关键词: 冬季气温, 纬向环流, 乌拉尔山

Abstract: Based on the observed temperature data at 89 meteorological stations and the NCEP-NCAR re-analysis data during the period from 1961 to2016, this study investigates three major modes of winter temperature over Xinjiang, China through empirical orthogonal function (EOF) method, and the characteristics of associated mid-high latitudes atmospheric circulation in the Northern Hemisphere. It can provide ideas and basis for climate prediction to discuss the possible causes of the abnormal winter temperature in Xinjiang. It reveals that the three major spatial modes of winter temperature in Xinjiang, which include the provincially consistent mode, anticlastic mode between the south and the north and anticlastic mode between the west and the east, could be divided further into 6 spatial distribution patterns as follows the uniformly relative cold (or warm) pattern, North being cold (or warm) and South being warm (or cold) pattern, and East being cold (or warm) and West being warm (or cold) pattern. Further analysis indicates that the atmospheric circulation impact factors on the distribution of the winter average temperature in Xinjiang included the polar and mid-latitude circulation interactions and the wave transmission from the latitude circles. The consistent cold (warm) pattern of winter temperature in Xinjiang was associated with the weakening (strengthening) west wind from the middle latitude in the northern hemisphere, and the strengthening (weakening) longitude circulation in the high latitude, the high pressure ridge development in the Ural Mountains, the deepening East Asia trough the East Asian Trough, the anomaly of negative height in south of 50 ° N. The difference between the pattern of cold East and warm West and the pattern of warm East and cold West lies in the mid-latitude 500 hPa positive anomaly center and the 700 hPa wind direction. The pattern of cold north and warm south is similar to the circulation feature of the consistent cold pattern in the northern region of 40 ° N, but higher in the southern region of 40 ° N from Central Asia to Xinjiang. The pattern of warm North and cold South pattern was associated with the weakening of Ural anomaly and the East Asian Deep Trough, and the control of shallow trough over Xinjiang and the impact of the shallow trough after the ridge in southern Xinjiang. This study revealed the indirect but important influencing factors on winter temperature in Xinjiang from 8 circulation indexes. The difference of the positive and negative phases of the AO index and the area index of the polar vortex in Asia can easily cause the regional variation of the average temperature in winter in Xinjiang, and the greater the absolute value, the more obvious the influence of dominance. When the Tibet Plateau-1 index and the Tibet Plateau-2 index are high, the winter mean temperature in southern Xinjiang tends to be higher. When the SCA index of the key area of Ural Mountains is large, the temperature in the north Xinjiang is easy to be low. When the Eurasian zonal circulation index and the regional westerly index are larger, the winter mean temperature in the western and northern regions of Xinjiang is apt to be higher.

Key words: winter temperature, zonal circulation, Ural Mountain