Inter-Decadal Variations Of Summer Precipitation In North China And Its Relationship With PDO

Based on summer precipitation in North China and ECMWF data and NOAA sea surface temperature data, this paper studies the inter-decadal variations of summer precipitation in North China and the linkage of it to general circulation of atmosphere and Pacific Decadal Oscillation (PDO) using statistic analysis and numerical simulation. Results show:(1) The summer precipitation in North China has gone through two major dry-damp phases, richer period from 1955 to 1968 and less period from 1977 to 1992 , and has obvious inter-decadal variations. It is adjusting period from 1969 to 1976. Abrupt change occurs at 1975. In different periods the general circulation of atmosphere has its own character.(2) From 1950s to 1990s, East Asian Summer Monsoon has gone through the inter-decadal variations, from the stronger to the weaker. It has a close connection with summer precipitation in North China. But their coordination is not incompletely consistent.(3) The connection between PDO and inter-decadal variations of summer precipitation in North China is studied, and it's found that colder(warmer) phases of PDO is coupled with warmer(colder) SST of the west wind drift region and colder(warmer) SST of Middle and East of Equatorial Pacific and richer(less) precipitation in North China.(4) Impacts of different PDO phases on the summer precipitation in North China are simulated with NCAR CCM3. Results of simulation are approximately the same to the results of diagnosis.