Regional co-variability of spatial and temporal soil moisture–precipitation coupling in North Africa: an observational perspective
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Published:2018-06-13
Issue:6
Volume:22
Page:3275-3294
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ISSN:1607-7938
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Container-title:Hydrology and Earth System Sciences
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language:en
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Short-container-title:Hydrol. Earth Syst. Sci.
Author:
Petrova Irina Y.ORCID, van Heerwaarden Chiel C.ORCID, Hohenegger Cathy, Guichard Françoise
Abstract
Abstract. The magnitude and sign of soil moisture–precipitation coupling (SMPC) is
investigated using a probability-based approach and 10 years of daily
microwave satellite data across North Africa at a 1∘ horizontal scale.
Specifically, the co-existence and co-variability of spatial (i.e. using soil
moisture gradients) and temporal (i.e. using soil moisture anomaly) soil
moisture effects on afternoon rainfall is explored. The analysis shows that
in the semi-arid environment of the Sahel, the negative spatial and the
negative temporal coupling relationships do not only co-exist, but are also
dependent on one another. Hence, if afternoon rain falls over temporally
drier soils, it is likely to be surrounded by a wetter environment. Two
regions are identified as SMPC “hot spots”. These are the south-western
part of the domain (7–15∘ N, 10∘ W–7∘ E), with
the most robust negative SMPC signal, and the South Sudanese region
(5–13∘ N, 24–34∘ E). The sign and significance of the
coupling in the latter region is found to be largely modulated by the
presence of wetlands and is susceptible to the number of long-lived
propagating convective systems. The presence of wetlands and an irrigated
land area is found to account for about 30 % of strong and significant
spatial SMPC in the North African domain. This study provides the first insight
into regional variability of SMPC in North Africa, and supports the potential
relevance of mechanisms associated with enhanced sensible heat flux and
mesoscale variability in surface soil moisture for deep convection
development.
Publisher
Copernicus GmbH
Subject
General Earth and Planetary Sciences,General Engineering,General Environmental Science
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