How Does the Partitioning of Evapotranspiration and Runoff between Different Processes Affect the Variability and Predictability of Soil Moisture and Precipitation?

摘要

Water stored as part of the land surface is lost to evapotranspiration and runoff on different time scales,and the partitioning between these time scales is important for modeling soil water in a climate model.Different time scales are imposed on evapotranspiration primarily because it is derived from differentreservoirs with different storage capacities, from the very rapid evaporation of canopy stores to the slowremoval by transpiration of rooting zone soil moisture. Runoff likewise ranges in time scale from rapidsurface terms to the slower base-flow. The longest time scale losses of water determine the slow variationof soil moisture and hence the longer time scale effects of soil moisture on precipitation. This paper showswith a simple analysis how shifting the partitioning of evapotranspiration between the different reservoirsaffects the variability of soil moisture and precipitation. In particular, it is concluded that a shift toshorter time scale reservoirs shifts the variance of precipitation from that which is potentially predictableto unpredictable.