Raindrop size distribution, DSD, is a critical microphysical parameter in the atmospheric science and cloud physics field.
computer science
Description
Raindrop Size Distribution
Raindrop
size distribution, DSD, is a critical microphysical parameter in the
atmospheric science and cloud physics field.
DSD varies with the intensity and type of rain. The different forms of
DSDs are highlighted below:
Exponential model- 
(Testik & Ana, 2007)
The
exponential model comprises of two parameters: a slope parameter 
and concentration parameter N0.
This model is better than M-P DSD since the latter is only equivalent to the
exponential model with a fixed N0.
Gamma model- 
(Testik & Ana, 2007)
Gamma
DSD is applied with a normalized parameter NW, whose value is equal
to the intercept parameters (,
m, and N0) of exponential DSD with the same median volume diameter,
D0, and water content. Its advantage is that parameters D0 and
NW have specific physical significance.
Log-normal model- 
(Joss & Encori, 1978)
In this model, NT refers to the total number of
concentration, 
the standard deviation and mean of the
Gaussian distribution. This model assumes that DSD parameters can be defined as
random variables from a multivariate Gaussian distribution.
Marshall and Palmer (M-P) model- 
(Rahman 2017)
M-P
model is a single DSD parameter model with a slope parameter.
This model was widely used in the last 50 years in radar-rain estimation and
bulk-scheme rain parameterization. This model considers a fixed N0
value and those experimental uncertainties are greater than the differences in
rainfall bulk characteristics such as radar or intensity reflectivity factor,
between the corresponding simpler exponential model and resulting gamma models.
The assumed form of DSD is important for remote rainfall sensing using weather
radars (Jameson & Kostinski, 2001). It is not possible to estimate Gamma
DSDs independently using radar observations; thus, they might not be useful in
rainfall microphysical observations using the High-Speed Optical Disdrometer
M-P DSD is better for measuring moderate rainfall intensity condition.
