The response of lake levels and areas to climatic change |
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| Authors: | I M Mason M A J Guzkowska C G Rapley F A Street-Perrott |
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| Institution: | 1. Mullard Space Science Laboratory, University College London, Holmbury St. Mary, RH5 6NT, Dorking, Surrey, UK
3. Environmental Change Unit, University of Oxford, 1a Mansfield Road, OX1 3TB, Oxford, UK
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| Abstract: | The levels and areas of lakes, particularly closed lakes (those without outlet) are known to be sensitive indicators of changes in climate, and so in principle they can play a role in monitoring current and future climatic changes. In this paper we derive solutions to the water balance equation giving the response of the level and area of closed lakes to steps, spikes and sinusoidal variations in aridity, and show that such a lake acts approximately as a simple low pass filter having a characteristic equilibrium response timeτ e. We also review the similar response of open lakes to changes in runoff. It is shown howτ e depends on lake geomorphology and climate, and for a number of lakes we calculateτ e values, ranging from 1.5 to 350 yr for closed lakes, and from 2.9 days to 2 yr for open lakes. We propose methods involving Fourier analysis for inverting closed lake level or area records to obtain plots of a simple aridity index C. It is shown that for all ≈ 200 of the world's large (? 100 km2) closed lakes, satellite remote sensing of lake levels and areas is currently sensitive enough to monitor variations in C (e.g. in average basin precipitation) of order 1% to 10% on the time-scale of years to decades. |
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