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881.
根据安康地区48年气象中的降水资料,采用线性回归法、累积距平法,以及5年滑动平均曲线研究方法,对安康地区48年降水变化从年、季、月的时间角度进行了比较,从而分析了安康地区降水变化特征及规律.结果表明,安康地区48年来,降水呈缓慢减少趋势,但21世纪后降水将呈现略微增加趋势,降水主要集中在夏季、春秋两季降水呈减少趋势,夏... 相似文献
882.
Features of aerosol optical depth and its relation to extreme temperatures in China during 1980-2001
Based on Total Ozone Mapping Spectrometer (TOMS) monthly aerosol optical thickness (AOT) measurements in 1980–2001 a study is made of space/time patterns and difference between land and sea of AOT 0.50 μm thick over China,which are put into correlation analysis with synchronous extreme temperature indices (warm/cold day and night).Results suggest that 1) the long-term mean AOT over China is characterized by typical geography,with pronounced land-sea contrast.And AOT has significant seasonality and its seaso... 相似文献
883.
Surface meteorological observations have been carried out at the Great Wall station (GW) and Zhongshan station (ZS) from 1984 to 2008 and from 1989 to 2008 respectively. The variation in mean air temperature and its trends are derived from the meteorological observation data recorded at both stations. The warming rate of the annual mean temperature at GW is similar to that at Bellingshausen station, which is about 3 km distant. Thus, the warming trend is representative of the King George Island region. The warming rate of ZS is less different from that at Davis station,which is about 100 km from ZS. It can be said that the meteorological data recorded at both stations are representative of the regions of the King George Island and east coast of the Antarctic. 相似文献
884.
Based on the daily OISST V2 with 0.25o horizontal resolutions, we study the variations of sea surface temperature (SST) extremes in the China Seas for different segments of the period 1982-2013. The two segments include the warming acceleration period from 1982 to 1997 and hiatus period from 1998 to 2013 when the global surface mean temperature (GSMT) was not significantly warming as expected during the past decades, or even cooling in some areas. First, we construct the regional average time series over the entire China Seas (15o–45oN, 105o–130oE) for these SST extremes. During the hiatus period, the regionally averaged 10th, 1th and 0.1th percentile of SSTs in each year decreased significantly by 0.40°C, 0.56°C and 0.58°C per decade, respectively. The regionally averaged 90th, 99th and 99.9th percentile of SSTs in each year decreased slightly or insignificantly. Our work confirmed that the regional hiatus was primarily reflected by wintertime cold extremes. Spatially, the trends of cold extremes in different intensity were non-uniformly distributed. Cold extremes in the near-shore areas are much more sensitivity to the global warming hiatus. Hot extremes trends exhibited non-significant tendency in the China Seas during the hiatus period. In word, the variations of the SST extremes in the two periods were non-uniform spatially and asymmetric seasonally. It is unexpected that the hot and cold extremes of each year in 1998–2013 were still higher than those extremes in 1982–1997. It is obvious that relative to the warming acceleration period, hot extremes are far more likely to occur in the recent hiatus as a result of a 0.3°C warmer shift in the mean temperature distribution. Moreover, hot extremes in the China Seas will be sustained or amplified with the end of warming hiatus and the continuous anthropogenic warming. 相似文献
885.
B. Mamtimin A.M.M. Et-TantawiD. Schaefer F.X. Meixner M. Domroes 《Journal of Arid Environments》2011,75(11):1105-1113
According to trend computations at three stations each in Sahara desert (Libya), characterized by a “hot” desert type (“BWh”, according to the Koeppen climate classification), and in Central Asia (Xinjiang, China) identified as a “cold” desert type (“BWk”, after Koeppen), increasing annual temperatures were detected over the period 1955-2005 corresponding with global temperature warming. From 1955-1978, negative (decreasing) temperature trends were, however, observed at all three hot desert stations and at two of the three cold desert stations. From 1979-2005, strikingly positive temperature trends were seen at all six stations. In seasonal respects, winter (December to February) and summer (June to August) show different temperature trends over the period 1955-2005: the hot desert experienced an increasing temperature trend at a greater extent in summer than in winter; vice-versa, in the cold desert positive trends were computed for winter and negative for summer. It can also be observed that mostly hot desert warming occurred in summer, opposite to cold desert warming in winter. 相似文献
886.
我国土地利用研究的发展态势与重点领域 总被引:19,自引:3,他引:16
进入21世纪以来,土地利用研究在与土地管理实践的密切结合中扩展了学术影响,提高了学科地位.在土地利用的调查与监测、综合属性评价、规划与设计、变化与机制、工程与技术等方面取得长足的进展.基于发展态势的分析,本文提出应加强土地利用的基础理论研究、重视土地利用的方法体系研究、拓展土地利用的研究视角和深化研究内涵、强化土地利用... 相似文献
887.
基于2005—2010年间我国入境旅游客源和旅游外汇收入的月数据,引入处理非平稳时间序列的经验模态分解(EMD)方法,进行两个要素的多尺度分解及对比。研究结果表明:(1)入境旅游客源与旅游外汇收入具有几乎一致的波动周期,分别为3个月、半年、1年及39个月。(2)入境旅游客源并不是旅游外汇收入变化的必要条件。如果外界条件不变,入境旅游客源的变化趋势以3个月周期震荡为主,上升速度极为缓慢;而旅游外汇收入则保持迅速提升,周期性波动并非其主要变化特征。(3)比起盲目吸引入境旅游客源,更应根据区域旅游资源特点与发展基础,寻找旅游业发展中新的增长点,才更具长远意义。 相似文献
888.
近50年山西高温日的时空分布及环流特征 总被引:6,自引:0,他引:6
利用1958-2008 年高低空气象观测资料以及山西省气象信息中心归档的109 站原始气象记录月报表及其信息化产品资料,分别以最高气温≥35℃、≥37℃、≥40℃为指标, 研究山西高温日的时空分布、变化趋势及环流特征,结果表明:①山西高温日最早出现在4 月中旬,最晚出现在9 月中旬,≥35℃、≥37℃和≥40℃的高温日均是6月下旬最多。②高温日数具有随纬度、随海拔的升高而减少,西部多于东部、南部多于北部、盆地多于山区的空间分布特征。≥40℃的高温区域主要集中在运城和临汾地区。③1984-2008 年,35℃以上的高温日数整体呈上升趋势;1979-2008 年,30a 间高温站次以153 站次/10a 的趋势增多;进入90 年代以后,不仅高温日数增多,而且高温持续时间、强度、范围都有增强趋势。④影响山西高温的500 hPa 环流形势主要有:副高纬向性、副高经向型以及大陆高压(脊)控制型3 类。在特定的流型配置下,T850≥25℃、T700≥13℃,T850≥26℃、T700≥14℃,T850≥28℃、T700≥15℃,T850≥32℃、T700≥16℃是山西省不同区域、不同风向影响时,≥35℃、≥37℃、≥40℃高温天气预报的临界值。 相似文献
889.
青藏高原蒸发皿蒸发量时空变化特征及其成因的定量分析(英文) 总被引:10,自引:1,他引:9
Despite the observed increase in global temperature, observed pan evaporation in many regions has been decreasing over the past 50 years, which is known as the "pan evaporation paradox". The "pan evaporation paradox" also exists in the Tibetan Plateau, where pan evaporation has decreased by 3.06 mm a-2 (millimeter per annum). It is necessary to explain the mechanisms behind the observed decline in pan evaporation because the Tibetan Plateau strongly influences climatic and environmental changes in China, Asia and even in the Northern Hemisphere. In this paper, a derivation based approach has been used to quantitatively assess the contribution rate of climate factors to the observed pan evaporation trend across the Tibetan Plateau. The results showed that, provided the other factors remain constant, the increasing temperature should have led to a 2.73 mm a-2 increase in pan evaporation annually, while change in wind speed, vapor pressure and solar radiation should have led to a decrease in pan evaporation by 2.81 mm a-2, 1.96 mm a-2 and 1.11 mm a-2 respectively from 1970 to 2005. The combined effects of the four climate variables have resulted in a 3.15 mm a-2 decrease in pan evaporation, which is close to the observed pan evaporation trend with a relative error of 2.94%. A decrease in wind speed was the dominant factor for the decreasing pan evaporation, followed by an increasing vapor pressure and decreasing solar radiation, all of which offset the effect of increasing temperature across the Tibetan Plateau. 相似文献
890.
贵州贞丰县水银洞金矿是黔西南地区一个重要和典型的微细浸染型(即卡林型)金矿。本文利用数学地质方法对水银洞金矿床的矿体数学特征进行了初步研究。矿石品位的统计分布特征表明,金矿石品位分布为典型的混合分布,说明该矿床为多次成矿作用叠加的产物。通过对混合总体进行筛分获得两个单一总体,它们分别对应两次成矿作用,即成岩期的金预富集和热液期的金叠加成矿,其中后者成矿强度大但不均匀,前者成矿强度小但较均匀。对矿体自相关特征的变异函数模拟结果表明,对该矿床进行勘探时可取沿矿体走向和倾向方向布置的矩形勘探网,提出今后矿山和外围的勘探可以使用比目前网距更宽的网距,即75×190m网距来控制矿体,这将大大降低勘探成本。趋势面分析结果表明,随着标高的降低,即往深部方向矿石品位的平均值和变异系数均呈现明显的下降趋势,说明向深部方向矿化程度减小,而矿化变得较均匀。结合矿区目前的勘探情况和趋势面分析结果,认为灰家堡背斜的北翼是矿区及其外围进一步找矿和勘探的重点区域。 相似文献