Spaceborne Ka/W double-frequency cloud and rain radar particle spectrum inversion method based on variational analysis

Abstract

The invention discloses a spaceborne Ka / W double-frequency cloud and rain radar particle spectrum inversion method based on variational analysis. The method comprises the steps of: receiving Ka and W wave band reflectivity factor observations, namely ZKa and Zw, in a radar scanning radial direction; performing three-dimensional linear interpolation by using a numerical mode to obtain the temperature T of observation points; determining the characteristics of the particles on each observation point, and calculating the backscattering cross section and the disappearance cross section of the cloud precipitation particles in the Ka and W wave bands; with parameters Dm and Nw in a gamma distribution model used as state vectors of variational analysis, the ZKa and ZW used as observed quantities, constructing a cost function of variational analysis, and considering the reflectivity factor and unit distance attenuation of cloud precipitation particle spectrum calculation in an observation operator; and minimizing the cost function by using an LBFGSB algorithm, and introducing a condition that the state variable Dm is non-negative to obtain Dm, Nw and a cloud precipitation particle spectrum. According to the method, the problem that attenuation correction is difficult due to the fact that earth surface signals cannot be observed due to Ka and W frequency band radar electromagnetic wave intensity attenuation when heavy rainfall is observed is solved.

Description

technical field [0001] The invention relates to a particle spectrum inversion method for a spaceborne dual-frequency radar, in particular to a particle spectrum inversion method for a spaceborne Ka / W dual-frequency radar based on variational analysis. Background technique [0002] The spaceborne Ka / W dual-frequency cloud and rain measurement radar can measure the reflectivity factor of Ka and W frequency bands, that is, Z Ka and Z W . Due to the difference in the scattering characteristics of cloud and precipitation particles in the two different frequency bands of Ka and W, compared with conventional cloud radar and precipitation radar, the combined observation of reflectivity factors in dual frequency bands can obtain more cloud and rain particle information, which is useful for cloud and precipitation research. Provide an important data base. Among them, in natural cloud precipitation, there is a positive correlation between the dual-wavelength ratio DFR and the partic...

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is that when heavy precipitation is observed, the strong attenuation of the Ka and W frequency band radar signals leads to the observation of no surface signal, and the difficulty of attenuation correction, which in turn affects the inversion of the particle spectrum of the spaceborne Ka / W dual-frequency cloud and rain radar

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