摘要
2024年12月大气环流的主要特征为:北半球极涡呈偶极型分布,欧亚中高纬为"两槽一脊"型;西太平洋副热带高压异常偏西,印缅槽偏弱,不利于我国降水天气的发生.12月全国平均降水量为5.3 mm,较常年同期偏少55.5％,为历史同期第五低;中东部雨雪稀少,北京、天津、辽宁降雪日数为历史同期最少;广东、广西、江西、福建等地降水偏少8成以上,出现中到重度气象干旱;全国平均气温为-2.9℃,较常年同期偏高0.1℃.月内冷空气较为活跃,出现了4次冷空气过程,其中2-3日强冷空气导致黑龙江北部、内蒙古东北部、新疆西北部等地部分地区出现大到暴雪;28-29日受强冷空气影响,全国出现大范围降温,其中江南地区、华南东部等地局地降温超过12℃.月内我国北方地区多大风天气,内蒙古、甘肃、宁夏局地出现沙尘天气;全国大气扩散条件总体偏好,雾-霾过程次数和强度较10年同期明显偏弱.
Abstract
The main characteristics of the general atmospheric circulation in December 2024 are as follows.In the Northern Hemisphere,the polar vortex was distributed in a dipole pattern,and the mid-high lati-tudes of Eurasia had a pattern of two troughs and one ridge.The western Pacific subtropical high was ab-normally westward,and the Indo-Myanmar trough was weak.Such a circulation pattern was not conducive to the occurrence of precipitation in China.In December,the average precipitation was only 5.3 mm,55.5％less than normal,ranking the fifth lowest for the same period in history.There was scarce rain and snow in the central and eastern part of China.The number of snowfall days in Beijing,Tianjin and Liaoning was the lowest on record for the same period.Precipitation in Guangdong,Guangxi,Jiangxi,Fujian and other places was reduced by more than 80％,resulting in moderate to severe meteorological drought.The na-tional average temperature was-2.9℃,0.1 ℃ higher than in the same period of the normal years.Cold air was active during the month,and four cold air processes appeared,among which the strong cold air from 2 to 3 December led to heavy snow to blizzards in the northeastern part of Heilongjiang,the north-eastern part of Inner Mongolia,the northwestern part of Xinjiang and other places.From 28 to 29 Decem-ber,a wide range of cooling appeared over China,and the temperature in the south to Yangtze River,the eastern part of South China and other places dropped over 12 ℃ as the consequence of strong cold air.Gale-force winds frequently appeared in northern China during the month,and sand-dust weather were observed in some local areas of Inner Mongolia,Gansu and Ningxia.Finally,the overall air diffusion conditions across the country were relatively favorable in this month,and the number of fog-haze processes and their intensity were clearly weaker than in the same period of the past decade.
维普
万方数据