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91.
选取1961-2008年武陵山片区18个气象观测站的逐日降水数据,通过线性回归、相关系数等统计方法,从时间和空间上分析了武陵山片区夏季暴雨天气的变化规律,并运用信息扩散技术计算出武陵山片区夏季暴雨天气风险的空间分布.结果显示,整个武陵山片区年平均暴雨日数呈上升趋势,区域内总体是东多西少、北多南少和中部高于边缘的分布特征;武陵山及附近地区受地形地貌和暴雨次数的影响暴雨量级较大,乌江、清江和资水等河流流域是武陵山片区暴雨气象灾害的重点预防区域.这对武陵山片区制定区域发展政策、防灾减灾及生态建设均有一定的指导意义. 相似文献
92.
An integrated index which can be used to indicate the advance of subtropical summer monsoon in East Asia has been proposed in this paper.The index was comhined by three variables including precipitation,wind and pseudo-equivalent potential tempera- ture.The northernmost summer monsoon location(NSML)was identified by using this index annually.It was found that the NSML ex- perienced an interdecadal shift in the period 1977—1979 based on the annual index analysis from 1961 to 2001.A comparison of the NSML with other four summer monsoon indices has also been made.The result showed that the NSML could well represent the interan- nual and interdecadal variability of summer monsoon precipitation in North China(beyond 35°N),while other four indices could well indi- cate the precipitation anomalies of East Asian summer monsoon along the Yangtze River valley(around 30°N). 相似文献
93.
本文提出了基于一对一模糊支持向量机多分类方法的非线性夏季雨型预报模型.该模型在一对一支持向量机多分类算法的基础上引入模糊隶属度函数,其构造的分类超平面可以忽略噪声样本对分类结果的影响.实验结果表明,该模型较传统的支持向量机多分类方法和线性物理统计方法,具有更好的预报能力和更强的抗干扰能力,可以较好地弥补基于统计理论的相关分析和回归方法在处理非线性问题时具有较大的局限性 相似文献
94.
用非线性主成分分析方法研究了欧亚地区1948-2007年60年夏季海平面气压距平场主要空间模态的非线性特征.结果表明,夏季欧亚地区海平面气压场异常变率具有显著的非线性特征,非线性主成分分析法有能力表示出更一般的低维结构特征.当第一非线性主成分取不同异常值时,对应的海平面气压异常空间分布型具有显著的非对称性.其解释方差为47.5%,比线性PCA第一模态高出12.8%,因而非线性较强.同时,第一非线性主成分时间变化表现为不均匀的周期为2~4年的年际振荡,其强度在1967年以后迅速增强.这个主要非线性空间模态与东亚地区大气内部非线性相互作用密切相关,反映了夏季欧亚地区环流非线性低频波活动的时空不对称性. 相似文献
95.
Two lacustrine sporopollen records obtained from the Qaidam Basin (in the non-monsoonal region) and the Linxia Basin (in the monsoonal transition zone) indicate that during the early Pleistocene open forest-steppe/steppe vegetation developed in the Qaidam Basin, while in the Linxia Basin an open cypress forest-steppe shifted to a conifer/conifer-steppe and then to open forest-steppe vegetation. Existing sporopollen records from the Chinese Loess Plateau (CLP) (in the monsoonal region) indicate that around the Sanmen Paleolake open forest-steppe shifted to pine/conifer-broadleaved mixed forest. The conifer cover then changed to a subtropical evergreen broadleaved forest distributed around the Nihewan Paleolake. These changes suggest that wetter conditions progressed from western China to the east, and the climate became more humid than that of today indicating a stronger Asian summer monsoon during the early Pleistocene. 相似文献
96.
1905~1990年徐州夏季气温资料表明,本世纪50年代后期凉夏出现频率呈上升趋势,至80年代后期又出现下降趋势。探讨这种气候变化趋势的特点及其成因,并对其未来发展作出预测。 相似文献
97.
北雁荡山风景区的旅游气候优势 总被引:1,自引:0,他引:1
唐德容 《浙江大学学报(理学版)》1990,17(3):349-354
本文首先根据生理气候的研究成果,结合北雁荡山风景区环境温废的时空分布规律,论L北雁荡山风景区是较理想的避寒和避暑胜地.然后,着重研讨气候主要因子的造景功能,深入讨论了自然降水是形成北雁荡山风景区瀑布奇观的主角.从温度与降水两方面揭示北雁荡山风景区的气候优势 相似文献
98.
99.
A physically-based statistical forecast model for the middle-lower reaches of the Yangtze River Valley summer rainfall 总被引:17,自引:0,他引:17
A new approach to forecast the middle-lower reaches of the Yangtze River Valley summer rainfall in June-August (JJA) is proposed in this paper. The year-to-year increment of the middle-lower reaches of the Yangtze River Valley is forecasted and hence the summer precipitation could be predicted. In this paper, DY is defined as the difference of a variable between the current year and the preceding year (year-to-year increment). YR denotes the seasonal mean precipitation rate of the middle-lower reaches of the Yangtze River Valley summer rainfall. After analyzing the atmospheric circulation anomalies in winter and spring that were associated with the DY of YR, six key predictors for the DY of YR have been identified. Then the forecast model for the DY of YR is established by using the multi-linear regression method. The predictors for the DY of YR are Antarctic Oscillation, the meridional wind shear between 850hPa and 200hPa over the Indo-Australian region, and so on. The prediction model shows a high skill for the hindcast during 1997-2006, with the average relative root mean square error is at 18%. The model can even reproduce the upward and downward trends of YR during 1984--1998 and 1998--2006. Considering that the current operational forecast models of the summer precipitation over the China region have the average forecast scores at 60%--70% and that the prediction skill for the middle-lower reaches of Yangtze River Valley summer precipitation remains quite limited up to now, thus this new approach to predict the year-to-year increment of the summer precipitation over the Yangtze River Valley (and hence the summer precipitation itself) has the potential to significantly increase the operational forecast skill of the summer precipitation. 相似文献
100.