Large Scale Perturbations in Extratropical Atmosphere-Part Ⅱ: On Geostrophic Waves

We have examined, in Part Ⅰ, the propagation mechanism and geostrophic property of classical Rossby waves in a non-divergent barotropic atmosphere. As we found that the non-divergent Rossby waves do not propagate in a hydrostatically equilibrium atmosphere, and do not manifest a good geostrophic property, an alternative large scale circulation pattern of geostrophic waves has been proposed (McHall, 1991a). The propagation mechanism and geostrophic property of these waves are examined in the present study.     

PRIMARY STUDY OF SULFATE AND CARBONACEOUS AEROSOLS IN BEIJING

Results of our aerosol study, performed during 1983-1984 in Beijing, demonstrate that ambient carbonaceous aerosols are derived mainly from coal combustion. Different SO, oxidation processes have been observed in summer and winter. The winter sulfate appears to be produced locally and associated with products of incomplete combustion.     

基于全球超导重力仪观测研究海潮和固体潮模型的适定性

利用国际地球动力学合作观测网络中20个台站22个高精度重力潮汐观测系列综合研究了目前使用的海潮和固体潮模型的适定性. 对原始观测数据实施仔细的预处理, 利用国际标准算法计算了潮汐重力参数. 基于负荷理论和不同全球海潮模型获得了8个主波的重力负荷矢量, 用二维平面插值技术获得了14个小波的负荷改正值. 顾及不同潮波振幅特征, 提出了计算台站平均观测残差和剩余残差矢量的“非等权均值法”, 分析了海潮负荷改正的有效性和振幅因子与理论模型间的差异, 同时还讨论了仪器标定问题. 获得了经海潮负荷改正后全球各台站平均潮汐重力参数, 结果说明观测与理论模型间的差异小于0.3%, 最大仪器标定误差不超过0.5%. 另外文章还用地表重力实测数据证实了Mathews理论中相对于周日O₁波而言, K₁波相位滞后略呈正值的结论.     

Microphysical Characteristics of Extreme-Rainfall Convection over the Pearl River Delta Region,South China from Polarimetric Radar Data during the Pre-summer Rainy Season

During the pre-summer rainy season, heavy rainfall occurs frequently in South China. Based on polarimetric radar observations, the microphysical characteristics and processes of convective features associated with extreme rainfall rates(ERCFs) are examined. In the regions with high ERCF occurrence frequency, sub-regional differences are found in the lightning flash rate(LFR) distributions. In the region with higher LFRs, the ERCFs have larger volumes of high reflectivity factor above the freezin...     

Preface to Special Issue on the National Report to the IUGG Centennial by CNC-IAMAS(2011–2018)

正The 27th General Assembly of the International Union of Geodesy and Geophysics(IUGG), which also marks the 100 th anniversary of IUGG, will be held during 8–18 July 2019 in Montréal, Canada. The Chinese National Committee(CNC)for the International Association of Meteorology and Atmospheric Sciences(IAMAS) has a more than 30-year tradition of     

利用FM-CW雷达研究对流层降水过程

由于FM-CW雷达硬件、信号处理以及多普勒偏振FM-CW雷达DARR可用性方面的进步,FM-CW对流层雷达领域可能出现新的突破。DARR具有很高的距离、多普勒速度和偏振分辨率。该雷达能获得每秒几厘米的多普勒分辨率,及每秒±9米的最大多普勒范围。使用两个直接安装在发射和接收天线中心馈电器后面的机械偏振器,工作时偏振角的范围在±90度之间。本文给出了实测的多普勒速度和测偏振反射率廓线。根据这些廓线对层状云降雨融化过程和雨滴谱进行了模拟和验证。     

地形降水机制

从降水量—地形高度对应关系图上可以清楚地看出山脉对水分循环的影响。图1和图2就是例子。在有些地理区城,这种对应关系是已为人们所了解,但在其它区域并非如此,许多年来关于这个问题的科学研究一直进行得很缓慢。本文回顾了目前人们对地形降水的了解。Bonacina(1945),     

Mesoscale Vortex Generation and Merging Process： A Case Study Associated with a Post-Landfall Tropical Depression

An observational analysis of satellite blackbody temperature (TBB) data and radar images suggests that the mesoscale vortex generation and merging process appeared to be essential for a tropical-depression-related heavy rain event in Shanghai, China. A numerical simulation reproduced the observed mesoscale vortex generation and merging process and the corresponding rain pattern, and then the model outputs were used to study the related dynamics through diagnosing the potential vorticity (PV) equation. The t...     

用微型干涉仪测地终端设备(MITES)测量基线的精度估计

<正> 1980年12月17日将轻便的MITES天线(见Bull.Geod.53,139—163,1979)设在Haystack天文台附近三座测量标志的顶部。这些天线获得了全球定位系统卫星(NAVSTAR/GPS)的射电干涉测量结果,经过分析后,便确定了这些测量标志之间的基线向量。     

Retrieval of water vapor profiles with radio occultation measurements using an artificial neural network

A new method applying an artificial neural network （ANN） to retrieve water vapor profiles in the troposphere is presented. In this paper, a fully-connected, three-layer network based on the backpropagation algorithm is constructed. Month, latitude, altitude and bending angle are chosen as the input vectors and water vapor pressure as the output vector. There are 130 groups of occultation measurements from June to November 2002 in the dataset. Seventy pairs of bending angles and water vapor pressure profiles are used to train the ANN, and the sixty remaining pairs of profiles are applied to the validation of the retrieval. By comparing the retrieved profiles with the corresponding ones from the Information System and Data Center of the Challenging Mini-Satellite Payload for Geoscientific Research and Application （CHAMP-ISDC）, it can be concluded that the ANN is relatively convenient and accurate. Its results can be provided as the first guess for the iterative methods or the non-linear optimal estimation inverse method.