2008年初我国南方雨雪低温天气的中期过程分析I：亚非副热带急流低频波

在中期时间尺度上分析了2008年1月10~16日我国南方雨雪过程特征及其可能机理,得到了以下结果：1）3个环流系统的演变过程相互匹配,共同造成了此次雨雪过程,它们分别为南支槽在我国南方地区的形成和加深、西太平洋副热带高压的北扩以及叶尼塞地区高压脊的东扩南侵;2）源自东北大西洋和西欧的Rossby波能量沿亚非副热带急流向下游传播,导致南支槽在我国南方地区形成和加深;3）与西太平洋副热带高压北扩所对应的异常环流中心,其实质为副热带急流扰动,来自上游南支槽区的Rossby波能量频散是其形成维持的主要原因,它也受来自贝加尔湖地区及热带西太平洋对流区的Rossby波能量的影响;4）亚非副热带纬向基本流制约着其一系列异常环流中心的纬向联系,里海冷堆及异常中心的形成恰好对应着南支槽在我国南方地区的加深和西太平洋副热带高压的北扩。     

黑潮和北大西洋海温异常在2008年1月我国南方雪灾中的可能作用的数值模拟

根据NCEP/NCAR再分析资料、NOAA扩展重建海表温度资料,利用中国科学院大气物理研究所全球大气环流谱模式（IAP-T42L9）模拟了大气环流对黑潮区、北大西洋海温异常偏暖的响应特征,并探讨了黑潮区、北大西洋海温异常在2008年1月我国南方雪灾中的作用。通过模拟场与观测场的比较表明,在考虑黑潮区和北大西洋海温异常偏暖的情况下,模式比较成功地模拟出了2008年1月我国南方发生低温、雨雪、冰冻天气的各种主要环流特征。黑潮区海温升高导致东亚沿海位势高度增加,西太平洋副热带高压偏北。它一方面不利于冷空气向下游输送,导致冷空气在我国长江流域及其以南地区堆积;另一方面加强了海洋的暖湿气流及向我国长江流域及其以南地区的水汽输送,为我国南方雨雪天气形成提供了充沛的水汽条件,有利于我国南方低温、雨雪、冰冻天气的持续。北大西洋海温异常偏暖对中高纬地区中西伯利亚阻塞高压的形成有重要作用。受其影响,我国除受东路冷空气活动的影响外,中纬度还不断有西路冷空气随着西风带槽脊东移影响我国东部地区。它是导致我国南方低温、雨雪、冰冻天气持续的另一个重要原因。     

SST THERMAL FORCING – A DISCUSSION ON THE MECHANISM OF ATMOSPHERIC LOW-FREQUENCY OSCILLATION

Dynamic and numerical methods are used to discuss the atmospheric response to SST thermal forcing. The results show that for planetary scale systems, the standing SST thermal forcing can quickly excite a stable atmospheric equilibrium state response, which is characterized by obvious large-scale teleconnection oscillation in east-west and south-north directions. For synoptic scale systems, the SST thermal forcing mainly excites the atmospheric low-frequency oscillation. Some basic relation and dynamic processes between SST thermal forcing and atmospheric response pattern are revealed and some new viewpoints are presented.     

横向雨量器的设计及由风引起的降水测量误差订正

该文提出了横向雨量器的设计原理。经30个站7年2.8万多次的坑式雨量器、台站雨量器和横向雨量器的对比观测, 证实降水量测量的绝对差值与横向降水量呈一元幂函数关系, 相关系数达0.99。在现行的台站观测业务中, 只要增加横向雨量器的并行观测, 就可对台站雨量器测量的降水量 (包括雪量) 实施订正。订正后的精度接近于坑式雨量器的测量精度。订正方法简便易行, 可应用于业务观测。     

M—γ尺度G—Chen坐标系中气候模式的研制（续完）

（上接本刊 2000年第 4期第 30页） 4土壤系统模式的建立及其参数化 　　覆盖地球陆地表面较薄的土壤覆盖物是一种性质变化很大的多孔物质。它的固相是由岩石风化成的无机物和伴有栖居于土壤的动植物有机产物所组成。这些物质的质地范围可从粗砂到细粘土，构成土壤层的物质随土壤剖面上下位置的不同而有很大区别。太原地区的土壤大致为壤土 (轻粘土 )，为讨论处理方便起见，我们略去了土质上下层之间的微小变化。 　　下面我们建立描述土壤热量和水分交换的运动方程，大气和土壤的质能交换主要是通过这两种过程实现…     

中国东部和印度季风区云辐射特性的比较

基于 ＩＳＣＣＰ和 ＥＱＢＥ资料,本文比较了中国东部和印度季风区的云和云辐射强迫的气候特征。虽然它们同属于亚洲季风区,并且有相似的降水季节特征,但它们各自的云和云辐射强迫特征差异很大。在印度区域,所有的云量有着相同的季节变化,最大云量分布都出现在夏季,且总云量中以高云量为主。而中国东部云量的季节变化都比较复杂,在总云量中以中、低云量为主,最大总云量出现在春季。冬季的总云量和中、低云量要大于夏季。在全球云量分布中,中国东部最典型的特征是：该地区为全球最大的雨层云覆盖区。与云的分布和变化相关,印度季风区最大的负短波云辐射强迫,最大的正的长波辐射强迫和最大的负的净云辐射强迫发生在夏季,而在中国东部,大的负的短波云辐射强迫发生在春夏之交。年平均的负的短波云辐射强迫在中国东部地区明显要大于在印度季风区。     

A modified Richards equation, its adjoint, and a new perspective on land data assimilation

Summary Richards equation, which is the key relationship for addressing basic soil hydrological processes within the rhizosphere and constitutes the basis for multiple-layer soil hydrology models for meteorological studies, is modified to include two vegetation processes: the transpiration (daytime) and hydraulic lift (nighttime). The analytical form of the adjoint system is derived and can serve as the guideline for discrete forms, as implemented in a variety of multiple layer land surface models. The modified equation and its adjoint model may be used to address at least two types of inverse problems: estimation of the initial soil moisture contents from sparse observations of related quantities; and retrieval of critical soil/vegetation parameters with observations of soil moisture contents (or other related quantities) distributed over a certain period of time. The former may be of more interest for numerical weather prediction studies, whereas the latter may be more valuable for longer time integration of climate models.     

Identification Standard for ENSO Events and Its Application to Climate Monitoring and Prediction in China

The El Niño–Southern Oscillation (ENSO) reflects anomalous variations in the sea surface temperature (SST) and atmospheric circulation over the tropical central–eastern Pacific. It remarkably impacts on weather and climate worldwide, so monitoring and prediction of ENSO draw intensive research. However, there is not yet a unique standard internationally for identifying the timing, intensity, and type of ENSO events. The National Climate Center of China Meteorological Administration (NCC/CMA) has led the effort to establish a national identification standard of ENSO events, which was officially endorsed by the National Standardization Administration of China and implemented operationally in NCC/CMA in 2017. In this paper, two key aspects of this standard are introduced. First, the Niño3.4 SST anomaly index, which is well-recognized in the international ENSO research community and used operationally in the US, has replaced the previous Niño Z index and been used to identify the start, end, and peak times, and intensity of ENSO events. Second, two new indices—the eastern Pacific ENSO (EP) index and the central Pacific ENSO (CP) index, based on the SST conditions in Niño3 and Niño4 region respectively, are calculated to first determine the ENSO type before monitoring and assessing the impacts of ENSO on China’s climate. With this standard, all historical ENSO events since 1950 are consistently re-identified; their distinct properties are diagnosed and presented; and the impacts of ENSO events under different types on China’s climate are re-assessed. This standard is also employed to validate the intensity, grade, and type of the ENSO events predicted by the NCC/CMA operational ENSO prediction system. The new standard and the thus derived unified set of re-analyzed historical ENSO events and associated information provide a good reference for better monitoring and prediction of future ENSO events.     

Single Particle Characterisation of the Aerosol in the Marine Boundary Layer and Free Troposphere over Tenerife, NE Atlantic, during ACE-2

In the framework of the 2nd Aerosol Characterization Experiment (ACE-2), in June and July 1997, size segregated samples were collected for single particle analysis on the island of Tenerife, in both the marine boundary layer (MBL) and the free troposphere (FT), to study the characteristics of the North Atlantic aerosol. A systematic assessment was made of the aerosol under background conditions and when the environment was perturbed by European emissions and/or Saharan dust. The aerosol particles were analysed by automated and manual SEM-EDX, followed by cluster analysis to identify the different particle types and their abundance. Basing on back trajectory calculations, particle numbers and volume concentrations, different periods can be identified regarding the origin of the sampled air masses. In the FT, the air masses were classified as clean Atlantic, Saharan dust from Africa or pollution from Europe. In the MBL, air masses were classified as clean, polluted or perturbed by emissions from Europe. For both the FT and MBL samples, the main changes in chemical composition were observed between the fine and coarse mode aerosol. The FT fine mode aerosol is dominated by S-poor aluminosilicates (62%) in the event of the dust samples or sulphates, carbonaceous particles (20%) and S-rich aluminosilicates (46%) in the polluted samples. For the larger fractions, a strong decreasing trend was observed for the sulphates (less than 20%) and carbonaceous particles (10%) in the polluted samples. The MBL fine mode was completely dominated by S-rich particles (polluted 55% and perturbed 59%), and to a lesser extent, carbonaceous and aged sea salt particles. In the coarse mode, the polluted air mass is dominated by sea salt particles (62%). Contrary to the fine fraction, the polluted air mass in the coarse fraction contained 5.3% of S-rich particles. The combined interpretation of the data from the analysis of size-fractioned particles and the calculated backward trajectories for air masses coming from Europe, Africa and the Atlantic, results in better insights on aerosol chemistry, especially for the comparison of the particle composition in the FT and the MBL.     

THE SOUTH CHINA SEA SUMMER MONSOON AND THE SEASONAL MODALITY AND WEST EXTENDING OF THE NORTHERN HEMISPHERE PACIFIC SUBTROPICAL HIGH

~~THE SOUTH CHINA SEA SUMMER MONSOON AND THE SEASONAL MODALITY AND WEST EXTENDING OF THE NORTHERN HEMISPHERE PACIFIC SUBTROPICAL HIGH@张韧$Department of Marine Meteorology, Institute of Meteorology, PLA University of Sciences & Technology, Nanjing 211101 China @何金海$Department of Atmospheric Sciences, Nanjing Institute of Meteorology, Nanjing 210044 China @董兆俊$Department of Marine Meteorology, Institute of Meteorology, PLA Uni…