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Conditional symmetric instability, frontogenetic forcing and rain‐band organization
Author(s) -
Lemaǐtre Y.,
Scialom G.,
Protat A.
Publication year - 2001
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.49712757806
Subject(s) - forcing (mathematics) , mesoscale meteorology , instability , snow , meteorology , atmosphere (unit) , atmospheric sciences , radar , physics , environmental science , climatology , geology , mechanics , computer science , telecommunications
The mesoscale organization and the thermodynamic structures of cloud bands and rain bands observed on 9 January 1988 during the seventh Intensive Observation Period of the European field experiment project FRONTS 87 are investigated using both radiosounding measurements and dual Doppler‐radar data. The combined role of the conditional symmetric instability (CSI) and of the frontogenetic forcing in this banded organization is quantitatively assessed. It is shown that the observations are in agreement with the subsequent scenario, cloud bands initiated by the large‐scale forcing in the presence of a weakly CSI unstable atmosphere evolve rapidly into CSI rolls. The detailed thermodynamics within one of these rain bands is shown to be in very good agreement with the ones predicted by the CSI theory. A different dynamic behaviour between the cloud bands and the rain bands is, however, shown. Some additional role is suspected to be played by microphysics processes, in particular by snow evaporation, in the reinforcement of CSI ascending motions.