A Study On The Time Symmetry Of Meteorological Disasters In

Global climate change has broken the natural ecosystem balance, causing many natural disasters over the past century. In particular, the sudden, unpredictable, harmfulness of extreme climate characteristics has a great influence to the regional environmental and social development. At the same time, meteorological disaster has become the most widely kind in all kinds of natural disasters. Xinjiang, the natural disasters more frequent areas in China, is a region that have a fragile ecological environment. So, study the characteristics of extreme climate change, analysis space-time evolution laws of main meteorological disasters such as drought, snow disaster and wind disaster, determine future disasters window in recent time, not only had a comprehensive understanding of regional climate change, protect and construt the ecological environment, but also had a practical significance in promoting economic development of agriculture, animal husbandry and reduce regional disaster risk.With the method of linear regression, M-K mutation test, Morlet wavelet analysis, and so on, this paper has analyzed the background of climate change, discusses the main factors such as solar activity, ENSO and atmospheric oscillation impact on meteorological disasters. Theory of symmetries as the mechanism, commensurability method as the methods, butterfly structure, and commensurability structure as the verification, we had determined the disaster time window. In the end, based on the above research, summed up the climate type in Xinjiang in recent20years and the disaster type in almost half a century, and discuss the physical mechanism of commensurability. The main results are as follows:(1) The annual average temperature appears a steadily rising trend from1961to2012, and the increase rate is0.307℃/10a, occurring a significant mutation in1990, exist a small scale5-10and a large scale20-25periodic trends. The average temperature of the four seasons change and the annual average temperature trends are basically identical, but the volatility is bigger. The temperature distribution presents good latitude variation law.Precipitation is relatively small, but still shows a rising trend at a rate of7.99mm/10a, occurring a significant mutation in1987, and exist18-25periodic trends. Winter precipitation increased most significantly, and summer precipitation increase rate is the largest. Affected by the west wind circulation and topography, precipitation spatial distribution is not uniform. The northern more than the southern, the west more than the east, the mountains more than plain and basin, and the windward slope more than the leeward slope.Annual average wind speed is slightly downward trend and the average reduction rate is-0.127m/s/10a, occurring a significant mutation in1981. The four seasons wind speed change trends are almost the same whit the all year round, but the extent is slightly different. The north wind days more than the southern Xinjiang on the space, but the southern Xinjiang affected by wind damage is much bigger.In recent20years, Xinjiang warming and rainfall trend is obvious for high temperature and rainy climate types.(2) See from the decadal distribution characteristics of snowstorms in altay, snow frequency in the1970s was16.7%which the same as that in1980s. The snow disaster frequency began to rise significantly in the1990s, and mostly in2001-2010(37.5%). Moderate-severe snowstorms are almost occurred in Altay, Qinghe and FYN, severe snowstorms are almost occurred in FYN, and the snow disaster occurred mainly in late autumn. See from the point of the sunspot number curve, the snow disaster often happened in decline stage of sunspot numbers, and the probability is62.5%and occurred mainly in solar maximum near in the valley. Commensurability, butterfly structures and the commensurable structures all show that2013year and2015year are the disaster window time of snow in Altay.(3) Time series of grades of flood/drought in south and north Tianshan showed partial drought before1987in the overall performance, while rainy and water logging after1987. Frequency of drought and rain water logging are basic quite in most of the site, but drought is slightly greater than the water logging. ENSO events have a certain degree of influence of flood/drought in south and north Tianshan. El Nino mainly affects the droughts, especially in North Slope of Tianshan, while La Nina mainly affects the floods, especially in South Slope of Tianshan. Commensurability, butterfly structures and the commensurable structures all show that2014a and2015a are the disaster window time of flood/drought in south and north Tianshan.(4) The annual gale days in Southern Xinjiang is12.9d, and the variation showed a trend of decreased significantly with the speed of3.3d/10a. Gale days are mostly happened in spring and summer. Space characterized by "bowl" shape distribution, namely "on both sides, the more closely to the center, the small, minimum center" The effects of ENSO events were relatively weak on wind speed change, but a high relativity of atmospheric oscillation and wind speed change was found, showing seasonal variation. Commensurability, butterfly structures and the commensurable structures all show that2013to2015year are the window time of strong wind anomaly in South Xinjiang.Comprehensive the above conclusions and all kinds of disaster season, we consider under the background of global warming, part of Xinjiang meteorological disaster type are "Growth form of autumn and winter" and "Reduce form of spring" in recent semi century.(5) At present, commensurability application in the trend from all kinds of disasters has been relatively mature, but the analysis of its physical mechanism is still in early exploration stage. We can study it from "Arnold tongue" and "Omics" perhaps.Focus of this study was to determine the disaster time window, period rich disaster trend judgment methods, verify the case more disasters, and provide a reference for disaster prevention and mitigation.