1961—2010年青海省霜冻灾害变化特征及风险区划

基于青海省历史日最低气温、青海省农作物种植总面积、农作物产量等要素,运用数理统计构建致灾因子危险性、暴露性和灾损敏感性指数,采用图表法和指数乘积法开展青海省霜冻灾害变化特征及风险区划。结果表明,青海省作物种植区均有霜冻灾害,中心集中在东部农业区的门源、大通、互助、湟源和湟中,柴达木盆地东部的德令哈、都兰和乌兰,以及贵南和共和等地;发生时段主要在4—9月,5月发生频率最高;年际间霜冻灾害呈波动增加趋势,但趋势不显著,年代际间霜冻灾害呈显著波动增加趋势;霜冻灾害高风险区主要分布在东北部的门源、互助、大通和祁连东部。     

1951-2006年南京气温变化特征

利用南京市1951年1月-2007年4月逐日温度观测资料,分析了南京市平均气温、极端气温、冷积温和热积温的变化趋势和特征。结果表明,在全球气候变暖的背景下,56a来南京平均气温明显上升,尤其是春、冬季升温显著,且春季升温大于冬季升温,而年极端最低气温和冷积温显著上升,年极端最高气温和热积温略有下降;冷冬皆分布在20世纪80年代以前,暖冬主要分布在90年代以后;春季提前并略有加长;夏季加长了约4候;秋季延迟并缩短了约2候;冬季缩短了约3候。     

作物生长岩-土环境中不同存在形态钾素含量动态变化

以较系统的观测资料,对土壤环境中的缓效态、速效态、水溶态钾素含量的动态变化进行探索.结果表明,缓效态钾的季节性动态变化制约着速效态、水溶态钾的季节性动态变化,但是后两者变化幅度较缓效态钾的大;这种动态变化同时受土壤类型和深度的影响.     

含铁绿柱石的改色机制研究

含铁绿柱石经γ射线辐照或特定温度热处理,可因铁价态的改变引起颜色发生相应变化。处理前后的吸收光谱和顺磁共振谱研究表明,辐作用使隧道位的Ｆｅ＾２＋氧化Ｆｅ％３＋,八一位上的Ｆｅ＾３＋还原为Ｆｅ＾２＋,热处理使隧道位及八面体位Ｆｅ＾３＋均还原为Ｆｅ＾２＋。     

中国西部大尺度流域建立分带式融雪径流模拟模型

针对中国西部大尺度流域利用遥感信息进行的融雪径流模拟模型建立过程,提供以数字地形因子分析为手段的分区,分带方法。在ＮＯＡＡ／ＡＶＨＲＲ卫星云图为主要监测信息源的前提下,应用支持软件,解决了图像纠正,图形转为图像后再与图像匹配等问题。同时,根据研究得出雪象元之阈值,使用监督分类的训练样本方法统计出流域内雪盖面积及各带的雪盖面积百分比。作为应用和检验,对黄河上游的曲什安流域进行样本操作,分３个垂直带各     

新疆玛纳斯河流域地下水预测研究

根据新疆玛纳斯河流域地下水年径流量的时间序列, 建立了用于描述和分析具有趋势和周期变化特性的地下径流量时间序列的组合模型应用模型对石河子地区地下水年径流量进行了预报, 为该地区水资源合理配置和优化调度提供科学依据      

黑河出山径流量年际变化特征和趋势研究

根据有关水文气象台站的观测数据,利用定级分类,滑动平均和波谱分析等方法,对黑河出山径流（莺落峡水文站）年际变化特征进行了分析研究,发现黑河出出径流的多年变化具有持续性,周期性和丰枯水变化较平稳,波幅不大等特性,并在此基础上对其未来变化的趋势进行了预测和分析。     

Preliminary Study on Horizontal Deformation and Tectonic Activity in the Northern Part of North China Using GPS Remeasurement Results

In this paper, the baseline variation and displacement vector was analyzed using the calculated results of GPS measurements carried out from 1995 to 1996 in North China. Based on these analytical results, we studied the recent tectonic activity. In general, the regional extension is dominant in the direction of proximately EW, but there is a difference in the SN direction. Extension is significant in the Shanxi fault-depression zone and Bohai region, while compression with strike-slip is characterized along the Yishui-Tancheng segment of the Tanlu fault zone. The baseline shortening zone is distributed along the Baotou-Zhangjiakou-Ninghe areas. It is a boundary zone of regional variation where many differences of crustal horizontal deformation are discovered between the southern part and the northern part of this zone. The baseline shortening zone in NE direction is distributed along the Jianchang-Tangshan-Gucheng area. It is consistent with the Tangshan-Xingtai seismic zone which indicates that tectoni     

Contrasts between the Interannual Variations of Extreme Rainfall over Western and Eastern Sichuan in Mid-summer

Rainfall amount in mid-summer(July and August)is much greater over eastern than western Sichuan,which are characterized by basin and plateau,respectively.It is shown that the interannual variations of extreme rainfall over these two regions are roughly independent,and they correspond to distinct anomalies of both large-scale circulation and sea surface temperature(SST).The enhanced extreme rainfall over western Sichuan is associated with a southward shift of the Asian westerly jet,while the enhanced extreme rainfall over eastern Sichuan is associated with an anticyclonic anomaly in the upper troposphere over China.At low levels,on the other hand,the enhanced extreme rainfall over western Sichuan is related to two components of wind anomalies,namely southwesterly over southwestern Sichuan and northeasterly over northeastern Sichuan,which favor more rainfall under the effects of the topography.Relatively speaking,the enhanced extreme rainfall over eastern Sichuan corresponds to the low-level southerly anomalies to the east of Sichuan,which curve into northeasterly anomalies over the basin when they encounter the mountains to the north of the basin.Therefore,it can be concluded that the topography in and around Sichuan plays a crucial role in inducing extreme rainfall both over western and eastern Sichuan.Finally,the enhanced extreme rainfall in western and eastern Sichuan is related to warmer SSTs in the Maritime Continent and cooler SSTs in the equatorial central Pacific,respectively.     

Contribution of new AAM data source to δLOD excitation

Data sets of the changes of the length of day (ΔLOD) measured by space geodetic techniques and of the atmospheric angular momentum (AAM) derived from global meteorological data by the National Meteorological Center (NMC) and the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) are used to reanalyze and study the excitations of ΔLOD, and to examine and compare the contribution of each AAM series to ΔLOD. The main results are as follows. 1. The AAM reanalyzed with the assimilated global meteorological data by NCEP/NCAR are more accurate and have lower noise than the original AAM derived by NMC. The NCEP/NCAR-based AAM is more consistent with the changes of the length-of-day series. 2. The NCEP reanalysed AAM data may better explain the non-tidal LOD variations on intraseasonal to interannual time scales, especially on the quasi-biennial time scale. The atmosphere cannot, however, explain all LOD variations; other excitation sources are possible. 3. The effects of atmosphere on the estimated values of tides for ΔLOD components up to a month are weak. The preliminary results of the annual and semiannual tides can be estimated after removing the effects of atmosphere from ΔLOD. Received: 27 May 1998 / Accepted: 22 March 1999