Energy exchange at a glacier surface: an alternative to aerodynamic methods of measurement
Analysis of wind-speed measurements made over a six-month period on an Antarctic glacier showed that conditions near the surface were dominated by gravity winds flowing downhill. In such conditions there is no satisfactory method of calculating the amount of energy exchanged between the glacier and the atmosphere. It is also difficult to extrapolate satisfactorily energy changes measured at a single point to the whole glacier. Moreover the loss of five days’ meteorological records may cause an error as large as the total change in energy content of the glacier during a year. In view of these difficulties it is more fruitful to measure the changes in energy content of the glacier directly. This can be done by accurate measurements of ice temperature and density near the surface. By defining the total energy content of a glacier as the heat required to melt it, fractional changes in the energy content and mass occurring over a year are equal and indicate the probable lifetime of the glacier. Estimates based on data from an Antarctic glacier suggest that the long-term change of energy of the glacier (≈ 1.5 W/m2) could be measured with an accuracy of 10% within a year.