Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 9 2 2009 10.5194/acpd-9-7971-2009 http://www.atmos-chem-phys-discuss.net/9/7971/2009/ http://www.atmos-chem-phys-discuss.net/9/7971/2009/acpd-9-7971-2009.html http://www.atmos-chem-phys-discuss.net/9/7971/2009/acpd-9-7971-2009.pdf 7971 7989 2009-03-25 IASI temperature and water vapor retrievals – error assessment and validation N. Pougatchev nikita.pougatchev@sdl.usu.edu T. August X. Calbet T. Hultberg O. Oduleye P. Schlüssel B. Stiller K. S. Germain G. Bingham Space Dynamics Laboratory, North Logan, Utah, USA EUMETSAT, Darmstadt, Germany German Meteorological Service, Meteorological Observatory, Lindenberg, Germany Integrated Project Office, Silver Spring, Maryland, USA The METOP-A satellite Infrared Atmospheric Sounding Interferometer (IASI) Level 2 products comprise retrievals of vertical profiles of temperature and water vapor. The error covariance matrices and biases of the most recent version (4.3.1) of the L2 data were assessed, and the assessment was validated using radiosonde data for reference. The radiosonde data set includes dedicated and synoptic time launches at the Lindenberg station in Germany. For optimal validation, the linear statistical Validation Assessment Model (VAM) was used. The VAM uses radiosonde profiles as input and provides optimal estimate of the nominal IASI retrieval by utilizing IASI averaging kernels and statistical characteristics of the ensembles of the reference radiosondes. For temperature temperatures above 900 mb and water retrievals above 700 mb, level expected and assessed errors are in good agreement. Below those levels, noticeable excess in assessed error is observed, possibly due to inaccurate surface parameters and undetected clouds/haze. Barret, B., De Maziere, M., and Mahieu, M: Ground-based FTIR measurements of CO from Jungfraujoch: characterization and comparison with in situ surface and MOPITT data, Atmos. Chem. Phys., 3, 4857–4878, 2003. Calbet, X., Schlüssel, P., Hultberg, T., Phillips, P., August, T.: Validation of the operational IASI level 2 processor using AIRS and ECMWF data, Adv. Space Res., 37, 2299–2305, 2006. Eyre, J. R.: Variational assimilation of remotely-sensed observations of the atmosphere, J. Met. Soc., 75(1B), 331–338, 1997. Global Space-based Inter-Calibration System (GSICS): http://www.orbit.nesdis.noaa.gov/smcd/spb/calibration/icvs/GSICS/index.html, last access: 2008. Lary, D. J. and Lait, L.: Using Probability Distribution Functions for Satellite Validation, Geoscience and Remote Sensing, IEEE Transactions, 44(5), 1359–1366, 2006. Migliorini, S., Piccolo, C., and Rodgers, C. D.: Intercomparison of direct and indirect measurements: Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) versus sonde ozone profiles, J. Geophys. Res., 109, D19316, doi:10.1029/2004JD004988, 2004. Pougatchev, N. S.: Validation of atmospheric sounders by correlative measurements, Appl. Opt., 47, 4739–4748, 2008. Rodgers, C. D. and Connor, B. J.: Intercomparison of remote sounding instruments, J. Geophys. Res., 108(D3), 4116, doi:10.1029/2002JD002299, 2003. Rodgers, C. D.: Retrieval of Atmospheric Temperature and Composition From Remote Measurements of Thermal Radiation, Rev. Geophys. Space Phys., 14, 609–624, 1976. Rodgers, C. D.: Characterization and error analysis of profiles retrieved from remote sounding measurements, J Geophys Res., 95, 5587–5595, 1990. Rodgers, C. D.: Inverse Methods for Atmospheric Sounding: Theory and Practice, World Scientific Publishing Co. Pte. Ltd., London, 2000. Schlüssel, P., Hultberg, T. H., Phillips, P. L., August, T., and Calbet, X.: The operational IASI Level 2 Processor, Adv. in Space Res., 36, 982–988, 2005. Smith, W. L., Larar, A. M., Mango, S. A., Howell, H. B., Knuteson, R. O., Revercomb, H. E., and Smith Jr., W. L.: The NOESS Sounding Testbed Interferometer – Remotely Sensed surface and atmospheric conditions during CLAMS, J. Atmos. Sci., 62, 1117–1133, 2005. Tobin, D. C., Revercomb, H. E., Knuteson, R. O., Lesht, B., Strow, L. L., Hannon, S. E., Feltz, W. F., Moy, L., Fetzer, E. J., and Cress, T: Atmospheric Radiation Measurement site atmospheric state best estimates for Atmospheric Infrared Sounder temperature and water vapor retrieval validation, J. Geophys. Res., 111, D09S14, doi:10.1029/2005JD006103, 2006. Vaisala Radiosonde RS92-SGP brochure: http://www.vaisala.com/files/Vaisala%20Radiosonde%20RS92-SGP%20brochure%202005.pdf, last access: 2009.