Global sea level change and thermal contribution   总被引：4，自引：0，他引：4  

Juncheng Zuo  Jianli Zhang  Ling Du  Peiliang Li  Lei Li 《中国海洋大学学报(英文版)》2009,8(1):1-8

The global long-term sea level trend is obtained from the analysis of tide gauge data and TOPEX/Poseidon data. The linear trend of global mean sea level is highly non-umiform spatially, with an average rate of 2.2 mm year-1 in T/P sea-level rise from October 1992 to September 2002. Sea level change duc to temperature vanation (the thermosteric sea level) is discussed. The results are compared with TOPEX/Poseidon altimeter data in the same temporal span at different spatial scales. It is indicated that the ther-mal effect accounts for 86% and 73% of the observed seasonal variability in the northern and southern hemispheres, respectively. The TOPEX/Poseidon observed sea level lags behind the TSI, by 2 months in the zonal band of 40°-60° in both the northern and southern hemispheres. Systematic differences of about 1-2cm between TOPEX/Poseidon observations and thermosteric sea level data are obtained. The potential causes for these differences include water exchange among the atmosphere, land, and oceans, and some pos-sible deviations in thermosteric contribution estimates and geophysical corrections to the TOPEX/Poseidon data.  相似文献   

珠穆朗玛峰地区雪冰中重金属浓度与季节变化   总被引：4，自引：0，他引：4  

段建平  任贾文  秦翔  李月芳 《地理学报》2007,62(1):22-29

对2005 年9 月采自珠穆朗玛峰北坡海拔6523 m 的东绒布冰川积累区一批雪坑样品中重金属Ba, Co, Cu, Zn 和Pb 的浓度利用电感耦合等离子体质谱仪进行了测试, 重金属浓度范围分别为(pg/ml); Ba2~227、Co2.8~15.7、Cu 10~120、Zn29~4948、Pb14~142。并利用气体稳 定同位素质谱仪MAT-252 对样品稳定氧同位素比率(δ¹⁸O) 进行了测试, 雪坑样品对应的时间为2004 年夏到2005 年秋, δ¹⁸O和重金属元素的浓度都存在着季节变化特征。在夏季风期间δ¹⁸O 值和重金属元素的浓度都很低,而在非夏季风期间δ¹⁸O值和重金属元素浓度升高,反映了不同的水汽来源对重金属浓度季节变化的影响及其环境意义。Co, Cu, Pb, Zn 的地壳富集系数(EF_c) 分别为: 3.6、27、33、180, 表明该地区Pb, Cu, Zn 已经受到了人类活动的污染, 其中Zn 受到的污染最大。  相似文献   

近61 a黄河流域霜冻日期时空分异特征及影响因素          下载免费PDF全文

张志高  徐晓曼  郭超凡  蔡茂堂  袁征  张明哲 《干旱区地理》2022,45(6):1685-1694

深入研究黄河流域霜冻演变规律,可为科学防范霜冻危害,促进气候资源合理开发利用提供依据。基于1960—2020年黄河流域83个气象站点统计资料,采用Mann-Kendall突变检验、Morlet小波分析和相关分析等方法,对黄河流域霜冻日期时空变化特征及其影响因素进行了分析。结果表明:(1)1960—2020年黄河流域平均初霜日期为10月8日,终霜日期为4月30日,平均无霜期161 d。61 a来初霜日以2.51 d·(10a)^-1的速率推迟、终霜日以-2.07 d·(10a)^-1的速率提前,无霜期以4.48 d·(10a)^-1的速率显著延长。20世纪70年代初霜日最早,终霜日最晚,无霜期最短,21世纪10年代初霜日最晚,终霜日最早,无霜期最长。(2)小波分析表明,黄河流域初、终霜日和无霜期均存在28 a左右的主周期变化。初霜日于2002年发生突变,终霜日于2000年突变,无霜期突变发生于2001年。(3)从空间分布来看,由上游、中游到下游地区初霜日逐渐延迟,终霜日逐渐提前,无霜期日数逐渐延长。初霜日在流域各地均呈推迟趋势,...  相似文献   

Analysis of the Decadal and Interdecadal Variations of the East Asian Winter Monsoon as Simulated by 20 Coupled Models in IPCC AR4     

HE Shengping  WANG Huijun 《Acta Meteorologica Sinica》2012,26(4):476-488

Using the output data of 20 coupled climate models used in IPCC AR4 and observational data from NCEP, the capability of the models to simulate the boreal winter climatology of the East Asian sea level pressure, 850-hPa wind, and surface air temperature; the decadal variations of the East Asian winter mon- soon (EAWM) intensity and EAWM-related circulation, and the interdecadal variations of EAWM-related circulation are systematically evaluated. The results indicate that 16 models can weakly simulate the declin- ing trend of the EAWM in the 1980s. More than half of the models produce relatively reasonable decadal variations of the EAWM-related circulation and the interdecadal di?erences of EAWM-related circulation between the boreal winters of 1960-1985 and 1986-1998, including the weakened Siberian high, Aleutian low, and East Asian trough, the enhanced Arctic oscillation and North Pacific oscillation, and a deepened polar vortex. It is found that the performance of the multi-selected-model ensemble in reproducing the spatial dis- tribution of the variations is encouraging, although the variational amplitudes are generally smaller than the observations. In addition, it is found that BCCR_BCM2.0, CGCM3.1_T63, CNRM_CM3, CSIRO_MK3.0, GISS-ER, INM_CM3.0, and MRI_CGCM2.3.2 perform well in every aspect  相似文献   

Microseismicity in a flooded potash mine,the Hope mine,Federal Republic of Germany     

C. Heick  D. Flach 《Pure and Applied Geophysics》1989,129(3-4):475-496

Measuring of microseismic events has been carried out at the former potash mine of Hope since early 1984.Analysis of the data demonstrates an immediate temporal relationship between brine introduction and onset of microseismic activity. The spatial distribution of the sources indicates a dependence on brine level height. Sources are found preferentially immediately next to roads and workings. Source radii, estimated from the frequency ranges in the seismograms, varied with the cross-section of neighbouring cavities and had a similar, order of size.Events occurred rarely in the previously flooded mine sections Similarly, the zone below a depth of approx. 600 m below sea level was virtually inactive.  相似文献   

Modeling long term lake variations by physically based stochastic dynamic models     

V. E. Privalsky 《Stochastic Environmental Research and Risk Assessment (SERRA)》1988,2(4):303-315

Several physically based stochastic dynamic models (SDM) are described including year-to-year variations of water volume in terminal and non-terminal lakes, streamflow of lake-fed rivers, and salinity of an inland sea (the Sea of Azov). All of these models are based upon the SDM of water volume of terminal lakes developed by Kritzky and Menkel in 1946 in co-operation with Kolomogorov. Explicit formulae are derived for second order statistical moments of the output processes, including variance, correlation function, spectra, etc., under the assumption that the forcing functions from stationary random sequences. The least-squares prediction problem is solved for both stationary and non-stationary cases. Some of the processes are shown to possess high statistical predictability. Actual predictions are compared with independent observations. Problems for further study are stated.  相似文献   

Historical changes in sediments of Pyramid Lake,Nevada, USA: consequences of changes in the water balance of a terminal desert lake   总被引：1，自引：0，他引：1  

Martin E. Lebo  John E. Reuter  Philip A. Meyers 《Journal of Paleolimnology》1994,12(2):87-101

Sediment cores from the shallow and deep basins of Pyramid Lake, Nevada, revealed variations in composition with depth reflecting changes in lake level, river inflow, and lake productivity. Recent sediments from the period of historical record indicate: (1) CaCO₃ and organic content of sediment in the shallow basin decrease at lower lake level, (2) CaCO₃ content of deep basin sediments increases when lake level decreases rapidly, and (3) the inorganic P content of sediments increases with decreasing lake volume. Variations in sediment composition also indicate several periods for which productivity in Pyramid Lake may have been elevated over the past 1000 years. Our data provide strong evidence for increased productivity during the first half of the 20th Century, although the typical pattern for cultural eutrophication was not observed. The organic content of sediments also suggests periods of increased productivity in the lake prior to the discovery and development of the region by white settlers. Indeed, a broad peak in organic fractions during the 1800's originates as an increase starting around 1600. However, periods of changing organic content of sediments also correspond to periods when inflow to the lake was probably at extremes (e.g. drought or flood) indicating that fluctuations in river inflow may be an important factor affecting sediment composition in Pyramid Lake.  相似文献   

On the detectability of a highly conductive layer in the upper mantle beneath the Black Forest crystalline using magnetotelluric methods     

Bülent Tezkan 《Geophysical Journal International》1994,118(1):185-200

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Observations of geomagnetic pulsations and variations with a new borehole magnetometer down to depths of 3000 m   总被引：1，自引：0，他引：1  

K. Spitzer 《Geophysical Journal International》1993,115(3):839-848

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A triaxial magnetometer has been developed for investigating the in situ skin effect of horizontal geomagnetic pulsations and variations in deep boreholes. The observations were carried out in the pilot borehole of the Continental Deep Drilling Program of Germany (KTB) down to depths of 3000 m and up to temperature of 90 C. A weak skin effect, due to the known very low conductivity of the penetrated crystalline rocks, of 90 to 95 per cent in amplitude and -5 to -10 rotation in phase has been observed at periods of 10 s and magnetometer depth of 2400 m.
An essential prerequisite for all calculations is the accurate determination of the orientation of the downhole magnetometer. It is demonstrated how oriented record samples of temporal variations at depth correlate precisely with those from the surface.
Results from surface magnetotelluric (MT) investigations show strong local distortions of the telluric field. The distortion of the MT tensor response has been determined by means of newly introduced skin-effect transfer functions, which are assumed to be undistorted.  相似文献   

The dip equator over Peninsular India and its secular movement     

G. K. Rangarajan  R. C. Deka 《Journal of Earth System Science》1991,100(4):361-368

A ground geomagnetic survey conducted in peninsular India has demarkated the dip equator for the epoch 1991.0. A well-defined southward migration in the last two decades is evident. The secular trend in the vertical component and the direction of the migration in the India zone are shown to be consistent. The migratory movement of the dip equator in different longitude sectors is compared to highlight the complex nature of the secular trends.  相似文献