Changes in Annual Maximum Number of Consecutive Dry and Wet Days during 1961–2008 in Xinjiang

Changes in the frequency or intensity of extreme weather and climate events profoundly impact both human society and the natural environment. Analysis of extreme precipitation events may effectively improve assessment of drought and flood forecasts.

Xinjiang, located in the northwest China, is characterized by an arid climate. As one of the most important irrigated agricultural production areas in China, Xinjiang has a vulnerable ecological environment and serious water shortage. So, precipitation changes have an important role in the sustainable ecological and regional socioeconomic environments. Increasing and intensifying weather extremes will further increase the sensitivity of the ecological environment to climate changes, particularly changes in precipitation. Therefore, understanding of changing properties of extreme precipitation events is important for preventing natural hazards, such as floods and droughts.

Based on daily precipitation dataset extracted from 51 meteorological stations across Xinjiang, researchers investigated the wetness and dryness variations during the period 1961–2008 by using two extreme precipitation indices. The two indices are annual maximum consecutive dry days (CDD) and annual maximum consecutive wet days (CWD).

The results indicate that CDD maximize in the Taklimakan and Turban basins of southeast Xinjiang, while minima are found in the Tianshan Mountains and the Ili river valley of northwest Xinjiang. On the contrary, the longest CWD are observed in the northwest Xinjiang and the shortest appeared in the southeast part of the region. On an annual basis, CWD temporal variability shows statistically positive trends and an increase rate of 0.1d/10a, but CDD temporal variability shows statistically negative trends and a decrease rate of 1.7d/10a. The CDD and CWD can better describe the wet and dry conditions than precipitation in Xinjiang. The results provide scientific basis for researching the variability of dryness and wetness under the context of climate change in Xinjiang.

The result has been published on Natural Hazards and Earth System Sciences, 2012, 12: 1353-1365. The paper can be downloaded from http://www.nat-hazards-earth-syst-sci.net/12/1353/2012/nhess-12-1353-2012.html.