Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft

1. Dive flight 8.03.03 flight 12.03.03 Dive Dive Dive Figure 7. The MIPAS-STR mounted in the instrument-tailored dorsal bay be-hind the pilot cabin. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft C. E. Blom, T. Gulde, M. Höpfner, C. Keim, G.Y. Liu, C. Piesch and C. Sartorius Forschungszentrum Karlsruhe GmbH, Institut für Meteorologie und Klimaforschung, Postfach 3640, 76021 Karlsruhe, FRG (cornelis.blom@imk.fzk.de) VALIDATION OF THE ENVISAT ATMOSPHERIC CHEMISTRY INSTRUMENTS BY CORRELATIVE MEASUREMENTS OF MIPAS-STR MIPAS-STR has been operated for ENVISAT validation from the high-altitude aircraft M55-Geophysica. We present results of the 22 July 2002 mid-latitude flight from Forli, Italy, close to the location of lower MIPAS-ENV tangent points for orbit 2051. In February/March 2003 an Arctic Geophysica campaign has been performed from Kiruna, Sweden, to validate gradients in the temperature and in the volume mixing ratio of the trace gases. We show examples of the MIPAS-STR measurements of the 8 March 2003 flight between Kiruna and Spitzbergen. Validation at middle latitudes: The 22 July 2002 flight from Forli, Italy Validation of gradients at high latitudes: Kiruna, February - March 2003 In July 2002 a Geophysica test campaign was extended with two flights aimed at an early validation of ENVISAT standard products. Below are results from the 22.06.2002 flight conducted with the so called chemistry payload, a combination of remote sensing and in-situ instruments. The results were presented at Envisat Validation Workshop in Frascati [1]. Profiles of HNO3 and O3 seem to agree well with the correlative measurements but vertical zigzag features, alternating for even and odd scans, are observed in the profiles of MIPAS-Envisat. This behaviour, not observed by MIPAS-STR, is mostly pronounced in the CH4 and N2O data from channel B but also present in the temperature profiles derived from channel A. It is probably caused by deficiencies in the radiometric calibration of the atmospheric spectra which is independently performed for forward and backward interferometer sweeps. Five flights were made with the Geophysica chemistry payload to validate gradients in the trace gas distributions measured by MIPAS, SCIAMACHY and GOMOS. No validation has yet been made but a few two-dimensional cross sections are shown to illustrate the measure-ments made by MIPAS-STR. Table 1. Coincidences of the MIPAS-STR and MIPAS-ENV measurements. Figure 1. Retrieved VMR profiles of O3 from MIPAS-STR and MIPAS-ENV. Figure 2. Retrieved VMR profiles of HNO3 from MIPAS-STR and MIPAS-ENV. Figure 9. The location of the tangent points of MIPAS-ENV and MIPAS-STR for the 08.03.03 and 12.03.03 flights. The points are colour coded depending on the tangent height (black for 6 km, red for 20 km). Note that the MIPAS-STR measurements of 08.03.03 are in the region of the SCIAMACHY limb measurements (see table 1). Figure 3. Retrieved VMR profiles of CH4 from MIPAS-STR#) and MIPAS-ENV. Figure 4. Retrieved temperature profiles from MIPAS-STR and MIPAS-ENV and the ECMWF analysis. Figure 5. The difference between the VMR of CH4 and the average profile of limb scans 7-17 (CH4 CH4mean) for MIPAS-ENV orbit 2051. Figure 6. The difference between temperature and mean temperature (T Tmean) of MIPAS-ENV orbit 2051. #) CFC-11 from channel 1 was used to obtain methane profiles: CH4 = 0.896 + 3200 × CFC-11. The coefficients are from HAGAR (High Altitude Gas chromatograph for Atmospheric Research) measurements for the 22.06.02 flight. MIPAS-STRatospheric aircraft:concept and strategy MIPAS-STR is a cryogenic mid IR (770-1940 cm-1; 5.15-13.0 µm) FT emission sounder [2]. Two-sided interferograms (L = 14 cm) are measured resulting in a spectral resolution (1/2L) of 0.035 cm-1. Data sampling is performed in time-equidistant mode [3] with accurate delay compensation to reduce noise due to sampling errors [4]. Low NESR, in flight < 8 nW/cm2·sr·cm-1 in channel 1 (770-1020 cm-1) and < 4 nW/cm2·sr·cm-1 in channel 2 (1150-1350 cm-1), and accurate pointing (1 arcmin precision) [5] has been achieved. After switch-on, the instru-ment runs fully autarkic according a predefined measurement strategy. Data retrieval is made with level-1 software [6], modified for continuous calibration measurements during the flight, and the level-2 Karlsruhe Optimized and Precise Radiative transfer Algorithm (KOPRA, [7]) with appropriate inversion routines [8]. The final results are 2-dimensional distributions of the trace gases in an altitude range covering the lowest stratosphere and the upper troposphere. Figure 10. Two-dimensional cross sections of the temperature and of HNO3, CFC-11 and ClONO2. The plots were made from 54 individual vertical profiles indicated with ‘+’ at the GPS altitude of the aircraft. Symbols in the lower part of the plots indicate the lowest tangent height used in the retrieval. The lowest tangent height is 6 km or, if clouds are in the field of view, higher. The clouds are monitored by the DC output of the detectors. About 10 sequences, measured before 2.6·104 s UTC, have not been analysed yet. Note the subsidence observed in the cross sections of the trace species when entering the polar vortex from the edge region. Refererences[1] G.Y. Liu, C.E. Blom, T. Gulde, C. Keim, M. Höpfner, P. Loës, C. Piesch, C. Sartorius and M. Volk, Validation of MIPAS on ENVISAT by correlative measurements of MIPAS-STR, Proceedings of "Envisat Validation Workshop", 9 -13 December 2002, Frascati, Italy (ESA SP-531), March 2003.[2] C. Piesch, T. Gulde, C. Sartorius, F. Friedl-Vallon, M. Seefeldner, M. Wölfel, C.E. Blom, and H. Fischer, Design of a MIPAS instrument for high-altitude aircraft, Proceedings of the 2nd Internat. Airborne Remote Sensing Conference and Exhibition, ERIM, Ann Arbor, MI, Vol. II, 199-208, 1996.[3] J. W. Brault, New approach to high-precision Fourier transform spectrometer design, Applied Optics, No. 35, 2891-2896, 1996. [4] W. Kimmig, Das Abtastverfahren der Interferogramme des flugzeuggetragenen Fourierspektrometers MIPAS-STR, Dissertation im Fach Physik, Universität Karlsruhe, Wissenschaftliche Berichte des Forschungszentrums Karlsruhe, FZKA 6665, 2001. [5] C. Keim, Entwicklung und Verifikation der Sichtlinienstabilisierung für MIPAS auf dem hochfliegenden Forschungsflugzeug M55 Geophysica, Dissertation im Fach Physik, Universität Karlsruhe, Wissenschaftliche Berichte des Forschungszentrums Karlsruhe, FZKA 6729, 2002.[6] Trieschmann, O, Level 0 to 1b Data Processing of the MIPAS-B2 balloon borne Fourier Transform Spectrometer, Technical Note, Document: PO-TN-IMK-GS-0003, ESA-Contract No. 11717/95/NL/CN and 12078/96/NL/GS, Revision 1.2, Karlsruhe, 17.05.2000 [7] Stiller, Gabriele P. (Editor) with contributions from T. v. Clarmann, A. Dudhia, G. Echle, B. Funke, N. Glatthor, F. Hase, M. Höpfner, S. Kellmann, H. Kemnitzer, M. Kuntz, A. Linden, M. Linder, G. P. Stiller, S. Zorn, The Karlsruhe Optimized and Precise Radiative transfer Algorithm (KOPRA), Forschungszentrum Karlsruhe, Wissenschaftliche Berichte des Forschungszentrums Karlsruhe, FZKA 6487, 2000. [8] M. Höpfner, C.E. Blom, T.v. Clarmann, H. Fischer, N. Glatthor, T. Gulde, F. Hase, C. Keim, W. Kimmig, K. Lessenich, C. Piesch, C. Sartorius, and G.P. Stiller, MIPAS-STR data analysis of APE-GAIA measurements, in IRS 2000: Current Problems in Atmospheric Radiation, W. L. Smith and Yu. M. Timofeyev (Eds.). A. Deepak Publishing, Hampton, Virginia. pp. 1136-1139, 2001. Figure 8. Measurement strategy Oversampled (tangent-height-sta-bilised, 1.25 km spaced) limb sounding and upward observa-tions with intermediate blackbody and deep-space measurements. Single sequences require about 2.5 min. resulting in a horizontal resolution in flight direction of 30 km. Acknowledgement Financial support by the Bundesministerium für Bildung und Forschung for the HGF-Vernetzungsfonds ”Generierung und Validierung von Datenprodukten aus Envisat-Messungen sowie deren Nutzung zur Erforschung der oberen Troposphäre und der Stratosphäre” (FKZ: 01SF9953) and through the Deutsches Zentrum fuer Luft- und Raumfahrt e.V. for the project ”Validierung von Datenprodukten des MIPAS-ENVISAT mittels Ballon-, Flugzeug- und bodengebundener Messungen” (FKZ: 50EE0203), the EU-project APE-INFRA (contract EVR1-CT2001-40020) and the European Space Agency is gratefully acknowledged. European Geophysical Society Nice, April 2003