraded regularly and some data products -level-1b spectra, level-2 O 3 , NO 2 , BrO and clouds data -have improved significantly. Validation results summarised in this paper and also reported in this special issue conclude that for limited periods and geographical domains they can already be used for atmospheric research. Nevertheless, current processor versions still experience known limitations that hamper scientific usability in other periods and domains. Free from the constraints of operational processing, seven scientific institutes (BIRA-IASB, IFE/IUP-Bremen, 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 -O 3 , NO 2 , SO 2 , H 2 O total columns; BrO, OClO Cloud and aerosol parameters are retrieved, suffering from calibration with the exception of cloud cover. 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 and will accompany regular processor upgrades.

Validation of MIPAS-ENVISAT NO<sub>2</sub> operational data

“…The independent validation of atmospheric chemistry satellite missions is a main objective of the NDACC (Lambert et al, 1999). Although measuring stratospheric NO 2 at poor vertical resolution, its ability to provide high-quality, continuous time-series at a variety of sites from pole to pole has been helpful in validating seasonal signals and meridian structures reported by NO 2 satellite sensors like HALOE (Gordley et al, 1996), GOME (Lambert et al, 2002), POAM III and SCIAMACHY (Piters et al, 2006). In this section we will study how partial stratospheric columns derived from MIPAS measurements are consistent with correlative observations reported by the various components of the NDACC.…”

Intercomparison of SCIAMACHY and SIM vis-IR irradiance over several solar rotational timescales

“…They have been made, for example, in Gueymard (2004Gueymard ( , 2006 but without taking into account the spectral response function (slit function) of the individual instruments. In contrast, proper use of instrument function were made in comparisons between SIM and SRPM spectral synthesis (Fontenla et al 2004;Harder et al 2005c;Fontenla & Harder 2005); SCIAMACHY and SIM to several reference spectra (Gurlit et al 2005;Skupin et al 2005a,b;Piters et al 2006). Most recent comparison using SCIAMACHY has been made by Dobber et al (2008) but it was limited to the 250-550 nm wavelength range.…”

Construction of merged satellite total O<sub>3</sub> and NO<sub>2</sub> time series in the tropics for trend studies and evaluation by comparison to NDACC SAOZ measurements

“…But although total ozone and NO 2 satellite observations by Earth Probe (EP-TOMS), Global Ozone Monitoring Experiment (GOME), followed by Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) and Ozone Monitoring Instrument (OMI), have been thoroughly validated at midlatitude by comparison with ground-based measurements (e.g. Piters et al, 2006;Balis et al, 2007;Lambert et al, 1998;Celarier et al, 2008;Ionov et al, 2008;Hendrick et al, 2011), with the exception of the last mentioned papers, the validation hardly applies to the tropics. The reason for that is the limited number of long series of ground-based ozone and NO 2 measurements available at this latitude.…”