Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 399685
Title Effects of soil moisture gradients on the path and the intensity of a West African squall line
Author(s) Wolters, D.; Heerwaarden, C.C. van; Vilà-Guerau de Arellano, J.; Cappelaere, B.; Ramier, D.
Source Quarterly Journal of the Royal Meteorological Society 136 (2010)653. - ISSN 0035-9009 - p. 2162 - 2175.
Department(s) Meteorology and Air Quality
Publication type Refereed Article in a scientific journal
Publication year 2010
Keyword(s) mesoscale convective complexes - land-surface - monsoon - variability - sahel - model - precipitation - dynamics - system - field
Abstract During the West African monsoon season, precipitation is strongly coupled to soil moisture availability. This interaction is generally understood as a positive feedback mechanism, and has been considered on very different spatial and temporal scales. Past research has mainly focused on this feedback in terms of the effects on general precipitation patterns, not on a single convective system. In this research, a single squall line is reproduced using the Weather Research and Forecasting Advanced Research (WRF-ARW) mesoscale weather model. Model results are analyzed and compared with surface and upper-air observations. A sensitivity analysis on the influence of soil moisture on the squall line is performed through five numerical experiments. In four experiments, soil moisture is increased or decreased with respect to a control experiment. This is done in two manners: by affecting soil moisture most strongly in the wetter places in the modelled domain and by affecting soil moisture most strongly in the drier places. Minor deviations occur in the path of the squall line after modifying soil moisture most strongly in the wetter places. Systematic deviations occur in its path after increasing soil moisture most strongly in the drier places. A mechanism is proposed that connects the applied soil moisture modifications to larger-scale flow patterns that determine the path of the squall line. In all five experiments, the precipitation intensity of the squall line strongly declines when the systemmoves towards western areaswith lower soil moisture values. It is concluded that a positive effect of local soil moisture on precipitation intensity in passing squall lines is likely on the considered length-scale of 100 km. Until now, this mechanism has only been shown for much smaller spatial scales.
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