Analysis On The Anomalies Of Dalian Rainy Season Precipitation And The Factors Affecting It

Based on the analysis of Dalian precipitation climate characteristics, this paper is particularly concerned with the preceding influencing factors and the corresponding general circulation anomalies characteristics of Dalian rainy season precipitation. The main conclusions are as followed:(1)The precipitation has obvious seasonal distribution characters in Dalian area. Rainy season (July and August) precipitation occupies more than a half of the annual precipitation, and the severe rainfall anomalous events occur most frequently during it.(2)The inter-annual and inter-decadal precipitation variations are obviously dissimilar in different seasons, but the precipitation in all seasons and the rainy season shows a decreasing tendency in the last 40 years.(3)There are different rainfall periodic variations in different seasons. Anomalies of rainy season precipitation have 20~22 years , 10~12 years and 2~3 years periodic oscillation.(4)The spatial distribution of rainy season precipitation shows different phase characteristics in various years.(5)There exist close relationships between Dalian rainy season precipitation and the solar activities, preceding winter 500hPa height fields, SSTA(6~8 monthly averaged in former year) in the middle of southern Pacific Ocean. The years near maximum years of solar activities tend to be dry, and the years near minimum years of solar activities tend to be wet. The teleconnection pattern called Europe-Pacific pattern at preceding January 500hPa height fields is the main distribution pattern impacted on Dalian rainy season precipitation. There are remarkable negative relationships between the rainy season precipitation and the SSTA(6~8 monthly averaged in former year) in the middle of southern Pacific Ocean.(6) The atmospheric circulations are significant different on each level of the troposphere in wet and dry years. In wet years, the corresponding convergence andascending actions are strengthened in the lower level, and the monsoon is remarkable with abundant water vapor. There exists teleconnection pattern called East Asia-Pacific distribution pattern at 500hPa height fields of the Northern Hemisphere. The westerly jet is strengthened, and the position of the subtropical high is more northward and westward than its normal position. In the dry years, the things listed above are opposite.