2007年3月3-5日辽宁省暴雪和大风天气的中尺度分析  

A mesoscale analysis of the snowstorm event of 3-5 March 2007 in Liaoning Province

作　　者：孙艳辉[1] 李泽椿 寿绍文[1] 

机构地区：[1]南京信息工程大学,南京210044 [2]国家气象中心,北京100081

出　　处：《气象学报》2012年第5期936-948,共13页Acta Meteorologica Sinica

基　　金：国家自然科学基金项目(41005027;40875025;40875030;40775033);气象灾害省部共建教育部重点实验室开放课题(KLME0905)

摘　　要：使用中尺度数值模式WRFV2.2.1对辽宁省2007年3月3—5日的暴雪和大风天气过程进行了数值模拟,结合10min一次的地面自动观测站资料和数字化多普勒天气雷达探测资料,研究了中尺度重力波的结构及其环境场特征,探讨了波动的激发机制。对流层上层中尺度重力波生成在350—250hPa(约9—11km),周期为2—3h,水平波长30—40km,波动沿水平方向传播约9h。地面气压扰动振幅约为2hPa,周期为2—3h,波动由西南向东北方向传播,方向与地面风向相反。沿波的传播方向,地面观测的逐时降水量呈波动特征,周期约为2h。对流层上层中尺度重力波减弱后,雷达降水回波强度出现显著的波动特征。对流层上层中尺度重力波生成在朝向脊区传播的高空急流出口区下方,300hPa环境场具有显著的切变不稳定特征。波动生成在理查逊数小于0.25的地区,在中尺度重力波生成的高度上,暖平流强,风速低,风切变大。中尺度重力波生成地区出现显著的不平衡气流,拉格朗日罗斯贝数大于0.7,水平散度倾向出现明显的大值,其中-▽w·V/z的量级明显大于其他各项,表明对流层上层重力波的生成及发展与环境场的显著风切变有关。The WRFV2.2.1 model is used to investigate the mechanism for a severe snowstorm event occured in Liaoning Prov- ince during 3 - 5 March 2007. With the help of the digital Doppler radar data and the pressure data per 10 minutes from the surface automated mesonet stations, the structure and the environment features of the mesoseale gravity waves, as well as the source of the gravity waves are studied. The results show that the WRF-simulated gravity waves developed in the upper layer of the troposphere between 350- 250 hPa （9- 11 km） with an period of 2 - 3 hours, the horizontal wavelength of 30 - 40 km, and propagating about 9 hours horizontally. The sea-level pressure perturbation amplitude is about 2 hPa, with a wave period of 2-3 hours, and propagates from southwest to northeast. Along the wave propagating path, the observed 1 hour snowfalls show significant wave feature, with a period of 2 hours. When the WRF-simulated gravity waves is weakened, the Doppler ra- dar reflectivity shows significant wave feature as well. The WRF-simulated mesoscale gravity waves were developed in an envi- ronment of strong shear instability at 300 hPa, under the exit region of an upper level jet streak propagating toward the ridge. The 300 hPa level where the gravity waves developed with Richardson number d0.25 is also featured of stronger warm inflow, weak wind, and strong wind shear. Unbalanced flow developed in the area of mesoscale gravity waves with Lagrange Rossby number 〉0.7. The magnitude of the horizontal divergence tendency is larger with the wind shear term contributed most. It is shown that the shear instability has strong effect on the development of the gravity waves.

关 键 词：WRF中尺度数值模式 中尺度重力波 切变不稳定 理查森数 拉格朗日罗斯贝数 非平衡流 

分 类 号：P458.2[天文地球—大气科学及气象学]