DOAS Zenith Sky Observations: 1. BrO Measurements over Bremen (53°N) 1993–1994

Observations of stratospheric BrO over Bremen (53°N) are reported for winter and early spring periods of 1993 and 1993/94. The BrO was observed by ground-based near-UV absorption spectroscopy of sunlight scattered in the zenith. Differential slant column densities for solar zenith angles 90°/80° in the range of9× 10¹³ (detection limit) to 4.5×10¹⁴ molecules/cm² having a high day-to-day variability were found. For the majority of the measurements no significant difference was observed between the morning and evening behaviour of BrO. Exceptions are the morning measurements from the winter of 1992/93 where an accelerated production of BrO was observed. We believe the latter best to be explained by the early morning rapid photolysis of elevated amounts of photo-labile Br-reservoirs formed during the night. The largest differential slant column densities of BrO were measured in December 1993 when the temperatures at 30 hPa dropped below 205 K. This might be an indication of heterogeneous conversion of bromine compounds on sulfate and other aerosols.     

Magnetic spiral arms in galaxies

The Doppler parameter distribution of Lyα absorption lines is calculated for a set of numerical simulations with different re-ionization histories. The differences in temperature between different re-ionization histories are as large as a factor of 3–4 depending on the spectrum of the ionizing sources and the redshift of helium re-ionization. These temperature differences result in observable differences in the Doppler parameter distribution. The best agreement with the observed Doppler parameter distribution between redshifts of 2 and 4 is found if hydrogen and helium are re-ionized simultaneously at or before a redshift of 5 with a quasar-like spectrum.     

磁层-电离层-热层耦合的模式计算和分析

对磁层-电离层电动耦合和电离层发电机两种效应进行了模式计算,并对所得的一些耦合现象作了综合讨论.结果表明,在中低纬和赤道区的电离层和地磁研究中必须考虑磁层-电离层耦合效应向中低纬区的穿透和屏蔽;潮汐发电机效应对极光区（电导率增高时）的作用也值得重视.这两效应的特征和相对重要性随磁暴的发展阶段而异,在高低纬区也各不相同,但都有明显的晨昏不对称性.此外,弱磁扰对中低纬电离层形态的影响也不容忽视.     

基于多架构混搭模式的极地海洋数据库建模技术研究

通过对极地海洋数据的特征及应用需求分析,基于"一种架构支持多类应用"的传统数据库模式已无法满足需求,本文提出采用"多种架构支持多类应用"模式的数据库设计理念,通过研究极地海洋数据分类分层管理体系,开展极地海洋原始数据层、基础数据层、综合数据层、成果数据层的存储管理机制、数据库体系架构设计、数据库模型设计等关键技术研究,开发数据库查询检索功能,满足用户对极地海洋数据的多样化查询检索、空间可视化展示、关联分析等需求,实现极地海洋数据的有效存储、高效应用和开放共享。     

Application of multivariate model based on three simulated sensors for water quality variables estimation in Shitoukoumen Reservoir,Jilin Province,China

This study applied a multivariate model based on three simulated sensors to estimating water quality variables in Shitoukoumen Reservoir, Changchun City, Jilin Province, China, including concentration of total suspended matter, concentration of chlorophyll-a and non-pigment matter absorption. Two field campaigns for spectra measurements with a total of 40 samples were carried out on June 13 and September 23, 2008. The in-situ spectra were recalculated to the spectral bands and sensitivities of the instruments applied in this paper, i.e. Landsat TM, Alos and P6, by using the average method. And the recalculated spectra were used for estimating water quality variables by the single model and multivariate model. The results show that the multivariate model is superior to the single model as the multivariate model takes the combined effects of water components into consideration and can estimate water quality variables simultaneously. According to R ² and RMSE, Alos is superior to other sensors for water quality variables estimation although the precision of non-pigment matter absorption inversion performed the second.     

H layering in the top meter of Mars

We explore the capability of a method of mapping the depth distribution of a hydrogen-rich layer in the top meter of Mars from the neutron currents measured by the Mars Odyssey Neutron Spectrometer. Assuming the soil can be modeled by two layers of known composition having different hydrogen contents, simulations allow an inversion of the neutron data into knowledge of depth and hydrogen content of the lower layer. The determination of these variables is sensitive to the hypothesis of chemical composition of the soil. We quantify this contribution to the uncertainty in the method first in terms of individual chemical elements and then in terms of macroscopic absorption cross sections. To minimize this source of error, an average composition was inferred from Mars Exploration Rover data. Possible compositions having a wide range of macroscopic absorption cross sections were used to evaluate the uncertainty associated with our calculations. We finally compare our results to ice table depth estimates predicted by two published theoretical models at locations where the composition is relatively well known. The fit is excellent in the southern high latitudes but questionable in the northern high latitudes. Possible explanations of these differences include the high geographical variations of the neutron currents relative to the spatial width of the response function of the instrument and the overly simple model we, of necessity, used for surface layering.     

The Cap and Water Trading in Australian Murray-Darling Basin for Wetlands Protection:The Possible Lessons for China

As the consequence of climate change, water that is received in Australian Murray-Darling Basin wetlands is declining and agricultural water demands are increasing. In order to keep the water use balance between environment protection including wetland protection and irrigation water use, the Australian government adopted a series of reforms in Murray-Darling Basin to address the environmental water shortage problem and encourage irrigators to use water more efficiently and plant high economic value crop. The water trading and cap are two major reforms in this process.In order to match up the environmental water demand such as wetland water use, based on the seasonal rainfall, dam level and environmental water demand, the cap system seasonally allocate how much water the irrigators can access as per water licenses. As the cap dramatically reduced the water access for irrigators, the water trading is aiming to use limited agricultural water more efficiently. The water trading scheme separate the water use right from the land property right and allow Australian farmers to trade their water licenses in the market. Water trading encouraged farmers who plant low value crops such as wheat and canola transfer their water entitles to farmers who plant high value crops such as grape. In the drought seasons, The Australian government can purchase the water licenses from irrigators to increase the environmental flows.This Australian water management system represents the most complicated and effective environmental and agricultural water use management in this world. There are possible many lessons that will help China to better manage the water use for wetland protection and farming practices.     

极地海洋环境评价理论与方法初探

极地海洋环境评价对于极地海洋生态系统保护尤为重要。由于对极地极端恶劣环境的监测能力不足,缺乏长期连续监测数据,极地海洋环境评价变得异常困难。针对目前极地海洋环境评价目标和评价因子均缺乏的情况,在已有文献基础上,本文提出了海水表层叶绿素浓度、海冰覆盖范围、海水表层温度和盐度四个极地海洋环境决定因子,分析了海冰覆盖范围与月份之间高度拟合的三次多项式分布关系,并在此基础上构建了极地海洋环境评价模型,最后提出了一种验证该模型的方法。基于第30、31、32次南极科考获取的海水表层叶绿素浓度、温度、盐度数据以及美国国家冰雪数据中心提供的对应时间内的海冰覆盖范围数据对提出的评价模型和方法进行了验证,实验结果表明:该评价模型及其验证方法具有有效性,根据评价结果能判定某个时间段内极地海洋环境相对于基准时间的变化趋势。     

EARTH ROTATION EQUATIONS CONTAINING BOTH NUTATION AND POLAR MOTION

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