06 Dec 2022
 | 06 Dec 2022

Evaluating Precipitation Distributions at Regional Scales: A Benchmarking Framework and Application to CMIP 5 and 6 Models

Min-Seop Ahn, Paul A. Ullrich, Peter J. Gleckler, Jiwoo Lee, Ana C. Ordonez, and Angeline G. Pendergrass

Abstract. A framework for quantifying precipitation distributions at regional scales is presented and applied to CMIP 5 and 6 models. We employ the IPCC AR6 climate reference regions over land and propose refinements to the oceanic regions based on the homogeneity of precipitation distribution characteristics. The homogeneous regions are identified as heavy, moderate, and light precipitating areas by K-means clustering of IMERG precipitation frequency and amount distributions. With the global domain partitioned into 62 regions, including 46 land and 16 ocean regions, we apply 10 established precipitation distribution metrics. The collection includes metrics focused on the maximum peak, lower 10th percentile, and upper 90th percentile in precipitation amount and frequency distributions, the similarity between observed and modeled frequency distributions, an unevenness measure based on cumulative amount, average total intensity on all days with precipitation, and number of precipitating days each year. We apply our framework to 25 CMIP5 and 41 CMIP6 models, and 6 observation-based products of daily precipitation. Our results indicate that many CMIP 5 and 6 models substantially overestimate the observed light precipitation amount and frequency as well as the number of precipitating days, especially over mid-latitude regions outside of some land regions in the Americas and Eurasia. Improvement from CMIP 5 to 6 is shown in some regions, especially in mid-latitude regions, but it is not evident globally, and over the tropics most metrics point toward over degradation.

Min-Seop Ahn et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on egusphere-2022-1106', Hong Yan, 24 Feb 2023
    • AC1: 'Reply on CC1', Min-Seop Ahn, 20 Apr 2023
  • RC1: 'Comment on egusphere-2022-1106', Anonymous Referee #1, 23 Mar 2023
    • AC2: 'Reply on RC1', Min-Seop Ahn, 20 May 2023
  • RC2: 'Comment on egusphere-2022-1106', Anonymous Referee #2, 12 May 2023
    • AC3: 'Reply on RC2', Min-Seop Ahn, 20 May 2023

Min-Seop Ahn et al.


Total article views: 581 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
440 122 19 581 31 4 4
  • HTML: 440
  • PDF: 122
  • XML: 19
  • Total: 581
  • Supplement: 31
  • BibTeX: 4
  • EndNote: 4
Views and downloads (calculated since 06 Dec 2022)
Cumulative views and downloads (calculated since 06 Dec 2022)

Viewed (geographical distribution)

Total article views: 586 (including HTML, PDF, and XML) Thereof 586 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
Latest update: 07 Jun 2023
Short summary
We introduce a framework for regional scale evaluation of simulated precipitation distributions with 62 climate reference regions and 10 metrics, and we apply it to evaluate CMIP5 and CMIP6 models against multiple satellite-based precipitation products. The common model biases identified in this study are mainly associated with the overestimated light precipitation and underestimated heavy precipitation. These biases persist from earlier generation models and have been little improved in CMIP6.