利用RIEMS-LRM对黄河河川径流的模拟研究

利用区域系统环境集成模式(RIEMS）和一个offline的大尺度汇流模型(LRM)对黄河的河川径流做了模拟。中国科学院大气物理所东亚中心从1991年开始建立和发展RIEMS，并验证RIEMS对东亚区域气候有较好的模拟能力。LRM是以线性时基不变假定为基础并能够计算水的水平传输的数学模型。RIEMS—LRM可以用来模拟和预测大尺度河流的河川径流。RIEMS—LRM在黄河上游河段的应用证实其有能力对大尺度河流的河川径流进行模拟。此外，作还分析了模拟误差产生的原因。     

Optical properties of cirrus transition zones over China detected by CALIOP

A transition zone near cirrus lateral boundaries can be detected by CALIOP (cloud–aerosol lidar with orthogonal polarization). In the present study, for such transition zones over China, a number of optical properties, such as the backscatter coefficient and depolarization ratio, showed transitional characteristics between cirrus and clear sky. The stepped horizontal profile showed sharp changes in particle number and morphology between cirrus clouds and clear sky. The color ratio, however, was unable to show cirrus transition features because of the low signal-to-noise ratio. Typical ice particles presented a color ratio of 0.55–1.25 and a depolarization ratio of greater than 0.12, which were significantly higher than those of clear sky. Therefore, optical properties in transition took the form of stepwise horizontal profiles. The proportion of typical-featured particles also demonstrated a stepped horizontal profile similar to the optical characteristics, but the relationship between the proportion and the optical characteristics was not uniform in the cirrus clouds, transition zone, and clear sky. Therefore, the optical changes in the transition zone were caused by not only the change in particle concentration, but also the change in the particles themselves. The probability density distribution of the transition-zone widths showed a positive skewness distribution, and transition zones with widths of 3–5 km occurred most frequently. Overall, transition-zone width decreased with increasing temperature and increased with increasing vertical and horizontal wind speeds. This trend demonstrated independence with the direction of the vertical and horizontal winds. These observations implied that the transitional features were caused by material exchange, such as entrainment and turbulent transport, near the cirrus lateral boundaries, and by the phase transformation of particles, such as sublimation.     

地形因子对降水的影响研究综述

围绕地形如何影响降水、地形对降水的增幅影响,特别是地形对暴雨的影响研究进行综述。地形对降水的作用主要涉及动力和热力方面,包括迎风坡的阻塞回流、背风涡的生成或加深。地形的起伏通过触发地形重力波的生成,促进天气系统的发展。最后提出,在地形影响降水的数值模拟研究方面,应把更多的数据类型和高分辨率地形相结合,开展数据资料同化研究;气候统计研究方面,应着重开展山地降水的强度、大气环流形势等分析,以提高降水预报准确率。     

露、霜、结冰天气现象综合判别

通过自动气象站的连续观测资料,结合人工观测的天气现象,根据露、霜、结冰的成因筛选出符合条件的基本指标作为综合判据。选取气温、相对湿度、地面温度、草面温度和近地面温度作为主要因子,综合考虑降水和天气状况对这些天气现象形成的影响。采用两个气象观测站的分钟观测资料以及人工观测天气现象记录进行统计分析。经过初选因子和精选指标,利用多要素的组合方法,提炼出自然状态下出现露、霜、结冰现象的综合判别指标,获得了较好效果,拟合率在80%以上。为进一步认识这些天气现象的发生和变化规律提供参考,也能为天气现象观测自动化提供依据。     

长江中下游1998年夏季梅雨期降水再循环研究

改进了Eltahir的降水再循环率计算模式,引入水汽变化量,使其可用于小于月际时间尺度的降水再循环评估。并利用1998年6~8月间长江中下游162个测站的旬蒸发和降水资料,结合NCEP/NCAR的高空逐日再分析资料,对长江中下游1998年梅雨期的降水再循环率做了计算。分析发现:1998年夏季暴雨时期长江中下游的降水平均约有三成来自当地的蒸发。区域蒸发的水汽在安徽南部和湖北东部对降水的贡献最大。区域平均再循环率的旬变化强烈,最高可达67.8%,最小只有0.8%。表明地表水文敏感,地-气相互作用不稳定。     

A global ocean reanalysis product in the China Ocean Reanalysis (CORA) project

The first version of a global ocean reanalysis over multiple decades (1979–2008) has been completed by the National Marine Data and Information Service within the China Ocean Reanalysis (CORA) project. The global ocean model employed is based upon the ocean general circulation model of the Massachusetts Institute of Technology. A sequential data assimilation scheme within the framework of 3D variational (3DVar) analysis, called multi-grid 3DVar, is implemented in 3D space for retrieving multiple-scale observational information. Assimilated oceanic observations include sea level anomalies (SLAs) from multi-altimeters, sea surface temperatures (SSTs) from remote sensing satellites, and in-situ temperature/salinity profiles. Evaluation showed that compared to the model simulation, the annual mean heat content of the global reanalysis is significantly approaching that of World Ocean Atlas 2009 (WOA09) data. The quality of the global temperature climatology was found to be comparable with the product of Simple Ocean Data Assimilation (SODA), and the major ENSO events were reconstructed. The global and Atlantic meridional overturning circulations showed some similarity as SODA, although significant differences were found to exist. The analysis of temperature and salinity in the current version has relatively larger errors at high latitudes and improvements are ongoing in an updated version. CORA was found to provide a simulation of the subsurface current in the equatorial Pacific with a correlation coefficient beyond about 0.6 compared with the Tropical Atmosphere Ocean (TAO) mooring data. The mean difference of SLAs between altimetry data and CORA was less than 0.1 m in most years.     

民用炸药库防雷地网分析

以一种较为简单可行的计算方法,对炸药库在复杂土壤环境下的防雷地网进行设计计算,并通过对新建炸药库接地工程前期设计和施工资料对比验收实测值,验证该设计计算方法的可行性。     

Emission of fine organic aerosol from traditional charcoal broiling in China

The indoor PM_2.5 aerosol samples for charcoal broiling source under Chinese traditional charbroiling and the ambient fine aerosols samples (PM_2.5) were collected in Beijing to investigate the characteristics of the charcoal broiling source and its impact on the fine organic aerosols in the atmosphere. The concentrations of 20 species of the trace organic compounds, including polycyclic aromatic hydrocarbons (PAHs), fatty acids, levoglucosan, and cholesterol in PM_2.5 were identified and quantified by GC/MS. The total PAHs and fatty acids emitted from charcoal broiling to PM_2.5 were 8.97 and 87,000 ng mg⁻¹ respectively. The concentrations of the light molecular weight (LMW) 3- and 4-ring PAHs were much higher than those of the high molecular weight (HMW) 5- and 6-ring PAHs. Fatty acids were the most abundant species in source profile, accounting for over 90% of all identified organic compounds. More polyunsaturated fatty acid (linoleic acids) than the saturated fatty acid (stearic acids) emitted in the cooking. Charcoal broiling is a minor source of PAHs compared to the source of biomass burning. Comparing the ratios of levoglucosan/fatty acid and levoglucosan/cholesterol in the charcoal broiling samples to the ambient samples, it is evident that meat cooking is an important source of fatty acids, but a less important source of cholesterol. Cooking, as one of the source of fine organic particles, plus other anthropogenic sources would be related to the formation of the severe haze occurred and spread over the urban atmosphere in most of the cities of China in the past several years.     

Increased water vapor supply in winter and spring leading to the arid Central Asian wetting in last 6000 years

Science China Earth Sciences - Paleoclimate reconstructions show that the arid Central Asia (ACA) is characterized by a wetting trend from the mid-Holocene (MH) to the Preindustrial period (PI),...     

考虑SSI效应的核电厂直立翼墙与排水沉管交叉体系静动力响应分析

某核电厂的联合泵房两侧直立翼墙以及排水沉管为交叉设计,且属抗震I类物项,因此,考虑土-交叉体系结构动力相互作用是抗震安全性评价的关键技术问题。以实际核电厂条件为背景,基于ANSYS分析平台建立了翼墙-沉管交叉体系-地基静动力分析模型,运用UPFs创建的粘弹性边界单元考虑无限地基辐射阻尼影响及地震动的输入,并精细化模拟地基材料的力学特性及交叉体系的空间分布形态,开展了静动力荷载联合作用下翼墙-沉管交叉体系的响应分析,探究交叉体系结构的应力、变形及加速度峰值等响应的变化规律。计算结果表明：直立翼墙与排水沉管交叉部位出现了应力集中现象,翼墙结构的竖向加速度响应与竖向及顺沉管水平向位移变形有较大变化,沉管在交叉部位的响应也有显著增加。研究成果可为核电厂取水工程构筑物的类似交叉体系设计提供技术参考。