A retrieval algorithm based on optimal estimation theory for ice cloud properties， including effective radius （re）， ice water content （IWC） and particle number concentration （NT）， has been investigated with simulated radar reflectivity factor （Ze） at 220 GHz in this paper.Four ice crystal habits， including spherical， hexagonal column， plate， and six-branch bullet rosette， are considered.Assuming a modified Gamma partical size distribution （PSD）， Look up table （LUT） has been build based on the scattering properties of spherical and nonspherical ice cloud particles at 220 GHz.Simulated Ze in LUT represents the measured vector， corresponding re and IWC is taken as a priori xa（rea， IWCa）， then rere、 IWCre and NTre are retrieved based on optimal estimation theory.If xa equals the simulated true solution， the retrieval results seem nearly the same with the truth.When xa is far from the truth， the algorithm still successfully find a solution close to the truth through several iterations because simulated radar measurement Ze contains significant information of ice cloud properties， which indicate that the algorithm does not only rely on the a priori accuracy.The algorithm error analysis shows， as xa getting closer to the true solution， retrieval error and iteration number became smaller， which demonstrate that a better a priori can improve the retrieval accuracy and speed up the convergence process.This algorithm is expected to be applied to the cirrus cloud microphysical parameter retrieval for Terahertz Cloud radar.
Xia DING
,
Xingyou HUANG
,
Jing HE
,
Yiwei HUO
,
Haitao WANG
. Simulation Research of Ice Cloud Microphysical Parameter Retrieval at 220 GHz[J]. Plateau Meteorology, 2020
, 39(5)
: 1080
-1088
.
DOI: 10.7522/j.issn.1000-0534.2019.00071
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