Preprints
https://doi.org/10.5194/hess-2022-58
https://doi.org/10.5194/hess-2022-58
 
01 Mar 2022
01 Mar 2022
Status: a revised version of this preprint is currently under review for the journal HESS.

Quantifying overlapping and differing information of global precipitation for GCM forecasts and El Niño–Southern Oscillation

Tongtiegang Zhao1,2, Haoling Chen1, Yu Tian3, and Xiaohong Chen1,2 Tongtiegang Zhao et al.
  • 1Center of Water Resources and Environment, School of Civil Engineering, Sun Yat-Sen University, Guangzhou, China
  • 2Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, China
  • 3Department of Water Resources, Institute of Water Resources and Hydropower Research of China, Beijing, China

Abstract. While El Niño–Southern Oscillation (ENSO) teleconnection has long been used in statistical hydroclimatic forecasting, global climate models (GCMs) provide increasingly available dynamical precipitation forecasts for hydrological modelling and water resources management. It is not yet known to what extent dynamical GCM forecasts provide new information compared to statistical teleconnection. This paper develops a novel Set Operations of Coefficients of Determination (SOCD) method to explicitly quantify the overlapping and differing information for GCM forecasts and ENSO teleconnection. Specifically, the intersection operation of the coefficient of determination derives the overlapping information for GCM forecasts and Niño3.4 index, and then the difference operation determines the differing information in GCM forecasts (Niño3.4 index) from Niño3.4 index (GCM forecasts). A case study is devised for the Coupled Forecast System model version 2 seasonal forecasts of global precipitation in December-January-February. The results show that the overlapping information for GCM forecasts and Niño3.4 index is significant for 34.94 % of global land grid cells, the differing information in GCM forecasts from Niño3.4 index is significant for 31.18 % of grid cells and the differing information in Niño3.4 index from GCM forecasts is significant for 11.37 % of grid cells. These results confirm the effectiveness of GCMs in capturing the ENSO-related variability of global precipitation and also illustrate where there is room for improvements of GCM forecasts. Furthermore, the bootstrapping-based significance tests of the three types of information facilitate in total eight patterns to disentangle the close but divergent association of GCM forecast correlation skill with ENSO teleconnection.

Tongtiegang Zhao et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2022-58', Anonymous Referee #1, 11 Mar 2022
    • AC1: 'Reply on RC1', Tongtiegang Zhao, 06 May 2022
  • RC2: 'Comment on hess-2022-58', Anonymous Referee #2, 19 Apr 2022
    • AC2: 'Reply on RC2', Tongtiegang Zhao, 06 May 2022

Tongtiegang Zhao et al.

Tongtiegang Zhao et al.

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Short summary
There exist both overlapping and differing information of global precipitation in GCM forecasts and ENSO teleconnection. The set operations of intersection and difference are effective in quantifying the overlapping and differing information. The set operations facilitate eight patterns to characterize the association of GCM forecast correlation skill with ENSO teleconnection.