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Preferential states in soil moisture and climate dynamics.
Paolo D'Odorico1, Amilcare Porporato
1Department of Environmental Sciences, University of Virginia, 291 McCormick Road, Box 400123, Charlottesville, VA 22904-4123, USA. paolo@virginia.edu
Summary
Summer soil moisture anomalies in continental regions influence subsequent precipitation probability. This land-atmosphere feedback can lock soil moisture into persistent dry or wet states, explaining prolonged summer droughts.
Area of Science:
- Earth and Environmental Sciences
- Atmospheric Science
- Hydrology
Background:
- Summer precipitation in midlatitude continental regions relies heavily on local moisture recycling via evapotranspiration.
- Reduced soil moisture can limit evapotranspiration, impacting planetary boundary layer dynamics through heat flux partitioning.
Purpose of the Study:
- To provide theoretical and experimental evidence for the hypothesis that summer soil moisture anomalies affect subsequent precipitation probability in continental regions.
- To investigate the feedback mechanisms between land surface moisture and atmospheric processes.
Main Methods:
- Theoretical modeling of land-atmosphere interactions.
- Experimental data analysis to support the hypothesis.
Main Results:
- Evidence supports a dependence between precipitation and antecedent soil moisture conditions.
- Summer soil moisture dynamics exhibit two preferential states: 'dry' and 'wet', with intermediate conditions being less probable.
- Positive feedbacks can sustain prolonged summer droughts initiated by spring surface moisture anomalies.
Conclusions:
- Land-atmosphere interactions play a crucial role in the persistence of summer droughts.
- Soil moisture anomalies can significantly influence regional precipitation patterns and drought duration.