Aufbau eines Wasserdampfradiometers und Messung von stratosphärischen Wasserdampfprofilen in den Tropen und in der Arktis

Abstract

This work discusses the development and deployment of a ground-based 22 GHz water vapour radiometer at a new tropical research station in Venezuela. The data analysis comprises data collected with a similar instrument in Ny-Ålesund, Spitsbergen, and with the new instrument on the Zugspitze, Germany during testing and finally in Venezuela. The new instrument is part of the ´´Mérida Atmospheric Research Station´´ (MARS) in Mérida/Venezuela. The facility was constructed in close collaboration with the Universidad de los Andes in Mérida, the Forschungszentrum Karlsruhe and the Universität Bremen. The drivers for the project were the validation activities for the SCIAMACHY instrument on ENVISAT. The WARAM 2 is the first permanent water vapour radiometer in the tropics and is now installed permanently on the Pico Espejo near Mérida, test operation started in March 2004. Measurements from the three sites Mérida, Zugspitze and Ny-Ålesund are presented in this work and a characterisation of the new instrument will be given. The main focus of this work lays on the retrieval of stratospheric water vapour profiles from the measured spectra. It was possible to calculate the distribution of water vapour over an altitude range from 25 km to 55 km with the Optimal Estimation Method. The vertical resolution in this altitude range increases from 12 km in the middle stratosphere to 16 km near the stratopause. Water vapour profiles from the three sites are in reasonable agreement with climatological data and some correlative data from an air borne instrument (AMSOS) and two space borne sensors (HALOE and MIPAS).