Nearly A Millennium, The World's Volcanic Activity And Distribution Of China's Drought And Flood The Relationship Between

The statistical relationship between the volcanism of the world in the past 1,000 years and precipitation in China is summarized in this study. The volcano records and precipitation data are different in time and spatial distribution. The period of 1,000 years is divided into two periods to be discussed. The relationship between volcanism and precipitation in China after major volcanic eruption in the past 500 years are discussed focusing on the spatial distribution patterns of precipitation. The dryness and wetness index of six regions in eastern China after major volcanic eruptions are analyzed in the A. D. 1000-1500. Furthermore, some cases on volcanism are also discussed in this text.A large number of cases of volcanic eruptions are selected from the book of Volcanoes of the World. More than 500 volcanoes and 847 eruptions cases whose Volcanic Explosive Index are equivalent to 3 or larger than 3 are included. Based on latitudes, volcanoes are divided into six regions. Those chronologies of volcanic eruptions last one thousand years comprise a lot of information such as the date of eruptions, the name of volcanoes, the value of VEI, longitude, latitude and so on.The precipitation data are also analyzed. The 500-year 1° × 1° grid precipitation anomaly series in the east of China have been used to compartmentalize precipitation spatial patterns in these regions during the last 500 years. The dryness and wetness index series of the six regions in the east of China in the A. D. 1000-1500 are interpolated into integrated data.Precipitation distribution patterns are established relative to the chronologies of volcanic eruptions. The superposed epoch analysis is adopted in this study to obtain precipitation patterns of several years after major eruptions. Due to the difference in volcanic activity intensity (VEI≥5, VEI ≥4, VEI≥3) , time (first half year, the latter half of the year) , and latitude (high, middle, low latitude) , the influence on precipitation distribution patterns is also different. The results show that influence of volcanic eruption on precipitation appears to be essentially complex. Some volcanoes have close connection with precipitation in China. If a volcano erupted in first half year, it is possible that it has an effect on climatic anomalies in the same year. Among them, the influence of high and middle latitude eruptions in Northern Hemisphere is most remarkable and dryness is apt to occurin north China and flood is apt to occur in the Yangtze valley. Precipitation distribution patterns in China are more sensitive to eruption occurred in middle and high latitude, but not so sensitive to eruptions that occurred in low latitude. The influence of volcanic eruptions on rainfall is obvious in the Yangtze valley and the Yellow River basin. The corresponding six regions dryness and wetness index after volcanic eruptions in A. D. 1000-1500 year is also analyzed. It is found that 1-4 regions are of drought and 5-6 regions are of much rain in the same year that erupted in high latitude in the Northern Hemisphere. It is also the same in the next year that erupted in middle and high latitude in the Northern Hemisphere.Finally, some cases on volcanism are discussed. There are some records about abnormal climatic phenomenon in historical document and those records are considered to be recordation with regard to volcano activities. Volcanic eruptions have an effect on the rainfalls in the middle and low reaches of the Yangtze valley in China. Moreover, the relationship between volcanism in different regions with precipitation distribution patterns can be gained from some examples of major volcanic eruptions for fifty years recently. It is inferred that there would not be direct relationship between eruption of Pinatubo and serious flood in the Yangtze valley in summer in 1991. The decrease in mean temperature of that year is much remarkable.