CASS、NTS660、RTK线路数据互转

简要介绍分析了CASS成图系统软件、NTS660全站仪和动态GPS-RTK的线路数据格式,编写了简明的应用转换程序,实现了三种产品格式的互转,达到资源共享,方便了测绘工作。     

软件TTC在高频GPS动态数据处理中的应用

在推导单基站GPS动态定位算法公式的基础上,探讨了应用Trimble Total Control 2.73软件对高频GPS动态数据进行处理分析的方法和流程。对某试验中的GPS数据进行处理,与GrafNav 7.8软件处理结果作了对比分析,给出了Trimble Total Control在高频GPS动态数据处理中的精度。     

LS和TLS在平面坐标转换中的应用

在超定线性方程Ax=b的解算中,最小二乘(LS)只考虑观测向量b的误差,而总体最小二乘(TLS)则同时顾及观测向量b和系数矩阵A均含误差的情况。本文以六参数模型在平面坐标转换中的应用为例,分别采用LS和TLS进行模型参数的求解。结果表明,2种方法所求参数并无显著差异,但是总体最小二乘更好地改善了坐标转换的内部精度,是一种更为合理的计算方法。     

Impact of anthropogenic activities on the hydrologic characters of the mainstream of the Tarim River in Xinjiang during the past 50 years

Changes in the hydrologic characters of the Tarim River Basin of Xinjiang Province during the past 50 years were studied to identify the key factors responsible for these changes. Observed hydrologic and socio-economic data provided the basis for this study. The impact of human activities on the decrease in the streamflow and changes in total dissolved solids (TDS) in the watercourse and groundwater of the mainstream were analyzed using the Mann–Kendall test, regression and principal component analysis. The results showed that during the past 50 years the streamflow in the headwater streams has increased slightly while the streamflow in the mainstream has decreased significantly. Human activities along the mainstream are the primary reason for the decreased streamflow, with the impact of human activities on the decrease in the streamflow of the mainstream being 65.61, 74.73 and 77.62% in the 1970s, 1980s and 1990s, respectively. The key factor that affected the TDS of the watercourse was the decreasing streamflow, which was caused by anthropological activities. However, the TDS of the groundwater was found to be affected significantly by groundwater depth. The degeneration of ecosystems in the lower reaches of the Tarim River was directly related with anthropogenic activities.     

Intra- and inter-specific variability in total and methylmercury bioaccumulation by eight marine fish species from the Azores

We relate fish biological and ecological characteristics to total and organic mercury concentrations to determine whether accumulation is influenced by trophic level, Hg concentration in the diet, and vertical distribution. Levels of total mercury and methylmercury were determined in the muscle tissue of eight species of fish: Pagellus acarne, Trachurus picturatus, Phycis phycis, P. blennoides, Polyprion americanus, Conger conger, Lepidopus caudatus and Mora moro, caught in the Azores. All such fishes are commercially valuable and were selected to include species from a wide range of vertical distributions from epipelagic (<200 m) to mesopelagic (>300 m) environments. Methylmercury was the major form accumulated in all species, comprising an average of 88.1% of total mercury. Concentrations of mercury (total and methylmercury) increased with age, length and weight. Based on data from other studies, mercury concentrations in fish diet were estimated. Mercury levels in food ranged from 0.08 to 0.32 ppm, dry weight. Hg concentrations in the food and in muscle tissue from different species were positively correlated. Total Hg levels in the muscles were approximately nine times those estimated in food. Total mercury concentrations in muscle were positively correlated with both trophic level and median depth. Such enhanced mercury bioaccumulation in relation to depth appears to be determined primarily by concentrations in food and ultimately by water chemistry, which controls mercury speciation and uptake at the base of the food chain.     

Softening of the subcontinental lithospheric mantle by asthenosphere melts and the continental extension/oceanic spreading transition

The majority of ophiolitic peridotites in the Alpine–Apennine system show evidence of extensive interaction between subcontinental lithospheric mantle and fractional melts of asthenospheric origin. This interaction led to petrological, structural, and geochemical changes in the lithospheric mantle, and was accompanied by a temperature increase to near-asthenospheric values, resulting in the thermomechanical erosion of the lithosphere. We term the parts of mantle lithosphere thus affected the asthenospherized lithospheric mantle or ALM.The thermal and rheological consequences of thermomechanical erosion are explored by modelling the temperature and rheological properties of the thinned lithosphere as a function of thickness of ALM and time since asthenospherization (i.e., since the beginning of thermal relaxation). Results are given both in terms of rheological profiles (strength envelopes) and total lithospheric strength (TLS) for different lower crustal rheologies. The TLS decreases as a consequence of thermomechanical erosion. This decrease is a non-linear function of the thickness of the ALM. While practically negligible if less than 50% of lithospheric mantle is affected, it becomes significant (up to almost one order of magnitude) if thermomechanical erosion approaches the Moho. The maximum decrease in TLS is achieved within a short time span (1–2 Ma) after the end of the heating episode.As a working hypothesis, we propose that thermomechanical erosion of the lithospheric mantle, related to lithosphere/asthenospheric melts interaction, can be an important factor in a geologically rapid decrease in TLS. This softening could lead to whole lithospheric failure and consequently to a transition from continental extension to oceanic spreading.     

Mesocosm experiments for evaluating the biological efficacy of ozone treatment of marine ballast water

Ballast water is a major pathway for the transfer of non-indigenous species in aquatic environments. The objectives of this study were to determine the ability of ozone to reduce the numbers of a spectrum of marine organisms collected from Puget Sound, Washington in replicated mesocosm (280 l) experiments, and estimate the minimum ozone concentrations as measured by total residual oxidant (TRO) required to reduce organism densities. Ozone treatment was effective in removing bacteria, phytoplankton, and mesozooplankton with initial TRO concentrations of 2–5 mg l⁻¹ as Br₂. Persistence of TRO resulted in an extended period of toxicity and cumulative mortality. TRO decay allowed bacteria populations to multiply when TRO levels fell below 0.5–1.0 mg l⁻¹ as Br₂. Phytoplankton chlorophyll a concentrations were rapidly reduced by ozone treatment and did not increase in any treatments or controls because of lack of light. Overall mesozooplankton viability was rapidly reduced by 90–99% in treatment TRO levels above 1.85 mg l⁻¹ as Br₂. Our study outlines novel protocols that can be used for testing different potential ballast water treatment systems in replicated and controlled mesocosm experiments.     

What Causes the Springtime Tropospheric Ozone Maximum over Northeast Asia？

Scientists have long debated the relative importance of tropospheric photochemical production versus stratospheric influx as causes of the springtime tropospheric ozone maximum over northern mid-latitudes. This paper investigates whether or not stratospheric intrusion and photochemistry play a significant role in the springtime ozone maximum over Northeast Asia,where ozone measurements are sparse.We examine how tropospheric ozone seasonalities over Naha(26°N,128°E),Kagoshima(31°N,131°E),and Pohang(36°N,129°E),which are located on the same meridional line,are related to the timing and location of the jet stream.The ozone seasonality shows a gradual increase from January to the maximum ozone month,which corresponds to April at Naha,May at Kagoshima,and June at Pohang.In order to examine the occurrence of stratospheric intrusion,we analyze a correlation between jet stream activity and tropospheric ozone seasonality.From these analyses,we did not find any favorable evidence supporting the hypothesis that the springtime enhancement may result from stratospheric intrusion.According to trajectory analysis for vertical and horizontal origins of the airmass,a gradual increasing tendency in ozone amounts from January until the onset of monsoon was similar to the increasing ozone formation tendency from winter to spring over mainland China,which has been observed during the build-up of tropospheric ozone over Central Europe in the winter-spring transition period due to photochemistry.Overall,the analyses suggest that photochemistry is the most important contributor to observed ozone seasonality over Northeast Asia.     

极地大气科学考察研究与展望

本文包括四部分。第一部分是对中国科学院大气物理研究所1984年以来的极地大气科学考察研究工作概要地作了回顾;第二部分是中国科学院大气物理研究所近5年来在极地大气科学方面研究的主要进展;第三部分是对未来极地大气科学考察研究的重点问题的展望与建议;第四部分是结论与讨论。作者认为,未来极地大气科学考察研究的重点问题应该包括:(1)南极北极冰雪变化差异成因,(2)北极冰雪变化异常与我国气候变化关系,(3)南极冰雪变化与人类未来。     

云对中国区域卫星观测臭氧总量精度影响的检验分析

根据卫星和地基观测, 比较了我国香河、 昆明、 瓦里关和龙凤山四个站点臭氧总量自1979年以来的变化。卫星与地基观测的臭氧总量长期趋势比较一致, 表明臭氧总量均有下降趋势, 但是卫星与地基各自观测的结果仍存在着显著的差别。为研究卫星与地基臭氧总量的差别, 以地基观测臭氧总量为参考, 检验云对历史TOMS (Total Ozone Mapping Spectrometer) 和GOME (Global Ozone Monitoring Experiment) 臭氧总量精度的影响。结果显示: 云 (云量或云顶高度) 增加了卫星臭氧总量误差, 降低数据精度。随着地面云量的增加, TOMS、 GOME臭氧总量相对误差在上述四个地点呈现明显的上升趋势 (瓦里关最为明显), 但最大变化幅度没有超过2.0%。TOMS臭氧总量相对误差随地面云量变化呈现区域性特点, 香河与龙凤山 (代表着中纬度高臭氧总量区域)、 昆明与瓦里关 (代表中、 低纬度高原低臭氧总量区域) 分别为两个变化特点接近的区域。GOME臭氧总量相对误差与云之间关系的区域特征不明显。利用卫星遥测FRESCO (Fast Retrieval Scheme for Clouds from the Oxygen A\|band) 云信息检验GOME卫星臭氧总量精度的表明, 只有当云量大于5成后GOME臭氧总量才显示出相对误差增加的现象, 但无明显趋势; 随着FRESCO云顶高度的增加, GOME臭氧相对误差在香河、 瓦里关均呈现明显的上升趋势并有3%左右幅度的变化。TOMS臭氧总量相对误差随着地面有效反射率的增加而增大, 且误差幅度超过2%; TOMS\|N7臭氧总量比TOMS\|EP约高2.0%~3.0%。分析还表明, 云内和云以下臭氧柱浓度在反演的卫星臭氧总量中的贡献很可能被高估了。