Space-time modelling of rainfall using Copulas - a quasi meta-gaussian approach

• Applicant: Professor Dr.-Ing. András Bárdossy
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: from 2008 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 78927420

• Final Report Year: 2014

Final Report Abstract

In the framework of this project we focused on new ways to describe the spatial behavior of precipitation. Copulas were used as a new tool for this purpose. As a first step a multisite precipitation model was developed. A new methodology for downscaling precipitation from Regional Climate Model output was tested both for German and South African conditions. While developing these models we discovered that meteorological model outputs do not reproduce the observed spatial dependence of precipitation. This leads to spatial inconsistencies, the model outputs have different errors depending on the spatial scale. We developed a method to correct this error and obtained downscaled precipitation which is statistically correct on all spatial scales. The spatial copula based method was also used to interpolate precipitation under topographical influence. A detailed comparison showed that the new interpolation method is superior to the conventional ones. The method forms the basis for the interpolation of precipitation on different temporal scales (from days to years) for South Africa.

Publications

• Copula based multisite model for daily precipitation simulation, Hydrology and Earth System Sciences, 13, 2299—2314, 2009
  Bárdossy, A. and G. Pegram
  
• Downscaling precipitation using RCMs and Circulation Patterns towards Hydrology, Water Resources Research, 47, W04505, 2011
  Bárdossy, A. and G. Pegram
  
• Multiscale spatial recorrelation of RCM precipitation to produce unbiased Climate Change scenarios over large areas and small, Water Resources Research, 48, W09502, 2012
  Bárdossy, A. and G. Pegram
  
• Downscaling Regional Circulation Model rainfall to gauge sites using recorrelation and circulation pattern dependent quantilequantile transforms for quantifying climate change, Journal of Hydrology , 504, 142—159, 2013
  Pegram, G. and A. Bárdossy
  
• Interpolation of precipitation under topographic influence at different time scales, Water Resources Research, 49, 4545—4565, 2013
  Bárdossy, A. and G. Pegram