首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
近30年藏西北高寒牧区气候变化特征   总被引:4,自引:0,他引:4  
唐洪  边多  胡军 《西藏科技》2006,(1):43-47
利用藏西北高寒牧区1971-2002年年平均气温、降水量、蒸发皿蒸发量、大风日数、各站≥0℃和≥5℃期间的初日、终日、持续日数、积温和降水量等32a的气象资料,分析了近30年藏西北高寒牧区的气候变化特征。结果发现:(1)藏西北高寒牧区年平均气温表现为一致的升温趋势;(2)阿里地区年降水量总趋势是缓慢下降;那曲地区年降水量总趋势是缓慢增加的。(3)蒸发量、大风日数呈逐年减少趋势;(4)那曲地区一带牧草青草期间的降水量缓慢增加,将非常有利于牧草的生长;而阿里地区牧草青草1期间的降水量本就有限,在降水量逐年缓慢下降趋势的背景下,牧草的生长将会受到很大的影响,这意味着阿里地区出现了暖干化趋势,将可能造成该地区干旱的加剧。  相似文献   

2.
本文利用1961~2010年玛多气象站气象观测资料,通过对其地区气温、降水量及蒸发量的年变化和春、夏、秋、冬四季及年代的变化分析,结果表明:近50年来玛多地区年平均气温和降水量均呈上升趋势,蒸发量呈下降趋势;气温的四季变化均有明显上升趋势,其中冬季的气温上升最为明显,增温率为0.71℃/10a。近50年极值气温变化更大,最低气温极值21世纪初10年比上世纪70年代偏高12-2℃,最高气温极值21世纪初10年比上世纪60年代偏高2.0℃;玛多县降水量呈上升趋势,冬季上升趋势相对较小;近50年的蒸发量虽然呈下降趋势,但蒸发量远远大于降水量,所以干旱期延长,气候趋于暖干化,对牧草的生长极为不利,气候原因使草场的退化速度加快。  相似文献   

3.
达桑 《西藏科技》2011,(1):42-45
利用西藏色林错流域气象观测站1961~2008年逐月平均气温、降水量等资料,分析了近50牟流域气温、降水的年际和年代际变化特征和异常年份,结果表明:近50年流域年平均气温以0.40℃/10a的速率显著升高,冬季增温最突出。平均最高气温除夏季变化趋势不大外,其它各季以0.21~0.35℃/10a的速度显著升高;年平均最低气温以0.56℃/10a的速度显著升高,明显高于最高气温的井幅。流域年降水量以20.4mm/10a的速率呈显著的增加趋势,四季降水量表现为增加趋势,为0.8~10.4mm/10a,以夏季增幅最大。20世纪60年代至90年代,除夏季外,其它3季和年平均气温都表现为逐年代增加趋势。年、季平均最高气温的年代际变化特征不明显。60年代流域降水表现为偏少的年代际变化特征;70年代夏季降水偏多,其它季节偏少;80年代夏、秋两季降水正常,冬、春季偏多;90年代,夏季偏少,秋、冬季偏多;进入21世纪前8年,秋季降水偏少,其它三季降水偏多,年降水量增幅明显。  相似文献   

4.
本文依据青海湖环湖地区的海晏、刚察、共和、天峻四站1961~2008年地面气象资料,分析了气候变化对该地区极端天气气候事件的影响。结果表明:环湖地区年平均气温总体呈升高趋势,年降水量共和略有减少,海晏、刚察、天峻略有增加。大雨、霜日、春旱事件呈增加趋势,大风、沙尘、雷暴、冰雹事件呈减少趋势。气温与大雨存在明显的正相关,与沙尘、早霜存在明显的负相关。雷暴与大风、雷暴与冰雹、大风与沙尘存在高相关性。  相似文献   

5.
青海湖流域气候变化及其水文效应   总被引:8,自引:0,他引:8  
利用青海湖流域内及周边6个气象站近50年来的逐日最高、最低、平均气温和降水量,青海湖水位、面积以及沙柳河和布哈河逐月径流资料分析了该流域的气候变化及其水文效应。结论认为:青海湖流域近年来最高气温以(0.29±0.17)℃/10年的速度增加(p>0.05),最低气温以(0.55±0.5)℃/10年的速度显著增加(p<0.05),平均气温以(0.28±0.03)℃/10年的速度显著增加(p<0.05),同时,年平均温差以(-0.12±0.02)℃/10年的速度显著减少(p<0.05)。与全球气候变暖相比,青海湖流域气温升高的速度更快。流域各站年降水量和日最大降水量呈增加趋势(p>0.05),降水天数和干旱期变化差异性较大。青海湖水位和面积分别以7.8cm/年和7.4km2/年的速度显著下降(p<0.01)。沙柳河、布哈河年径流量呈略微减少趋势(p>0.1),而且分别在4月~5月和12至次年4月减少趋势显著(p<0.05)。气候变化和水文效应相关分析表明,青海湖水位与流域平均气温呈显著负相关(p<0.01),而水位变化量、沙柳河和布哈河径流量与降水量呈显著正相关(p<0.01)。  相似文献   

6.
王瑾  蔡演军  安芷生  刘娟 《资源科学》2013,35(6):1300-1309
利用遥感影像和多源地理信息提取峻河流域高寒灌丛,分析近30年来区域高寒灌丛分布面积的变化,并与峻河流域年平均温度、年降水量、年蒸发量以及蒸发量和降水量的比值进行对比,探讨影响高寒灌丛面积变化的气候因子.研究结果表明:①峻河流域高寒灌丛面积在10年尺度上具有一定的波动性,1977年-1990年高寒灌丛的面积增加14.37km2,1990年-2000年高寒灌丛面积减少了12.61km2,2000年-2009年高寒灌丛面积又增加了8.53km2;②峻河流域高寒灌丛面积变化与该区域的温度和降水变化没有直接的相关关系,但与蒸发量与降水量的比值呈反相关;③峻河流域高寒灌丛面积变化与整个青海湖流域的干旱强度变化相关,干旱强度越大,高寒灌丛分布面积减小,反之,干旱强度减小,高寒灌丛面积增加.  相似文献   

7.
柴达木盆地气温降水的长序列变化及与水资源关系   总被引:4,自引:2,他引:2  
傅小城  王芳  王浩  段水强 《资源科学》2011,33(3):408-415
根据柴达木盆地8个气象观测站点1960年-2009年共50年的逐月平均气温及降水量资料,综合运用线性趋势分析及Mann-Kendall趋势检验等气象统计分析方法对柴达木盆地气温及降水的变化趋势进行了分析。结果表明在过去的50年里,柴达木盆地经历了明显的升温过程,且增温幅度越来越大,特别是进入20世纪90年代,总的升温幅度在0.5℃/10a左右,远大于同期全球的升温幅度;柴达木盆地降水也略有上升,变化幅度6.2mm/10a左右。从空间分布上看,柴达木盆地气温增幅从东到西逐渐增高,而降水倾向率则逐渐减小。季节分布上,盆地内冬季的气温升温幅度最为明显,增温幅度达0.72℃/10a左右,降水倾向率则夏季最大,达3.4mm/10a。累积距平曲线及Mann-Kendall趋势突变检验综合分析表明,柴达木盆地气温在20世纪80年代有一个明显的增温过程,增温起点在1987年左右。气温、降水的变化也在一定程度上影响到水资源量的变化,相关分析表明,地表水资源量与降水呈显著相关关系,但与气温关系不明显。另外,上一年降水也对地表水资源量有一定的影响。  相似文献   

8.
选用镶黄旗国家气象观测站1992年—2021年平均气温、降水、日照时数、2 min平均风速、大风日数、沙尘暴日数等气象要素资料,采用线性趋势分析法对镶黄旗地区近30年气候变化特征进行了分析。分析得出:1992年—2021年镶黄旗地区年平均气温以0.397℃/10 a的速率呈明显的上升趋势;年降水量以15.231 mm/10 a的速率呈下降趋势;日照时数以23.362 h/10 a的速率呈下降趋势;2 min平均风速以0.414 (m/s)/10 a的速率呈下降趋势;大风日数以1.646 d/10 a的速率呈下降趋势;沙尘暴日数以1.646 d/10 a的速率呈下降趋势。  相似文献   

9.
近40年来烟台地区气温与降水量变化的关系研究   总被引:9,自引:0,他引:9  
利用烟台地区1960~1999年的气象资料,分析了近40年来该区气温与降水量之间的关系.结果表明,从20世纪60年代至90年代,气温呈上升趋势,而全年、夏季、秋季降水量则随温度上升而减少,二者之间表现出显著线性相关.春季降水量与气温相关性不明显,二者不达显著水平.冬季降水量与冬季平均气温之间相关性显著,降水量随温度升高而增加,可用二次多项式回归方程量化表示.这样,该区气温状况如何,为预测未来降水趋势提供了信息,对合理利用本地气候资源具有实际意义.  相似文献   

10.
近45年羊卓雍湖西部流域气候的变化特征初探   总被引:1,自引:0,他引:1  
本文利用浪卡子站建站以来的年平均气温、降水量、蒸发量、最高气温、最低气温资料,运用统计方法来分析了近45年羊卓雍湖西部流域的年际和年代际变化。结果表明:近45年来,羊卓雍湖西部流域年平均气温、最高气温、最低气温呈显著的升高趋势,升幅分别为0.29℃/10a、0.1℃/10a、1.1℃/10a;年降水量表现为不显著的增加趋势,平均每10年增加3.8mm。  相似文献   

11.
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors.  相似文献   

12.
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007.  相似文献   

13.
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction.  相似文献   

14.
Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies.  相似文献   

15.
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China's science enterprise by making S&T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party's Leading-member Group at CAS, which was held from 7 to 11 January in Beijing.  相似文献   

16.
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means.  相似文献   

17.
Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said.  相似文献   

18.
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants."  相似文献   

19.
The main premise of this article is that in information societies generally, and in virtual social contexts particularly, a distinctive style of interaction to facilitate the communication of difference, heterotopic communication , has emerged. It rests on two cultural foundations: an ideological belief in the positive, socially integrating power of communication, and a prevailing ethic of instrumental rationality, subjective individualism, and strategically practiced self-interest. The former is demonstrated by the use of simulation and spectacle as sources of information; exhibitionism/voyeurism as a communicative style; and the awareness of surveillance. The latter is seen in the competitive use of knowledge as a commodity; a surface globalism masking deep parochialism; lateral as well as vertical information inequity; and the use of public versus private as strategies for engagement rather than as spaces. Those who engage in heterotopic communication resort to their 'own devices' both in the sense of personal agendas, strategies, interests, and interpretations, and in the form of the telecommunication tools that help realize them. These personal and technological devices allow individuals with the right educational and technical resources to avoid exposure to disagreement, difference, or other information that does not serve their direct purposes or reflect their particular views of the world; yet they also help convey the appearance of openness, availability, and cooperation. This style of interaction is used strategically in combination with information and communication technologies to gain social or economic advantages, but it may encourage social separatism and parochialism, inhibit the negotiation of disputes, and emphasize competing interests.  相似文献   

20.
Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号