盛夏南海北部台风和热带低压登陆前、后的对比分析   总被引：2，自引：0，他引：2  

顾平  李训强 《海洋预报》1996,13(3):13-20

盛夏南海北部台风与热带低压登陆前、后对比诊断分析表明，影响这两类热带低值系统发展的物理因子和过程为：涡度平流作用对二者在海上发展都不利；有利的大尺度环境流场造成的气旋性辐合、气压场作功以及积云对流活动造成的涡度、扰动动能、热量的积累是台风，低压发展的基本因子；台风发展以斜压转换过程明显，热带低压发展以正压转换过程为主。  相似文献   

Sensitivity of the Simulated Tropical Intraseasonal Oscillation to Cumulus Parameterizations          下载免费PDF全文

JIA Xiaolong  LI Chongyin 《Acta Meteorologica Sinica》2008,22(3):257-276

The sensitivity of the simulated tropical intraseasonal oscillation or MJO （Madden and Julian oscillation） to different cumulus parameterizations is studied by using an atmospheric general circulation model （GCM）--SAMIL （Spectral Atmospheric Model of IAP LASG）. Results show that performance of the model in simulating the MJO alters widely when using two different cumulus parameterization schemes-the moist convective adjustment scheme （MCA） and the Zhang-McFarlane （ZM） scheme. MJO simulated by the MCA scheme was found to be more realistic than that simulated by the ZM scheme. MJO produced by the ZM scheme is too weak and shows little propagation characteristics. Weak moisture convergence at low levels simulated by the ZM scheme is not enough to maintain the structure and the eastward propagation of the oscillation. These two cumulus schemes produced different vertical structures of the heating profile. The heating profile produced by the ZM scheme is nearly uniform with height and the heating is too weak compared to that produced by the MCA, which maybe contributes greatly to the failure of simulating a reasonable MJO. Comparing the simulated MJO by these two schemes indicate that the MJO simulated by the GCM is highly sensitive to cumulus parameterizations implanted in. The diabatic heating profile plays an important role in the performance of the GCM. Three sensitivity experiments with different heating profiles are designed in which modified heating profiles peak respectively in the upper troposphere （UH）, middle troposphere （MH）, and lower troposphere （LH）. Both the LH run and the MH run produce eastward propagating signals on the intraseasonal timescale, while it is interesting that the intraseasonal timescale signals produced by the UH run propagate westward. It indicates that a realistic intraseasonal oscillation is more prone to be excited when the maximum heating concentrates in the middle-low levels, especially in the middle levels, while westward propagating disturbances  相似文献   

鄂尔多斯盆地寒武系碳酸盐岩台地相模式及其对古气候的响应     

胡晨林 《地质论评》2023,69(Z1):17-18

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面向四维变分资料同化的NSAS积云深对流参数化方案的简化及线性化研究     

龚建东  刘永柱  张林 《气象学报》2019,77(4):595-616

GRAPES全球四维变分资料同化系统需要积云深对流参数化方案的线性化与伴随方案,直接采用原始复杂参数化方案进行线性化并不可行,需要发展简化光滑方案来减缓非线性与非连续性特征。GRAPES全球模式采用NSAS积云对流参数化方案,积云深对流对环境的反馈主要通过补偿下沉来实现,研究突出补偿下沉作用,忽略降水蒸发、动量反馈等贡献,形成简化方案。采用输入温、湿度廓线加入不同幅度小扰动方法,评估参数化方案计算的温度、比湿时间倾向对输入扰动的敏感性,检验非线性与非连续特征。提出避免或减缓非连续“开关”的方法,在简化方案的基础上发展了简化光滑方案。简化光滑方案与原始积云深对流方案相比,在对流触发上一致,在对流的位温与比湿倾向、降水的时序模拟等方面相似,而在减缓非线性、避免非连续性方面显著优于原始方案。基于简化光滑方案发展的线性化方案表明,对小于2倍分析增量幅度的扰动,线性化方案可以较好地模拟非线性方案的扰动发展。发展的简化光滑方案具有合理性和实用性。   相似文献   

2014-07-14豫北局地冰雹机制分析          下载免费PDF全文

杜丽娅  许庆娥 《陕西气象》2015,(5):21-26

利用常规气象资料、NCEP再分析资料、多普勒雷达资料、FY-2E静止卫星和区域自动站观测资料,对2014年7月14日豫北地区新乡和濮阳两地相继发生的局地冰雹天气过程进行分析,结果表明:两地的局地强对流天气过程发生在高空急流轴的右侧、西风槽的槽前和850hPa西南显著流线的左前侧,且中低层没有明显的冷暖平流;新乡的大风、冰雹天气是在积云合并加强并形成中-β尺度的强对流云团的过程中形成的,在雷达回波上表现为明显的回波合并过程,合并后的回波特征呈现出倾斜上升的强回波中心及其下方的弱回波区,在雷达径向速度图上表现为较强的斜升气流和中气旋;濮阳的大风、冰雹是由脉冲风暴导致的,该风暴所在的多单体风暴具有稳定的移动和传播路径,对脉冲风暴发生、发展落区有很好的指示意义。  相似文献   

Study on the Dynamic Process of the Onset of South China Sea Summer Monsoon   总被引：1，自引：0，他引：1       下载免费PDF全文

ZHANG Lifeng  ZHANG Yongchui  ZHANG Ming 《Acta Meteorologica Sinica》2008,22(4):511-521

By using the NCEP/NCAR reanalysis data from 1958 to 1997, we first looked into the atmospheric flow conditions in the one month immediately prior to the onset of the South China Sea summer monsoon （SCSSM） each year. A monthly-averaged zonal basic flow of 40-yr composite was then calculated. The stability of Rossby wave in the basic flow was studied based on the spherical barotropic vorticity equation. Furthermore, the spectral function expansion method was adopted to define and compute the evolvement of a developing wave packet. The results indicate that there exists barotropic instability of spherical Rossby wave in the climatically-averaged flow field before the SCSSM onset. The instability is triggered by the westerly jet stream in the Southern Hemisphere, and the strongest instable perturbation lies to the south of the westerly jet stream. The peak of the developing spherical Rossby wave packet propagates from mid and high latitudes to low latitudes, though not crossing the equator, spurring the cumulus convection in the tropical zones. The eruption of the cumulus convection and its spread to monsoon regions help to speed up the adjustment of the general circulation and the SCSSM onset. It is concluded that elements that contribute to the SCSSM onset are on global scale, albeit the onset itself looks like a local phenomenon.  相似文献   

RegCM3积云参数化方案对中国南方夏季强降水过程模拟的影响   总被引：3，自引：0，他引：3  

李建云  王汉杰 《气候与环境研究》2008,13(2):150-160

利用区域气候模式RegCM3的最新并行版本,选择Anthes-Kuo、MIT-Emanuel和Grell 3种积云参数化方案,对2003年7月发生在淮河流域的强降水过程进行了多组模拟试验,重点分析比较了3种参数化方案对降水总量分布、主要降水时段和基本气象要素场的模拟能力,并相对实测降水和要素场进行了统计检验.对比分析试验结果,发现RegCM3对中国南方夏季强降水具有较好的模拟能力,不同参数化方案对中高层流场特征的模拟没有实质性差异.但对低层850 hPa流场结构 (切变线、副高、低空急流、湿舌等) 和水汽输送状况模拟存在一定差异,这也是它们能否正确模拟降水分布及过程、强度等特征的关键,也是Kuo方案降水模拟效果相对优于其他两种参数化方案的主要原因.  相似文献   

积云参数化对0613号台风“珊珊”数值模拟的影响研究   总被引：3，自引：2，他引：1  

吴林  王刚  沈晗  李江南 《气象研究与应用》2008,29(4):14-16

使用W RF的ARW动力核心模拟台风"珊珊",以研究各种积云参数化方案对于台风路径,强度和降水分布等的影响。研究表明,环境场对积云参数化的选取不敏感,积云参数化对台风的强度和路径模拟有明显的影响,KF方案模拟的台风强度较强,增强过程明显,后期移速偏快。KF和BM J对降水的模拟较好,GD方案不够理想。  相似文献   

碎雨云碎积云混淆和漏记原因分析及识别方法     

邹兴奋  刘志辉 《气象研究与应用》2010,31(Z2)

通过对以下三种云天状况进行集体观摩学习,分析总结出碎雨云和碎积云容易混淆及漏记的原因,从而正确识别碎雨云和碎积云:测站没有降水,将测站上降雨云层下面的碎雨云误记为碎积云;反之,测站有降水,但不管降水时间长短,也不管降雨量大小,又统统将测站上空所有的碎云误记为碎雨云;因观测员粗心大意,将测站上空降雨云层其下量不多的派生出来的碎雨云漏记。  相似文献   

IMPACTS OF CUMULUS PARAMETERIZATION AND RESOLUTION ON THE MJO SIMULATION   总被引：1，自引：1，他引：0  

贾小龙  李崇银  凌健 《热带气象学报(英文版)》2009,15(1):106-110

Madden-Julian Oscillations (MJO) in six integrations using an AGCM with different cumulus parameterization schemes and resolutions are examined to investigate their impacts on the MJO simulation. Results suggest that the MJO simulation can be affected by both resolution and cumulus parameterization, though the latter, which determines the fundamental ability of the AGCM in simulating the MJO and the characteristics of the simulated MJO, is more crucial than the former. Model resolution can substantially affect the simulated MJO in certain aspects. Increasing resolution cannot improve the simulated MJO substantially, but can significantly modulate the detailed character of the simulated MJO; meanwhile, the impacts of resolution are dependent on the cumulus parameterization, determining the basic features of the MJO. Changes in the resolution do not alter the nature of the simulated MJO but rather regulate the simulation itself, which is constrained by cumulus parameterization schemes. Therefore, the vertical resolution needs to be increased simultaneously. The vertical profile of diabatic heating may be a crucial factor that is responsible for these different modeling results. To a large extent, it is determined by the cumulus parameterization scheme used.  相似文献