基于ASCAT散射计数据的2012年南极周边海面风场特征分析

利用2012年全年的ASCAT散射计风场数据,对55°S以南的南极周边海域海面风场开展了时空分布特性统计分析。结果表明:对于南极周边海域,7月平均风速最大,为12 m·s-1,12月平均风速最小,为8 m·s-1,冬季大于夏季;该区域平均风速主要在9—12 m·s-1之间,全年出现的天数280天,约占全年的77%;风速10 m·s-1所占比例也是冬季大于夏季。从全年来看,南极周边海域在冬季(4—6月)和春季(7—9月)风速普遍较大。该区域0°W—60°W海域内风速明显比其他海域要小。     

A new insight into land use classification based on aggregated mobile phone data

Land-use classification is essential for urban planning. Urban land-use types can be differentiated either by their physical characteristics (such as reflectivity and texture) or social functions. Remote sensing techniques have been recognized as a vital method for urban land-use classification because of their ability to capture the physical characteristics of land use. Although significant progress has been achieved in remote sensing methods designed for urban land-use classification, most techniques focus on physical characteristics, whereas knowledge of social functions is not adequately used. Owing to the wide usage of mobile phones, the activities of residents, which can be retrieved from the mobile phone data, can be determined in order to indicate the social function of land use. This could bring about the opportunity to derive land-use information from mobile phone data. To verify the application of this new data source to urban land-use classification, we first construct a vector of aggregated mobile phone data to characterize land-use types. This vector is composed of two aspects: the normalized hourly call volume and the total call volume. A semi-supervised fuzzy c-means clustering approach is then applied to infer the land-use types. The method is validated using mobile phone data collected in Singapore. Land use is determined with a detection rate of 58.03%. An analysis of the land-use classification results shows that the detection rate decreases as the heterogeneity of land use increases, and increases as the density of cell phone towers increases.     

华北地区香河站对流层NO_2的MAX-DOAS光谱仪观测及变化特征分析

利用中国科学院大气物理研究所香河大气探测综合试验站2010年3月至2012年2月(2年)的多轴差分吸收光谱仪(MAX-DOAS)观测数据和32 m高塔常规气象资料,反演了华北地区香河站对流层NO2柱浓度,分析了该区域NO2柱浓度的季节变化特征。研究表明:可见光455~485 nm、紫外330~370 nm都可以作为MAX-DOAS工作波段很好地反演NO2;香河地区NO2柱浓度夏季最低,几乎保持在2×1016 cm–2以下,春、秋季次之,在3×1016 cm–2上下小范围浮动,冬季最高,可达4.5×1016 cm–2;月平均最低值出现在7月,最高值出现在11月。NO2柱浓度与风速、风向密切相关:来自东边唐山方向的风,风速越大时NO2浓度越高,因为唐山是NO2的高值区之一;其它方向风速越大,浓度越低。春、夏两季NO2柱浓度日变化趋势比较平缓,秋、冬两季日变化明显,秋季正午偏高,冬季早晚偏高。     

基于NCEP风向数据的中国夏季降水估算研究

提出一个基于NCEP风向数据估算全国夏季降水的模型。根据NCEP地面气压、经纬向风数据计算得到全国1971—2000年夏季各月盛行风向;并将盛行风向与宏观坡向夹角的余弦值作为降水的坡向因子,以此区分山体迎风坡和背风坡降水的空间分布。利用站点观测资料、数字高程模型数据、坡向、坡度因子,采用逐步回归分析法,建立估算夏季降水的回归方程,得到全国1971—2000年夏季各月及总降水量的空间分布图,并对模型结果进行检验与对比分析。结果表明,此方法估算夏季总降水量的平均绝对误差为27 mm,平均相对误差为11.8%。模型结果能体现迎风坡与背风坡的雨量差,符合客观规律,能够定性、定量地再现中国夏季降水的实际空间分布特征。     

Influencing factors of gas content evaluation for shale gas： a case study of Lower Paleozoic Wuling fold belt in Upper Yangtze Basin

Factors of shale gas accumulation can be divided into the external and internal factors, according to accumulation mechanism and characteristics of shale gas. The internal factors mainly refer to parameters of organic geochemistry, mineral components and physical parameters. Six factors were presented in this study, i. e. organic matter, maturity, quartz, carbonate, clay mineral and pore. The external factors mainly refer to geologic environment of shale gas reservoir, including four factors： temperature, pressure, depth and thickness. Based on the experiment results of 26 samples of drilling cores from Wuling fold belt in Lower Paleozoic Silurian of the Upper Yangtze Basin, combined with the integrated analysis of geology, logging and test, the correlation of the gas content of shale gas to the above-mentioned ten factors was concluded. Six important evaluation indicators were preliminarily established in the gas-bearing core area of marine shale in the Upper Yangtze Basin.     

Empirical Analysis of City Contact in Zhujiang （Pearl） River Delta,China

In traditional urban geography, city contact research is a classic study element in city research. In general, researchers use the traditional gravity model to characterize the contacts that exist between two cities. The traditional gravity model assumes ideal condi- tions, but these preconditions and their results often do not exist in realistic conditions. Thus, we used a modified gravity model to char- acterize the city contacts within a specific region. This model considers factors such as intercity complementarities, government inter- vention, and the diversity of the transportation infrastructure which is characterized as the transportation distance instead of the tradi- tional Euclidean distance. We applied this model to an empirical study of city contact in the Zhujiang （Pearl） River Delta （PRD） of China. The regression results indicated that the modified gravity model could measure city contact more accurately and comprehen- sively than the traditional gravity model, i.e., it yielded a higher adjusted R2 value （0.379） than the traditional gravity model result （0.259）. Our study also suggests that, in addition to urban-regional and metropolitan development, the complementarities of the basic functions of cities at the administrative and market levels, as well as the corporeal and immaterial levels, play very significant roles in the characterization of city contact. Given the complexity of city contact, it will be necessary to consider more relevant influential fac- tors in the modified gravity model to characterize the features of city contact in the future.     

A water movement study in Lianzhou Bay,Guangxi Province,China

This study investigates the physical conditions (water depth, current speed, salinity, temperature) in Lianzhou Bay, a shallow coastal bay in southern China, during two expeditions in the dry and wet seasons of 2011. Based on these expedition data, basic hydrodynamic parameters like Brunt-Väisälä Frequency, Richardson Number, Rossby radius, and Resonance Period are calculated. The results show that Lianzhou Bay is characterized by comparatively small quantity of freshwater input and weak stratification. Strong tides, which are spatially uniform within the bay, cause turbulent mixing. Residence time of the water is shorter in winter due to a stronger coastal current in that season. Consideration of the water movement may help to reduce the harmful ecological impact of aquaculture waste water discharge.     

Evaluation of three harvest control rules for Bigeye Tuna (Thunnus obesus) fisheries in the Indian Ocean

The stock of Bigeye tuna(Thunnus obesus) in the Indian Ocean supports an important international fishery and is considered to be fully exploited. The responsible management agency, the Indian Ocean Tuna Commission(IOTC), does not have an explicit management decision-making framework in place to prevent over-fishing. In this study, we evaluated three harvest control rules, i) constant fishing mortality(CF), from 0.2 to 0.6, ii) constant catch(CC), from 60000 to 140000 t, and iii) constant escapement(CE), from 0.3 to 0.7. The population dynamics simulated by the operating model was based on the most recent stock assessment using Stock Synthesis version Ⅲ(SS3). Three simulation scenarios(low, medium and high productivity) were designed to cover possible uncertainty in the stock assessment and biological parameters. Performances of three harvest control rules were compared on the basis of three management objectives(over 3, 10 and 25 years): i) the probability of maintaining spawning stock biomass above a level that can sustain maximum sustainable yield(MSY) on average, ii) the probability of achieving average catches between 0.8 MSY and 1.0 MSY, and iii) inter-annual variability in catches. The constant escapement strategy(CE=0.5), constant fishing mortality strategy(F=0.4) and constant catch(CC=80000) were the most rational among the respective management scenarios. It is concluded that the short-term annual catch is suggested at 80000 t, and the potential total allowable catch for a stable yield could be set at 120000 t once the stock had recovered successfully. All the strategies considered in this study to achieve a ‘tolerable' balance between resource conservation and utilization have been based around the management objectives of the IOTC.     

基于空间综合分析的长株潭城市群结构评价与优化策略

长株潭城市群空间特征及优化策略可作为我国多中心城市群空间优化的典型样本之一.本文运用多维度空间分析方法,对长株潭城市群空间展开现状测度与评价,尊重城市群阶段特征,选取针对性指标对比反映空间内在特征.在采用核密度法分析2013年和2017年湖南省152个区县第二产业与就业指标的空间变化后,得出长株潭城市群已初步形成空间—...     

基于地基GPS遥感的大连地区大气水汽总量变化特征

基于大连地区地基GPS综合观测网遥感反演了大气水汽总量（PWV）,分析了大连地区PWV空间变化、逐月变化和日变化特征以及PWV变化与降水的关系,并利用大连本站2005-2011年的探空资料拟合了大连地区地面温度和大气加权平均温度的关系。结果表明：大连本站的PWV与探空积分的水汽含量相关系数达到0.988,均方根误差为2.5 mm。大连地区PWV南北分布比较均匀;PWV最大的月份为7-8月,最大月平均值约40 mm,PWV最小的月份为1月,最小月平均值小于4 mm;大连地区PWV春季和冬季日变化幅度约0.5 mm,夏季和秋季日变化幅度约1.3 mm。夏季和秋季的PWV日变化呈单峰型,春季和冬季的PWV日变化呈多峰型; 在降水发生前8 h 大气水汽总量有明显增加过程,对降水的发生有指示作用。