Two dimensional bias correction of temperature and precipitation copulas in climate models

Authors

  • C. Piani,

    Corresponding author
    1. Department of Computer Science, Mathematics, and Science, American University of Paris, Paris, France
    • Corresponding author: C. Piani, Department of Computer Science, Mathematics, and Science, American University of Paris, 31, Avenue Bosquet, Paris FR-75007, France. (cpiani@aup.edu)

    Search for more papers by this author
  • J. O. Haerter

    1. Center for Models of Life, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
    Search for more papers by this author

Abstract

[1] In common climate model bias-correction procedures, temperature and precipitation are corrected separately, thereby degrading the dynamical link represented within the model. We propose a methodology that advances the state-of-the-art by correcting not just the 1D intensity distributions separately but the full two-dimensional statistical distribution. To assess the effectiveness of the proposed method, it is applied to the REMO regional climate model output using point measurements of hourly temperature and precipitation from 6 weather stations over Germany as observations. A standard cross-validation is performed by dividing the data into two nonoverlapping 15 year periods. Results show that the methodology effectively improves the temperature-precipitation copula in the validation period, unlike separate 1D temperature and precipitation corrections which, by construction, leave the copula unchanged. An unexpected result is that a relatively small number (<5) of temperature bins are required to achieve significant improvements in the copula. Results are similar for all stations.

Ancillary