关键词: 干旱, 游程理论, Copula函数, 修订

Abstract:

Based on the monthly precipitation of 613 meteorological stations in China during 1961-2010, the standardized precipitation index (SPI) was caculated, firstly. Then, the drought events were selected by using the run length theory, and the probability distribution fucnctions of drought intensity and drought duriation were tested by using K-S test. And on this basis the joint probability distribution function of dought intensity and drought duriation was established by using the Compula function, and the influence of the revised and unrevised drought duration distribution function on different types drought joint probability and recurrence peroid was contrastively analyzed. The results show that the drought intensity variable conformed to Gamma disttibution, while the drought duriation didn’t completely accord with the exponential function. Therefore, it was necessary to revise the drought duration distribution function so as to pass the K-S test. Under the revised drought duration distribution function condition, the joint probability of most drought types decreased, while that of a few increased, and the joint return peroid of different types drought increased. The difference of the maximum and minimum joint return peroid wasn’t obvious as the intensity of drought increased under the same drought duration, but that obviously enlarged as the drought duration increased under the same drought intensity.

Key words: drought, run length theory, Copula function, revision