Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 8 4 2008 10.5194/acpd-8-13775-2008 http://www.atmos-chem-phys-discuss.net/8/13775/2008/ http://www.atmos-chem-phys-discuss.net/8/13775/2008/acpd-8-13775-2008.html http://www.atmos-chem-phys-discuss.net/8/13775/2008/acpd-8-13775-2008.pdf 13775 13799 2008-07-18 Water vapor transport in the lower mesosphere of the subtropics: a trajectory analysis T. Flury S. C. Müller K. Hocke N. Kämpfer Institute of Applied Physics, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland The Institute of Applied Physics operates an airborne microwave radiometer that measures the rotational transition line of water vapor at 183.3 GHz. Measurements were acquired on board a Learjet once a year in the period 1998 to 2006. Water vapor profiles are retrieved for the altitude range from 15 to 75 km along the flight track. We report on a water vapor enhancement in the lower mesosphere above India and the Arabic Sea measured on our flight mission in November 2005 conducted during EC-project SCOUT-O3. The flight led from Switzerland to Australia and back. We find an enhancement of up to 25% in the lower mesospheric H₂O volume mixing ratio measured on the return flight one week after the outward flight. The origin of the air is traced back by means of a trajectory model in the lower mesosphere. During the outward flight the air came from the Carribean and crossed the Atlantic Ocean. On the return flight the air came from China and orginated from mid latitudes. Thus the large variability of H₂O VMR during our flight is explained by a change of the winds in the lower mesosphere. Berger, U.: Modeling of middle atmosphere dynamics withLIMA, J. Atmos. Solar Terr. Phys., 70, 8–9, 1170–1200, \doi10.1016/j.jastp.2008.02.004, June 2008. Brasseur, G P. and Solomon, S.: Aeronomy of the Middle Atmosphere Chemistry and Physics of the Stratosphere and Mesosphere Series: Atmospheric and Oceanographic Sciences Library, vol. 32, 3rd rev. and enlarged ed., XII, 646 pp., Hardcover, ISBN: 978-1-4020-3284-4, 2005. Buehler, S., Eriksson, P., Kuhn, T., von Engeln, A., and Verdes, C.: ARTS, the Atmospheric Radiative Transfer Simulator, J. Quant. Spectrosc. Ra., 91, 65–93, 2005. Deuber, B., Haefele, A., Feist, D G., Martin, L., Kampfer, N., Nedoluha, G E., Yushkov, V., Khaykin, S., Kivi, R., and Vömel, H.: Middle Atmospheric Water Vapour Radiometer – MIAWARA: Validation and first results of the LAUTLOS/WAVVAP campaign, J. Geophys. Res., 110, D13306, \doi10.1029/2004JD005543, 2005. Eriksson, P., Jimenés, C., and Buehler, S A.: Qpack, a general tool for instrument simulation and retrieval work, J. Quant. Spectrosc. Ra., 91, 47–64, \doi10.1016/j.jqsrt.2004.05.050, 2005. Feist, D G., Geer, A J., Müller, S., and Kämpfer, N.: Middle atmosphere water vapour and dynamical features in aircraft measurements and ECMWF analyses, Atmos. Chem. Phys., 7, 5291–5307, 2007. Fleming, E. L., Chandra, S., Barnett J. J., and Corney, M.: Zonal mean temperature, pressure, zonal wind and geopotential height as functions of latitude, Adv. Space Res., 10, 12, 11–59, doi:10.1016/0273-1177(90)90383-E, 1990. Hoppel, K W., Baker, N L., Coy, L., Eckermann, S D., McCormack, J P., Nedoluha, G E., and Siskind, D E.: Assimilation of stratospheric and mesospheric temperatures from MLS and SABER into a global NWP model, Atmos. Chem. Phys. Discuss., 8, 8455–8490, 2008. Müller, S., Kämpfer, N., Feist, D., Haefele, A., Milz, M., Sitnikov, N., Schiller, C., Kiemle, C., and Urban, J.: Validation of stratospheric water vapour measurements from the airborne microwave radiometer AMSOS, Atmos. Chem. Phys., 8, 3169–3183, 2008. Plumb, R A.: A "tropical pipe" model of stratospheric transport, J. Geophys. Res., 101, 3957–3972, \doi10.1029/95JD03002, 1996. Rodgers, C D.: Inverse Methods for Atmospheric Sounding: Theory and Practice, vol 2 of Series on atmospheric, oceanic and planetary physics, World Scientific Publishing Co. Pte. Ltd., P.O. Box 128, Farrer Road, Singapore 912805, 2000. Shepherd, T G.: The middle atmosphere, J. Atmos. Sol.-Terr. Phy., 62, 1587–1601, 2000. Sonnemann, G R. and Grygalashvyly, M.: The zonal wind effect on the photochemistry within the mesosphere/mesopause region, Adv. Space Res., 32, 719–724, \doi10.1016/S0273-1177(03)00406-X, 2003. Vasic, V., Feist, D G., Müller, S., and Kämpfer, N.: An airborne radiometer for stratospheric water vapor measurements at 183 GHz, IEEE T. Geosci. Remote, 43, 1563–1570, \doi10.1109/TGRS.2005.846860, 2005.