Preprints
https://doi.org/10.5194/egusphere-2022-886
https://doi.org/10.5194/egusphere-2022-886
 
22 Sep 2022
22 Sep 2022
Status: this preprint is open for discussion and under review for Atmospheric Measurement Techniques (AMT).

Simulation and sensitivity analysis for cloud and precipitation measurements via spaceborne millimeter wave radar

Leilei Kou1, Zhengjian Lin2, Haiyang Gao1, Shujun Liao2, and Piman Ding3 Leilei Kou et al.
  • 1Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Kay Laboratory for Aerosol Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China
  • 2School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China
  • 3Shanghai Institute of Satellite Engineering, Shanghai 201109, China

Abstract. This study presents a simulation framework for cloud and precipitation measurements via spaceborne millimeter wave radar composed of nine sub modules. To demonstrate the influence of the assumed physical parameters and optimizing the microphysical modeling of the hydrometeors, we first conducted a sensitivity analysis. The results indicated that the radar reflectivity was highly sensitive to the particle size distribution (PSD) parameter of the median volume diameter and particle density parameter, which can cause reflectivity variations of several to more than 10 dB. The variation in the prefactor of the mass-power relations that related to riming degree may result in an uncertainty of approximately 30–45 %. The particle shape and orientation also had a significant impact on the radar reflectivity. The spherical assumption may result in an average overestimation of the reflectivity by approximately 4–8 %, dependent on the particle shape and orientation modeling. Typical weather cases were simulated using optimal physical modeling accounting for the particle shapes, typical PSD parameters corresponding to the cloud precipitation types, mass-power relations for snow and graupel, and melting modeling. We present and validate the simulation results for a cold front stratiform cloud and a deep convective process with observations from W-band cloud profiling radar (CPR) on the CloudSat satellite. The simulated brightness band features, echo structure, and intensity showed good agreement with the CloudSat observations; the average relative error in the vertical profile was within 20 %. Our results quantify the uncertainty in the millimeter wave radar echo simulation that may be caused by the physical model parameters and provide a scientific basis for optimal forward modeling. They also provide suggestions for prior physical parameter constraints for the retrieval of the microphysical properties of clouds and precipitation.

Leilei Kou et al.

Status: open (until 02 Nov 2022)

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Leilei Kou et al.

Leilei Kou et al.

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Short summary
Forward modeling of spaceborne millimeter wave radar composed of nine sub modules is presented. We quantify the uncertainties in radar reflectivity that may be caused by the physical model parameters via a sensitivity analysis. The simulations with optimal and conventional setting are compared with CloudSat data, and the improvement of optimal simulation are evaluated and analyzed. The results are instructive to the optimization in forward modeling and microphysical parameter retrieval.