Stratospheric Profiling of HDO from Far Infrared Limb Measurements by TELIS

Abstract

Water vapour is the dominant greenhouse gas in the troposphere and has been increasing in the stratosphere as well. It is generally believed that stratospheric water vapor affects ozone chemistry in the stratosphere. HDO, one of the rare isotopologues, has been recently monitored by several operational satellite instruments by detecting thermal emission in the infrared and microwave range. The balloon-borne TELIS (Terahertz and submillimeter Limb Sounder) instrument has been cooperatively developed by a consortium of European institutes, i.e. DLR, SRON, and RAL. Together with MIPAS-B and mini-DOAS operated by KIT and Heidelberg University, respectively, TELIS was installed on a stratospheric balloon gondola and has participated in four scientific campaigns since 2009. The high spectral resolution spectrometer TELIS allows the vertical information of the rare isotopologues between about 10 and 40 km by resolving power of individual lines. The concentration profile of HDO in the upper tropospheric and lower stratospheric can be observed by both the 1.8 THz (far infrared) channel and the 480--650 GHz (submillimeter) channel. For the far infrared frequency channel, the HDO product is retrieved from the 1818.50 GHz transition. We make use of the retrieval code PILS (Profile Inversion for Limb Sounding) to carry out the inversion and to assess the accuracy of the retrieval product. In this work, we present the HDO retrievals from the 2009--2011 winter polar campaigns and compare the profiles with ones by other limb sounders, e.g. Odin/SMR, SCISAT/ACE-FTS, and Envisat/MIPAS. The outcome of this comparison helps us to better understand the measurement capabilities of the TELIS instrument and to make contribution to cross-validation of these spaceborne sensors.