中国南方2008年与2016年两次低温雨雪冰冻天气过程对比分析

利用2.5° ×2.5°NCEP/NCAR月平均资料、1° ×1°FNL再分析资料、 国家气候中心1951年至2016年1月西太平洋副热带高压脊线和西伸脊点两项环流指数,从事件实况(降水、 气温和冰冻灾害)、环流条件、能量条件、水汽条件和动力条件几个方面出发,对2008年1月10日至2月2日和2016年1月20至25日发生在中国南方的两次低温雨雪冰冻天气过程做了对比分析.研究表明:(1)"0801南方雪灾"的主要特征表现为降水范围大、过程持续时间长、灾害重;2016年1月低温雨雪冰冻过程的主要特征表现为降水范围小、过程持续时间短、灾害轻."0801南方雪灾"冷空气强度不如2016年1月强.(2)造成"0801南方雪灾"的亚欧大环流背景为"北脊南槽"型,2016年1月低温雨雪冰冻的亚欧环流形势中低纬同位相,从西伯利亚到伊朗为脊,中蒙由低涡控制.(3)与"0801南方雪灾"相比,2016年1月低温雨雪冰冻期间我国南方对流层中下部10°～20°N的温差较强.(4)"0801南方雪灾"水汽输送偏北(到达34°N)且更高(到达300 hPa),2016年1月低温雨雪冰冻期间水汽输送偏南(到达28°N)且较低(到达400 hPa).(5)"0801南方雪灾"水汽输送轨迹在5000 m、3000 m和1500 m高度均以西南路径为主,2016年1月低温雨雪冰冻期间水汽输送轨迹在5000 m、3000 m和1500 m高度均以西北路径为主,冷空气沿着低压底部从西北移至南方变性增湿.(6)2008年1月26至28日整层垂直运动弱,但向上扩展高(至200 hPa);2016年1月22日至24日垂直运动强,但扩展高度低(500 hPa以下).

A comparative study of the two weather processes with cold and snowing in southern China in 2008 and 2016

In this paper, a comparative study of two weather processes with cold and snowing in southern China occurred over the period from 10th January to 2nd February, 2008 and from 20th January to 25th January, 2016 was performed by using 2. 5° × 2. 5° NCEP/NCAR monthly average data, 1° × 1° FNL reanalysis data and Janu-ary West Pacific subtropical ridge line and western ridge point circulation indexes from 1951 through 2016 from the National Climate Center, from the truth (precipitation, temperature and disasters), circulation conditions, energy, water vapor conditions and dynamic conditions. The following conclusions can be drawn:(1) The first event was featured as having precipitation of large areas, the process lasted long and caused heavy disaster; the second event was characterized as having precipitation of small areas, the process lasted short and caused light disaster. However, the intensity of cold air of the first event was much stronger than that of the second event. (2) The Asia-Europe circulation background of the first event was north ridge and south trough. However, in the second event the circulation pattern in low and middle latitudes was the same phase, featuring as a ridge from Siberia to Iran and a low vortex controlling China and Mongolia. (3) The temperature difference between 20 and 30 N in the middle and lower of troposphere in the second event was stronger than that in the first event. ( 4 ) The water vapor transport from south to north extended to 34° N and reached 300 hPa in the first event, but it extended to 28° N and reached 400 hPa in the second event. (5) In the first event, the water vapor at the heights of 5000 m, 3000 m and 1500 m came from the southwesterly path, but in the second event the water vapor at the same heights came from the northwesterly path. (6) The vertical movement of the whole layer was small in the first event but it was extended upward to 200 hPa; in contrast, it was strong in the second event but it was extended upward to 500 hPa.