On the Physics of High CAPE
Name
atsc-JAS-D-23-0060.1.pdf
Description
Published version
Size
13.98 MB
Format
Adobe PDF
Checksum (MD5)
0d7a846487dde670b6bb8246e4ffd73e
Author(s)
Emanuel, Kerry
Date Issued
November 10, 2023
Journal
Journal of the Atmospheric Sciences
Publisher
American Meteorological Society
Citation
Emanuel, K., 2023: On the Physics of High CAPE. J. Atmos. Sci., 80, 2669–2683.
Version
Final published version
Abstract
Large values of convective available potential energy (CAPE) are an important ingredient for many severe convective storms, yet there has been comparatively little research on how, physically, such large values arise or why they take on the observed values and climatology. Here we build on recently published observational and theoretical work to construct a simple, one-dimensional coupled soil–atmosphere model of preconvective boundary layer growth, driven by a single diurnal cycle of prescribed net surface radiation. Based on this model and previously published research, we suggest that high CAPE (>∼1000 J kg−1) results when air masses that have been significantly modified by passage over dry, lightly vegetated soils are advected over moist and/or moderately vegetated soils and then exposed to surface solar heating. Several diurnal cycles may be needed to raise the moist static energy of the boundary layer to levels consistent with high CAPE. The production of CAPE and erosion of convective inhibition (CIN) are strongly affected by the potential temperature of the desert-modified air mass, the level of near-surface soil moisture (and root-zone soil moisture if significant vegetation is present), the type of soil, and the characteristics of the vegetation. Consequently, CAPE production and severe convective weather may be significantly affected by regional-scale land-use changes and by climate change.
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DOI of Published Version
https://doi.org/10.1175/JAS-D-23-0060.1
