THE QUALITY OF MEAN AND VARIANCE ESTIMATES FOR NORMAL AND LOGNORMAL DATA WHEN THE UNDERLYING DISTRIBUTION IS MISSPECIFIED

Theoretical and simulation results are employed to evaluate mean and variance estimaies for normal datawhen a lognormal distribution is assumed and for lognormal data when a normal distribution is assumed.Misspecifying the distribution leads to the use of suboptimal estimation methods.However,the resultsshow that the suboptimal methods still produce estimators of good quality(low bias and variance)relativeto the minimum variance unbiased estimators for each distribution,at least when practical efficiency isconsidered.     

东亚季风强弱变化及其对初夏我国东部地区降水的影响

本文通过对东亚季风系统的分析,发现东亚季风存在3-4年左右的长期振荡.这类振荡与赤道东太平洋海面温度变化有相互作用,形成一个相互反馈的耦合振荡过程.据此提出海温通过季风系统的变化影响初夏我国东部地区降水分布的可能长期天气过程.     

AN INTEGRATED APPROACH TO AIR MASS CLASSIFICATION IN THE NORTH CENTRAL UNITED STATES

Both subjective and objective schemes for air mass classification offer advantages to climatological studies. An integrated approach is developed and applied to 850 mb level data in the north central United States. Each air mass type was initially delimited by a subjective analysis. Final limits were then determined with an objective technique that separates temperature curves into normal components based on interpretation from the subjective method. Continental air was most frequent in all seasons except summer. The methodology also allows estimation of classification error.     

ON THE SENSITIVITY OF CONCLUSIONS ABOUT THE BASES OF COGNITIVE DISTANCE

The “ecological fallacy’ inherent in two studies of the correlation of cognitive distance with objective distance and travel time is considered. The studies reach opposite conclusions using similar types of data, but both involve different types of aggregation of cognitive-distance judgments. It is shown that, under certain circumstances, correlations based on aggregate data can lead to reverse conclusions to those based on more behaviorally valid disaggregate data. Hence such aggregation is unjustifiable and, as a result, neither study's conclusions can be relied upon.     

ON THE SENSITIVITY OF CONCLUSIONS ABOUT THE BASES OF COGNITIVE DISTANCE

The “ecological fallacy’ inherent in two studies of the correlation of cognitive distance with objective distance and travel time is considered. The studies reach opposite conclusions using similar types of data, but both involve different types of aggregation of cognitive-distance judgments. It is shown that, under certain circumstances, correlations based on aggregate data can lead to reverse conclusions to those based on more behaviorally valid disaggregate data. Hence such aggregation is unjustifiable and, as a result, neither study's conclusions can be relied upon.     

华西秋雨的多年变化

根据1951—1980年资料分析发现,长江上游宜昌站9月和10月的径流量变化与华西秋雨的变化有密切关系。因此,有可能利用宜昌站1882—1980年的流量资料来研究华西秋雨近百年的变化。分析结果表明,华西秋雨的多年变化具有明显的周期性和阶段性:9月的主要周期约为3年和17年,10月则约为13年。并按照正、负距平的分布特点,将9月划分为8个阶段、10月划分为9个阶段。这些阶段的出现与大气环流的变化有关;9月份与西太平洋高压脊西伸位置有关,10月则与印度低压的强弱相联系。     

A CLIMATE DEPARTURE INDEX FOR THE STUDY OF CLIMATIC VARIABILITY

Three versions of a Climate Departure Index (CDI) are presented for studying how “normal” or “unusual” a particular year or event is compared to the long-term average for the region under consideration. Comparisons of a Simple CDI, Absolute Value CDI and Least-Squares CDI are made through the use of hypothetical examples and two case studies involving seasonal snowfall variations in northern New England and last spring-freeze date variations in the southeastern United States. Results clearly show that the Simple CDI is the inferior formulation owing to a compensation problem whereby above and below average sites within a region for a particular year cancel each other when computing the index value. Little difference in identifying extreme years was found between use of the Absolute Value CDI and Least-Squares CDI in the case studies examined. Nevertheless, a hypothetical example suggests that the least-squares approach for closeness of fit is the more appropriate method, thus making the Least-Squares CDI the preferred version.     

青海湖水文特征及水位下降原因分析

青海湖自有记载以来,湖水位一直处于下降之中。通过分析流域内的各项水文因子的特征及湖泊水量平衡,看出流域内降水有逐步变小的趋势;湖泊长期处于水量收支负平衡中,致使湖水水位下降。降水变小及湖水位下降又改变了流域水文环境,使径流变小、径流系数下降。通过进一步分析发现,青海湖对降水变化的敏感性要大于其它因子的变化。     

A STATISTICAL APPROACH TO THE PROBLEM OF MISSING SPATIAL DATA USING A FIRST-ORDER MARKOV MODEL*

Geographical data sets sometimes contain missing observations that need to be estimated. A statistical approach to the problem is discussed for multivariate normal spatial data sets satisfying the first-order spatial Markov property with constant mean, where the information at neighboring or contiguous observed sites is used to estimate the missing values. The completed data are used to estimate the parameters of the distribution. The procedure is iterative. The approach is a special case of the Orchard and Woodbury missing information principle. The paper concludes with an illustrative empirical example using rainfall data from an area of Kansas and Nebraska. The quality of the estimates for different sites are compared.     

南宋以来太湖流域大涝大旱及近期趋势估计

本文研究南宋以来太湖地区大旱大涝并对近期大旱大涝趋势作了估计。     

塔里木河中游的研究概况

本文综合分析古人与前人的有关描述塔河中游资料，对塔河中游地区的研究进展进行综合；并确定塔河中游研究进展划分四个阶段；前历史时期人类研究塔河中游的萌芽阶段，本世纪３０年代到解放前描述塔河阶段，解放后到本世纪９０年代研究塔河中游的重大理论发展阶段和９０年代后研究塔河中游的新纪元时代。并概括各阶段主要成果。     

甘青地区中晚全新世植被变化与人类活动

史前时期人类对环境的影响是近几年来国际研究的热点。在甘青地区，全新世的孢粉资料比较多。但在中晚全新世，该区人类对环境的影响作用及其程度仍不清楚，许多孢粉分析资料中并没有充分考虑人类活动的影响。本文选取孢粉分辨率较高、代表性较好的青海湖、兰州、秦安大地湾三地的资料，着重研究了其中乔木成分的变化。分析发现，孢粉组合中乔木成分的变化与气候变化的趋势并不一致。通过对考古及历史资料的分析，笔者认为，该区的植被很早就受到人类活动的影响。自全新世中期，本区植被中的乔木成分波动下降。5000－3000a BP期间，史前农业对植被的影响较大。3000－2000a BP期间，植被略有恢复。2000a BP以后，人为影响加剧，植被中乔木成分迅速下降。研究者认为，依赖孢粉资料重建中晚全新世的气候变化历史应当慎重。     

略论地理学文献的发展特征-兼论地理文献研究的实际意义

本文主要讨论地理文献特征,阐明文献分布的规律. 地理学是研究地表各种自然、人文现象的内在联系及演变规律的科学.它富于综合性、区域性,又是和许多学科交叉叠合的一门跨界学科.地理学的这些性质、特征必然反映到文献上来.地理文献的使用寿命比一般学科文献要长;地理文献的来源或分布要比一般学科文献格外分散.本文通过对若干文摘期刊及书刊引用文献统计分析,表明从事地理研究所参考引用的期刊文献,仅25%左右来自地理期刊,从事综合及总结性研究时高于这个此例,从事部门地理或带有技术性研究时低于这个比例.大部分参考文献则来源于相关学科期刊,这是地理工作者经常要比较多时间翻阅各种书刊去搜集资料的原因. 最后,本文阐述了从事地理文献研究对了解地理学发展趋势、选择课题、查找文献以及改进文献管理工作的实际意义.     

FACTORS INFLUENCING THE VARIABILITY OF MIDWINTER SNOW-DEPTH DECREASE IN THE NORTHERN GREAT PLAINS OF THE UNITED STATES

Meltwater from snow provides an important source of fresh water for agriculture, domestic use, and hydroelectric power in many regions of the world. In the winter and early spring, however, rapid ablation of the snowpack can lead to environmental hazards such as flooding.

Most snowmelt research has relied on measured data, which have limited the spatial and temporal resolution of the studies. Generally, these studies have been conducted at single locations over periods of a few days to a few weeks. This project investigates snowdepth changes on a more expansive scale by using a one-dimensional mass- and energy-balance model (SNTHERM) to compute the convective and radiative fluxes associated with large snow-depth change events. Midwinter snow-depth changes and the variability in snow-depth changes are evaluated for a 25-year time period over the northern Great Plains region of the United States during February.

Statistical analyses indicate that variations in sensible heat flux have the greatest influence on midwinter variability of snow-depth changes. This is shown by the consistently strong relationship between modeled sensible heat-flux values and changes in snow depth over the entire study period and at nearly every station. Mean daily temperature followed by mean daily dew-point temperature show the next strongest statistical relationships with snow-cover ablation. Radiative fluxes and net solar radiation in particular, have low correlations with changes in snow depth and are therefore found to have little impact on snow-depth change variability during the month of February. Although net solar radiation is not highly correlated with the variability of decreases in depth, its energy input is nevertheless an important source of energy for ablation processes. [Key words: snow melt, modeling, Great Plains.]     

云南城市职能分类探讨

采用城市劳动力资料, 运用在城市经济基础研究之上的多变量聚类与统计分析相结合的方法, 根据最新统计资料, 首次对云南省全部城市进行了统一的综合职能分类, 共分出５个大类４ 个亚类, 分类结果对认识云南城市的职能结构和了解每一个城市的职能特点具有重要意义, 在方法上与实践中有广泛的认识价值和应用价值。     

我国汛期降水与ENSO不同位相的联系

利用本世纪以来较长年代的降水资源，分析了ＥＮＳＯ与我国各地汛期降水间的联系。结果表，不仅ＥＮＳＯ暖位相与冷位相我国汛期降水距平百分率的分布存在明显差异，而且ＥｌＮｉｎｏ年与其次年、ＬａＮｉｎｏ年与其次年降水距平面分率的分布均存在显差异。     

南极格罗夫山核心区冰下地形测绘

格罗夫山地区位于中山站和冰穹A之间,是中国进行南极内陆科学综合考察的重点区。我们先后组织过5次格罗夫山地区的考察工作,开展了地质构造、古气候环境、陨石、冰盖运动监测、基础测绘和气象观测等多学科考察研究。2010年中国第26次南极科学考察期间,格罗夫山考察队利用专业探地雷达对格罗夫山东部核心区进行了冰下地形测绘工作。本文利用野外采集的测量数据(GPS/GPR数据),经数据处理后,利用专业的制图软件Corel Draw首次绘制出了格罗夫山核心区两幅冰下地形图,初步揭开了这一区域冰原岛峰冰下的地貌形态,对于今后研究整个格罗夫山地区真实的基岩地貌和可能存在的上新世古冰下沉积盆地具有探索性意义。本文还对哈丁山-萨哈罗夫岭间横截面进行分析,发现这两个冰原岛峰之间的槽谷形态已经发育成熟。     

THE HISTORICAL GEOGRAPHY OF HONG KONG INVESTMENTS IN THE ASEAN REGION

Conventional studies of “Third World multinationals” tend to focus on their recent origins. This paper argues that the transnational operations of Hong Kong firms have had a long tradition originating in its Overseas Chinese networks and in the colonial experience of many Southeast Asian countries. Based on secondary and primary data, this paper takes a historical view to describe how the ASEAN operations of Hong Kong transnational corporations (HKTNCs) and their foreign direct investment (HKFDI) have evolved over more than a century to become one of the most important economic players in the ASEAN region. Four phases of their historical development are benchmarked in this paper. Before World War II, HKTNCs in the commercial and banking sectors had a notable presence in the region. It was, however, in the post-war period that HKTNCs and their FDI flows flourished. During the period 1945–69, industrialisation took off in Hong Kong and this led to the expansion of manufacturing HKTNCs into the ASEAN region. The real zenith of outward investment from Hong Kong was the 1970s and 1980s so that in the 1990s Hong Kong has become one of the largest investors in Indonesia, Singapore and Thailand.     

十八世纪我国长江下游等地区的气候

关于1500-1900年小冰期气候问题是历史时期气候变化研究中的一个重要课题.本文根据我国晴雨录、古代天气日记、诗文等历史文献资料来讨论小冰期中一个相对温暖时期(十八世纪)的气候.研究表明,这个时期冬季(12-2月)平均气温比现在低1.0℃(杭州、苏州)到1.5℃(南京).但其间还有10年以上时间尺度的起伏波动,在温暖时段,冬季平均气温仍比现在低0.5-1.6℃,在寒冷时段,冬季平均气温比现在低2.1-2.4℃.但十八世纪大部分时期春季反比现在暖些.对湿润状况分析表明,十八世纪长江中下游地区比现代潮湿,反映了当时大气环流与今有较大差别.杭州古风向记录(1723-1769年)分析表明,当时盛行风向与现在不同:冬季西北风频率比现在多,春秋盛行东北风时间比现在长,频率比现在多.     

博斯腾湖流域气候及湖陆风

通过流域多个气象站的资料，分析了流域气候条件，并通过对湖区测点的气象观测资料与陆区测点－ 焉耆站的同步资料对比分析，讨论了博斯腾湖区域小气候其湖陆风特征。