CollectHomepage AdvertisementContact usMessage

Arid Land Geography ›› 2021, Vol. 44 ›› Issue (5): 1250-1260.doi: 10.12118/j.issn.1000–6060.2021.05.06

• Climatology and Hydrology • Previous Articles     Next Articles

Anomalous circulation characteristics of precipitation anomalies in northwest China in April and precursory SST signal

LU Guoyang(),LIN Shu,WANG Rui,LIU Liwei,HUANG Pengcheng,LIN Jingjing   

  1. Lanzhou Regional Climate Center, Lanzhou 730020, Gansu, China
  • Received:2020-08-18 Revised:2020-11-24 Online:2021-09-25 Published:2021-09-22

Abstract:

Using April precipitation data from stations in northwest China from 1981 to 2019, NCEP/DOE reanalysis data, and NOAA sea temperature field data, the anomalous characteristics of April precipitation in northwest China and the characteristics of the synchronous circulation field are studied to identify possible precursor SST signals and discuss influence mechanisms. The results indicate the following. (1) April precipitation in northwest China is, for the most part, uniformly distributed over the entire region, with obvious interannual and decadal changes. (2) When there exists a “negative, positive, negative, and positive” anomalous wave train distribution from the Northeast Atlantic to East Asia, the low trough over Balkhash Lake is relatively strong, the large trough over East Asia is weak, and a significant southerly airflow prevails in the northwest China with significant upward movement. In addition, sufficient water vapor transport from the eastern ocean of China and the Bay of Bengal form a strong water vapor convergence area in the northwest China, which is favorable to precipitation in northwest China. For the converse distribution, the situation is opposite. (3) In early February, the North Atlantic tripole index shows a significant positive correlation with the April precipitation in the northwest China; this can be used as a precursor to the April precipitation forecast. Further analysis shows that the non-adiabatic heating due to SST anomalies in the North Atlantic can stimulate the downstream dispersion of Rossby wave energy; as a result, Western Europe, the Urals, Balkhash Lake, and Northeast Asia present a “negative, positive, negative, and positive” teleconnection pattern. This type of abnormal Rossby wave energy dispersion is consistent with that of the abnormal precipitation in April, which affects the abnormal April precipitation in the northwest region of China.

Key words: precipitation, abnormal atmospheric circulation, North Atlantic tripol, teleconnection pattern, northwest China