Kirsten L. Findell, Pierre Gentine, Benjamin R. Lintner and Christopher Kerr
Nature Geoscience, 4, 434-439, doi:0.1038/NGEO1174, 2011.
Paper (PDF 1.4MB).
© Copyright 2011 by the Nature Publishing Group.
Abstract
Moisture and heat fluxes from the land surface to the atmosphere form a critical
nexus between surface hydrology and atmospheric processes, particularly those
relevant to precipitation. Although current theory suggests that soil moisture
generally has a positive impact on subsequent precipitation, individual studies
have shown support both for1-4 and against5-7 this positive feedback. Broad
assessment of the coupling between soil moisture and evapotranspiration, and
evapotranspiration and precipitation, has been limited by a lack of large-scale
observations. Quantification of the influence of evapotranspiration on precipitation
remains particularly uncertain. Here, we develop and apply physically based,
objective metrics for quantifying the impacts of surface evaporative and sensible
heat fluxes on the frequency and intensity of convective rainfall during summer,
using North American reanalysis data. We show that high evaporation enhances the
probability of afternoon rainfall east of the Mississippi and in Mexico. Indeed,
variations in surface fluxes lead to changes in afternoon rainfall probability of
between 10 and 25% in these regions. The intensity of rainfall, by contrast, is
largely insensitive to surface fluxes. We suggest that local surface fluxes represent
an important trigger for convective rainfall in the eastern United States and Mexico
during the summer, leading to a positive evaporation- precipitation feedback.
Citation Findell, K. L., P. Gentine, B. R. Lintner and C. Kerr, 1999: Probability of afternoon precipitation in eastern United States and Mexico enhanced by high evaporation. Nature Geoscience, 4, 434-439, doi:0.1038/NGEO1174, 2011.