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Title: Land and atmospheric controls on initiation and intensity of moist convection: CAPE dynamics and LCL crossings

item YIN, JUN - Duke University
item ALBERTSON, JOHN - Duke University
item Rigby Jr, James
item PORPORATO, AMILCARE - Duke University

Submitted to: Water Resources Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/8/2015
Publication Date: 10/28/2015
Publication URL:
Citation: Yin, J., Albertson, J., Rigby Jr, J.R., Porporato, A. 2015. Land and atmospheric controls on initiation and intensity of moist convection: CAPE dynamics and LCL crossings. Water Resources Research. 51: 8476–8493, doi: 10.1002/2015WR017286.

Interpretive Summary: Convective precipitation can be some a driver of flooding and erosion and is often difficult to predict. This work extends earlier models of the daytime growth of the atmospheric boundary layer to understand the development of available convective energy and how surface conditions such as soil moisture influence the potential for precipitation. Models of atmospheric convection such as this are valuable for understanding the fundamental behavior of these systems as well as for use in larger scale models used in weather and climate prediction.

Technical Abstract: The local role that land-atmosphere interactions play in the rainfall process has been explored by investigating the initiation of moist convection as the top of the atmospheric boundary layer (ABL) crosses the lifting condensation level (LCL). However, this LCL crossing alone is not a sufficient indicator of the probability and intensity of subsequent convective precipitation, which is instead better characterized by the so-called convective available potential energy (CAPE). In this study, both the LCL crossing and CAPE are jointly considered as the primary indicators of the occurrence and intensity of moist convection in order to analyze the land-atmosphere interactions through a simple soil-plant system and a zero-dimensional mixed-layer model. For the free atmospheric conditions observed at the Central Facility in the Southern Great Plains, the ABL analysis shows both dry and wet soil can be conducive to early moist convection depending on atmospheric conditions but CAPE always tends to be larger under wetter soil conditions. The combination of the two indicators LCL crossing and CAPE further allows us to classify free atmosphere and soil moisture regimes into positive and negative feedback regimes for moist convection.