The Impact Of Strong Volcanic Eruptions On Chinese Precipitation In Recent 540 Years

Rainfall anomalies have serious effect on ecosystem, agriculture and human life. Volcano activity is one of the most important nature factors that drives climate changes over an extended time scale from days to centuries. Further analysis of the relation between volcano and irregular rainfall have an important significance. In order to identify changes in the precipitation of volcanic signal, here, we use the BCC_CSM1.1 model, in Coupled Model Intercomparison Project 5(CMIP5), to simulate the monthly rainfall from 1471～2010 for China, which use the REOF method to partition in precipitation. The annals of strong eruptions (Volcanic eruption index(VEI≥4) over the last 540 years is used to relate volcano activity and irregular rainfall by Superposed Epoch Analysis(SEA). Monte Carlo method is used to conduct the significance test for the result of the superposed analysis. Conclusions are:(1) Precipitation changes from 1471 to 2010 are divided into six districts based on REOF. They are named Northeast region, Northwest region, North China region, th e Yangtze River region, the southeast coastal region and Southwest region.(2) The effects of different latitudes and intensities of volcanic eruptions on the pr ecipitation in regions of China are different; summer precipitation change is more sign ificant than the annual. annual precipitation was decreased in all latitudes of the north ern hemisphere and the southern hemisphere 0-20°S zones. It reduced to annual precip itation maximum within the 20-45 °N zones, but to summer precipitation maximum wit hin the 20-45°N zones, decreases of precipitation in the summer is higher than the ye ar. After volcanic eruptions happened in 20-90°S zones of Southern Hemisphere, preci pitation increased significantly within the following first and second year. When the in tensity of volcanic eruptions VEI≥6, annual precipitation changed most significantly.(3) There are difference precipitations in different parts of China in response to the volcanic eruptions. In Northeast region, after the volcanic eruption VEI=5 happened, precipitation increased significantly. However, after the volcanic eruption VEI≥6 happened, precipitation decreased significantly within the eruption year. The first annual precipitation decreased significantly within the 0-20°N zones after eruptions. Precipitation increased at the eruption year within the 20-45°N zones after eruptions. In Northwest region, after the volcanic eruption VEI=4 happened, precipitation increased significantly in the second year afterwards. Precipitation decreased in all latitude zones and at other levels of volcanic eruptions. In North China region, precipitation decreased at different levels of eruptions. When compared VEI>6 to VEI=4 and VEI=5, the annual precipitation is significant at earlier years, and the significant years are more. Precipitation were reduced significantly in addition to volcanic eruption 20-45°N zones after volcanic eruptions. Precipitation within the 0-20°N and 0-20°S zones decreased to the most,But changes within 20-45°N zones after volcanic eruptions were not significant. In the Yangtze River region, after volcanic eruption VEI=4 and within the 45-90°N zones happened, precipitation increased in the following second and fourth year. Other latitudes decreased with varying levels. In South China coastal areas, precipitation increased after volcanic eruptions within the 20-45°N ,20-90°S zones. And the greater the level of volcanic eruptions, the more precipitation increased. In Southwest region, the higher level of volcanic eruptions, the more precipitation decreased.