台风“云娜”在近海强度变化及结构特征的数值研究Ⅱ:云微物理参数化对强度和路径的影响  

Numerical research onintensity change and structure feature of Typhoon Rananim near shore.Ⅱ:Impact of cloud microphysical parameterization on intensity and track.

作　　者：程锐[1,2] 宇如聪[1] 徐幼平[1,2] 傅云飞[3] 

机构地区：[1]中国科学院大气物理研究所LASG,北京100029 [2]中国科学院研究生院,北京100049 [3]中国科学技术大学,合肥230026

出　　处：《气象学报》2009年第5期777-786,共10页Acta Meteorologica Sinica

基　　金：国家"973"项目我国南方致洪暴雨监测与预测的理论和方法研究第四课题(2004CB418304)

摘　　要：在分析云微物理参数化对云结构和降水特征的影响的基础上,研究云微物理参数化过程对台风"云娜"强度与路径的影响。结果表明:云微物理过程对台风强度和路径有一定影响,其中不考虑雨水蒸发冷却效应后,比其他试验最终地面最大风速强7 m/s以上,但此时登陆地点误差最大,与对照试验偏离150 km左右。我们还从螺旋雨带结构变化及环境风切变影响角度分析台风临近登陆时强度模拟减弱的原因,发现过强的外围螺旋雨带以及环境风场垂直切变对于台风的加深、维持是不利的,他们可能会造成"云娜"临近登陆时强度的下降。不难看出,云微物理过程可以加强甚至产生外螺旋雨带,当外围雨带发展加强之后,可以引起局地辐合强度增强,从而限制了大量水汽和能量向台风内核输送,从而会导致台风强度下降。此外,外围螺旋雨带的发展,还可以从对流层中层带来干冷空气入侵行星边界层;而当入流边界层中雨水下落时,其自身的蒸发也会使周围气块温度下降;这些干冷气团在入流气流的输送下进入台风内核,从而对云墙产生了"冷侵蚀",最终引起台风强度下降。因此,减小上述两方面的模拟误差,应能改进台风"云娜"登陆过程中强度的模拟效果。In this study, we continuely discuss the impacts of cloud microphysical paramet erization scheme on the modeling intensity and track of Typhoon Rananim based on the Part I of the paper （“Impact of cloud microphysical parameterization on cl oud structure and precipitation features＂）. The results indicate that the cloud microphysical processes have some impact on the intensity and track of typhoon. The 36 hour maximum simulated surface wind speed is about 7 m/s greater than that of all other experiments when the cooling effect due to evaporation o f rain water is excluded; however, the model landfall location has the biggest b ias, about 150 km against the control experiment. Finally, we find that the stro ng outer simulated rainband and the vertical shear of the environmental flow are unfavorable for the deepening and maintaining of typhoon and can result in its intensity loss near the landfall. It can be easily seen that the cloud microphys ical processes can strengthen and even create the outer spiral rainbands, which can then increase the local convergence away from the TC center and prevent much moisture and energy from transportation to the inner core of the typhoon. Also, the developed outer rainbands are supposed to bring dry and cold air masses fro m the middle troposphere to the planetary boundary layer. The other branch of th e cold airflow comes from the evaporation of rain water itself in the planetary boundary layer while the droplets are falling. Thus the cutoff of the warm and moist air masses to the inner core and the invasion of cold and dry ones to the eyewall region are expected to bring about the intensity decay of the modeled t yphoon. As a result, the simulated deepening and maintaining of Typhoon Rananim during its landing should be improved through the reduction of those two kinds of model errors.

关 键 词：台风强度 云微物理参数化 螺旋雨带 环境风切变 

分 类 号：P458.124[天文地球—大气科学及气象学]