Is the variogram a good tool for assessing the spatial variability of vertical profiles of reflectivity ?
, Delobbe, L.
Earth and related Environmental sciences
C-band Doppler radar
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Various methods have been proposed in the literature to correct for the errors arising from nonuniform vertical profiles of reflectivity (VPR). All these methods consist in estimating the shape of the VPR and to use it for extrapolating the radar reflectivities measured at high altitude towards ground level. These methods require an assumption on the spatial homogeneity of the VPR over appropriate subdomains during a considered time step. This assumption of spatial homogeneity must therefore ideally be verified in order to apply any correction. In this paper we will explore the ability of a geostatistical tool called variogram to assess the spatial variability of the VPR in volume reflectivity files. The data are measured by the Wideumont radar in Belgium. It is a C-band Doppler radar that performs a 5-elevation scan from 0.3° to 6.0° every 5 minutes and a 10-elevation scan from 0.5° to 17.5° every 15 minutes. Some relevant parameters of the 10-elevation scan are given in Delobbe and Holleman (2006). The final objective of this study is to characterize the spatial and temporal variability of VPRs for different types of meteorological situations and to determine consistent spatial and temporal scales for VPR identification and correction. In this paper we will concentrate on the spatial variability aspect onldy. This paper is organized as follows. We first develop the theory related to variograms applied on VPRs. Then an analysis of one theoretical example is given. This analysis will illustrate some difficulties in the calculation of the variograms. Finally, an analysis of the variograms obtained for several selected observed situations is done and the results are discussed.
CitationMohymont, B.; , Delobbe, L. (2008). Is the variogram a good tool for assessing the spatial variability of vertical profiles of reflectivity ?. , Issue Proceedings of the International Symposium on "Weather Radar and Hydrology (WRaH 2008), 1/4/2015, IRM,