ABSTRACT. The relationships between temperature, precipitation and radiation on glacier equilibrium lines are investigated, using 70 glaciers for which the mass balance and meteorological observations have been carried out for sufficiently long periods. It is found that the characteristic climate at glacier equilibrium lines can be described using the summer 3 months' temperature in a free atmosphere, annual total precipitation, and the sum of global and long-wave net radiation. All of these are measured at or very near the equilibrium-line altitudes. Then, it is shown how the shift of the equilibrium line will occur as a result of a climatic change. Finally, the effect of the shift of the equilibrium line on the annual mean specific mass balance is analytically derived and compared with observations. The present results make it possible to identify the altitudes in climate models where glacierization should begin, and to evaluate the mass-balance changes as a result of possible future changes in the climate.

The relationships between temperature, precipitation and radiation on glacier equilibrium lines are investigated, using 70 glaciers for which the mass balance and meteorological observations have been carried out for sufficiently long periods. It is found that the characteristic climate at glacier equilibrium lines can be described using the summer 3 months’ temperature in a free atmosphere, annual total precipitation, and the sum of global and long-wave net radiation. All of these are measured at or very near the equilibrium-line altitudes. Then, it is shown how the shift of the equilibriumline will occur as a result of a climatic change. Finally, the effect of the shift of the equilibrium line on the annualmean specific mass balance is analytically derived and compared with observations. The present results make it possible to identify the altitudes in climate models where glacierization should begin, and to evaluate the mass-balance changes as a result of possible future changes in the climate.

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The difficulties of the aerial survey of the Aletsch Glacier lay in establishing ground control in the high mountains and locally on the moving glacier surface, and in plotting featureless névés on the autograph. The major problem in plotting proved to be the delineation of the margins of active glaciers where marginal zones were thickly covered with debris or fresh snow, or where it was necessary to define the boundary between the active glacier and stagnant ice. The distinction between active and stagnant ice is based on movement and nourishment, that is, on characteristics not directly visible in the air photographs, and the boundary is too often a matter of personal judgment. The authors hold that this boundary would be better omitted on an accurate map of the type discussed, while the glacierized area should be represented only in so far as ice is clearly indicated by surface features. A further provisional boundary might be given to indicate suspected buried ice. The paper emphasizes the importance of favorable glacier conditions when the control photographs are taken, to facilitate the mapping and interpretation of glaciological features.

No abstract