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961.
962.
当均匀的纬圈风应力作用于赤道海洋时,在东、西边界附近由于平衡的物理过程不同,其响应特征也不同。当盛吹一个方向的风时,例如东风,东边界的温跃层会变浅(冷水),而西边界的温跃层变深。当东风吹了t0时间而改吹西风时,无论东边界的温跃层还是西边界的温跃层都要持续到2t0时间后,才改变其发展方向。这表明边界上的物理场带有长的“惯性”或长的“记忆”。但西边界信号向东传播的速度比东边界向西传播的速度要快,且振幅也大,从这个意义上讲,ElNino事件先兆从西边界附近出现后,能迅速影响到西、中太平洋,也即西边界附近更易成为ElNino事件的源地,特别是强的ElNino事件。 相似文献
963.
基于GIS的安徽省重大农业气象灾害测评系统 总被引:15,自引:0,他引:15
以安徽省重大农业气象灾害的气候规律分析及遥感监测方法的基础,利用地理信息系统技术,设计并建立了省级农业气象灾害测评系统。该系统运用结构化设计原理,根据用户需求及系统建设的基本目标,确定了系统结构及主要功能,以为主要支撑软件,建立了安徽省干旱,洪涝及低温冷害的基本数据库、灾害监测评估模型和应急反应及决策服务系统。 相似文献
964.
This work concerns an analysis of inter-basin and inter-layer exchanges in the component ocean part of the coupled ECHAM4/OPYC3
general circulation model, aimed at documenting the simulation of North Atlantic Deep Water (NADW) and related thermohaline
circulations in the Indian and Pacific Oceans. The modeled NADW is formed mainly in the Greenland– Iceland–Norwegian Seas
through a composite effect of deep convection and downward cross-isopycnal transport. The modeled deep-layer outflow of NADW
can reach 16 Sv near 30 °S in the South Atlantic, with the corresponding upper-layer return flow mainly coming from the “cold
water path” through Drake Passage. Less than 4 Sv of the Agulhas “leakage” water contributes to the replacement of NADW along
the “warm water path”. In the South Atlantic Ocean, the model shows that some intermediate isopycnal layers with potential
densities ranging between 27.0 and 27.5 are the major water source that compensate the NADW return flow and enhance the Circumpolar
Deep Water (CDW) flowing from the Atlantic into Indian Ocean. The modeled thermohaline circulations in the Indian and Pacific
Oceans indicate that the Indian Ocean may play the major role in converting deep water into intermediate water. About 16 Sv
of the CDW-originating deep water enters the Indian Ocean northward of 31 °S, of which more than 13 Sv “upwell” mainly near
the continental boundaries of Africa, South Asia and Australia through inter-layer exchanges and return to the Antarctic Circumpolar
Current (ACC) as intermediate-layer water. As a contrast, only 4 Sv of Pacific intermediate water is connected to “upwelling”
flow southward across 31 °S while the magnitude of northward deep flow across 31 °S in the Pacific Ocean is significantly
greater than that in the Indian Ocean. The model suggests that a large portion of the deep waters entering the Pacific Ocean
(about 14 Sv) “upwells” continually into some upper layers through the thermocline, and becomes the source of the Indonesian
throughflow. Uncertainties in these results may be related to the incomplete adjustment of the model’s isopycnal layers and
the sensitivity of the Indonesian throughflow to the model’s geography and topography.
Received: 12 August 1997/Accepted: 12 March 1998 相似文献
965.
—Upper ocean thermal data and surface marine observations are used to describe the three-dimensional, basinwide co-evolution
of interannual variability in the tropical Pacific climate system. The phase propagation behavior differs greatly from atmosphere
to ocean, and from equatorial to off-equatorial and from sea surface to subsurface depths in the ocean. Variations in surface
zonal winds and sea surface temperatures (SSTs) exhibit a standing pattern without obvious zonal phase propagation. A nonequilibrium
ocean response at subsurface depths is evident, characterized by coherent zonal and meridional propagating anomalies around
the tropical North Pacific: eastward on the equator but westward off the equator. Depending on geographic location, there
are clear phase relations among various anomaly fields. Surface zonal winds and SSTs in the equatorial region fluctuate approximately
in-phase in time, but have phase differences in space. Along the equator, zonal mean thermocline depth (or heat content) anomalies
are in nonequilibrium with the zonal wind stress forcing. Variations in SSTs are not in equilibrium either with subsurface
thermocline changes in the central and western equatorial Pacific, with the former lagging the latter and displaced to the
east. Due to its phase relations to SST and winds, the basinwide temperature anomaly evolution at thermocline depths on an
interannual time scale may determine the slow physics of ENSO, and play a central role in initiating and terminating coupled
air-sea interaction. This observed basinwide phase propagation of subsurface anomaly patterns can be understood partially
as water discharge processes from the western Pacific to the east and further to high latitudes, and partially by the modified
delayed oscillator physics.
Received: 17 January 1997 / Accepted: 10 March 1998 相似文献
966.
在自然界与人类系统水分平衡概念的基础上,提出了作降水评价的供需平衡模式。该模式对全面发挥由降水所形成的各种主要水资源成分的潜力是有用的。用此模式作了个例试验,并提出在水分不足地区缓解水分欠缺的途径。 相似文献
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