Battaglia A, Tanelli S, Mroz K, Tridon F
National Center Earth Observation University of Leicester Leicester UK; Earth Observation Science, Department of Physics and Astronomy University of Leicester Leicester UK.
Jet Propulsion Laboratory California Institute of Technology Pasadena California USA.
J Geophys Res Atmos. 2015 May 16;120(9):4090-4101. doi: 10.1002/2014JD022866. Epub 2015 May 4.
This paper illustrates how multiple scattering signatures affect Global Precipitation Measuring (GPM) Mission Dual-Frequency Precipitation Radar (DPR) Ku and Ka band reflectivity measurements and how they are consistent with prelaunch assessments based on theoretical considerations and confirmed by airborne observations. In particular, in the presence of deep convection, certain characteristics of the dual-wavelength reflectivity profiles cannot be explained with single scattering, whereas they are readily explained by multiple-scattering theory. Examples of such signatures are the absence of surface reflectivity peaks and anomalously small reflectivity slopes in the lower troposphere. These findings are relevant for DPR-based rainfall retrievals and stratiform/convective classification algorithms when dealing with deep convective regions. A path to refining the rainfall inversion problem is proposed by adopting a methodology based on a forward operator which accounts for multiple scattering. A retrieval algorithm based on this methodology is applied to a case study over Africa, and it is compared to the standard DPR products obtained with the at-launch version of the standard algorithms.
本文阐述了多次散射特征如何影响全球降水测量（GPM）任务双频降水雷达（DPR）Ku和Ka波段反射率测量，以及它们如何与基于理论考量的发射前评估相一致，并得到机载观测的证实。特别是，在存在深厚对流的情况下，双波长反射率剖面的某些特征无法用单次散射来解释，而多次散射理论却能轻松解释这些特征。此类特征的例子包括地表反射率峰值的缺失以及对流层下部异常小的反射率斜率。这些发现对于处理深厚对流区域时基于DPR的降雨反演和层状/对流分类算法具有重要意义。通过采用基于考虑多次散射的前向算子的方法，提出了一条改进降雨反演问题的途径。基于该方法的反演算法应用于非洲的一个案例研究，并与使用标准算法的发射版本获得的标准DPR产品进行了比较。
