Evaluation of Prediction Ability of the CMA-CPSv3 Model for the South Asian High and the West Pacific Subtropical High in Summer

Abstract

In order to evaluate the predictive simulation ability of the CMA-CPSv3 climate prediction model （hereafter CMA-CPSv3 model） on two high-pressure systems， the South Asian High and the Western Pacific Subtropical High， that affect summer precipitation in China， the return simulated data by the CMA-CPSv3 model starting in March and May from 2001 to 2020 and ERA5 reanalysis data were used to firstly evaluate the model’s predictive ability on the characteristic indices of the two high-pressure systems， and then analyze the predictive ability of the differences in predicting the summer circulation system and water vapor characteristics between two high-pressure systems in the same good year and the same bad year， as well as their impact on summer precipitation in China， were compared.The possible reasons for the stronger prediction of the two high-pressure systems were explored.The main conclusions were as follows： （1） The CMA-CPSv3 model has the best prediction effect on the average ridge position of the West Pacific subtropical high and the South Asian high， with the predicted results of the intensity index and area index being significantly stronger or larger； Compared with the forecast starting in March， the forecast results starting in May have a certain improvement in the prediction of the West Pacific subtropical high.（2） The CMA-CPSv3 model has well predicted the circulation situation at 100 hPa and 500 hPa， with good predictions for temperature and wind fields.However， the predicted range of the South Asian High and the West Pacific Subtropical High is generally stronger.（3） The predicted positions of the ridge line of the two high-pressure systems in the same good year and the same poor year are relatively good， and the predicted areas and intensities are significantly stronger.The prediction deviation for the same good year is relatively small.It can better predict the spatial distribution of water vapor flux in East Asia and the distribution pattern of summer precipitation in China.（4） The upward motion of the predicted two high pressure systems in the longitude region is weaker than the ERA5 result， which may be one of the reasons for the larger range and stronger intensity of the predicted South Asian High and West Pacific Subtropical High.

Keywords

• cma-cpsv3 model
• simulation capability assessment
• south asian high pressure
• west pacific subtropical high
• characteristic index