The use of bivariate copulas for bias correction of reanalysis air temperature data

PLoS One. 2019 May 8;14(5):e0216059. doi: 10.1371/journal.pone.0216059. eCollection 2019.

Abstract

Air temperature data retrieved from global atmospheric models may show a systematic bias with respect to measurements from weather stations. This is a common concern in local climate studies. The current study presents two methods based upon copulas and Conditional Probability (CP) to predict bias-corrected mean air temperature in a data-scarce environment: CP-I offers a single conditional probability as a predictor, CP-II is a pixel-wise version of CP-I and offers spatially varying predictors. The methods were applied on daily air temperature in the Qazvin Plain, Iran that were collected at 24 weather stations and 150 ECMWF ERA-interim grid cells from a single month (June) over 11 years. We compared the methods with the commonly applied conditional expectation and conditional median methods. Leave-k-out cross-validation and correlation scores show that the new methods reduced the bias with 44-68% for the full data set and with 34-74% on a homogeneous subarea. We conclude that the two methods are able to locally improve ECMWF air temperatures in a data-scarce area.

MeSH terms

  • Agricultural Irrigation
  • Agriculture
  • Climate Change* / statistics & numerical data
  • Data Interpretation, Statistical
  • Iran
  • Models, Statistical
  • Temperature*

Grants and funding

The authors received no specific funding for this work.