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Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/hess-2017-530
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
12 Sep 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Hydrology and Earth System Sciences (HESS).
Regional co-variability of spatial and temporal soil moisture - precipitation coupling in North Africa: an observational perspective
Irina Y. Petrova1,a, Chiel C. van Heerwaarden2, Cathy Hohenegger1, and Françoise Guichard3 1Max Planck Institute for Meteorology, Hamburg, Germany
2Meteorology and Air Quality Group, Wageningen University, Wageningen, The Netherlands
3CRNM-GAME, CNRS-Météo France, Toulouse, France
anow at: Laboratory of Hydrology and Water Management, Ghent University, Ghent, Belgium
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 1° horizontal resolution. 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 studied at 100 km scale. 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 of 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 Sudanian 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 amount of long-lived propagating convective systems. The presence of wetlands and irrigated land areas is found to account for about 30 % of strong and significant spatial SMPC in North African domain. This study provides the first insight into regional variability of SMPC in North Africa, and supports potential relevance of mechanisms associated with enhanced sensible heat flux and meso-scale variability in surface soil moisture for deep convection development.

Citation: Petrova, I. Y., van Heerwaarden, C. C., Hohenegger, C., and Guichard, F.: Regional co-variability of spatial and temporal soil moisture - precipitation coupling in North Africa: an observational perspective, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2017-530, in review, 2017.
Irina Y. Petrova et al.
Irina Y. Petrova et al.
Irina Y. Petrova et al.

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Short summary
In North Africa rain storms can be as vital as devastating. The present study uses multi-year satellite data to better understand how and where soil moisture conditions affect development of rainfall in the area. Our results reveal two major regions, in the southwest and southeast, where drier soils show higher potential to cause rainfall development. This knowledge is essential for the hydrological sector, and can be further used by models to improve prediction of rainfall and droughts.
In North Africa rain storms can be as vital as devastating. The present study uses multi-year...
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