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A climatology of convective available potential energy in Great Britain
Author(s) -
Holley D. M.,
Dorling S. R.,
Steele C. J.,
Earl N.
Publication year - 2014
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.3976
Subject(s) - convective available potential energy , cape , climatology , environmental science , convective instability , convective inhibition , convection , geography , meteorology , geology , natural convection , archaeology , combined forced and natural convection
Deep moist convection ( DMC ) requires three ingredients: instability, moisture and lift. One measure that incorporates two of these, instability and moisture, is convective available potential energy ( CAPE ). A 10‐year climatology of CAPE over Great Britain is presented covering the period 1 June 2002–31 May 2012, based on a 9‐km grid spacing implementation of the Weather Research and Forecasting ( WRF ) model, with two‐way interactive nesting. Appropriate tests are carried out to verify model reliability by comparing simulated and observed CAPE . CAPE is found to be highly variable both spatially and temporally, the highest values being produced during Spanish plume events. A strong relationship is confirmed between surface temperature and CAPE magnitude, the highest CAPE across Great Britain during this period locally exceeding 3000 J kg −1 . In an average year, 15 days produce CAPE in excess of 500 J kg −1 somewhere in Great Britain, 4 days > 1000 J kg −1 and 1 day > 1500 J kg −1 . Three main CAPE seasons are identified: ‘land dominated CAPE ’ between April and September, ‘sea dominated CAPE ’ between September and January and ‘low CAPE ’ from January to April. The southern North Sea witnesses significant CAPE all year round because of a combination of favourable synoptic situations, including warm air plumes in spring/summer and cold air incursions over warmer seas in winter. CAPE is not a direct predictor of thunderstorm incidence, due in part to the confounding effect of convective inhibition ( CIN ). However, at the annual scale, when comparing against an existing days of thunder climatology, we observe a close correspondence with >500 J kg −1 CAPE frequency.