Synoptic-scale atmospheric circulation anomalies associated with summertime daily precipitation extremes in the middle–lower reaches of the Yangtze River Basin
The mechanisms of short-lived precipitation extremes in boreal summer over the middle–lower reaches of the Yangtze River Basin (MLYRB) during 1961–2014 are explored using gridded observational and reanalysis datasets. Daily precipitation extremes are defined by the 75th and 95th percentiles and identified for selected regions in the MLYRB. Moisture budget analysis is utilized to quantify the major factors responsible for the variability of extreme precipitation events. Then the atmospheric variables are composited according to these extreme events, to illustrate the temporal evolution of the corresponding synoptic-scale structures. The results show that moisture flux convergence plays a dominant role in the variations of extreme rainfall for both percentile events, and the contribution of evaporation is not evident. Moreover, the dynamic component associated with changes in atmospheric circulation makes a larger contribution than the nonlinear component, followed by the thermodynamic component, owing to changes in specific humidity. The moisture transport pathways increase with increasing magnitude of extreme rainfall intensity. Circulation field anomalies move into the MLYRB during the onset of precipitation extremes for both percentile cases, with stronger anomalies occurring for the 95th percentile cases. Furthermore, the water vapor fluxes transported from the Northwest Pacific are pronounced during the 95th percentile events. A cross-section of specific humidity and vertical gradient of equivalent potential temperature further indicates that dynamic properties play a crucial role in the development of extreme precipitation events linked with quasi-stationary frontal activities across the MLYRB during the past few decades. Composites of Eady growth rate and outgoing longwave radiation anomalies reveal that extratropical cyclones passing through the MLYRB produce a large amount of extreme rainfall by synoptic disturbance.
KeywordsExtreme precipitation event Moisture budget analysis Atmospheric variables Eady growth rate
We thank two anonymous reviewers for their professional comments and suggestions that were greatly helpful for further improvement of the quality of this manuscript. This study is jointly supported by National Natural Science Foundation of China (Key Program) (Nos. 41630532; 41605057; 41330423), Natural Science Foundation and Sci-tech development project of Shandong Province (No. ZR2018MD014; J15LH10), International Partnership Program of Chinese Academy of Sciences (No. 134111KYSB20160031), R&D Special Fund for Public Welfare Industry (meteorology) (No. GYHY201506012), Project funded by China Postdoctoral Science Foundation (No. 119100582H; 1191005830), and the Young Academic Backbone in Heze University (No. XY14BS05). Helpful comments and suggestions from Dr. Tianjun. Zhou and Bo Wu are appreciated.
- Field CB, Barros VR, Dokken DJ, Mach KJ, Mastrandrea MD, Bilir TE, Chatterjee M, Ebi KL, Estrada YO, Genova RC (2014) IPCC, 2014: climate change 2014: impacts, adaptation, and vulnerability. Part A: Global and sectoral aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USAGoogle Scholar
- Hogg WD, Hogg AR (2010) Historical trends in short duration rainfall in the Greater Toronto Area, report for the Toronto and Region Conservation Authority. http://trca.on.ca/dotAsset/105189.pdf
- Li T (2012) Synoptic and climatic aspects of tropical cyclogenesis in western North Pacific. Cyclones: formation, triggers and control, Oouchi K, Fudeyasu H (eds), Nova Science Publishers, Inc., Hauppauge, pp 61–94Google Scholar
- Liebmann B, Smith CA (1996) Description of a complete (interpolated) outgoing longwave radiation dataset. Bull Am Meteor Soc 77:1275–1277Google Scholar
- Rayner NA, Parker DE, Horton EB, Folland CK, Alexander LV, Rowell DP, Kent EC, Kaplan A (2003) Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. J Geophys Res Atmos 108:4407. https://doi.org/10.1029/2002JD002670 CrossRefGoogle Scholar
- Tao SY, Chen LX (1987) A review of recent research on the east Asian summer monsoon in China. In: Chang CP, Krishnamurti TN (eds) Review of monsoon meteorology. Oxford Univ. Press, New York, pp 60–92Google Scholar