基于“配料”的梅雨锋强降水预报方法

在梅雨锋暴雨预报中应用“配料法”，通过降水量的基本公式解释了强降水形成的基本配料，给出了建立配料的基本步骤，同时，通过一次暴雨个例分析，具体阐述了“配料法”在梅雨锋暴雨预报中的应用。结果表明，基于暴雨等强对流天气形成物理机理认识的基础上，所选取的可降水量等动力、热力因子与暴雨有着较好的对应关系，通过分析以上关键物理因子建立的过程，可以给出暴雨潜势预报。     

中国兴农网用户认证模块设计

中国兴农网自市场信息模块设立以来,吸引了越来越多的用户发布和浏览信息,而对这些信息及发布人行为的管理渐渐纳入日程。该文介绍了为中国兴农网信息发布系统提供的一个安全的用户认证系统,在实际操作中,PHP语言与Oracle数据库的结合使用较好地实现了这一目标,有效地实现了用户的管理,包括注册、修改、授权、删除等功能,并且通过用户的认证,安全地控制了农网市场信息的发布流程。该文从设计思路出发,探讨了功能设计、程序设计语言、数据库的选择与实现等几个具体的问题。     

2004年气象因子对棉花生长的影响

针对2004年石河子气象因子对棉花减产的影响进行分析,得出棉花减产因素为:春季土墒、花期暴雨、铃期低温、病虫害、早霜,并提出了相应的对策。     

THE ANALYSIS OF TROPICAL CYCLONE PRECIPITATION AFFECTING THE LIAODONG PENINSULA

1 INTRODUCTIONTropical cyclones (TCs) moving north and gettingto the Liaodong Peninsula and waters of the Yellowand Bohai Seas are in their late phase of life cycle.While weakening rapidly, TCs carry a large amount ofwarm and humid air that forms heavy ra…     

一个气候系统模式FGCM0对东亚副热带西风急流季节变化的模拟

对IAP/LASG气候系统模式试验版(FGCM0)模拟对流层上层东亚副热带西风急流季节变化的能力进行评估, 分析FGCM0模拟的东亚副热带西风急流季节变化与NCEP/NCAR再分析资料的差异及其与对流层大气南北温差的关系.结果表明, FGCM0模拟的冬季和夏季西风急流垂直结构、水平结构和季节变化与NCEP/NCAR再分析资料基本一致, 但FGCM0模拟的东亚副热带西风急流在高原附近地区冬季和夏季都偏强, 沿115°E中国大陆地区上空模拟的急流强度冬季偏弱, 夏季明显偏强.夏季FGCM0模拟的急流中心位于高原东北部的40°N附近地区, 强度偏强, 位置偏东, 而此时NCEP/NCAR再分析资料中的急流中心却位于高原北侧.此外, FGCM0模拟的急流在5月份的北移和8月份的最北位置上与NCEP/NCAR再分析资料差异较大.分析副热带西风急流与对流层南北温差的季节变化发现, 急流出现的位置总是对应着对流层南北温度差较大区域, 与再分析资料相比, FGCM0模拟的温度差在冬季基本一致, 夏季差异较大.与降水的模拟相联系发现, FGCM0模拟得到的与实际不一致的偏西偏北的强降水中心与200 hPa上的东亚副热带急流位置和强度不合理具有密切关系.相关分析表明, 冬季西风急流强度与日本南部海区的感热通量、夏季与青藏高原地区的地面感热通量有明显的正相关关系, 而FGCM0能够较好地模拟冬季西风急流强度与地面感热通量之间的相关关系, 但模拟夏季青藏高原地区感热通量和副热带西风急流之间相关关系的能力相对较差, 夏季西风急流强度与OLR之间却有一定的关系.由于与强降水区相联系的OLR低值区对应着较大的对流凝结加热, 再加上模式中位于青藏高原东南部较大的地面感热加热, 增强了对流层的南北向温度差, 进而影响东亚副热带急流强度和位置.因此, FGCM0模拟的夏季副热带急流位置和强度偏差与高原附近地区的地面感热加热、大气射出长波辐射等的模拟偏差具有密切的关系.     

基于ArcGIS Engine的地理信息数据库管理系统设计与实现

随着社会的发展,空间信息在国土、规划等各领域的应用越来越广泛,且其容量也呈几何级增长,如何安全高效地管理、分发空间数据,成为深入应用地理信息系统功能的必要前提。本文以作者实际工作为基础,介绍了利用ESRI公司最新产品ArcGIS Engine开发包设计实现地理信息数据库管理系统的具体方法。     

预应力混凝土双压花锚具性能的低周重复荷载试验研究

通过对预应力混凝土一种新型双压花锚具足尺寸试件的试验,研究了这种锚具在低周重复荷载下的性能及其特点、锚具受周期荷载后再次承受静力荷载作用时的性能以及周期荷载的不同应力循环幅度对锚具性能的影响。试验结果表明:双压花锚具达到了国家标准规定的周期荷载性能要求;随着周期荷载循环次数的增加,锚具每个循环的荷载与变形关系呈近似线弹性关系;锚具在历经50次重复加卸荷后,其静载性能发生了很大变化,而最大承载力和极限变形能力没有降低。     

Application of ensemble kalman filter to geophysical parameters retrieval in remote sensing:A case study of kernel-driven BRDF model inversion

Remote sensing can provide multi-spatial resolution, multi-temporal resolution multi-spectral band and multi-angular data for the observation of land surface. At present, one of research focuses is how to make the best of these data to retrieve geophysical parameters in conjunction with their a priori knowledge and simul-taneously consider the influence of data uncertainties on inversion results[1-5]. The essence of remote sensing lies in inversion. It is difficult to precisely retrieve parame…     

Miocene Bahean stratigraphy in the Longzhong Basin, northern central China and its implications in environmental change

Fossil mammal-riched Neogene strata are widely distributed in the southeast corner of the huge Longzhong Basin at Tianshui, Gansu Province, northern central China. Hipparion weihoense, a typical member of late Middle Miocene Bahean stage, was recently excavated at Yaodian along a well-exposed outcrop. Owing to the importance of the Bahean stage in the mammalian evolution and its potential for environmental change, we suggested a name of Yaodian Formation for the stratigra- phy, which is correlated to the Bahe Formation at Lantian, Shaanxi. High resolution paleomagnetic dating of the section shows that the Yaodian Formation covers the period between 11.67 Ma and 7.43 Ma, with the site bearing Hipparion weihoense being estimated at about 10.54―10.30 Ma, providing first magnetostratigraphic chronology for the Bahean Stage. The Yaodian Formation consists of fluvial channel deposits (11.67―10.40 Ma) at the bottom, floodplain deposits in the middle (10.40―9.23 Ma) and shallow lake sediments at the top (9.23―7.43 Ma). This upward fining sequence suggests that the relief in nearby mountain ranges such as West Qinling to the south and Huajia Ling to the north was greatly reduced after long-term denudation, fluvial transport capacity was low, and finally the drainage system was disintegrated, replaced with broad-shallow lakes in which only fine sediments like mud and marlite were deposited, indicating an old stage of development of a planation surface. A remarkable shift in ecology and climatic environment was found at 7.4―7.7 Ma when paleoclimate changed from early warm humid to late dry as indicated by sedimentary facies changed from early shallow lake sequence to late eolian red clays and a former coniferous-deciduous mixed forest was replaced by grassland, leading to great growth of Hipparion Fauna of Baodean stage in the region. Therefore, it is estimated that the present high relief of Qinling and drainage pattern did not come into being until Late Pliocene in response to intensive neotectonism and climate change.     

华北平原冬麦田土壤CH4的吸收特征研究

利用静态箱/气相色谱(GC)法,对华北平原冬小麦拔节-成熟期间麦田土壤CH₄气体通量进行了测定,得出华北平原典型冬麦田土壤是大气CH₄的弱吸收汇。试验期间土壤CH₄通量存在明显的季节变化和日变化,麦田拔节-成熟期间土壤CH₄通量日平均值为-18.3μg·m^-2·h^-1,波动范围为-4.3-24.4μg·m^-2·h^-1;在土壤CH₄通量的日变化中,观测到麦田土壤在午间和夜间都有一个吸收峰,峰值出现的时间因生育期不同而有所不同。试验期间CH₄通量日平均值与土壤温度关系不明显,而与土壤水分呈负相关(α=0.01);日变化中土壤CH₄通量与地表温度的相关性较差,而与5cm地温相关密切。麦田拔节-成熟期间土壤CH₄通量日平均值随NH4+-N施用量的增加呈递减规律,农田秸秆还田后不利于土壤对CH₄的吸收。