References

ACP

Atmospheric Chemistry and Physics

ACP

1680-7324

Copernicus GmbH

Göttingen, Germany

10.5194/acp-7-4905-2007

Validation of MIPAS HNO3 operational data

Wang

D. Y.

¹ ² Höpfner

¹ Blom

C. E.

¹ Ward

W. E.

² Fischer

¹ Blumenstock

¹ Hase

¹ Keim

¹ Liu

G. Y.

¹ Mikuteit

¹ Oelhaf

¹ Wetzel

¹ Cortesi

³ Mencaraglia

³ Bianchini

³ Redaelli

⁴ Pirre

⁵ Catoire

⁵ Huret

⁵ Vigouroux

⁶ De Mazière

⁶ Mahieu

⁷ Demoulin

⁷ Wood

⁸ Smale

⁸ Jones

⁹ Nakajima

¹⁰ Sugita

¹⁰ Urban

¹¹ Murtagh

¹¹ Boone

C. D.

¹² Bernath

P. F.

¹² ¹³ Walker

K. A.

¹² ¹⁴ Kuttippurath

¹⁵ ¹⁶ Kleinböhl

¹⁵ ¹⁷ Toon

¹⁷ Piccolo

¹⁸

Institut für Meteorologie und Klimaforschung (IMK),Forschungszentrum Karlsruhe und Universität Karlsruhe, Karlsruhe, Germany

Physics Department, University of New Brunswick, Fredericton, New Brunswick, Canada

Istituto di Fisica Applicata "N.~Carrara" (IFAC) del Consiglio Nazionale delle Ricerche (CNR), Firenze, Italy

Dipartimento di Fisica,CETEMPS, Universita' di L'Aquila, L'Aquila, Italy

Laboratoire de Physique et Chimie de l'Environnement, Université d'Orléans (LPCE-CNRS), Orléans, France

Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium

Institut d'Astrophysique et de Géophysique, University of Liège (ULg), Liège, Belgium

National Institute for Water and Atmospheric Research (NIWA), Lauder, Otago, New Zealand

University of Wollongong, Wollongong, Australia

National Institute for Environmental Studies, Tsukuba, Japan

Department of Radio and Space Science, Chalmers University of Technology, Göteborg, Sweden

Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada

Department of Chemistry, University of York, Heslington, York, UK

Department of Physics, University of Toronto, Toronto, Canada

Institute of Environmental Physics, University of Bremen, Bremen, Germany

CNRS/LMD Ecole Polytechnique, Palaiseau Cedex, France

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA

Department of Physics, Oxford University, Oxford, UK

21 09 2007

7 18 4905 4934

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Nitric acid (HNO3) is one of the key products that are operationally retrieved by the European Space Agency (ESA) from the emission spectra measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard ENVISAT. The product version 4.61/4.62 for the observation period between July 2002 and March 2004 is validated by comparisons with a number of independent observations from ground-based stations, aircraft/balloon campaigns, and satellites. Individual HNO3 profiles of the ESA MIPAS level-2 product show good agreement with those of MIPAS-B and MIPAS-STR (the balloon and aircraft version of MIPAS, respectively), and the balloon-borne infrared spectrometers MkIV and SPIRALE, mostly matching the reference data within the combined instrument error bars. In most cases differences between the correlative measurement pairs are less than 1 ppbv (5–10%) throughout the entire altitude range up to about 38 km (~6 hPa), and below 0.5 ppbv (15–20% or more) above 30 km (~17 hPa). However, differences up to 4 ppbv compared to MkIV have been found at high latitudes in December 2002 in the presence of polar stratospheric clouds. The degree of consistency is further largely affected by the temporal and spatial coincidence, and differences of 2 ppbv may be observed between 22 and 26 km (~50 and 30 hPa) at high latitudes near the vortex boundary, due to large horizontal inhomogeneity of HNO3. Similar features are also observed in the mean differences of the MIPAS ESA HNO3 VMRs with respect to the ground-based FTIR measurements at five stations, aircraft-based SAFIRE-A and ASUR, and the balloon campaign IBEX. The mean relative differences between the MIPAS and FTIR HNO3 partial columns are within ±2%, comparable to the MIPAS systematic error of ~2%. For the vertical profiles, the biases between the MIPAS and FTIR data are generally below 10% in the altitudes of 10 to 30 km. The MIPAS and SAFIRE HNO3 data generally match within their total error bars for the mid and high latitude flights, despite the larger atmospheric inhomogeneities that characterize the measurement scenario at higher latitudes. The MIPAS and ASUR comparison reveals generally good agreements better than 10–13% at 20–34 km. The MIPAS and IBEX measurements agree reasonably well (mean relative differences within ±15%) between 17 and 32 km. Statistical comparisons of the MIPAS profiles correlated with those of Odin/SMR, ILAS-II, and ACE-FTS generally show good consistency. The mean differences averaged over individual latitude bands or all bands are within the combined instrument errors, and generally within 1, 0.5, and 0.3 ppbv between 10 and 40 km (~260 and 4.5 hPa) for Odin/SMR, ILAS-II, and ACE-FTS, respectively. The standard deviations of the differences are between 1 to 2 ppbv. The standard deviations for the satellite comparisons and for almost all other comparisons are generally larger than the estimated measurement uncertainty. This is associated with the temporal and spatial coincidence error and the horizontal smoothing error which are not taken into account in our error budget. Both errors become large when the spatial variability of the target molecule is high.

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