摘要
The instrumental records of precipitation, including some historical documentary evidence, show that the rainfall in North China during the rainy season (July and August) exhibits an interdecadal variability similar to the Sahelian rainfall. Both these areas exhibited a weak interdecadal rainfall variability prior to the 1950s, and experienced a long-lasting drought since the 1960s, with two rainfall decreasing transitions, one around the year 1965 and another in the late 1970s. NCEP/NCAR reanalysis data are used to analyze the associated changes in atmospheric circulation during the second decrease transition. The changes of local atmospheric circulation at the end of the 1970s, at both lower and upper levels, contribute to the less precipitation in North China and the Sahel.
The instrumental records of precipitation, including some historical documentary evidence, show that the rainfall in North China during the rainy season (July and August) exhibits an interdecadal variability similar to the Sahelian rainfall. Both these areas exhibited a weak interdecadal rainfall variability prior to the 1950s, and experienced a long-lasting drought since the 1960s, with two rainfall decreasing transitions, one around the year 1965 and another in the late 1970s. NCEP/NCAR reanalysis data are used to analyze the associated changes in atmospheric circulation during the second decrease transition. The changes of local atmospheric circulation at the end of the 1970s, at both lower and upper levels, contribute to the less precipitation in North China and the Sahel.
