Evaluating Seasonal Climate Forecasts from Dynamical Models over South America

Jiaying Zhang, Kaiyu Guan, Rong Fu, Bin Peng, Siyu Zhao, Yizhou Zhuang

Research output: Contribution to journalArticlepeer-review


Seasonal climate forecasts have socioeconomic value, and the quality of the forecasts is important to various societal applications. Here we evaluate seasonal forecasts of three climate variables, vapor pressure deficit (VPD), temper-ature, and precipitation, from operational dynamical models over the major cropland areas of South America; analyze their predictability from global and local circulation patterns, such as El Niño–Southern Oscillation (ENSO); and attribute the source of prediction errors. We show that the European Centre for Medium-Range Weather Forecasts (ECMWF) model has the highest quality among the models evaluated. Forecasts of VPD and temperature have better agreement with observations (average Pearson correlation of 0.65 and 0.70, respectively, among all months for 1-month-lead predictions from the ECMWF) than those of precipitation (0.40). Forecasts degrade with increasing lead times, and the degradation is due to the following reasons: 1) the failure of capturing local circulation patterns and capturing the linkages between the patterns and local climate; and 2) the overestimation of ENSO’s influence on regions not affected by ENSO. For regions affected by ENSO, forecasts of the three climate variables as well as their extremes are well predicted up to 6 months ahead, providing valuable lead time for risk preparedness and management. The results provide useful information for further de-velopment of dynamical models and for those who use seasonal climate forecasts for planning and management.

Original languageEnglish (US)
Pages (from-to)801-814
Number of pages14
JournalJournal of Hydrometeorology
Issue number4
StatePublished - Apr 2023


  • Atmospheric circulation
  • Climate prediction
  • Dynamical system model
  • Extreme events
  • Forecast verification/skill
  • Seasonal forecasting

ASJC Scopus subject areas

  • Atmospheric Science


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