Response of Solar Activity in the evolution of drought and flood in the Hetao and its vicinity area

摘要

Based on the drought and flood grads of 21 meteorology stations in Hetao and its vicinity from 1700–2006, response of Solar Activity in the evolution of droughtflood was analyzed. The results showed that Hetao region was prone to droughtflood at the peak of sunspot, and the region was easier to drought at the troughs of sunspot. The number of the sunspot had observably increased during 1927–2006 than during 1700–1926. At the same time, the frequency of drought in Hetao had increased 5 times during 1927–2006 than during 1700–1926. When the solar activity was stronger (weaker) than normal, the strength of the surface heating in the Tibetan Plateau was stronger (weaker) either, which caused drought in Inner Mongolia and flood in Ningxia and Shanxi province.