LAPS上海本地化及其在局地对流天气中的应用研究     

唐玉琪  刘红亚  岳彩军  顾问 《气象科学》2019,39(1):50-61

本文首先基于地面自动站、探空、雷达和卫星资料,开展局地分析预报系统(Local Analysis and Prediction System,LAPS)上海本地化研究,并结合2010—2014年夏季6个局地对流天气个例对其性能进行检验评估。结果表明:雷达径向风资料对LAPS风速分析影响较大,使分析场风速廓线与探空廓线的均方根误差缩小约7.66%;风云卫星资料能够改善LAPS温度和相对湿度,使分析场温度、相对湿度廓线与探空廓线的均方根误差分别缩小约9.09%和14.01%;探空气球飘移对本文LAPS分析场检验影响不明显。进一步将LAPS分析场用于2011年8月13日、2014年8月4日两次局地对流个例分析表明:LAPS高时空分辨率的分析场能够反映中小尺度天气系统的时空变化,在天气尺度背景并不十分有利于对流生成的情况下,热岛、海陆风环流的形成和持续对上海夏季局地对流天气的发生和发展起到关键作用。  相似文献   

Characteristics of oceanic mesoscale variabilities associated with the inverse kinetic energy cascade     

Mengmeng Li  Zhiliang Liu  Jianing Li  Chongguang Pang 《海洋学报(英文版)》2021,40(7):42-57

Oceanic geostrophic turbulence theory predicts significant inverse kinetic energy(KE) cascades at scales larger than the energy injection wavelength. However, the characteristics of the mesoscale variabilities associated with the inverse KE cascade in the real oceans have not been clear enough up to now. To further examine this problem,we analyzed the spectral characteristics of the oceanic mesoscale motions over the scales of inverse KE cascades based on high-resolution gridded altimeter data. The applicability of the quasigeostrophic(QG) turbulence theory and the surface quasigeostrophic(SQG) turbulence theory in real oceans is further explored. The results show that the sea surface height(SSH) spectral slope is linearly related to the eddy-kinetic-energy(EKE) level with a high correlation coefficient value of 0.67. The findings also suggest that the QG turbulence theory is an appropriate dynamic framework at the edge of high-EKE regions and that the SQG theory is more suitable in tropical regions and low-EKE regions at mid-high latitudes. New anisotropic characteristics of the inverse KE cascade are also provided. These results indicate that the along-track spectrum used by previous studies cannot reveal the dynamics of the mesoscale variabilities well.  相似文献   

一次梅雨锋特大暴雨中尺度气旋和MCS的分析     

周后福  陈健  姚筠  单乃超  吴语燕  黄勇  卢燕宇  吴文玉  侯灿 《气象科技》2023,51(4):551-561

利用自动气象站、多普勒雷达、FY4A、ECMWF模式、NCEP再分析资料,对2020年7月17—19日特大暴雨过程进行分析。结果表明：特大暴雨出现在安徽大别山附近和庐江两地,是中尺度气旋扰动环境下准静止的中尺度对流系统(MCS)以及MCS中准静止的涡旋状单体所产生。特大暴雨在高能量、强不稳定背景下,由中部和东部的中尺度气旋传播所致。中尺度气旋传播过程中单体不断新生、合并增强且移动缓慢,配合急流、辐合、干侵入、垂直环流等因素对组织化的MCS发展演变起到相当作用。低层切变线南侧到华南的西南急流,将水汽输送到安徽并在此有强烈辐合;高空、低空和超低空都存在急流,高低空急流耦合加剧MCS的强烈发展;地面辐合线是前期MCS的触发机制,伴随干冷空气的入侵,加大了大气的斜压性和MCS的对流不稳定;梅雨锋南北两侧都有垂直环流圈,即对流与高空急流之间通过对流加热在高空急流入口处产生热成风调整,维持梅雨锋的发展演变,强的上升下沉运动促进MCS的加强和降水的连续发生;大别山地形抬升和上游狭管效应是两地特大暴雨诱因。  相似文献   

2012年夏季海南岛东岸上升流区的混合观测   总被引：1，自引：0，他引：1  

李明明  谢玲玲  宗晓龙  张书文  周磊  李君益 《海洋学报(英文版)》2018,37(9):1-12

The turbulent mixing in the upwelling region east of Hainan Island in the South China Sea is analyzed based on in situ microstructure observations made in July 2012. During the observation, strong upwelling appears in the coastal waters, which are 3℃ cooler than the offshore waters and have a salinity 1.0 greater than that of the offshore waters. The magnitude of the dissipation rate of turbulent kinetic energy ε in the upwelling region is O(10–9 W/kg), which is comparable to the general oceanic dissipation. The inferred eddy diffusivity K_ρ is O(10–6 m~2/s), which is one order of magnitude lower than that in the open ocean. The values are elevated to K_ρ≈O(10–4 m~2/s) near the boundaries. Weak mixing in the upwelling region is consistent with weak instability as a result of moderate shears versus strong stratifications by the joint influence of surface heating and upwelling of cold water.The validity of two fine-scale structure mixing parameterization models are tested by comparison with the observed dissipation rates. The results indicate that the model developed by Mac Kinnon and Gregg in 2003 provides relatively better estimates with magnitudes close to the observations. Mixing parameterization models need to be further improved in the coastal upwelling region.  相似文献   

Transfer function-based 2D/3D interactive spatiotemporal visualizations of mesoscale eddies     

Fenglin Tian  Lingqi Cheng 《International Journal of Digital Earth》2020,13(5):546-566

ABSTRACT

In this paper, we present a transfer function-based approach to developing an interactive visualization algorithm for ocean mesoscale eddies. Spatiotemporal coherence and viewport coherence are achieved. Evenly spaced streamlines are only integrated for visible portions of the datasets that maintain a relatively stable visual pattern resolution. The interactive transfer function is introduced to extract 2D and 3D eddy features, such as the Okubo-Weiss parameter, from background ocean currents, and a highly efficient GPU-based framework with an output-sensitive performance is utilized. Using the high-resolution 2D/3D ocean current datasets Maps of Sea Level Anomalies (MSLA) and Hybrid Coordinate Ocean Model (HYCOM), the feasibility and efficiency of our framework are demonstrated.  相似文献   

带偏航角串列式两风机复杂尾流场数值模拟     

段鑫泽  程萍  万德成 《海洋工程》2019,37(2):50-58

在多风机风电场中,通过主动调节上游风机的偏航角度,抑制上游风机尾流对下游风机的影响,减少风力机机组之间的尾流相互干扰,以达到提高整个风电场效率的目的。采用基于开源平台Open FOAM自主开发的FOWT-UALM-SJTU求解器中风电场求解模块ALMWindFarmFoam,将致动线模型与CFD方法相结合,利用大涡模拟(LES)计算研究当上游风机处于不同偏航角度时,两风机之间的复杂尾流干扰效应。对比分析偏航角度改变时,上下游风机气动功率的输出特性,尾流速度变化以及风机的尾涡结构。数值模拟结果表明:在上下游风机沿流向方向距离保持不变的情况下,随着上游风机偏航角度的变化,上下游风机的尾流干扰现象以及下游风机的入流条件会发生明显改变,并会对下游风机的气动功率输出以及两风机风电场的整体流场产生显著影响。  相似文献   

The influence of vegetation cover on evapotranspiration atop waste rock piles,Elk Valley,British Columbia     

Erin M. Nicholls  Gordon B. Drewitt  Stephanie Fraser  Sean K. Carey 《水文研究》2019,33(20):2594-2606

Surface mining in the Elk Valley, British Columbia, involves removing vegetation, soil, and rock to access underlying metallurgical coal. Subsequent waste rock is placed into adjacent valleys, frequently burying headwater streams. Due to their coarse texture, waste rock piles increase infiltration and percolation, increasing solute transport and concentration of geochemicals in downstream surface waters. Previous research suggests that weathering solutes are transport limited, and it is hypothesized that revegetation will enhance evapotranspiration (ET) and reduce percolation through the waste rock, potentially reducing loading. This study examined the surface‐atmosphere water and energy exchanges using the eddy covariance technique for three waste rock surfaces with different levels of reclamation: (a) an ~25‐year‐old mixed coniferous forest, (b) a grass site, and (c) bare waste rock. Measurements were taken from May to October in 2013 and 2014. Soil moisture and matric suction were measured to 1‐m depth. Sap flow at the forested site was measured to partition transpiration from total ET. In all years, ET rates were greatest at the forested site, followed by the grass cover and lowest at the bare waste rock site. Growing season ET rates at the forest were 56% higher than grass in 2013 and 35% higher in 2014. At the vegetated sites, climate was the main driver of ET, with high radiation, and warm and dry conditions enhancing fluxes. Maximum ET at these sites corresponded with peak growing season, with vegetation increasing both transpiration and rainfall interception. At the bare rock site, ET was weakly related to atmospheric conditions, and ET rates briefly increased during periods following rainfall when near‐surface soil moisture was enhanced. Transpiration comprised 29% of overall ET at the forest site from late July to early October. Results suggest that vegetation establishment can be incorporated into mine reclamation plans to enhance ET rates and limit percolation, potentially reducing downstream geochemical loads.  相似文献   

基于卫星测高和卫星遥感海面温度探测的南海中尺度涡旋对比分析     

李惠玲  郭金运  文汉江 《大地测量与地球动力学》2018,38(11):1170-1173

基于海表面温度数据和海面高度异常数据，采用矢量几何法提取南海的中尺度涡旋并进行统计分析。结果显示，从海表面温度和海面高度异常数据都可以提取涡旋，两者的提取能力差异很小。由海表面温度数据可以提取较小尺度的涡旋，但跟踪涡旋时存在不稳定性；由海面高度异常数据虽然不能检测到较小尺度的涡旋，但跟踪涡旋相对稳定。两种数据所提取涡旋的时间和空间分布规律具有一致性。  相似文献   

南海中尺度涡温盐异常三维结构   总被引：4，自引：1，他引：3  

谢旭丹  王静  储小青  程旭华 《海洋学报》2018,40(4):1-14

基于1994-2015年海面高度异常数据，采用winding-angle中尺度涡旋探测算法识别出南海范围内共5 899个反气旋涡（AE）和3 792个气旋涡（CE），结合世界海洋数据集（WOD13）及中国科学院南海海洋研究所（SCSIO）温盐观测数据集，采用基于变分法的客观插值方法，合成了南海及南海各区域中尺度涡的温盐异常三维结构。结果表明，本文采取的插值方式能有效地获得涡旋三维结构，垂向尺度上也与前人研究结果较为一致。在平均状态下，南海AE温盐异常强度明显大于CE，AE正位温异常主体结构深度约440 m，而CE仅在320 m以浅维持涡旋结构；两者最大位温异常均出现在次表层约80 m上下，AE达2.02℃，CE达-1.60℃。盐度异常影响深度约150 m，最大盐度异常出现在50 m深附近，AE达-0.24，CE达0.28，同时由于涡旋在不单调变化的背景盐度场中引起海水下沉（上升），AE盐度异常结构呈"上负下正"而CE呈"上正下负"式结构。南海各区域合成涡旋的温、盐异常的影响程度并不完全相同，可能与各区域涡旋的生成机制及背景温盐场有关。  相似文献   

A case study of a Kuroshio main path cut-off event and impacts on the South China Sea in fall-winter 2013–2014     

郑全安  何宗儒  谢玲玲  李明明 《海洋学报(英文版)》2019,38(4):12-19

This study examines a Kuroshio main path(KMP) cut-off event east of Taiwan Island occurred in fall-winter2013–2014 and its impacts on the South China Sea(SCS) by analyzing satellite altimetry and mooring observations. Satellite altimeter sea level anomaly(SLA) images reveal a complete process that a huge cyclonic eddy(CE) from the Pacific collided with the Kuroshio and the western boundary from 15 October 2013 to 15 January 2014. Mooring observations evidenced that the Kuroshio upper ocean volume transport was cut off more than 82% from 17×106 m~3/s in September to 3×106 m~3/s in November 2013. The KMP cut-off event caused the Kuroshio branching and intruding into the SCS and strengthened the eddy kinetic energy in the northern SCS west of the Luzon Strait. Using the total momentum as a dynamic criterion to determine the role of eddy collision with the Kuroshio reasonably explains the KMP cut-off event.  相似文献