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991.
Hydrogeological information for the territories of the Republic of Estonia, Leningrad province, and northern Pskov province of the Russian Federation is generalized. A unified groundwater flow model was developed for the Lomonosov-Voronkovskii aquifer, including its Estonian part is developed. The methodological approaches for solving transboundary problems as applied to groundwater are determined. The results of studying transboundary hydrodynamic interaction in Lomonosov-Voronkovskii aquifer in the Russian-Estonian boundary area are given. The direction of undisturbed groundwater flow is determined, and changes caused by the exploitation of the aquifer are assessed. 相似文献
992.
Steven L. Morey Mark A. Bourassa Dmitry S. Dukhovskoy James J. O’Brien 《Ocean Dynamics》2006,56(5-6):594-606
A coupled ocean and boundary layer flux numerical modeling system is used to study the upper ocean response to surface heat
and momentum fluxes associated with a major hurricane, namely, Hurricane Dennis (July 2005) in the Gulf of Mexico. A suite
of experiments is run using this modeling system, constructed by coupling a Navy Coastal Ocean Model simulation of the Gulf
of Mexico to an atmospheric flux model. The modeling system is forced by wind fields produced from satellite scatterometer
and atmospheric model wind data, and by numerical weather prediction air temperature data. The experiments are initialized
from a data assimilative hindcast model run and then forced by surface fluxes with no assimilation for the time during which
Hurricane Dennis impacted the region. Four experiments are run to aid in the analysis: one is forced by heat and momentum
fluxes, one by only momentum fluxes, one by only heat fluxes, and one with no surface forcing. An equation describing the
change in the upper ocean hurricane heat potential due to the storm is developed. Analysis of the model results show that
surface heat fluxes are primarily responsible for widespread reduction (0.5°–1.5°C) of sea surface temperature over the inner
West Florida Shelf 100–300 km away from the storm center. Momentum fluxes are responsible for stronger surface cooling (2°C)
near the center of the storm. The upper ocean heat loss near the storm center of more than 200 MJ/m2 is primarily due to the vertical flux of thermal energy between the surface layer and deep ocean. Heat loss to the atmosphere
during the storm’s passage is approximately 100–150 MJ/m2. The upper ocean cooling is enhanced where the preexisting mixed layer is shallow, e.g., within a cyclonic circulation feature,
although the heat flux to the atmosphere in these locations is markedly reduced. 相似文献
993.
Geomagnetic factor of Dst variations in the selective generation of ionospheric characteristic waves
HF Waves of rotating polarization have been experimentally studied on the Magadan-Petropavlovsk-Kamchatskii path. It has been obtained that the degree of suppression of one of the characteristic waves during the selective polarization generation depends on the Dst value and sign. It has been established that changes in the amplitude ratio of the signals received from the antennas of clockwise and counterclockwise polarization are maximal at a quiet geomagnetic field when Dst is positive. Under the conditions of medium disturbance of the geomagnetic field and small-scale negative Dst values, it has not been ruled out that the second characteristic wave can be observed at a receiving point in the case when one of the characteristic waves is generated. Selective polarization generation of one of the characteristic waves can be mainly masked by an increase in small-scale irregularities of ionospheric plasma. 相似文献
994.
利用静态箱/气相色谱(GC)法,对华北平原冬小麦拔节-成熟期间麦田土壤CH4气体通量进行了测定,得出华北平原典型冬麦田土壤是大气CH4的弱吸收汇。试验期间土壤CH4通量存在明显的季节变化和日变化,麦田拔节-成熟期间土壤CH4通量日平均值为-18.3μg·m-2·h-1,波动范围为-4.3-24.4μg·m-2·h-1;在土壤CH4通量的日变化中,观测到麦田土壤在午间和夜间都有一个吸收峰,峰值出现的时间因生育期不同而有所不同。试验期间CH4通量日平均值与土壤温度关系不明显,而与土壤水分呈负相关(α=0.01);日变化中土壤CH4通量与地表温度的相关性较差,而与5cm地温相关密切。麦田拔节-成熟期间土壤CH4通量日平均值随NH4+-N施用量的增加呈递减规律,农田秸秆还田后不利于土壤对CH4的吸收。 相似文献
995.
The aim of this paper is to evaluate current knowledge and uncertainties associated with the impact of increasing greenhouse
gas and aerosol concentrations on the West African monsoon. For this purpose, coupled and time-slice simulations are used.
A global measure of the monsoon changes is defined in order to avoid regional biases and to try and obtain significant results.
The position and width of the monsoon in latitude are the main focuses. There is almost no agreement between the Coupled General
Circulation models from the Coupled models Inter-Comparison project—Phase II in regard to the impact of climate change on
the monsoon. Moreover, very simple discriminations between the models seem inappropriate to get a better signal. The role
of the different forcings in time-slice simulations is then investigated. The sea surface temperature (SST) and particularly
the pattern of the SST are shown to be the most important forcing. This accounts for the diversity of the results either from
the coupled or the forced simulations with different SST changes. With a fixed SST, but of a smaller magnitude in AMJ, there
are still uncertainties, coming first from the Atmospheric General Circulation models and the way they balance greenhouse
gas and global SST increase. Finally the uncertainty due to the Land Surface models (LSMs) is not negligible. The greenhouse
gas and the LSMs are shown to have more impact in August, when the monsoon is at its highest latitude on the continent. 相似文献
996.
DVD技术在气象影视素材库建设中的应用 总被引:2,自引:0,他引:2
分析了如何将高品质DVD制作技术应用到省级气象影视素材库建设中的方法,以及充分利用DVD的高画质、多音轨、多字幕等相关制作技术为气象影视工作服务的技巧。 相似文献
997.
WANG Guoan HAN Jiamao ZHOU Liping XIONG Xiaogang TAN Ming WU Zhenhai PENG Jun 《中国科学D辑(英文版)》2006,49(1)
Recent stable carbon isotope studies have shown that the occurrence of C4 plants on the Earth was much later than that of C3 plants and there was a global ex-pansion of C4 biomass around 5―8 million years ago[1]. Although far fewer species use the C4 pat… 相似文献
998.
东天山觉罗塔格地区夹白山一带晚古生代构造格局及演化 总被引:13,自引:0,他引:13
研究区早石炭世经历了中天山古陆北缘被动陆缘向活动陆缘沟弧盆体系演化的全过程.阿齐山-雅满苏岛弧带于维宪期发育在广宽陆棚海之上.岛弧为大型背形结构,雅满苏断裂带为火山喷发的主要通道,弧前盆地生成于弧沟间隙部位.晚石炭世早期,弧后区发生扩张作用而塌陷形成向形的边缘盆地.晚石炭世末,北侧康古尔洋区以弧弧对接方式关闭,弧区伴有深成花岗岩浆侵位.早二叠世早期进入松弛阶段,在弧间及弧后南缘产生上叠断陷盆地.晚二叠世右旋走滑变动席卷全区,最后大型造山带与地块之间发生块体右旋滑移错位,由此奠定了现今的盆山构造格局初貌. 相似文献
999.
西藏日土县松西地区过铝质花岗岩的地球化学特征及构造背景 总被引:1,自引:3,他引:1
西藏羌塘北部松西地区分布有白云母二长花岗岩,岩石以高Al、K和低Fe、Mg组分为特征,ANKC值平均1.16,大于1.1,属典型的过铝质花岗岩类.CaO/Na2O在0.257~0.516之间,平均0386,地球化学特征显示其是泥质岩局部熔融所形成的.40Ar-39Ar年龄为101.42Ma±0.18Ma,形成时代为早白垩世晚期.它的出现标志着班公湖-怒江结合带闭合后继续向北发生陆内俯冲,是后碰撞构造环境形成的花岗岩. 相似文献
1000.