rainreflectivity

Volume reflectivity of rain

Since R2021a

Syntax

volrefl = rainreflectivity(freq,rr)

volrefl = rainreflectivity(freq,rr,pol)

Description

volrefl = rainreflectivity(freq,rr) returns the volume reflectivity of rain, computed using the Marshall-Palmer Model.

volrefl = rainreflectivity(freq,rr,pol) specifies the polarization of the transmitted and received waves.

Examples

Rain Volume Reflectivity

Estimate the rain volume reflectivity of a side-looking airborne SAR operating in the L band at 1.5 GHz for rain rates of 0.25 mm/hr, 1 mm/hr, 4 mm/hr, and 16 mm/Hr.

f = 1.5e9;
rr = [0.25 1 4 16];

Compute the rain volume reflectivity.

volref = rainreflectivity(f,rr);

Plot the rain volume reflectivity as a function of the rain rate.

semilogx(rr,volref,'.-')
xlabel('Rain Rate (mm/hr)')
ylabel('Volume Reflectivity (dB/m)')

Input Arguments

freq — Radar frequency

positive real scalar | vector

Radar frequency in hertz, specified as a positive real scalar or a vector.

Data Types: double

rr — Rain rate

real scalar | vector

Rain rate in millimeters per hour, specified as a real scalar or a vector.

Data Types: double

pol — Polarization of transmitted and received waves

'HH' (default) | 'HV' | 'VV' | 'VH' | 'RCPRCP' | 'RCPLCP' | 'LCPLCP' | 'LR' | 'HRCP' | 'VLCP' | 'RCPV' | 'LCPH'

Polarization of transmitted and received waves, specified as one of these.

Value	Transmitted Wave	Received Wave
'HH'	Horizontal polarization	Horizontal polarization
'HV'	Horizontal polarization	Vertical polarization
'VV'	Vertical polarization	Vertical polarization
'VH'	Vertical polarization	Horizontal polarization
'RCPRCP'	Right-hand circular polarization	Right-hand circular polarization
'RCPLCP'	Right-hand circular polarization	Left-hand circular polarization
'LCPLCP'	Left-hand circular polarization	Left-hand circular polarization
'LR'	Left-hand polarization	Right-hand polarization
'HRCP'	Horizontal polarization	Right-hand circular polarization
'VLCP'	Vertical polarization	Left-hand circular polarization
'RCPV'	Right-hand circular polarization	Vertical polarization
'LCPH'	Left-hand circular polarization	Horizontal polarization

Data Types: char | string

Output Arguments

volrefl — Volume reflectivity of rain

matrix

Volume reflectivity (radar cross-section per unit volume) of rain in square meters per cubic meter, returned as a matrix. The rows of volref correspond to the radar frequency values in freq. The columns of volref correspond to the rain rate values in rr.

More About

Marshall-Palmer Model

The rain clutter reflectivity is computed based on the commonly used Marshall-Palmer drop-size distribution model. The model assumes raindrops are generally small with respect to the wavelength and are nearly spherical, indicating Rayleigh scattering.

The Marshall-Palmer model matches experimental results with measured data up to the Ka-band. Additionally, rain is not a static target, and exhibits its own motion spectrum. The motion spectrum is typically centered at some velocity with a recognizable velocity bandwidth. Data suggests a velocity bandwidth sometimes as high as 8 m/s, with a median velocity bandwidth of about 4 m/s.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2021a