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Characteristics of cold pools observed in narrow valleys and dependence on external conditions
Author(s) -
Sheridan P. F.,
Vosper S. B.,
Brown A. R.
Publication year - 2013
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.2159
Subject(s) - transect , radiosonde , geology , inversion (geology) , terrain , cold front , atmospheric sciences , inversion temperature , drop (telecommunication) , warm front , meteorology , environmental science , geomorphology , geography , oceanography , structural basin , telecommunications , cartography , computer science
Observations from the recent COLd‐air Pooling EXperiment (COLPEX) field campaign are used to relate the intensity of cold pools within two small valleys (O(100 m) depth and O(1 km) width) to flow conditions within the airmass passing over the valley. The temperature structure of the cold pools is examined using transects of ground‐based sensors through the valleys and radiosonde releases from within the valley, in order to evaluate simple two‐dimensional concepts of cold‐pool formation due to sheltering. The cold‐pool spatial and temporal structure is found to be consistent between different nights when strong cold pools occurred. Initially a sharp surface inversion occurs similarly at all points within the valley, with isentropes roughly terrain‐parallel. The inversion layer at the bottom of the valley then grows deeper, spreading over the bottom portion of the valley, and cross‐valley isentropes eventually become horizontal. By defining appropriate measures of the relative temperature drop within the cold pool, and non‐dimensional valley depth diagnosed with respect to the speed and stability of the approaching flow, the measurements are shown to be consistent with previous relationships determined for simple two‐dimensional valleys.