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To qualify the risk of extreme weather events for power supply security during the long-term power system transformation process, this paper proposes a risk probability evaluation method based on probabilistic production simulation. Firstly, the internal relationship of extreme weather intensity and duration is depicted using the copula function, and the influences of extreme weather on power security are described using the guaranteed power output ability coefficient, which can provide the extreme scenario basis for probabilistic production simulation. Then, a probabilistic production simulation method is proposed, which includes a typical-year scenario and extreme weather events. Meanwhile, an index system is proposed to qualify the power security level, which applies the loss of load expectation (LOLE) and time of loss of load expectation (TOLE) under different scenarios and other indices to reveal the long-term power security trend. Finally, the long-term power supply risks for the Yunnan provincial power system are analyzed using the proposed method, validating that the proposed method is capable of characterizing the influences of extreme weather on power security. The security level of different long-term power transformation schemes is evaluated. [ABSTRACT FROM AUTHOR]

The stable oxygen isotopic composition (δ 18 O) of different water bodies can provide valuable information for investigation of hydrological processes, and it is an effective natural tracer that can be used to characterize the moisture sources of precipitation. In this study, to analyze the influence of moisture sources and meteorological variables on variations of precipitation δ 18 O, a project of monitoring intense precipitation events was conducted through three entire years (2009–2011) at the Kunming, Mengzi, and Tengchong stations in Yunnan Province, southwest China. The results suggested that variations of precipitation δ 18 O in Yunnan exhibit a significant seasonal variability. The use of high-resolution data revealed a significant anti-temperature effect as well as an amount effect. Additionally, we found that precipitation δ 18 O does not follow the amount effect during some rainfall events of two consecutive days. In detail, the first day has higher precipitation amount than the second day. However, the precipitation δ 18 O values of the second day are more negative than those from the first day. Significantly positive correlations between precipitation δ 18 O and wind speed at different pressure levels (800, 700, 500, and 300 hPa) demonstrate that wind speed is an important controlling factor of variations of precipitation δ 18 O. Backward trajectory results generated by the HYSPLIT model show that the moisture sources for precipitation with low δ 18 O during the wet season are mainly from the Bay of Bengal (BoB), Arabian Sea (AS), and South China Sea (SCS). By comparison, the high δ 18 O values of precipitation during the dry season are found to correspond to remote westerly air masses and inland re-evaporated vapor. Moreover, the precipitation δ 18 O associated with typhoons is much lower than that of the normal precipitation events. These findings indicate that the stable isotopic composition of precipitation is closely related to meteorological variables and is rapidly responsive to changes in sources of moisture. [ABSTRACT FROM AUTHOR]