Dryness and wetness variations on different time scales in Shanghai were analyzed using the Standardized Precipitation Index （SPI） based on monthly precipitation data for 1873-2005. The SPI on scales of 3, 6, 12 and...Dryness and wetness variations on different time scales in Shanghai were analyzed using the Standardized Precipitation Index （SPI） based on monthly precipitation data for 1873-2005. The SPI on scales of 3, 6, 12 and 24 months has been calculated. The SPI on 3, 6, 12 and 24 months present 4 wet periods prevailed during 1873-1885, 1904-1923, 1938-1960 and 1983-2005, and 3 dry episodes during 1886-1903, 1924-1937 and 1961-1982. Significant periods of higher wavelet power in the SPI-24 months occurred on the time scales of 2-7-year band in around 1880-1890, 1910-1950 and 1970-1990, and at 8-15-year band in 1920-1960 and 1965-2000 respectively. Periodicities in the SOl and ENSO indices are similar to those in SPI-24 months with little difference, namely, in the SPI-24 months, there are significant periods at the 2-7- and 8-15-year bands during 1930-1940. The periodicity components in individual SPI-24 months, SOl and ENSO indices are more complicated, showing the wetness and dryness variability in Shanghai is controlled by more than one physical factors. The research results indicate that the Shanghai area has experienced dryness and wetness variability on different time scales during the past 133 years.展开更多
It is important and necessary to get a much longer precipitation series in order to research features of drought/flood and climate change. Based on dryness and wetness grades series of 18 stations in Northern China of...It is important and necessary to get a much longer precipitation series in order to research features of drought/flood and climate change. Based on dryness and wetness grades series of 18 stations in Northern China of 533 years from 1470 to 2002, the Moving Cumulative Frequency Method （MCFM） was developed, moving average precipitation series from 1499 to 2002 were reconstructed by testing three kinds of average precipitation, and the features of ell mate change and dry and wet periods were researched by using reconstructed precipitation series in the present paper. The results showed that there were good relationship between the reconstructed precipitation series and the observation precipiration series sincc 1954 and their relative root mean-square error were below 1.89%, that the relation between reconstructed series and the dryness and wetness grades series were nonlinear and this nonlinear relation implied that reconstructed series were reliable and could became foundation data for researching evolution of the drought and flood. Analysis of climate change upon reconstructed precipitation series revealed that although drought intensity of recent dry period from mid- dle 1970s of 20th century until early 21st century was not the strongest in historical climate of Northern China, intensity and duration of wet period was a great deal decreasing and shortening respectively, climate evolve to aridification situa- tion in Northern China.展开更多
基金Frontier Project of Nanjing Institute of Geography and Limnology,CAS, No.CXNIGLAS200814National Forestry Science and Technique Foundation during the 11th Five-Year Plan Period,No.2006BAD03A1601+1 种基金Project of Huaihe River Basin,No.HRM200708National Climate Center,China Meteorological Administration, No.CCSF2007-35
文摘Dryness and wetness variations on different time scales in Shanghai were analyzed using the Standardized Precipitation Index （SPI） based on monthly precipitation data for 1873-2005. The SPI on scales of 3, 6, 12 and 24 months has been calculated. The SPI on 3, 6, 12 and 24 months present 4 wet periods prevailed during 1873-1885, 1904-1923, 1938-1960 and 1983-2005, and 3 dry episodes during 1886-1903, 1924-1937 and 1961-1982. Significant periods of higher wavelet power in the SPI-24 months occurred on the time scales of 2-7-year band in around 1880-1890, 1910-1950 and 1970-1990, and at 8-15-year band in 1920-1960 and 1965-2000 respectively. Periodicities in the SOl and ENSO indices are similar to those in SPI-24 months with little difference, namely, in the SPI-24 months, there are significant periods at the 2-7- and 8-15-year bands during 1930-1940. The periodicity components in individual SPI-24 months, SOl and ENSO indices are more complicated, showing the wetness and dryness variability in Shanghai is controlled by more than one physical factors. The research results indicate that the Shanghai area has experienced dryness and wetness variability on different time scales during the past 133 years.
文摘It is important and necessary to get a much longer precipitation series in order to research features of drought/flood and climate change. Based on dryness and wetness grades series of 18 stations in Northern China of 533 years from 1470 to 2002, the Moving Cumulative Frequency Method （MCFM） was developed, moving average precipitation series from 1499 to 2002 were reconstructed by testing three kinds of average precipitation, and the features of ell mate change and dry and wet periods were researched by using reconstructed precipitation series in the present paper. The results showed that there were good relationship between the reconstructed precipitation series and the observation precipiration series sincc 1954 and their relative root mean-square error were below 1.89%, that the relation between reconstructed series and the dryness and wetness grades series were nonlinear and this nonlinear relation implied that reconstructed series were reliable and could became foundation data for researching evolution of the drought and flood. Analysis of climate change upon reconstructed precipitation series revealed that although drought intensity of recent dry period from mid- dle 1970s of 20th century until early 21st century was not the strongest in historical climate of Northern China, intensity and duration of wet period was a great deal decreasing and shortening respectively, climate evolve to aridification situa- tion in Northern China.
