An Analysis and Comparison of Satellite-Observed

Cloud Cover and Water Vapor at Hanle, India and Yanbajing, Tibet

Project Status: Completed January, 2004

Reports: The final report is now available for general release to interested parties (contact D. Andre Erasmus for more information on obtaining a copy) 

Project Overview

Two sites in the Himalayan region are being considered for next-generation Imaging Atmospheric Cherenkov Telescopes (IACTs) by the Max Planck Institute (MPI) for Nuclear Physics (MPIK). According to criteria provided by MPIK, these sites would need to be located at high altitude to realize an improved light yield and reduce absorption in the atmosphere. As is the case with optical telescopes, a large fraction of cloud-free nights is required. An analysis of satellite data can therefore provide the information needed to evaluate observing conditions at potential IACT sites. The sites considered in this study are Hanle (32.78^o N, 78.96^o E) in India and Yanbajing (30.11^o N, 90.53^o E) in Tibet.

There are three main components to the site comparison:

(i) An analysis of cloud cover and water vapor at the two sites

(ii) A climatological analysis and evaluation of the study period in relation to long-term climatic conditions

(iii) A mapping of cloud cover over an area (~ 100 km x 100 km) around Yanbajing

The satellite data set covers the period from July 1998 to June 2003 (with a 2½ month gap from 15 October - 31 December, 2001).