Cold Pool Responses to Changes in Soil Moisture
This study examines the role of soil moisture in modulating convective cold pool properties in an idealized modeling framework that uses a cloud‐resolving model coupled to an interactive land surface model. Five high‐resolution simulations of tropical continental convection are conducted in which th...
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| Published in: | Journal of advances in modeling earth systems 2020-08, Vol.12 (8), p.n/a |
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| Main Authors: | , , |
| Format: | Article |
| Language: | eng |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | This study examines the role of soil moisture in modulating convective cold pool properties in an idealized modeling framework that uses a cloud‐resolving model coupled to an interactive land surface model. Five high‐resolution simulations of tropical continental convection are conducted in which the initial soil moisture is varied. The hundreds of cold pools forming within each simulation are identified and composited across space and time using an objective cold pool identification algorithm. Several important findings emerge from this analysis. Lower soil moisture results in greater daytime heating of the surface, which produces a deeper, drier subcloud layer. As a result, latent cooling through the evaporation of precipitation is enhanced, and cold pools are stronger and deeper. Increased propagation speed, combined with wider rain shafts, results in wider cold pools. Finally, the rings of enhanced water vapor that surround each cold pool when soil is wet disappear when the soil moisture is reduced, due to the suppression of surface latent heat fluxes. Instead, short‐lived “puddles” of enhanced water vapor permeate the cold pools. The results are nonlinear in that the properties of the cold pools in the two driest‐soil simulations depart substantially from the cold pool properties in the three simulations initialized with wetter soil. The dividing line between the resulting wet‐soil and dry‐soil regimes is the permanent wilting point. Below the permanent wilting point, transpiration is subdued due to a sharp increase in water stress. These results emphasize the role of land surface‐boundary layer‐cloud interactions in modulating cold pool properties.
Plain Language Summary
When rain falls from storm clouds, some of the rain evaporates. In order to evaporate, the rain absorbs energy from the air around it, cooling the surrounding air. As the air cools, it becomes denser and accelerates toward the ground, forming a region of wind that blows downward (a “downdraft”). Then, upon reaching the surface, this cool, dense air collects and spreads out to form a cold pool. Cold pools are important because, as the cold pool spreads out, it pushes the environmental air in its path out of the way, forcing it upward. When this surrounding air is pushed upward, it can create a new storm cloud. In this study, we use computer model simulations to examine the effects of changing the wetness of the soil (the “soil moisture”) on the cold pools. We first identify and track |
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| ISSN: | 1942-2466 1942-2466 |