Indication of water vapor transport into the lower stratosphere above midlatitude convective storms:: Meteosat Second Generation satellite observations and radiative transfer model simulations

Past studies using a variety of satellite instruments have demonstrated the possibility of detecting lower stratospheric water vapor against a cold background of deep convective storm tops. The method is based on the brightness temperature difference (BTD) between the water vapor absorption and infrared window bands, assuming a thermal inversion above the cloud top level. This paper confirms the earlier studies, documenting positive BTD values between the 6.2 mu m and 10.8 mu m bands in Meteosat Second Generation (MSG) Spinning Enhanced Visible and InfraRed Imager (SEVIRI) imagery above tops of deep convective storms over Europe. The observed positive BTD values for a case from 28 June 2005 are compared to calculations from a radiative transfer model, and possible reasons for their existence are discussed. A localized increase in positive BTD is observed at the later stages of storm evolution, and this increase is likely a signal of water vapor being transported by this particular storm from the troposphere into the lower stratosphere. (C) 2008 Elsevier B.V. All rights reserved.