A Review of Aerosol Optical Properties and Radiative Effects

Atmospheric aerosols influence the earth's radiative balance directly through scattering and absorbing solar radiation, and indirectly through affecting cloud properties. An understanding of aerosol optical properties is fundamental to studies of aerosol effects on climate. Although many such studies have been undertaken, large uncertainties in describing aerosol optical characteristics remain, especially regarding the absorption properties of different aerosols. Aerosol radiative effects are considered as either positive or negative perturbations to the radiation balance, and they include direct, indirect (albedo effect and cloud lifetime effect), and semi-direct effects. The total direct effect of anthropogenic aerosols is negative (cooling), although some components may contribute a positive effect (warming). Both the albedo effect and cloud lifetime effect cool the atmosphere by increasing cloud optical depth and cloud cover, respectively. Absorbing aerosols, such as carbonaceous aerosols and dust, exert a positive forcing at the top of atmosphere and a negative forcing at the surface, and they can directly warm the atmosphere. Internally mixed black carbon aerosols produce a stronger warming effect than externally mixed black carbon particles do. The semi-direct effect of absorbing aerosols could amplify this warming effect. Based on observational (ground-and satellite-based) and simulation studies, this paper reviews current progress in research regarding the optical properties and radiative effects of aerosols and also discusses several important issues to be addressed in future studies.     

The Research on Stability of Surrounding Rock in Gob-Side Entry Driving in Deep and Thick Seam

Geotechnical and Geological Engineering - The gob-side entry driving is driving in low pressure area, which bears less support pressure and is easy to maintain, so it is widely used. Taking the...     

基于NWC甚低频信号的日出效应的观测与分析

频率在3~30 kHz的甚低频(VLF,Very Low Frequency)波具有较小的传播损耗和较高的趋肤深度,可以在地球-低电离层波导中实现长距离传输,广泛应用于航海导航、对潜通信等领域,且在电离层遥测方面具有十分重要的意义.基于武汉大学自主研发的VLF接收机在武汉接收的NWC(North West Cape)台站信号,本文通过分析2018年4月23日—2020年7月22日的观测数据研究了日出期间NWC信号的幅度响应及其特点和规律.结果表明NWC信号日出期间的幅度响应主要包括两种极小值结构：2个幅度极小值(SR1、SR2)的Type Ⅰ结构和3个幅度极小值(SR1、SR2、SR3)的Type Ⅱ结构.在以SR1出现时间为时间零点进行时序叠加分析后发现,Type Ⅰ结构比Type Ⅱ具有更强的规律性和稳定性.在Type Ⅰ结构下,SR2出现时间的波动范围、平均值、标准差分别为43~65 min、54.2 min、4.4 min,而在Type Ⅱ结构下,SR2和SR3出现时间的波动范围分别为48~93 min、80~120 min,平均值分别为64.7 min、96.4 min,标准差分别为10.2 min、11.7 min.在27个月的观测期内,3—7月份Type Ⅰ结构的出现概率100%,未出现Type Ⅱ结构,而在1—2月和8—12月Type Ⅰ结构出现的概率明显下降,最低降至1月份的20.7%,而Type Ⅱ在1月、2月、11月的出现概率均高于70%.按春秋分交替变化(周期1和周期2)的统计结果,在周期1内Type Ⅰ和Type Ⅱ结构出现的概率分别为91.5%、8.5%,而在周期2内Type Ⅰ结构出现的概率降至41.9%,Type Ⅱ结构出现概率则升至58.1%,这表示观测期间内Type Ⅱ结构主要出现在秋冬季,春夏季发生概率较低.

     

我国市县地球物理监测资源评估

我国地球物理监测站网主要由GNSS、定点形变、重力、地电、地磁、地下流体六大观测站网组成,由国家站、省级站和市县站构成基本监测单元。市县站观测手段多、站点数量庞大,是地球物理监测站网的重要组成部分。为摸清市县站监测资源底数、统筹利用市县监测数据,中国地震局历时2年完成了我国市县地震监测资源评估工作。基于此项工作,本文从观测环境、观测系统、数据质量和预报应用四个方面对我国市县地球物理监测资源进行简要分析,评估结果显示: 37.8%的测项评估为合格,可直接纳入国家地球物理数据库管理,47.9%的测项评估为基本合格,可纳入国家市县数据库管理,14.3%的测项评估为不合格,需要停测或者优化改造。针对评估结果,简要分析了市县监测运维工作存在的主要问题并提出具体可行的解决建议,为提升市县站监测质量提供参考。     

南极长城站夏季哨声的观测与分析

在中国首次南极考察期间,我们对哨声和VLF发射进行了37天的连续观测。本文首先对观测设备作了介绍,在对观测资料进行统计分析的基础上就哨声类型、发生率、色散特征等作了描述,然后重点对磁暴期间两天的哨声活动作了较细致的分析,并由此推求出其传播途径上的电子浓度变化。观测到了磁暴期间等离子体层的倒空现象和其后的回填过程。计算表明,倒空的速率为109el/cm2·s,向上的回填通量为5x108 el/cm2·s。     

Global-Scale Coupling Characteristics between Geomagnetic Storms and Ionospheric Disturbances

Geomagnetism and Aeronomy - To explore the global-scale coupling characteristics between ionospheric disturbances and geomagnetic storms, and research the near-Earth space environment, the time...     

Characteristics of shallow geothermal fields in major cities of Tibet Autonomous Region

Based on the project titled "Investigation and evaluation of shallow geothermal energy in major cities of Tibet Autonomous Region", the distribution characteristics and occurrence conditions of shallow geothermal fields in these cities were introduced in this paper. To this end, relevant data in Lhasa, Shigatse and Nyingchi Cities through vertical thermometry was a focus, so as to analyze groundwater temperature and the distribution law of strata with constant temperature. Then through comprehensive comparisons and analysis of the relationship between groundwater temperature and climate, differences in this aspect of Nagqu City were taken as a typical case to clarify formation of geothermal field and corresponding influence on groundwater temperature, furthermore providing basic data for rational development and utilization of shallow geothermal energy in Tibet Autonomous Region.     

城市排水管道健康状况检测与评估内外业流程一体化方案设计与应用

城市排水管道健康状况检测和评估是城市管理运营的重要内容之一,是及时发现排水管道安全隐患的有效措施,可为排水管道养护、改建、修复、运行提供科学准确的依据。因此,检测和评估报告本身的真实性、准确性、科学性显得尤为重要。本文详细介绍了城市排水管道健康状况检测和评估内外业流程一体化方案的设计及应用,具体从4个方面进行了阐述：①资源配置及方案设计依据的选择;②外业现场作业流程的设计;③内业作业流程的设计;④检测和评估报告内容纲要的设计及应用。     

5月12日汶川8.0级地震强余震观测的电磁同震效应

2008年5月12日汶川8.0级大地震发生后,在武都汉王地震台及其附近地区进行了为期22d的余震序列电磁异常连续监测,观测到多次余震事件的电磁同震现象。通过与汉王强震台的地震记录数据比较发现,同震信号存在于所有的电场和磁场记录分量中,它们与地震波的到达同步,而不是在地震发生的时刻出现。地震发生时的电磁辐射信号似乎在记录数据中有所显示,但是与地震波到达观测点时的电磁信号相比幅度要小得多