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1.
Glacier changes since the early 1960s,eastern Pamir,China   总被引：2，自引：0，他引：2  
Glaciers in the eastern Pamir are important for water resources and the social and economic development of the region.In the last 50 years,these glaciers have shrunk and lost ice mass due to climate change.In order to understand recent glacier dynamics in the region,a new inventory was compiled from Landsat TM/ETM+ images acquired in2009,free of clouds and with minimal snow cover on the glacierized mountains.The first glacier inventory of the area was also updated by digitizing glacier outlines from topographical maps that had been modified and verified using aerial photographs.Total glacier area decreased by 10.8%±1.1%,mainly attributed to an increase in air temperature,although precipitation,glacier size and topographic features also combined to affect the general shrinkage of the glaciers.The 19.3–21.4 km~3 estimated glacier mass loss has contributed to an increase in river runoff and water resources.  相似文献   

2.
Variation in intermediate water salinity in the South China Sea (SCS) between the 1960s and 1980s was studied using historical hydrographic data. The results demonstrate that the water was significantly fresher in the 1980s than in the 1960s, indicating that vertical mixing at intermediate water depth was reduced in the 1980s. This was partially because of the change of the SCS meridional overturning circulation (MOC) connecting local intermediate water with deep water. Data assimilation showed a 0.5Sv (1 Sv=10 6m 3/s) reduction in the strength of the MOC, which is about one third of the mean SCS MOC. Because the SCS MOC is linked to the Pacific Ocean, such an interdecadal variation in the intermediate water SCS may reflect anthropogenic climate change in the world ocean.  相似文献   

3.
Stream temperatures are sensitive to climate change and runoff regime variations. A comprehensive understanding on the effects of glacial melting on the stream temperatures are important in the Tibetan Plateau, of which contains the largest ice volume outside Polar Regions. This study documented the high-resolution stream temperature thermal regimes from glacier-fed and non-glacial rivers at four sites, versus a high-resolution glacier mass balance monitoring at Zhadang glacier, during summer melt seasons from 2007-2009 in the Nam Co basin of southern Tibetan Plateau. The results showed mean summer stream temperature and magnitude of daily thermal variation were lower at all sites when compared with alpine glacierized environments at lower latitudes. Mean stream temperatures for glacier-fed rivers(4.0℃ to 6.5℃)were minimum and least variable near the glacier terminus with increasing toward downstream(+0.13℃ km~(–1) to +0.28℃ km~(–1)). Meanwhile, stream temperature in 2008 was similar to that in 2007 and2009. For the non-glacial rivers, mean stream temperatures was about 9.0℃ with significantly warmer in summer months in 2009 and 2007 than that in 2008. These differences indicated that stream temperature was strongly influenced by discharge and precipitation. Particularly, the glacier mass balance played a large role on the stream temperature directly when the glacier melt contributed more than 50% of the glacial river runoff. Our results demonstrated the stream thermal variability from southern Tibetan rivers and provided new insight into the influence of glacier mass balance on stream thermal variability in high-altitude river system.  相似文献   

4.
Glaciers in the Tomor region of Tianshan Mountains preserve vital water resources.However,these glaciers suffer from strong mass losses in the recent years because of global warming.From 2008 to 2009,a large-scale scientific expedition has been carried out in this region.As an individual reference glacier,the tongue area of Qingbingtan glacier No.72 was measured by the high precise Real Time Kinematic-Global Position System (RTK-GPS).In this paper,changes of the tongue area of Qingbingtan glacier No.72 has been studied based on topographic map,remote sensing image and the survey during 2008-2009 field campaign.Results indicated that the ice surface-elevation of the tongue area changed-0.22±0.14 m a-1 from 1964 to 2008.The estimated loss in ice volume was 0.014±0.009 km3,which represented a ～20 % decrease from the 1964 volume and was equivalent to average annual mass balance of-0.20±0.12 m water equivalent for the tongue area during 1964-2008.Terminus retreated by 1852 m,approximately 41 m a-1,with the area reduction of 1.533 km2 (0.034 km2 a-1) from 1964 to 2009.Furthermore,the annual velocity reached to ～70 m a-1.Comparing with the other monitored glaciers in the eastern Tianshan Mountains,Qingbingtan glacier No.72 experienced more intensive in shrinkage,which resulted from the combined effects of climate change and glacier dynamic,providing evidence of the response to climatic warming.  相似文献   

5.
Lake monitoring by remote sensing is of significant importance to understanding the lake and ambient ecological and environmental processes. In particular, whether lake water storage variation could predict lake surfacial temperature or vice versa has long fascinated the research community, in that it would greatly benefit the monitoring missions and scientific interpretation of the lake change processes. This study attempted to remotely detect the dynamics of the Aral Sea and pursue the relationships between varying lake water storage attributes and surface water temperature by using MODIS LST(Moderate-resolution Imaging Spectroradiometer Land Surface Temperature) 8-day composite products, satellite altimeter data, and actual meteorological measurements. Their associations with lake Surface Water Temperatures(SWT) were then analyzed. Results showed the lake water surface areas and elevations of the North Aral Sea tended to increasing trend from 2001(2793.0 km~2, 13.6 m) to 2015(6997.8 km~2, 15.9 m), while those of the South Aral Sea showed a decreasing trend during 2001(20 434.6 km~2, 3.9 m) and 2015(3256.1 km~2, 0.9 m). In addition, the annual daytime and nighttime lake SWT both decreased in the North Aral Sea, while only the daytime SWT in the South Aral Sea exhibited an increase, indicating a rising deviation of diurnal temperatures in the South Aral Sea during the past 15 yr. Moreover, a lower correlation was found between variations in the daytime SWT and storage capacity in the South Aral Sea(R~2 = 0.33; P 0.05), no fair correlations were tested between lake water storage and daytime SWT in the North Aral Sea nor between lake water storage and nighttime SWT in either part of the sea. These results implied that climate change, if any at least during the research period, has no significant effects on lake dynamics over the two sectors of the Aral Sea with anthropogenic disturbances. However, climate change and human activities may overlap to explain complex consequences in the lake storage variations. Our results may provide a reference for monitoring the spatiotemporal variations of lakes, increasing understanding of the lake water storage changes in relation to the lake SWT, which may benefit the ecological management of the Aral Sea region, in the effort to face the likely threats from climate change and human activities to the region.  相似文献   

6.
This paper investigates the size distribution of submarine landslides on the middle continental slope of the East China Sea (ECS) using the size of the landslide source regions. Geomorphometric mapping is used to identify 102 mass movements from multibeam bathymetric data and to extract morphological information about the head scarps and side walls. These mass movements have areas ranging between 0.06 km2 and 15.51 km2 and volumes between 0.002 km3 and 2 km3. The area vs volume relationship of these failure scarps is approximately linear, suggesting a fairly uniform failure thickness in each event with scarce deep excavating landslides. The cumulative area distribution of the slope failures can be described by an inverse power law. The submarine landslides on the mid-ECS continental slope could be considered as a large-scale self-organizing system because they have the characteristics of a dissipative system in a critical state.  相似文献   

7.
本文选择黄河三角洲大汶流自然保护区为研究对象,以多时相遥感影像,对土地利用类型进行解译分析。同时,以平均低潮线作为分析基线,提取海岸线变化信息。结果表明:1996-2009年研究区面积净增13.35km2。各种土地利用类型中滩涂所占面积最大,养殖池所占比例最小,但增幅明显。芦苇地面积后期增长迅速,指示研究区生态环境趋向转好。自然因素(黄河来水来沙量)和人类活动(黄河调水调沙工程,湿地恢复工程,滩涂规模开发以及人类开垦造田)是研究区土地利用类型变化的直接驱动力。1976-2009年研究区海岸净造陆面积217.14km2,沙嘴变幅为29.2km。黄河入海水沙量和滨海区的海洋潮流条件共同影响着海岸线的变迁。  相似文献   

8.
Reclamation is one of the fastest-growing land use type developed in coastal areas and has caused degradation and loss of coastal wetlands as well as serious environmental problems. This paper was aimed at monitoring the spatiotemporal patterns of coastal wetlands and reclamation in the Yangtze Estuary during the 1960s and 2015. Satellite images obtained from 1980 to 2015 and topography maps of the 1960 s were employed to extract changes of reclamation and coastal wetlands. Area-weight centroids were calculated to identify the movement trend of reclamation and coastal wetlands. The results show that from the 1960 s to 2015, the net area of natural wetlands declined by 574.3 km~2, while man-made wetlands and reclamation increased by 553.6 and 543.9 km~2, respectively. During the five study phases, the fastest areal change rate natural wetlands was –13.3 km~2/yr in the period of 1990–2000, and that of man-made areas was 24.7 km~2/yr in the same period, and the areal change rate of reclamation was 27.6 km~2/yr in the period of 2000–2010. Conversion of coastal wetlands mainly occurred in the Chongming Island, Changshu City and the east coast of Shanghai Municipality. Reclamation was common across coastal areas, and was mainly attributed to settlement and man-made wetlands in the Chongming Island, Lianyungang City and the east coast of Shanghai Municipality. Natural wetlands turned into farmlands and settlement, and man-made wetlands gained from reclamation of farmlands. The centroid of natural wetlands generally moved towards the sea, man-made wetlands expanded equally in all directions and inland, and the centroid of reclamation migrated toward Shanghai Municipality. Sea level rise, erosion-deposition changes, and reclamation activities together determine the dynamics of the Yangtze Estuary wetlands. However, reclamation activities for construction of ports, industries and aquaculture are the key causes for the dynamics. The results from this study on the dynamics of coastal wetlands and reclamation are valuable for local government to put forward sustainable land use and land development plans.  相似文献   

9.
Asatypicalmarshriver,theBielahongRiverliesinthehinterlandofthehoiangPlain.ItrisesinandgoeSthroughl~areasofplainma-rsh.Themarshrateinthebasinis45Percent.ThehydrologicalcharacteristicsoftheBielahongRiverbasincanreflectthehydrologicalcharacteristicsofthewholernaxshplain.Thereare1.119x106hamarshintheSanjiangPlain.AlterlOng-timedevelopment,marshisstillthemainnaturallandscapeandsoiltypeintheplain.Waterisoneofthemostactiveelementsinmarshecosystem.Itaffectsplantsgrowth,speciesdistribution,soilfo…  相似文献   

10.
A severe Cochlodinium geminatum red tide (>300 km2) was observed in the Zhujiang (Pearl) River estuary, South China Sea in autumn 2009. We evaluated the environmental conditions and phytoplankton community structure during the outbreak. The red tide water mass had significantly higher dissolved inorganic phosphate (DIP), ammonia, and temperature, but significantly lower nitrite, nitrate, dissolved inorganic nitrogen (DIN), and DIN/DIP relative to the non-red-tide zones. The phytoplankton assemblage was dominated by dinoflagellates and diatoms during the red tide. C. geminatum was the most abundant species, with a peak density of 4.13×107 cell/L, accounting for >65% of the total phytoplankton density. The DIN/DIP ratio was the most important predictor of species, accounting for 12.45% of the total variation in the phytoplankton community. Heavy phosphorus loading, low precipitation, and severe saline intrusion were likely responsible for the bloom of C. geminatum.  相似文献   

11.
After the winter and summer current structures on two or three latitudinal sections in Taiwan Strait were obtained from the measured current data, the seawater fluxs through the sections were calculated. In summer, the currents in the central and northern part of Taiwan Strait normally flow northward at a net flux of 3.32×106m3/s. In winter, the high temperature and salinity Kuroshio and South China Sea water enter Taiwan Strait from the southem section at 1.69×106m3/s and 0.59×106 m3/s respectively, while the East China Sea water enters Taiwan Strait from the northern section at 1.02×106m3/s. About 0.40×106 m3/s of the seawater enters the South China Sea along the coast of Fujian and Guangdong; the other 0.62×106 m3/s of the seawater is mixed with the Kuroshio water and the South China Sea water in the northern sea areas. The net northward flux is 1.74×106m3/s in winter.  相似文献   

12.
The rate of evaporation of seawater droplets in the air-sea boundary layer can be estimated by its salinity change compared to the sea surface salinity. A micro-chemical method based on Farlow (1954) is developed for quantitative determination of the salinity of an individual droplet without the error due to further evaporation after sampling. A halide ion-sensitive sampling surface is prepared by colloidally dispersing brown silver dichromate into the gelatin layer of a commercially available film. The reaction of soluble chlorides with the silver salt leaves a clear white halo with diametera on the brown film to reveal the volume of the droplet. After the film is developed in a water vapor saturated atmosphere, the halo grows to diameterd with the original as the embryo to indicate the quantity of chloride ion involved in the action. The ratio ofd/(a1.5) is a function of the salinity of the droplet. The method can be used to determine the salinity of seawater droplet of 10−6 to 10−10 gram. Details of the principle and preparation, and calibration of the reagent film, are presented. Contribution No. 1708 from the Institute of Oceanology, Academia Sinica. The research was supported by the Chinese National Natural Science Foundation. The paper was prepared while the author was a visiting scholar at the Department of Atmospheric Sciences, AK-40, University of Washington, Seattle, Washington 98195, USA (from May to July, 1989), and Scripps Institution of Oceanography, A-030, University of California, La Jolla, California 92093, USA (from September, 1989 to February, 1990).  相似文献   

13.
Temperature and salinity profile data, collected by southern elephant seals equipped with autonomous CTD-Satellite Relay Data Loggers(CTD-SRDLs) during the Antarctic wintertime in 2011 and 2012, were used to study the evolution of water property and the resultant formation of the high density water in the Mackenzie Bay polynya(MBP) in front of the Amery Ice Shelf(AIS). In late March the upper 100–200 m layer is characterized by strong halocline and inversion thermocline. The mixed layer keeps deepening up to 250 m by mid-April with potential temperature remaining nearly the surface freezing point and sea surface salinity increasing from 34.00 to 34.21. From then on until mid-May, the whole water column stays isothermally at about~(-1).90℃while the surface salinity increases by a further 0.23. Hereafter the temperature increases while salinity decreases along with the increasing depth both by 0.1 order of magnitude vertically. The upper ocean heat content ranging from 120.5 to 2.9 MJ m~(-2), heat flux with the values of 9.8–287.0 W m~(-2) loss and the sea ice growth rates of 4.3–11.7 cm d~(-1) were estimated by using simple 1-D heat and salt budget methods. The MBP exists throughout the whole Antarctic winter(March to October) due to the air-sea-ice interaction, with an average size of about 5.0×10~3 km~2. It can be speculated that the decrease of the salinity of the upper ocean may occur after October each year. The recurring sea-ice production and the associated brine rejection process increase the salinity of the water column in the MBP progressively, resulting in, eventually, the formation of a large body of high density water.  相似文献   

14.
Stormwater runoff in rural townships has a high potential for water quality impairment but little information is available on strormwater runoff pollution from rural townships.To investigate the characteristics of runoff pollution in a rural township,a catchment(2.32 ha) in Linshan Township,Sichuan,China was selected to examine runoff and quality parameters including precipitation,flow rate,and total nitrogen(TN),dissolved nitrogen(DN),total phosphorus(TP),dissolved phosphorus(DP),particulate phosphorus(PP),chemical oxygen demand(COD) and suspended solid(SS) in 12 rainfall events occurring between June 2006 and July 2007.Results show that the annual pollutant loads were 47.17 kg ha-1 for TN,6.64 kg ha-1 for TP,1186 kg ha-1 for COD,and 4297 kg ha-1 for SS.DN and PP were the main forms of nitrogen and phosphorus in stormwater runoff.TP,COD and SS showed medium mass first flushes,in which nearly 40% of the total pollutant masses were transported by the first 30% of total flow volume.The peak of pollutant concentration appeared before the peak of runoff due to the first flush of accumulative pollutants in impervious areas and drainage ditches.The EMC values of TN,TP,DN and PP were negatively correlated to the maximum rainfall intensity,precipitation,total flow volume,and runoff duration(P<0.05,n=12),while EMC of COD and SS were not related to any rainfall characteristics.The FF30(FF,First Flush) for TN,TP,COD and SS were positively correlated to the maximum rainfall intensity(P<0.05,n=12),and TP was also positively correlated to the average rainfall intensity(P<0.05,n=12),indicating that the magnitude of first flush increased with the rainfall intensity in the Linshan Township.  相似文献   

15.
Based on a ship survey during January 1998, the characteristics of the flow, the thermohaline properties and the volume transport of the Arabian Sea are discussed. A strong westward flow exists between 10.5?N and 11?N, part of which turns to the south as the Somali current near the coast at about 10?N and the rest turns north. At the passage between the African continent and the So- cotra Island, the northern branch separates into two flows: the left one enters the passage and the right one flows eastward along the southern slope of the island. Off the island the flow separates once more, most of it meandering northeast and a small fraction flow- ing southeast. Volume transport calculation suggests that the tidal transport is one or two orders of magnitude smaller than the total transport in this region and it becomes more important near the coast. The average velocity of the flow in the upper layer (0-150 m) is about 20 cm s-1, with a maximum of 53 cm s-1 appearing east of the Socotra Island, and the subsurface layer (200-800 m) has an aver- age velocity of 8.6 cm s-1; the velocity becomes smaller at greater depths. The depth of the seasonal thermocline is about 100 m, above which there is a layer with well mixed temperature and dissolved oxygen. High-salinity and oxygen-rich water appears near the surface of the northern Arabian Sea; a salinity maximum and oxygen minimum at 100 m depth along 8?N testifies the subduction of surface water from the northern Arabian Sea. Waters from the Red Sea and the Persian Gulf also influence the salinity of the area.  相似文献   

16.
The general trend of three elements (precipitation, runoff and evaporation) of the water balance of the Changjiang River Basin is discussed from the regional distribution of the mean annual values of view, i.e. isogram. The distribution of precipitation is non-uniform. The distribution of runoff mainly supplied from precipitation is more uniform than that of precipitation. The distribution of the evaporation from land is much more uniform than that of precipitation and runoff. Time distribution of these three elements shows the characteristics of comparatively distinct yearly variation and few variation between years. The relationship between precipitation and runoff, and between precipitation and evaporation in the humid region in the Changjiang River is analyzed. The slopes of their straight line correlation are nearly equal. The internal relationship between variables should be paid attention to, otherwise, a pseudo correlation may be resulted in. The paper provides the method of quantitative computa  相似文献   

17.
ＡＮＡＮＡＬＹＳＩＳＯＦＷＡＴＥＲＲＥＳＯＵＲＣＥＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＴＨＥＲＩＶＥＲＳＩＮＴＨＥＮＯＲＴＨＥＲＮＳＬＯＰＥＯＦＴＨＥＫＵＮＬＵＮＭＯＵＮＴＡＩＮＳＸｕＹｏｕｐｅｎｇ（许有鹏）；ＧａｏＹｕｎｊｕｅ（高蕴珏）（Ｄｅｐａｒｔ...  相似文献   

18.
The variation in Arctic sea ice has significant implications for climate change due to its huge influence on the global heat balance. In this study, we quantified the spatio-temporal variation of Arctic sea ice distribution using Advanced Microwave Scanning Radiometer(AMSR-E) sea-ice concentration data from 2003 to 2013. The results found that, over this period, the extent of sea ice reached a maximum in 2004, whereas in 2007 and 2012, the extent of summer sea ice was at a minimum. It declined continuously from 2010 to 2012, falling to its lowest level since 2003. Sea-ice extent fell continuously each summer between July and mid-September before increasing again. It decreased most rapidly in September, and the summer reduction rate was 1.35 × 10~5 km~2/yr, twice as fast as the rate between 1979 and 2006, and slightly slower than from 2002 to 2011. Area with 90% sea-ice concentration decreased by 1.32 × 10~7 km~2/yr, while locations with 50% sea-ice concentration, which were mainly covered by perennial ice, were near the North Pole, the Beaufort Sea, and the Queen Elizabeth Islands. Perennial Arctic ice decreased at a rate of 1.54 × 10~5 km~2 annually over the past 11 years.  相似文献   

19.
Landsat images, real-time kinematic GPS measurements, and topographic maps were used to determine changes in ice elevation, volume, and areal extent of the Laohugou No. 12 glacier (Qilian Mountains, China) between 1957 and 2007. The glacier experienced significant thinning and areal shrinkage in the ablation zone, but slight thickening in part of the accumulation zone. Elevation decreased by 18.6±5.4 m between 1957 and 2007 in the regions covered by the GPS measurements. The total volume loss for the entire glacier was estimated to be 0.218 km3 using a third-order polynomial fit method. The area diminished by 0.28 km2 between 1957 and 1994, 0.26 km2 between 1994 and 2000, and 0.28 km2 between 2000 and 2007, suggesting that the rate of loss in glacial coverage has increased since the mid-1990s. Significant increases in annual mean air temperature may have contributed to shrinkage and thinning of the glacier.  相似文献   

20.
I Introduction Phytoplankton play an important role in the primary production of ocean (Ning et al., 1995). They are impor-tant biological mediators of carbon turnover in seawater ecosystems (Zhu et al., 1993). Phytoplankton in Jiaozhou Bay have been preliminarily studied on the subjects of community structure, primary productivity and carbon budget (Qian et al., 1983; Guo et al., 1992; Jiao et al., 1994). It has been found that seasonal variation of phytoplankton cell abundance presents w…  相似文献   

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