Atmospheric Moisture Recycling: Role of Advection and Local Evaporation

Abstract

Abstract An approximate formulation of how much moisture that precipitates out comes from local evaporation versus horizontal transport, referred to as “recycling,” has allowed new estimates of recycling to be mapped globally as a function of length scale. The recycling is formulated in terms of the “intensity of the hydrological cycle” I, which is alternatively referred to as a “precipitation efficiency” as it denotes the fraction of moisture flowing through a region that is precipitated out, and a “moistening efficiency,” M, which is defined as the fraction of moisture evaporated from a region to that flowing through. While datasets of the pertinent quantities have improved, they still contain uncertainties. Results show that often the intensity is not greatest at times of greatest precipitation because moisture transport into the region is also a maximum, especially in the monsoonal regions. The annual cycle variations of I are fairly small over North America and Europe while large seasonal variations ...