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Microfronts in the nocturnal boundary layer
Author(s) -
Mahrt Larry
Publication year - 2019
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.3451
Subject(s) - stratification (seeds) , intermittency , turbulence , nocturnal , boundary layer , atmospheric sciences , turbulence kinetic energy , meteorology , climatology , warm front , environmental science , planetary boundary layer , cold front , potential temperature , geology , mechanics , physics , seed dormancy , botany , germination , astronomy , dormancy , biology
Previous studies of submeso motions in the nocturnal boundary layer have concentrated on wave‐like motions. Our study concentrates on common microfronts by analyzing three contrasting datasets. Passage of warm microfronts lead to increased wind speed, increased turbulent intensity and decreased stratification. These events have been previously examined indirectly in terms of patches of warmer turbulent air as part of turbulent intermittency. Cold microfronts generally lead to less turbulence mixing and greater stratification, although individual cold microfronts vary considerably. Both the warm and cold microfronts in our data are usually embedded within a thermally indirect circulation (rising cold air and sinking warm air). The kinetic energy required for this indirect circulation appears to be provided by deep propagating disturbances that extend above the surface inversion layer. The large variability of microfront structure at a given site and the variability between sites are examined.