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Modeling rainfall drop size distribution in southern England using a Gaussian Mixture Model
Author(s) -
Ekerete K'ufreMfon E.,
Hunt Francis H.,
Jeffery Judith L.,
Otung Ifiok E.
Publication year - 2015
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1002/2015rs005674
Subject(s) - log normal distribution , gamma distribution , environmental science , goodness of fit , meteorology , gaussian , statistics , statistical physics , attenuation , mathematics , exponential function , probability distribution , atmospheric sciences , physics , mathematical analysis , quantum mechanics , optics
Understanding and modeling the rainfall drop size distribution is important in a number of applications, in particular predicting and mitigating attenuation of satellite signals in the millimeter band. Various standard statistical distributions have been proposed as suitable models, the first widely accepted being the exponential distribution. Subsequently, gamma and lognormal distributions have been shown to provide better rainfall rate computations. Some empirical studies have revealed bimodal distributions under some circumstances. A natural question to ask therefore is how often gamma and lognormal distributions fit the empirical data. In this paper we fit lognormal and gamma distributions to 1 min slices of rainfall drop size distributions taken from 7 year data from the Chilbolton Observatory in southern England. The chi‐square goodness of fit of the models against the data is calculated, and it is found that failure to fit is greater than would normally be expected. This failure to fit is broken down and examined against seasonal variations, different rain rates, atmospheric temperature, and wind speed. Possible reasons for the lack of fit are explored, and alternative fits using models based on Gaussian Mixture Models are developed and found to be an improvement.