The Temporal And Spatial Features Of The Spring Temperature And The Cold Wave Processes In Northeast China And Its Diagnosis Analysis

Based on 1960-2000 daily temperature data of 99stations in Northeast China and NCEP reanalysis data, the spring temperature in Northeast China is analyzed, and the results indicate:1 The spring temperature in Northeast China presents upward tendency and the cycle periods of14 years and 4 to 6 years. Meanwhile abrupt change is significant between the year of 1984 and 1985.2 the spring temperature in Northeast China falls into 4 spatial types, i.e. the Heilongjiang type, the southern Liaoning type, the eastern Jilin type, and the southeast Inner Mongolia type, all of which invariably exhibit upward tendency, while the upward tendency of the southeast Inner Mongolia type is the most obvious one. The occurance of cold wave decreases in every spatial type among which the eastern Jilin type is the most obvious, especially in the perios of late 1980's. Meanwhile, different cycle period and abrupt change time exists in every spatial type of spring temperature.3 In the years of cold spring, the Inner Mongolia High and the Aliushen Low are strengthened with the low index of the east Asia trough and the negative anomaly center of temperature over Northeast China from surface to tropopause while the contrary conditions occur in the years of warm spring.4 Positive correlation exists between spring air temperature and the SAT of Nino3 area. The incidence of cold wave increases in the eastern Jillian during Lanina year, especially in April. Northeast china is susceptible to the dominance of surface high pressure with the stronger Aliushen Low during the Lanina year. Meanwhile Tibetan High in upper troposphere is strengthened more easily. In the no-lanina year is the contrary.5 Intraseasonal discrepancy exists in the extremely temperature decrease corresponding with the four type of spring temperature. The cold wave incidence of the Heilongjiang type tend to be more in May, while the others in April. Synthetic analysis of cold wave processes indicate that Northeast China is mainly influenced by the cold air from Balkan Lake and e sea. From the point of 1000HPA, the incidence of cold wave in the southern Liaoning, the eastern Jilin, and Inner Mongolia southeast are affected by Inner Mongolia high, while in Heilongjiang by the deepen and strengthen of low pressure in Northeast China.