近40年西南地区的气候变化事实   总被引：67，自引：11，他引：56  

马振锋  彭骏  高文良  田宏 《高原气象》2006,25(4):633-642

利用西南地区(云南、贵州、重庆、四川、西藏)1961—2000年139个气象观测站常规地面观测资料年平均值,对西南地区近40年来气候的年际和年代际变化特征进行了分析。揭示了青藏高原、川西高原、云贵高原在20世纪后40年气温上升、降水增加、湿度增大趋势显著,而在四川盆地东北部和西南部的气温则存在明显的下降趋势,表明西南地区气候变化与全球变暖存在非同步性。通过对各气候要素年际和年代际变化序列的分离,得出了西南地区不同气候要素基本都存在明显的年际和年代际变化振荡周期,对这些气候要素存在的突变现象进行了检验,发现气温首先在青藏高原地区开始突变,然后是云贵高原区,最后是四川盆地、贵州东部丘陵区。其他气候要素的突变时间多数也是先从青藏高原开始。由此可见,西南地区气候要素在高海拔地区比低海拔地区突变时间为早,全球气温突变要比西南地区的气温突变要早。  相似文献   

琼中35年气候变化分析     

郑锋  王刚 《气象研究与应用》2006,27(4):37-39

利用琼中1971~2005年温度、降水、日照资料进行分析,得出:温度明显上升,日照略有增多,降水则呈下降趋势;不同季节气候变化不同,冬、春季温度回升明显,冬、春、秋季降水偏少;冬、春季气候呈暖干化趋势,对农业生产不利。  相似文献   

The Interface Configuration of the Fresh‐/Dead Sea Water – Theory and Measurements     

E. Salameh  H. E.‐Naser 《洁净——土壤、空气、水》2000,28(6):323-328

The high‐density Dead Sea water (1.235 g/cm³) forms a special interface configuration with the fresh groundwater resources of its surrounding aquifers. The fresh groundwater column beneath its surroundings is around one tenth of its length compared to oceanic water. This fact alone indicates the vulnerability of the fresh groundwater resources to the impacts of changes in the Dead Sea level and to saltwater migration. Ghyben‐Herzberg and Glover equations were used to calculate the volumes of water in coastal aquifers which were replaced by freshwater due to the interface seaward migration as a result of the drop in the level of the Dead Sea. For that purpose, the dynamic equation of Glover approach has been integrated to accommodate that type of interface readjustment. The calculated amounts of freshwater which substituted salt Dead Sea water due to the migration of interface are 3.21 · 10¹¹ m³, from a Dead Sea level of –392 m to τ411 m below sea level. The average porosity of coastal aquifers was calculated to range from 2.8 to 2.94%. Geoelectric sounding measurements showed that areas underlying the coastal aquifers formerly occupied by the Dead Sea water are gradually becoming flushed and occupied by freshwater. The latter is becoming salinized due to the residuals of Dead Sea water in the aquifer matrix, the present salinity of which is lower than that of the Dead Sea water. At the same time salt dissolution from the Lisan Marl formation is causing collapses along the shorelines in the form of sinkholes, tens of meters in diameter and depth.  相似文献   

Morphology and Dynamics of Alluvial Fan and Its Research Prospects     

Dengyun Wu  Zhikun Ren  Lü Honghua  Jinrui Liu  Guanghao Ha  Chi Zhang  Menghao Zhu 《地球科学进展》2020,35(4):389-403

Alluvial fans can preserve historical records of sediment transport to middle and lower river systems or piedmont basins, which are considered to be sensitive recorders of climate change and tectonic activity. In this paper, the morphological characteristics, control factors and future development trend of alluvial fan are summarized and described. The main understanding is as follows: \mathrm{①} According to the gravity flow and traction flow process, fan can be divided into debris flow alluvial fan and fluvial fan. The former is formed under the action of debris gravity flow deposits, which is related to the occasional flood and burst flow in a short time. The latter is braided tributaries depositions which are gradually shallower and spread radially in the direction of fan toe under the traction water transport. \mathrm{②} The erodibility of underlying bedrock can affect the scale of downstream alluvial fan, which depends on the sediment production and store factors in the catchment. The easily eroded bedrock may produce more sediment, making the alluvial fan area larger. In the contrast, the erodibility of rocks in the source area can also affect the slope and hydrological characteristics of the valley so that more sediment is deposited in the upstream basin and the alluvial fan formed in the downstream is smaller. \mathrm{③} Tectonic activity is the pre-condition for the development of alluvial fans, which provides a space for alluvial fans depositions. Faulting in the piedmont can change the position and morphology of the ancient alluvial fan, and also cause deformation or distortion of the thick sedimentary sequence to record the regional tectonic activity. The quaternary alluvial fan sequence corresponds well to the climate change during the glacial-interglacial period. However, the influence of the flood events caused by extreme meteorological events on alluvial fan deposition should be focused on. \mathrm{④} The application of a series of new techniques and methods will help to carry out deep research on alluvial fan in the future, such as high-resolution observation technique, physical simulation experiment, and precise dating.  相似文献   

乌蒙山区毕节市耕地土壤养分丰缺评价及其变化趋势          下载免费PDF全文

骆珊  张德明  彭成龙  安亚运  龚桂源 《贵州地质》2020,37(3):258-258

碱浸脱硅处理高硅铝土矿时,会产生大量的含硅碱液,要实现其循环利用,需对含硅碱液进行脱硅。本文分别以初始硅渣、焙烧硅渣、硅渣与石灰混合为脱硅剂,对比考查含硅碱液的脱硅效果,并分析脱硅机理。结果表明,当添加25g/L的初始硅渣时,脱硅率仅为47.96%;将硅渣在600℃焙烧后,脱硅率提升至66.67%。焙烧后的硅渣明显提升了脱硅活性,当混合添加25g/L焙烧硅渣和钙硅比为1的CaO,脱硅率达到93%,主要是硅渣作为异相成核的晶核 ,在脱硅过程中的晶体生长以及CaO的协同脱硅作用,混合添加焙烧渣和CaO的高脱硅能力为氧化铝工业生产提供了再循环脱硅剂,并为含硅碱液的循环利用提供了可能性。  相似文献   

High-resolution patterns of palaeoenvironmental changes during the Little Ice Age and the Medieval Climate Anomaly in the northwestern Iberian Peninsula     

《地学前缘(英文版)》2020,11(5):1461-1475

A high resolution core(9.7 yr cm~(-1)) from the Chao de Veiga Mol raised bog(NW Iberian Peninsula) was analyzed to identify plant macrofossils,estimate peat humification and calculate hydroclimatic indices based on current bog species,with the overall aim of determining the climate conditions associated with evolution of the bog during the Medieval Climate Anomaly and the Little Ice Age.These proxies,together with historical and climate data,proved to be good indicators of the changes in bog surface wetness.Analysis:of the core led to identification of 9 different periods:two corresponding to the so-called Medieval Climate Anomaly(930 to 1345 AD,1075-665 calibrated years before present [cal.yr BP]);four corresponding to the Little Ice Age(1345 to 1905 AD;665-105 cal yr BP);and three corresponding to the last century(1905 to2000 AD).The findings revealed a generally dry climate that lasted until the 14 th century,followed by a transition to a long period with a more humid,but characteristically very variable climate,which ended at the beginning of the 20 th century and was followed by a rapid transition to more humid conditions and finally,a change to drier conditions.The Medieval Climate Anomaly was indicated by the abundance of dry-adapted mosses(Leucobryum glaucum,Hypnum cupressiforme) and characterized by warm dry conditions and high levels of peat humification,with alternating wet phases.The LIA period was dated by a large abundance of Sphagnum species(an indicator of wetness) and a gradual increase in the humification index.However,four different climate phases were differentiated in this period.High-resolution reconstruction of the evolution of the CVM bog and the multiproxy approach have together enabled a more detailed identification of climatic variations in this area,which are generally consistent with the global models,as well as better definition of the elusive climatic oscillations in the last millennium and confirmation of the importance of local modulation of global models.The study provides new information and a detailed chronology of climatic events that will help to refine local modulation of the climate evolution model in the still quite unexplored region of the NW Iberian Peninsula,a key area for understanding the paleoclimatic dynamics in SW Europe.  相似文献   

Combining multisource satellite data to estimate storage variation of a lake in the Rift Valley Basin,Ethiopia     

《International Journal of Applied Earth Observation and Geoinformation》2020

Integration of remote sensing data sets from multiple satellites is tested to simulate water storage variation of Lake Ziway, Ethiopia for the period 2009-2018. Sixty Landsat ETM+/OLI images served to trace temporal variation of lake surface area using a water extraction index. Time series of lake levels were acquired from two altimetry databases that were validated by in-situ lake level measurements. Coinciding pairs of optical satellite based lake surface area and radar altimetry based lake levels were related through regression and served for simulating lake storage variation. Indices for extracting lake surface area from images showed 91–99 % overall accuracy. Lake water levels from the altimetry products well agreed to in-situ lake level measurements with R² = 0.92 and root mean square error of 11.9 cm. Based on this study we conclude that integrating satellite imagery and radar altimetry is a viable approach for frequent and accurate monitoring of lake water volume variation and for long-term change detection. Findings indicate water level reduction (4 cm/annum), surface area shrinkage (0.08km²/annum) and water storage loss (20.4Mm³/annum) of Lake Ziway (2009–2018).  相似文献   

Recent climate trends on the northern slopes of the Tianshan Mountains, Xinjiang, China     

Hongfeng Zhang  Zhiyun Ouyang  Hua Zheng  Xiaoke Wang 《山地科学学报》2009,6(3):255-265

In arid regions, mountains fulfill important ecological and economic functions for the surrounding lowlands. In the scenario of global warming, mountain ecosystems change rapidly, especially in the arid region of northwestern China. This paper provides an assessment of the changes in temperature and precipitation in the historical records of climate on the northern slopes of the eastern Tianshan Mountains. A Mann-Kendall nonparametric trend and Sen＇s tests are employed to analyze the interannual changes and innerannual variability in temperature and precipitatiofi in the regions of low to high altitude. The present study finds that the largest increases in annual temperature are observed at stations in the low altitude regions. The significant increasing trends in temperature tend to occur mainly in late winter and early spring at stations from middle to high altitude, but in summer and autumn at stations of low altitudes. The increasing trends in annual precipitation are found from the middle to high altitude areas, but decreasing trends are found in the low altitude areas. The significant increasing trends in precipitation occur mostly in winter and earlier spring at stations from the middle to high altitudes, while the increasing and decreasing trend coexists at stations of low altitude with most of the significant trend changes occurring in March, June and August.  相似文献   

A preliminary assessment of threats to arctic marine mammals and their conservation in the coming decades     

Henry P. Huntington 《Marine Policy》2009

Over the next several decades, arctic marine mammals will face threats from six areas of human influence: climate change, environmental contaminants, offshore oil and gas activities, shipping, hunting, and commercial fisheries. This paper reviews these factors, the nature and magnitude of the threats they pose, current scientific understanding and management of those threats, and the potential for effective conservation action. Climate change, offshore oil and gas activities, and commercial fisheries likely pose the greatest threats. Addressing the combined effects of all six factors, however, will be particularly difficult but essential to prevent declines beyond those that have already occurred.  相似文献   

基于CBERS影像的速生林信息提取方法研究     

温庆可  张增祥  刘斌  徐进勇  乔竹萍 《国土资源遥感》2009,(4):68-71,77

提出了一种运用遥感技术提取速生林信息的方法,实现了大区域速生林分布情况的检测。该方法基于CBERS影像多年际时间曲线趋势,根据速生林生长周期中被砍伐并翻地的特殊阶段表现在遥感影像上的不同电磁波谱特征,对其进行检测,从而实现速生林地的提取。在广东省雷州市试验的结果表明,速生林信息提取的总体精度为88%,CBERS CCD图像可以用于大区域的速生林信息提取。  相似文献