Solar Radiation Measurements in the High Himalayas (Everest Region)

Abstract

This paper discuses the solar radiation data assembled during the two recent expeditions to the Everest area. These were the Himalayan Scientific and Mountaineering Expedition of 1960?61, led by Sir Edmund Hillary, and the American Mount Everest Expedition of 1963, led by Norman Dyhrenfurth. Measurements were made at about 19,000 and 18,000 ft, respectively, in the Northern Hemisphere spring, the first series being conducted under generally cloudless conditions and the second with mainly cloudy skies. The observations included not only (a) total incoming sun and sky radiation received on a horizontal surface (global radiation), but also (h) the reflected component (short-wave albedo) from glacial and firm surfaces under different snow conditions, and (c) the subdivision of the radiant fluxes into spectral bands. The 1961 series extended over about 20 days and the 1963 series over 50 days. It is believed that the figures presented here are the first to be published for this type of information at altitudes approaching 20,000 ft, from ground-based instrumentation. Problems arising from the nature of the exposure of the instruments, especially considering the fact that the observing sites are essentially high valleys and not isolated mountain peaks, are discussed.