青海气候条件对牧草再生性影响的研究

选取1994～2001年河南、甘德两站牧草再生草资料及同期气象资料，通过分析同一地区不同时期及同一时期不同地区气候条件对牧草再生性的影响，建立了牧草再生草产量气候模式，讨论了再生草增、减产的气候条件。研究得出：同一地区不同时期和同一时期不同地区因气候条件不同，割草不一定能增产。     

元数据管理在空间信息共享中的应用

空间信息共享一直以来阻碍着GIS的发展,元数据是解决其共享的技术手段之一。本文在分析元数据和元数据管理存在问题的基础上提出了建立元数据库管理元数据,详细分析了元数据库中元数据定义、元数据查询和元数据编辑这三大管理模块,最后在信息共享平台中,对外建立统一的元数据库访问接口,对内建立针对每个数据源的数据访问引擎,实现实现多源异构分布的空间数据的集成。     

GPS新近发展及其军事应用

本文简述了GPS的最新发展动态，着重分析了GPS在精确制导武器上的应用形式和效果，指出了GPS制导技术存在的局限性及其未来发展趋势。     

明代军事地理研究概述

军事地理是谋兵布防的平台。明代被迫在南北两条战线作战：北部沿长城一线防御少数民族南下；东南沿海抗击倭寇入侵。因此，明代格外重视军事地理的研究，研究成果丰硕，著述很多。概述明代军事地理研究成果，不仅是回顾历史，而是借鉴经验。一些著作中提出的御敌方略至今有参考价值。     

GGM02 – An improved Earth gravity field model from GRACE

A new generation of Earth gravity field models called GGM02 are derived using approximately 14 months of data spanning from April 2002 to December 2003 from the Gravity Recovery And Climate Experiment (GRACE). Relative to the preceding generation, GGM01, there have been improvements to the data products, the gravity estimation methods and the background models. Based on the calibrated covariances, GGM02 (both the GRACE-only model GGM02S and the combination model GGM02C) represents an improvement greater than a factor of two over the previous GGM01 models. Error estimates indicate a cumulative error less than 1 cm geoid height to spherical harmonic degree 70, which can be said to have met the GRACE minimum mission goals. Electronic Supplementary Material Supplementary material is available in the online version of this article at     

Assessing Similarity of Geographic Processes and Events

The increased availability of spatiotemporal data collected from satellite imagery and other remote sensors provides opportunities for enhanced analysis of geographic phenomena. Much of the new data includes regular snapshots of the environment. Comparison of these snapshots can provide information about changes to the phenomena of interest. However, conventional GIS data models and analytical tools lack capabilities to adequately handle massive multidimensional data. One of the fundamental tools necessary to meet such challenges is query support to retrieve and summarize data according to dynamic geographic phenomena, such as geographic events and processes, of interest. Such query support depends upon abilities to assess spatiotemporal similarity so that data representing geographic events that exhibit the spatiotemporal characteristics of interest can be identified in a GIS database. To this end, this paper introduces a method to assess similarity of geographic events and processes (such as storms) based on their spatiotemporal characteristics (such as distribution of precipitation). We developed six indices to capture static and dynamic characteristics of geographic events and applied the Dynamic Time Warping method to temporal sequences of the six indices to examine the similarity among these events. With a case study, we demonstrated the proposed indices and method capable of comparing spatiotemporal characteristics of events as recorded in a GIS database and categorizing spatiotemporal data into groups of events according to their behavior in space and time.     

冻土器的快速修复及改进

冻土器观测是地面气象观测项目之一.虽经多年使用,但至今仍没有改进.各站在冬季的观测使用中,最普遍出现的故障是内管中的铁链中断,中断后的链子堆积在冰柱上端而无法确定冻土刻度.冰柱稍短时,由于铁链堆积重量大造成冰柱整体下滑,出现记录失真.因此,发现铁链中断时,要及时修复.下面介绍快速修复冻土器的方法及改进措施.     

施放氢气球时存在的安全隐患及防范措施

针对采用球服务中的安全隐患，提出有效的防范措施，对开展此项工作的同志有很好的借鉴意义。     

一类广义Hamilton系统的辛格式

通过引人泊松括号，分析了无限维Hamilton的性质，并将其推广到广义Hamilton系统，且从理论和实用角度讨论了这类广义Hamilton系统的辛格式构造问题，从而为辛几何算法在一般的时间发展方程的数值求解提供新的具体途径。     

A mechanism for decadal changes of ENSO behavior: roles of background wind changes

This study explains why a number of El Nino properties (period, amplitude, structure, and propagation) have changed in a coherent manner since the late 1970s and why these changes had almost concurred with the Pacific decadal climate shift. Evidence is presented to show that from the pre-shift (1961-1975) to the post-shift (1981-1995) epoch, significant changes in the tropical Pacific are found in the surface winds and temperature, whereas changes in the thermocline are uncertain. Numerical experiments with the Cane and Zebiak model demonstrate that the decadal changes in the surface winds qualitatively reproduce the observed coherent changes in El Nino properties. The fundamental factor that altered the model's El Nino is the decadal changes of the background equatorial winds and associated upwelling. The annual cycle is also necessary for the mean state to modulate El Nino. From the pre- to post-shift epoch, the changes in the background winds and upwelling modify the structure of the coupled mode (eastward displacement of the equatorial westerly anomalies) by reallocating anomalous atmospheric heating and SST gradient along the equator. This structural change amplifies the ENSO cycle and prolongs the oscillation period by enhancing the coupled instability and delaying transitions from a warm to a cold state or vice versa. The changes in the mean currents and upwelling reduce the effect of the zonal temperature advection while enhance that of the vertical advection; thus, the prevailing westward propagation is replaced by eastward propagation or standing oscillation. Our results suggest a critical role of the atmospheric bridge that rapidly conveys the influences of extratropical decadal variations to the tropics, and the possibility that the Pacific climate shift might have affected El Nino properties in the late 1970s by changing the background tropical winds and the associated equatorial upwelling.