| 杨贵名,毛冬艳,孔期. 2009. “低温雨雪冰冻”天气过程锋区特征分析[J]. 气象学报, 67(4):652-665, doi:10.11676/qxxb2009.065 |
| “低温雨雪冰冻”天气过程锋区特征分析 |
| Analysis of the frontal characteristics of the cryogenic freezing rainand snow weather |
| 投稿时间：2008-08-07 修订日期：2008-09-27 |
| DOI：10.11676/qxxb2009.065 |
| 中文关键词: 冷暖气团，锋面坡度，逆温强度，锋生，位涡，等熵气流 |
| 英文关键词:Cold and warm air, Frontal slope, Inversion intensity, Frontogenesis, Potential vorticity, Isentropic flow |
| 基金项目:科技部“科研院所社会公益研究专项课题”：不利气象条件对公路安全影响机理及对策研究项目(2004DIB3J100) |
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| 中文摘要: |
| 2008年初低温雨雪冰冻期间（包括4次过程），冷暖气团长期对峙是“低温雨雪冰冻”天气持续的主要原因；准静止锋稳定、少动，锋面较平缓；等 经向和垂直向梯度不断加强；冷暖气团形成的逆温很明显；主锋区前部上空存在多层锋区现象；锋区渐强，最强时在10个纬度内南北温差达20 ℃以上；相对湿度≥90%的高湿度区的移动趋势、范围、垂直伸展高度均与4次过程吻合较好；锋生函数的分布与 密集区的分布一致，呈向北倾斜上升状，滇黔地区准静止锋区域内，多数时间段有锋生发生，华南地区上空静止少动的锋生中心，正是低温雨雪冰冻期间准静止锋长期稳定的原因之一；南北风交界线的移动趋势与低温雨雪冰冻过程趋势一致，4次过程都伴有偏南风低空急流；当副热带高空急流逐渐加强、水平风垂直切变加强并向下伸展时，低空急流加强；高位涡舌向下伸展，高纬的高位涡舌与主锋区的中高层相对应，中纬度高位涡舌与副热带锋区对应；湿位涡斜压项MPV2量级较小，但其与4次过程的对应关系非常好；锋区上界和下界等熵面上的气流能较好地反映准静止锋区上、下界特征；约290 K等熵面上（锋区下界以下）在贵州均为偏东气流，这是贵州及江南大部长时间维持低层冷气团的主要原因。 |
| 英文摘要: |
| During the cryogenic freezing rain and snow weather at the beginning of 2008(including four weather processes), the main reason for this peculiar weather was that the cold air and the warm air confronted each other for a long time. The quasi-stationary front in South China was stable and less movable. The frontal slope was gentle, and ▽Θse intensified gradually along longitude and vertical direction. The inversion ( <0 ) was strong. There were several-layers frontal zones in the upper lever of the foreside of the main frontal zone. When the front was the strongest, the temperature difference from the south to north within the 10 latitudes extended to more than 20 ℃. The moving tendency, extension and the extending height of the moisture areas which the relative humidity was larger than 90% corresponded well with the four processes. The distribution of the frontogenesis was consistent with the large areas of the ▽Θse, and it tilted northwards with the height. Frontogenesis was taken place more times in area of the quasi-stationary front in Guizhou bounded Yunnan. The less movable frontogenesis center in South China was one of the reasons for the long-maintaining of the quasi-stationary front in South China during the cryogenic freezing rain and snow weather. The movement of the north-south wind boundary was consistent with the southward advance tendency of the four processes. All these four processes were companied by the southerly low level jet. When the subtropical high level jet and intensified gradually and extended downwards, the low level jet intensified. The high PV tough extended downwards during every process, while that in high-latitude was coincident with the main frontal zone in the middle-high level, while the high PV tough in middle-latitude corresponded well with the subtropical frontal zone. MPV2 as the horizontal component of the moisture potential vorticity was small, but corresponded well with the four processes. The flow on the isentropic surface of the upper and lower frontal zone boundaries could better reflect the characteristics of the upper and low boundaries of the quasi-stationary front in South China. There was easterly wind on the 290 K isentropic surface (below the low boundary of the front)in Guizhou, which was the main reason for the long-maintaining of the low level cold air-mass in Guizhou and most areas to the south of the Yangtse. |
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