摘要
利用NCEP 1°×1°资料和实况观测资料,针对2013年冬季云南4次降雪过程,使用诊断和对比的方法,分析研究4次降雪过程在形成机理等方面的异同点。研究发现:4次降雪中南支槽型降雪强度和范围明显强于无南支槽型;700 hPa上高度场北高南低型和锋区密集型为主要环流形势;南支槽前的西南暖湿气流与北方冷空气的交汇,会导致降水的明显加强。4次降雪过程云南西侧都有充沛的水汽输送,水汽通量增大是云南降雪的必备条件,降雪落区在辐合中心的偏东、偏北一侧、θ_(se)线陡立区附近及暖湿不稳定区域和高空急流入口右侧与地面锋区垂直环流相耦合的区域。强大的地面冷高压南压和地面冷空气的参与,能够为降雪提供有利的温度条件,更有利于降雪天气的产生和维持。
By using upper air observational data, surface observational data, NCEP 1°×1°reanalysis data, 4 snow processes in Yunnan in winter 2013 were comparative analyzed and diagnosed. The similarities and differ- ences were analyzed about formation mechanism of 4 snow processes, and so on. The results showed that in the 4 snow processes in Yunnan, snowing intensity and area caused by the south trough pattern was stronger than no south trough pattern on 500 hPa obviously, the north higher and south lower about height fields, the front area density on 700 hPa. Precipitation was obviously strengthened by the south west warm meets cold air. The strong water vapor flux convergence belt and area can better indicate the snow processes of Yunnan. The snow always ap- pears in the area of strong water vapor convergence and closed to the side of strong cold air in the east and north of the convergence center. Because the updraft and the down＆aft in the south and the north coexisted, the meso - scale vertical circulation near the front area may establish. When the cold air from the north moved to the south, the θsc sharpness area also moved to the south, the coupling between the right entrance of the upper jet and the vertical circulation of the frontal zone, and then caused the water vapor brought by the south warm moist airflow to condense and the unstable energy to release, providing enough uplift condensation condition for the snow. Temperature condition was provided by moving bout ground cold air, and were in favor of generating to south about stronger ground cold high and involving a- and supporting.
出处
《云南地理环境研究》
2017年第1期69-76,共8页
Yunnan Geographic Environment Research
基金
昆明市区域创新与科技惠民重点项目(TQ2015 1 S 00169)
云南省气象局科研项目(TQ201603)
关键词
诊断分析
南支槽
水汽通量辐合
θse线陡立区
地面冷空气
diagnosis analysis
south trough
water vapor convergence
θsc sharpness area
the ground ofcold air
