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891.
The sea level derived from TOPEX/Poseidon(T/P) altimetry data shows prominent long term trend and inter-annual variability.The global mean sea level rising rate during 1993-2003 was 2.9 mm a-1.The T/P sea level trend maps the geographical variability.In the Northern Hemisphere(15°-64°N),the sea level rise is very fast at the mid-latitude(20°-40°N) but much slower at the high-latitude,for example,only 0.5 mm a-1 in the latitude band 40°-50°N.In the Southern Hemisphere,the sea level shows high rising rate both in mid-latitude and high-latitude areas,for example,5.1 mm a-1 in the band 40°-50°S.The global thermosteric sea level(TSL) derived from Ishii temperature data was rising during 1993-2003 at a rate of 1.2 mm a-1 and accounted for more than 40% of the global T/P sea level rise.The contributions of the TSL distribution are not spatially uniform;for instance,the percentage is 67% for the Northern Hemisphere and only 29% for the Southern Hemisphere(15°-64°S) and the maximum thermosteric contribution appears in the Pacific Ocean,which contributes more than 60% of the global TSL.The sea level change trend in tropical ocean is mainly caused by the thermosteric effect,which is different from the case of seasonal variability in this area.The TSL variability dominates the T/P sea level rise in the North Atlantic,but it is small in other areas,and shows negative trend at the high-latitude area(40°-60°N,and 50°-60°S).The global TSL during 1945-2003 showed obvious rising trend with the rate of about 0.3 mm a-1 and striking inter-annual and decadal variability with period of 20 years.In the past 60 years,the Atlantic TSL was rising continuously and remarkably,contributing 38% to the global TSL rising.The TSL in the Pacific and Indian Ocean rose with significant inter-annual and decadal variability.The first EOF mode of the global TSL from Ishii temperature data was the ENSO mode in which the time series of the first mode showed steady rising trend.Among the three oceans,the first mode of the Pacific TSL presented the ENSO mode;there was relatively steady rising trend in the Atlantic Ocean,and no dominant mode in the Indian Ocean. 相似文献
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A slowdown of sea surface height(SSH) rise occurred in the Nordic(GIN) seas around 2004.In this study,SSH satellite data and constructed steric height data for the decades before and after 2004(i.e.,May 1994 to April 2014)were used for comparative analysis.The findings indicate that the rate of slowdown of SSH rises in the GIN seas(3.0 mm/a) far exceeded that of the global mean(0.6 mm/a).In particular,the mean steric height of the GIN seas increased at a rate of 4.5 mm/a and then decreased at a slower pace.This was the main factor responsible for the stagnation of the SSH rises,while the mass factor only increased slightly.The Norwegian Sea particularly experienced the most prominent slowdown in SSH rises,mainly due to decreased warming of the 0–600 m layer.The controlling factors of this decreased warming were cessation in the increase of volume of the Atlantic inflow and stagnation of warming of the inflow.However,variations in air-sea thermal flux were not a major factor.In the recent two decades,mean halosteric components of the GIN seas decreased steadily and remained at a rate of 2 mm/a or more because of increased flow and salinity of the Atlantic inflow during the first decade,and reduction in freshwater inputs from the Arctic Ocean in the second decade. 相似文献
895.
长江口海平面上升预测及其对滨海湿地影响 总被引:1,自引:0,他引:1
选择吴淞站和吕四站2个验潮站数据,通过统计学方法进行长江口海平面上升预测,从而构建了一套长江口地区较完备的海平面上升情景库:以2013年为基准年份,其最佳预测值的范围在2030年、2050年、2100年分别为50~217 mm,118~430 mm,256~1215 mm。以此情景库为基础,探究海平面上升变化对长江口滨海湿地的影响,结果表明:随着海平面上升值的增加,长江口滨海湿地的面积不断减少;在基于验潮站数据作趋势外推得到的情景下,湿地面积减少较平缓,而在考虑全球变暖背景的情景下,湿地面积减少迅速;且不论在何种情景下,时间尺度越大,湿地减少的面积越大。 相似文献
896.
随着社会主义市场经济的建立,人才市场的日臻完善,人才的合理流动也日渐加剧,跨行业(地区)甚至跨国的人才流动已司空见惯。流动趋势主要是欠发达地区向发达地区、国有企业向三资企业。值得注意的是,国有企业高层次的专业技术人员、管理人员和掌握一技之长的员工外流现象呈明显上升趋势。邓小平同志早就高瞻远瞩地指出:“未来的竞争关键是人才的竞争。” 相似文献
897.
人教社高中地理教材必修一第二章“地球的大气”,地球外部圈层包括水圈、大气圈、生物圈,其中大气圈是与人类生活关系最为密切的圈层,对人类的生存意义重大。笔者认为这章的地理课程资源应从身边的地理,生活中地理人手,引导学生亲身观察实践、合作探究是最有效的方式更具有现实性。 相似文献
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