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Parametrization of ice‐particle size distributions for mid‐latitude stratiform cloud
Author(s) -
Field P. R.,
Hogan R. J.,
Brown P. R. A.,
Illingworth A. J.,
Choularton T. W.,
Cotton R. J.
Publication year - 2005
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 - 10.1256/qj.04.134
Subject(s) - parametrization (atmospheric modeling) , ice cloud , particle size distribution , ice nucleus , moment (physics) , cloud physics , ice crystals , environmental science , power law , precipitation , meteorology , atmospheric sciences , particle size , distribution (mathematics) , statistical physics , physics , cloud computing , mathematics , geology , classical mechanics , statistics , mathematical analysis , thermodynamics , computer science , nucleation , optics , paleontology , radiative transfer , operating system
Particle size distributions measured by the UK C‐130 aircraft in ice stratiform cloud around the British Isles are analysed. Probability distribution functions over large scales show that the zeroth, second and fourth moments (equivalent to concentration, ice water content and radar reflectivity) as well as mean particle size have monomodal distributions. Rescaling of the size distributions requiring knowledge of two moments reveals a ‘universal’ distribution that has been fitted with analytically integrable functions. The existence of the ‘universal’ distribution implies that two‐moment microphysics schemes are adequate to represent particle size distributions (PSDs). In large‐scale models it may be difficult to predict two moments, and so power laws between moments have been found as functions of in‐cloud temperature. This means that a model capable of predicting ice water content and temperature can predict ice PSDs to use for calculations requiring knowledge of the size distribution (e.g. precipitation rate, radar reflectivity) or to make direct use of the power laws relating moments of the size distribution. © Royal Meteorological Society, 2005. Contributions by P. R. Field, P. R. A. Brown and R. J. Cotton are Crown copyright.