【Introduction】
    
      This study analyzes the interannual and interdecadal variability of spring and summer precipitation over the Three-River-Source (TRS) region (31.5°−36.5°N, 89.5°−102.5°E) in China using four datasets (CN05.1, GPCP, CRU, and station datasets). A general consistency is revealed among the four datasets regarding the interannual and interdecadal variability of TRS precipitation during 1979−2015, demonstrating a confidence of the four datasets in representing the precipitation variability over TRS region. The TRS spring and summer precipitation shows distinct intereannual and interdecadal variability with an overall increasing trend in the spring precipitation and an interdecadal oscillation in the summer precipitation (Fig. 1). The regimes associated with the interannual variability of TRS spring and summer precipitation are further investigated. The interannual variability of TRS spring precipitation is essentially modulated by an anomalous easterly water vapor transport (WVT) branch associated with the leading mode of Eurasian spring circulation. The El Niño-Southern Oscillation (ENSO) may affect the interannual variability of TRS spring precipitation via causing southerly WVT anomalies towards the TRS region. The interannual variability of TRS summer precipitation is essentially modulated by an anomalous southwesterly WVT branch over the TRS region, which is mainly associated with an Eurasian wave-train connected with summer North Atlantic Oscillation. A strong East Asian summer monsoon and an El Niño-decaying summer may also contribute to the southwesterly WVT anomalies over TRS region. 

【Citation】

Sun, B. and Huijun Wang, 2018: Interannual variation of the spring and summer precipitation over the Three-River-Source region in China and the associated regimes. Journal of Climate, doi: 10.1175/JCLI-D-17-0680.1 (in press)
 

Fig. 1. Time series of anomalies of areal mean (a, c) spring and (b, d) summer precipitation over TRS region relative to the base period 1979−2009 (unit: mm d−1). (a) and (b) are original time series, and (c) and (d) are five-year running mean time series.