关键词: 东北地区, 冻土, 积雪, 保温作用, 地表平均气温, 负积温

Abstract:

Based on the daily data of frozen soil depth， snow depth， average temperature， average surface temperature and precipitation of 121 meteorological stations in Northeast China， the variation characteristics of frozen soil and the influence on frozen soil by meteorological elements in winter half year of 1964 to 2017 were analyzed. The results show that： the correlation coefficients between snow depth， average temperature， and surface average temperature with frozen soil depth are relatively high， but the correlation with precipitation is small. In the 1960s， the average temperature， average surface temperature and negative accumulated temperature are the lowest， and the maximum frozen soil depth is the deepest； while the climate warming， the maximum frozen soil depth decreased significantly at the rate of 6.15 cm?（10a）^-1. In winter-half year， the average maximum frozen soil depth is 123 cm， showing a significant latitudinal distribution， increasing from Liaodong Peninsula to the north of Greater Khingan Mountains； with the increase of latitude and altitude， the average temperature and surface temperature decrease， the negative accumulated temperature increase， and surface-air temperature difference increases from north to south. The maximum depth of frozen soil decreases in more than 90% of the stations， and the decreasing rate is mainly 0.1~10 cm?（10a）^-1. The duration of frozen soil increases with the increase of latitude； the monthly maximum depth of frozen soil and snow appear in March and January respectively， and the increase of maximum frozen soil depth lags behind that of snow. Due to the heat preservation effect of snow on surface temperature， the frozen soil depth increases obviously， when the snow depth is shallow， while with the increase of snow depth， the frozen soil depth changes little， snow has played role in insulation on frozen soil. For stations in high latitudes， limit value of snow for heat preservation is about 30 cm； for coastal stations， the limit value of snow for heat preservation is about 5 cm； in the same terrain， the value of snow for heat preservation in shallow frozen soil area also varies with the characteristics of altitude and climate. The response of the maximum frozen soil depth to the rising of the average surface temperature is more significant， the maximum frozen soil depth will decrease by 8.4 cm and 10.6 cm when the average surface temperature and average temperature increases by 1 ℃， and the maximum frozen soil depth will decrease by 4.9 cm when the negative accumulated temperature decreases by 100 ℃·d.

Key words: Northeast China, frozen soil, snow, thermal insulation, surface average temperature, negative accumulated temperature