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The role of radiation geometry in the climate response of Mount Kenya's glaciers, part 3: The latitude effect
Author(s) -
Kruss Phillip D.,
Hastenrath Stefan
Publication year - 1990
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.3370100309
Subject(s) - latitude , equator , geology , glacier , elevation (ballistics) , climatology , northern hemisphere , atmospheric sciences , physical geography , geometry , geodesy , geomorphology , geography , mathematics
Two earlier papers in this series investigated the role of solar radiation geometry in defining the glacier climate of Mount Kenya from the references of both horizontal and sloping surfaces. The present study examines the effect of latitude through a series of model simulations for clear‐sky conditions. This study answers the question about whether sloping or horizontal surfaces are the most appropriate for climatic heat and mass budget studies of glaciers throughout the region from 0° to 60° latitude, and also investigates, in quantitative terms, the latitude‐forced changes in radiation amount reaching high mountain glaciers owing to geometry effects. While preserving mountain topography, calculations were performed successively for the Equator, 15°, 30°, 45°, and 60°N and S. For the mountain as a whole, values tend to be larger for horizontal than for sloping surfaces, except for the domains poleward of 45° latitude. The altitudinal variation of radiation is, for the true equatorial location of Mount Kenya, characterized by an overall decrease upward, for both horizontal and sloping surfaces, as a consequence of the topographic obstruction increasing from the peripheral towards the central higher portions of the mountain. The altitudinal pattern changes with latitude, such that at 60°N radiation increases towards higher elevation bands, which are better exposed when solar elevation angles are low. Similar to results for the complete mountain, for the extremely steep southward facing Diamond Glacier, radiation drops off from the Equator towards the higher latitudes of the Southern Hemisphere, with values smaller for sloping than for horizontal surfaces. In the Northern Hemisphere, by contrast, the Diamond Glacier surface is most favourably oriented for radiation around 30–45°N. The latitude effect on the mountain climate is moderate within the tropical belt, while substantially different radiation characteristics result with a shift to high latitudes. Overall it is found that the use of a horizontal reference surface is as good an approximation, and typically an even more acceptable one, at higher latitudes than at the Equator. This is not so for only the steepest of glaciers.