Articles | Volume 13, issue 11
Atmos. Chem. Phys., 13, 5791–5811, 2013
Atmos. Chem. Phys., 13, 5791–5811, 2013
Research article
14 Jun 2013
Research article | 14 Jun 2013

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

G. Wetzel1, H. Oelhaf1, G. Berthet2, A. Bracher*,3, C. Cornacchia4, D. G. Feist5, H. Fischer1, A. Fix6, M. Iarlori7, A. Kleinert1, A. Lengel1,**, M. Milz8, L. Mona4, S. C. Müller9,***, J. Ovarlez2, G. Pappalardo4, C. Piccolo10,****, P. Raspollini10, J.-B. Renard2, V. Rizi7, S. Rohs11,*****, C. Schiller11,†, G. Stiller1, M. Weber3, and G. Zhang1 G. Wetzel et al.
  • 1Institute for Meteorology and Climate Research (IMK), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
  • 2Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), CNRS, Orléans, France
  • 3Institute of Environmental Physics and Remote Sensing (IUP/IFE), University of Bremen, Bremen, Germany
  • 4CNR-IMAA, Consiglio Nazionale delle Ricerche – Istituto di Metodologie per l'Analisi Ambientale, Tito Scalo, Potenza, Italy
  • 5Max Planck Institute for Biogeochemistry, Jena, Germany
  • 6Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
  • 7CETEMPS – Dipartimento di Scienze Fisiche e Chimiche – Università degli Studi, L'Aquila, Italy
  • 8Department of Computer science, Electrical and Space engineering, Luleå University of Technology, Kiruna, Sweden
  • 9Institute of Applied Physics (IAP), University of Bern, Bern, Switzerland
  • 10Istituto di Fisica Applicata "Nello Carrara" (IFAC), del Consiglio Nazionale delle Ricerche (CNR), Firenze, Italy
  • 11Institute for Energy and Climate Research – Stratosphere (IEK-7), Forschungszentrum Jülich, Jülich, Germany
  • *now at: Alfred Wegener Institute (AWI), Bremerhaven, Germany
  • deceased
  • **now at: Carl Zeiss AG, Oberkochen, Germany
  • ***now at: METEOTEST, Bern, Switzerland
  • ****now at: Met Office, Exeter, UK
  • *****now at: Institute for Energy and Climate Research – Troposphere (IEK-8), Forschungszentrum Jülich, Jülich, Germany

Abstract. Water vapour (H2O) is one of the operationally retrieved key species of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument aboard the Environmental Satellite (ENVISAT) which was launched into its sun-synchronous orbit on 1 March 2002 and operated until April 2012. Within the MIPAS validation activities, independent observations from balloons, aircraft, satellites, and ground-based stations have been compared to European Space Agency (ESA) version 4.61 operational H2O data comprising the time period from July 2002 until March 2004 where MIPAS measured with full spectral resolution. No significant bias in the MIPAS H2O data is seen in the lower stratosphere (above the hygropause) between about 15 and 30 km. Differences of H2O quantities observed by MIPAS and the validation instruments are mostly well within the combined total errors in this altitude region. In the upper stratosphere (above about 30 km), a tendency towards a small positive bias (up to about 10%) is present in the MIPAS data when compared to its balloon-borne counterpart MIPAS-B, to the satellite instruments HALOE (Halogen Occultation Experiment) and ACE-FTS (Atmospheric Chemistry Experiment, Fourier Transform Spectrometer), and to the millimeter-wave airborne sensor AMSOS (Airborne Microwave Stratospheric Observing System). In the mesosphere the situation is unclear due to the occurrence of different biases when comparing HALOE and ACE-FTS data. Pronounced deviations between MIPAS and the correlative instruments occur in the lowermost stratosphere and upper troposphere, a region where retrievals of H2O are most challenging. Altogether it can be concluded that MIPAS H2O profiles yield valuable information on the vertical distribution of H2O in the stratosphere with an overall accuracy of about 10 to 30% and a precision of typically 5 to 15% – well within the predicted error budget, showing that these global and continuous data are very valuable for scientific studies. However, in the region around the tropopause retrieved MIPAS H2O profiles are less reliable, suffering from a number of obstacles such as retrieval boundary and cloud effects, sharp vertical discontinuities, and frequent horizontal gradients in both temperature and H2O volume mixing ratio (VMR). Some profiles are characterized by retrieval instabilities.

Final-revised paper