Collective Impacts of Orography and Soil Moisture on the Soil Moisture-Precipitation Feedback
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Date
2017-11-28
Publication Type
Journal Article
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yes
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Abstract
Ensembles of convection-resolving simulations with a simplified land surface are conducted to dissect the isolated and combined impacts of soil moisture and orography on deep-convective precipitation under weak synoptic forcing. In particular, the deep-convective precipitation response to a uniform and a nonuniform soil moisture perturbation is investigated both in settings with and without orography. In the case of horizontally uniform perturbations, we find a consistently positive soil moisture-precipitation feedback, irrespective of the presence of low orography. On the other hand, a negative feedback emerges with localized perturbations: a dry soil heterogeneity substantially enhances rain amounts that scale linearly with the dryness of the soil, while a moist heterogeneity suppresses rain amounts. If the heterogeneity is located in a mountainous region, the relative importance of soil moisture heterogeneity decreases with increasing mountain height: A mountain 500 m in height is sufficient to neutralize the local soil moisture-precipitation feedback.
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published
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Journal / series
Volume
44 (22)
Pages / Article No.
11682 - 11691
Publisher
American Geophysical Union
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Edition / version
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Date collected
Date created
Subject
soil moisture-precipitation feedback; convection-resolving modeling; orography
Organisational unit
03360 - Schär, Christoph (emeritus) / Schär, Christoph (emeritus)
02717 - Institut für Atmosphäre und Klima / Inst. Atmospheric and Climate Science