共查询到19条相似文献，搜索用时 109 毫秒
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大气重力波是地球大气层中广泛存在的重要大气动力学扰动,研究其分布和变化规律对理解大气物理、大气结构以及大气动力学等具有重要意义.传统大气重力波探测手段,如雷达和探空气球等,均存在探测时间短、有效探测高度低等缺点,全球卫星导航系统（GNSS）掩星观测具有全天候、低成本、高精度等优点,被广泛应用于地球大气探测和研究,为研究区域或全球重力波变化和活动特征提供了新的观测手段.本文利用中国第一颗搭载GNSS掩星设备气象卫星——风云3C （FY-3C）获得的掩星数据,反演得到2014年8月—2016年12月大气温度轮廓线,并首次估计重力波参数分布,分析了重力波参数的时空变化分布特征.结果表明,海陆季节性对流导致冬夏两季的重力波势能强于春秋两季,赤道对流作用导致赤道区域重力波强于两极,夏季南半球中低纬度地区重力波活动频繁,冬季北半球中低纬度区域重力波活动频繁.重力波随着高度的上升,势能逐渐下降.另外,地形是低层大气重力波的主要来源. 相似文献
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平流层和中层大气研究的进展 总被引：16，自引：4，他引：12
平流层和中层大气研究是20世纪70年代以来持续得到大气科学界和日地物理界共同关注的研究前沿.中国科学界在文化大革命结束后立即抓住这一前沿作为发展重点之一.20多年来,中国科学院大气物理研究所等单位较为系统地开展了这一方向的研究,并在一些方面进行了前沿性的工作.作者着重介绍以下几方面的进展:(1)平流层和中层大气探测设施与探测方法;(2)大气臭氧、平流层气溶胶的监测与分析;(3)行星波在中层大气环流与大气臭氧分布中的作用;(4)重力波在中层大气的传播特征与作用;(5)平流层-对流层交换的动力物理与化学问题. 相似文献
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重力波对特大暴雨的触发作用 总被引：23，自引：10，他引：23
暴雨是一种中尺度天气现象,但是它是在一定的大尺度背景下发生的,如发展着的锋面、低涡和气旋。由于这些系统的发展总是非地转平衡的,因而会激发出强的重力波。这种重力波在条件不稳定大气中传播时,低层辐合和上升气流能组织积云加热,这种积云加热反过来会促使重力波发展,在地面形成中尺度高低压系统。本文在线性绝热情况下求解大气运动方程,得到了重力波解。这种重力波解在位相上涡度中心比散度中心落后π/2,因而暴雨区落在中低压与中高压之间,且由于降水扩散,暴雨中心偏向中高压一边。在垂直结构上在对流层上层可以得到暖性中高压。理论上估计了暴雨团移动的速度和中高低压的强度等。并将理论结果与一次特大暴雨的实例进行了比较,两者是一致的。因而提出重力波在条件不稳定大气中可以是发动暴雨的一种机制。 相似文献
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选取四川省的一次暴雨个例分析研究大气中对流活动和重力波的相互内在联系。针对这次暴雨过程,采用MICAPS探空资料和天气雷达资料,并且结合天气学分析以及重力波指数的分析方法对暴雨的形成原因和重力波的机制进行了研究。结果表明:重力波与暴雨有一定的内在联系,重力波引导了暴雨的发展;非线性平衡方程对于诊断大幅度的重力波有很好的指示作用。 相似文献
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WANG Xiujuan LEI Hengchi FENG Liang ZHU Jiangshan LI Zhaoming JIANG Zhongbao 《大气和海洋科学快报》2020,(2):163-170
利用高精度微压计数据,详细分析了2016年11月20–21日佛山地区一次局地暴雨的重力波动态频谱特征,结果表明:重力波激发了此次暴雨,暴雨发生前,重力波呈现出振幅间歇性增大,周期范围不断增宽的过程;其中,暴雨前约4 h出现了重力波最大振幅80–160 Pa,相应的周期范围为140–270min。强雷暴对重力波的作用是积极的,会增大波的振幅,产生中心振幅约80–100 Pa,周期范围210–270 min重力波;尤其是,强雷暴激发了更短周期(≤36 min),振幅约10 Pa的重力波。大振幅重力波提前于暴雨出现,比雷达,卫星识别出强对流早了约4h,这一特征或许对局地强对流预警有指示意义。 相似文献
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１９８５～１９９２年在北京，贵阳及河北满城进行了多次强对流过程大气重力波探测研究中，发现灾害性冰雹出现前３～６小时即有周期为１０～４０分，振幅超过３０Ｐａ的大气微压重力波间歇性的活动。这一发现为灾害性冰雹过程的临近预报提供了重要指标，在此基础上使用重力波动态（三维）谱分析技术并设计了相应的微机系统软件，实现了大气重力波数据的实时采集分析和连续动态显示，从而研制成将微压波探头，数据采集，微机动态谱实 相似文献
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《大气和海洋科学快报》2020,(2)
利用高精度微压计数据,详细分析了2016年11月20–21日佛山地区一次局地暴雨的重力波动态频谱特征,结果表明:重力波激发了此次暴雨,暴雨发生前,重力波呈现出振幅间歇性增大,周期范围不断增宽的过程;其中,暴雨前约4 h出现了重力波最大振幅80–160 Pa,相应的周期范围为140–270min。强雷暴对重力波的作用是积极的,会增大波的振幅,产生中心振幅约80–100 Pa,周期范围210–270 min重力波;尤其是,强雷暴激发了更短周期(≤36 min),振幅约10 Pa的重力波。大振幅重力波提前于暴雨出现,比雷达,卫星识别出强对流早了约4h,这一特征或许对局地强对流预警有指示意义。 相似文献
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《高原气象》2021,40(3):590-602
大气重力波对全球大气的动力、热力结构具有重要影响,研究重力波参数气候特征是研制全球大气模式中重力波参数化的一个重要环节,通过引入重力波的影响,有利于提高大气模式的预报能力。本文利用2014-2017年太原地区(112.55°E,37.78°N)高垂直分辨率探空资料,对其对流层(2～9 km)、下平流层(17～24 km)大气重力波参数的气候特征及其之间差异特征进行研究。结果表明:(1)在1-12月,相对于对流层,下平流层的平均重力波水平波长、周期、固有相速、能量上传百分比均偏大,垂直波长均偏小,但群速在2月、5-9月偏大,其他月份偏小;(2)对流层与下平流层之间的重力波参数偏差、绝对差较大,相关性弱;(3)对流层、下平流层的重力波参数及其之间的偏差,在不同区间范围内的占有率分布特征存在明显差异;通过研究太原地区上空对流层、下平流层大气重力波参数的气候及其之间差异特征,进一步补充了中国区域的大气重力波参数气候特征,有利于研制更适合中国区域数值预报模式的重力波参数化方案。 相似文献
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Local breeding of growing modes(LBGM) is a method used to generate initial condition perturbation(ICP) for convection-permitting ensemble forecasts. Equal weights(EWs) are usually presumed in LBGM during the localization of ICP, without considering different contributions of the grid points within the local radius. To address this problem, Gaussian weights(GWs) are proposed in this study, which can accommodate the varied influences of the grids inside the local radius on the central grid through a Gaussian function. Specifically, two convection-permitting ensemble forecast experiments based on LBGM with GWs and EWs are compared and analyzed respectively for two squall line cases. The results showed that the use of the GWs intensified the local characteristics of the ICP and made the distribution of the ICP fields more flow-dependent. Kinetic energy spectrum of the ICP indicated that there could be more large-scale information in the ICP by using the GWs. In addition, mesoscale information also improved slightly. For forecast of nonprecipitation variables, GWs improved the relationship between the root-mean-square error and the spread and contributed to the forecasting accuracy of wind, temperature, geopotential height, and humidity. For the precipitation forecast, GWs simulated the precipitation structure successfully and provided better probability forecasting during the evolution of the two squall line processes than the EWs. 相似文献
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Considering the multiscale character of LFO (low-frequency oscillation) in the tropical atmosphere, the effects of SST on LFO in the tropical atmosphere are discussed by using an absolute ageostrophic, baroclinic model. Here, SST effects include sea surface heating and forcing of SST anomalies (SSTAs). Studies of the influences of sea surface heating on LFO frequency and stability show that sea surface heating can slow the speed of waves and lower their frequency when SST is comparatively low; while higher SST leads to unstable waves and less periods of LFO. Since the impact of a SSTA on ultra-long waves is more evident than that on kilometer-scale waves, long-wave approximation is used when we continue to study the effect of SSTAs. Results indicate that SSTAs can lead to a longer period of LFO, and make waves unstable. In other words, positive (negative) SSTAs can make waves decay (grow). 相似文献
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本文应用谱方法,诊断、计算了1964—1985年间,6个厄尔尼诺年和6个反厄尔尼诺年北半球月、季大气非绝热热流量距平场。结果表明:厄尔尼诺现象对大气非绝热热流量距平场具有显著影响,大气的响应表现为低纬和中高纬非绝热热流量正负距平中心有组织的优势排列,其位相或强度存在低频振荡,并且差值中心表现为双月周期。反厄尔尼诺年,大气具有分布不变,但距平中心基本上为反位相的响应形式。最后,通过海气相关分析,指出了海温异常是决定大气非绝热热流量异常的最重要的原因。 相似文献
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Impacts of SST and SST Anomalies on Low-Frequency Oscillation in the Tropical Atmosphere 总被引：4，自引：0，他引：4
Considering the multiscale character of LFO effects of SST on LFO in the tropical atmosphere （low-frequency oscillation） in the tropical atmosphere, the are discussed by using an absolute ageostrophic, baroclinic model. Here, SST effects include sea surface heating and forcing of SST anomalies （SSTAs）. Studies of the influences of sea surface heating on LFO frequency and stability show that sea surface heating can slow the speed of waves and lower their frequency when SST is comparatively low; while higher SST leads to unstable waves and less periods of LFO. Since the impact of a SSTA on ultra-long waves is more evident than that on kilometer-scale waves, long-wave approximation is used when we continue to study the effect of SSTAs. Results indicate that SSTAs can lead to a longer period of LFO, and make waves unstable. In other words, positive （negative） SSTAs can make waves decay （grow）. 相似文献
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Month-Long Simulations of Gravity Waves over North America and North Atlantic in Comparison with Satellite Observations 
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下载免费PDF全文 Mesoscale simulations of gravity waves in the upper troposphere and lower stratosphere over North America and North Atlantic Ocean in January 2003 are compared with satellite radiance measurements from the Advanced Microwave Sounding Unit-A (AMSU-A). Four regions of strong gravity wave (GW) activities are found in the model simulations and the AMSU-A observations: the northwestern Atlantic, the U.S. Rockies, the Appalachians, and Greenland. GWs over the northwestern Atlantic Ocean are associated with the midlatitude baroclinic jet-front system, while the other three regions are apparently related to high topography. Model simulations are further used to analyze momentum fluxes in the zonal and meridional directions. It is found that strong westward momentum fluxes are prevalent over these regions over the whole period. Despite qualitative agreement between model simulations and satellite measurements, sensitivity experiments demonstrate that the simulated GWs are sensitive to the model spin-up time. 相似文献
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P. L. Read 《Dynamics of Atmospheres and Oceans》1985,9(2):135-207
A series of numerical simulations of steady wave flows in a rotating fluid annulus, subject to internal heating and various thermal boundary conditions, is examined to characterise their structures, energetics and potential vorticity transport properties. The last of these characteristics, together with more conventional scaling considerations, indicate the possibility of applying quasi-geostrophic theory to the interior flow in a formulation similar to the inviscid, adiabatic models of Kuo and White.The analytical model of White, describing finite amplitude, neutral baroclinic eddies and mean flows as illustrations of the Charney-Drazin non-acceleration theorem, is then extended to include uniform diabatic heating and the effects of different forms of lateral shear in the background mean zonal flow. Like the solutions discussed by White, those obtained in the present paper consist of steady, internal jet, mean zonal flows, and baroclinic and barotropic Rossby wave components, all having the same three-dimensional wavenumber. Provided the diabatic heating is proportional to the stratification of the background flow, measured by the square of the Brunt-Vaisälä frequency N, the potential vorticity equation remains homogeneous. All the solutions are then characterised by zero net transfer of potential vorticity despite the possibility of non-zero eddy fluxes of heat or momentum and non-trivial Lorenz energy cycles.A series of particular three-component solutions (which, like some of the solutions discussed by White, do not obey conventional lateral boundary conditions) is examined as possible theoretical analogues of the steady waves observed in the numerical simulations of the laboratory flows, and is found to agree encouragingly well in the spatial variations of their mean flows, eddy stream function (pressure) and eddy fluxes of heat and momentum. Potential vorticity fluxes in the numerical simulations are relatively small (though crucially non-zero), supporting the possible analogy with the analytical model and exposing some limitations of the latter in not accounting for weak dissipation and forcing processes present in the laboratory flows.Further implications of the results are discussed, including possible analogies between the laboratory experiments and certain features in planetary atmospheres and oceans. 相似文献
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用近50年逐日气象观测记录和城市发展统计资料分析了东北平原腹地3个不同规模城市,即大城市长春,中等城市延吉和山区小城镇临江的年和季节平均气温、最高最低气温等,发现其差别很大,其排序不一定同城市化速率(人口和国内生产总值GDP)、土地利用或能见度趋势对应。但气温日较差趋势均与城市化速率成比例。3个城市气温趋势均表现为变暖,且最低气温趋势大于最高气温趋势;冬季变暖强于夏季。这说明影响夜间或冬季气温的才是城市热岛的主要驱动因子。冬、夏最高气温趋势排序一致,除临江外,最低气温趋势排序与最高气温相反。临江冬季最低气温趋势最强,可能与其特殊地理环境造成的弱风气候有关。最低气温趋势排序与城市化速率排序大致相同,最高气温趋势排序相反。综合对比分析表明,这3个城市气候变暖差异的主要因子不可能是土地利用,而是城市人为热释放和空气污染,后者主要影响夜间的射出长波辐射。二者的影响范围趋势应该同城市化速率成比例,对气温趋势有明显影响。其次,不能忽略地理环境因子对气温趋势及其排序的影响。不过,气温日较差在一定程度上可以削弱城市地理因素等的影响,其趋势是一个反映城市化对气候影响的的合适指标。研究还表明,需要重视空气污染对长波辐射的影响并应该在数值模式辐射参数化中加以考虑。 相似文献
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This study investigates the spatial and temporal variability of global stratospheric gravity waves (GWs) and the characteristics of GW activity during sudden stratospheric warming (SSW) using the GPS radio occultation measurements from the COSMIC mission during September 2006 to May 2013. Corresponding to the COSMIC RO observational window and analysis method, GW potential energy (Ep) with vertical scales no shorter than ～2 km is resolved. It is found that the distributions of GW Ep over 20-30 km and 30-38 km show similar spatial and seasonal variations. The variations of GW Ep with altitude and latitude along the westerly wind are identified in different seasons over 60°-80°W. In the middle and high latitudes, seasonal cycles are distinct in the time-latitude and time-altitude distributions of GW activities, which show larger Ep in winters when westerly wind dominates and smaller Ep in summers when easterly wind dominates. The influence of quasi-biennial oscillation on GW activity is recognized in the tropics. GW Ep enhances closely following the occurrence of minor SSW events; while during major events, GW Ep may not enhance, and sometimes may even weaken, in the regions where reversals of zonal wind occur, probably caused by the filtering impact of the 0 m s-1 wind level on the GWs. 相似文献
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A set of new parameterizations for the friction velocity and temperature scale over gently
sloped terrain and in calm synoptic conditions are theoretically derived. The friction velocity is
found to be proportional to the product of the square root of the total accumulated heating in the
boundary layer and the sinusoidal function of the slope angle, while the temperature scale is
proportional to the product of the boundary layer depth, the sinusoidal function of the slope angle
and the potential temperature gradient in the free atmosphere. Using the new friction velocity
parameterization, together with a parameterization of eddy diffusivity and an initial potential
temperature profile around sunrise, an improved parameterization for the thermally induced upslope
flow profile is derived by solving the Prandtl equations. The upslope flow profile is found to be
simply proportional to the friction velocity. 相似文献