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rainreflectivity

Volume reflectivity of rain

    Description

    example

    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

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    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)')

    Figure contains an axes object. The axes object contains an object of type line.

    Input Arguments

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

    Data Types: double

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

    Data Types: double

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

    ValueTransmitted WaveReceived Wave
    'HH'Horizontal polarizationHorizontal polarization
    'HV'Horizontal polarizationVertical polarization
    'VV'Vertical polarizationVertical polarization
    'VH'Vertical polarizationHorizontal polarization
    'RCPRCP'Right-hand circular polarizationRight-hand circular polarization
    'RCPLCP'Right-hand circular polarizationLeft-hand circular polarization
    'LCPLCP'Left-hand circular polarizationLeft-hand circular polarization
    'LR'Left-hand polarizationRight-hand polarization
    'HRCP'Horizontal polarizationRight-hand circular polarization
    'VLCP'Vertical polarizationLeft-hand circular polarization
    'RCPV'Right-hand circular polarizationVertical polarization
    'LCPH'Left-hand circular polarizationHorizontal polarization

    Data Types: char | string

    Output Arguments

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    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

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    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™.

    Introduced in R2021a