Journal Article

Validation of MIPAS-ENVISAT H2O operational data collected between July 2002 and March 2004

Fischer, H, Milz, M., Rohs, S., Wetzel, G., Renard, Jean-Baptiste, Mona, L., Fix, A., Ovarlez, J., Cornacchia, C, Rizi, V., Feist, D. G., Lengel, A., Piccolo, C., Bracher, A., Oelhaf, Hermann, Berthet, Gwenaël, Iarlori, M., Müller, S.C., Pappalarda, G., Raspollini, P., Kleinert, A., Schiller, C., Weber, M., Zhang, G.

2013

Overview

Water vapour (H2O) is one of the operationallyretrieved key species of the Michelson Interferometer forPassive Atmospheric Sounding (MIPAS) instrument aboardthe Environmental Satellite (ENVISAT) which was launchedinto its sun-synchronous orbit on 1 March 2002 and operateduntil April 2012. Within the MIPAS validation activities,independent observations from balloons, aircraft, satellites,and ground-based stations have been compared to EuropeanSpace Agency (ESA) version 4.61 operational H2Odata comprising the time period from July 2002 until March2004 where MIPAS measured with full spectral resolution.No significant bias in the MIPAS H2O data is seen in thelower stratosphere (above the hygropause) between about15 and 30 km. Differences of H2O quantities observed byMIPAS and the validation instruments are mostly well withinthe combined total errors in this altitude region. In the upperstratosphere (above about 30 km), a tendency towardsa small positive bias (up to about 10 %) is present in theMIPAS data when compared to its balloon-borne counterpartMIPAS-B, to the satellite instruments HALOE (HalogenOccultation Experiment) and ACE-FTS (AtmosphericChemistry Experiment, Fourier Transform Spectrometer),and to the millimeter-wave airborne sensor AMSOS (AirborneMicrowave Stratospheric Observing System). In themesosphere the situation is unclear due to the occurrenceof different biases when comparing HALOE and ACE-FTSdata. Pronounced deviations between MIPAS and the correlativeinstruments occur in the lowermost stratosphere and upper troposphere, a region where retrievals of H2O are mostchallenging. Altogether it can be concluded that MIPAS H2Oprofiles yield valuable information on the vertical distributionof H2O in the stratosphere with an overall accuracy ofabout 10 to 30% and a precision of typically 5 to 15% –well within the predicted error budget, showing that theseglobal and continuous data are very valuable for scientificstudies. However, in the region around the tropopause retrievedMIPAS H2O profiles are less reliable, suffering froma number of obstacles such as retrieval boundary and cloudeffects, sharp vertical discontinuities, and frequent horizontalgradients in both temperature and H2O volume mixing ratio(VMR). Some profiles are characterized by retrieval instabilities.

• Publisher: European Geosciences Union,Copernicus Publications
• Subject: Rymdteknik / Sciences of the Universe / Space Technology