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21.
Atmospheric forcing of the eastern tropical Pacific: A review 总被引:1,自引:8,他引:1
Jorge A. Amador Eric J. Alfaro Omar G. Lizano Victor O. Magaa 《Progress in Oceanography》2006,69(2-4):101
The increase in marine, land surface, atmospheric and satellite data during recent decades has led to an improved understanding of the air–sea interaction processes in the eastern tropical Pacific. This is also thanks to extensive diagnoses from conceptual and coupled ocean–atmosphere numerical models. In this paper, mean fields of atmospheric variables, such as incoming solar radiation, sea level pressure, winds, wind stress curl, precipitation, evaporation, and surface energy fluxes, are derived from global atmospheric data sets in order to examine the dominant features of the low level atmospheric circulations of the region. The seasonal march of the atmospheric circulations is presented to depict the role of radiative forcing on atmospheric perturbations, especially those dominating the atmosphere at low levels.In the tropics, the trade winds constitute an important north–south energy and moisture exchange mechanism (as part of the low level branch of the Hadley circulation), that determines to a large extent the precipitation distribution in the region, i.e., that associated with the Inter-Tropical Convergence Zone (ITCZ). Monsoonal circulations also play an important role in determining the warm season precipitation distribution over the eastern tropical Pacific through a large variety of air–sea–land interaction mechanisms. Westward traveling waves, tropical cyclones, low latitude cold air intrusions, and other synoptic and mesoscale perturbations associated with the ITCZ are also important elements that modulate the annual rainfall cycle. The low-level jets of the Gulf of California, the Intra-Americas Sea (Gulf of Mexico and Caribbean Sea) and Chocó, Colombia are prominent features of the eastern tropical Pacific low-level circulations related to sub-regional and regional scale precipitation patterns. Observations show that the Intra-Americas Low-Level Jet intensity varies with El Niño/Southern Oscillation (ENSO) phases, however its origin and role in the westward propagation and development of disturbances that may hit the eastern tropical Pacific, such as easterly waves and tropical cyclones, are still unclear. Changes in the intensity of the trade winds in the Caribbean Sea and the Gulf of Mexico (associated with eastern tropical Pacific wind jets) exert an important control on precipitation by means of wind–topography interactions. Gaps in the mountains of southern Mexico and Central America allow strong wind jets to pass over the continent imprinting a unique signal in sea surface temperatures and ocean dynamics of the eastern tropical Pacific.The warm pools of the Americas constitute an important source of moisture for the North American Monsoon System. The northeastern tropical Pacific is a region of intense cyclogenetic activity, just west of the coast of Mesoamerica. Over the oceanic regions, large-scale properties of key variables such as precipitation, moisture, surface energy fluxes and wind stress curl are still uncertain, which inhibits a more comprehensive view of the region and stresses the importance of regional field experiments. Progress has been substantial in the understanding of the ocean and atmospheric dynamics of the eastern tropical Pacific, however, recent observational evidence such as that of a shallow meridional circulation cell in that region, in contrast to the classic concept of the Hadley-type deep meridional circulation, suggests that more in situ observations to validate theories are still necessary.This paper is part of a comprehensive review of the oceanography of the eastern tropical Pacific Ocean. 相似文献
22.
热带印度洋偶极子发生和演变机制的数值研究 总被引:5,自引:0,他引:5
对中国科学院大气物理研究所(IAP)大气科学和地球流体力学数值模拟国家重点实验室(LASG)发展的第三代海洋模式(L30T63 OGCM)进行了改进。分析了该模式1959年1月—1998年12月的40a积分结果,以此研究热带印度洋偶极子发生、发展和消亡的物理机制。对数值模拟结果的分析表明,赤道印度洋表面异常东风引起的异常环流结构是偶极子发生、发展的主要动力学原因,其表面异常东风转换为异常西风所引起的异常环流结构调整是偶极子消亡的主要动力学原因;海气界面热通量异常的交换对热带印度洋海表温度距平偶极子模态的形成和演变起着重要的作用;垂直输送作用是热带印度洋次表层海温偶极子模态发生和演变的主要物理机制。 相似文献
23.
M.L. Botter-Carvalho P.J.P. Santos P.V.V.C. Carvalho 《Estuarine, Coastal and Shelf Science》2007,71(3-4):508-516
We describe the structure, reproductive cycle, fecundity, growth, and mortality of a harvested population of the ghost shrimp Callichirus major. Samples were collected at monthly intervals from September 1999 to October 2000 on an urban sandy beach (08°11′S 34°55′W) in northeastern Brazil. During this period the sex ratio did not differ significantly from 1:1 (0.98 M: 1 F). Minimum and maximum sizes of the Dorsal Oval were 2.59 and 12.19 mm for males and 4.46 and 12.62 mm for females, respectively. Ovigerous females were found throughout the period, except between August and September 2000. Maximum lifespan was estimated as 3.3 and 3.4 years for females and males, respectively. This northeastern population differed from others previously studied in southern and southeastern Brazil, in regard to sex ratio, maximum attained size, maturation size, period and duration of the reproductive cycle, and fecundity. We interpret these regional differences as evidence for over-fishing at the study site, and suggest that large-scale management plans for callianassid populations should use regional population parameters. 相似文献
24.
热带西太平洋海洋上层热含量的分布特征及其年际变化的分析 总被引:1,自引:0,他引:1
选用海面至20℃等温线所处深度水层的平均温度来表征研究海域海洋上层热含量。利用这一特征值,分析1986—1990年期间热带西太平洋边缘海域海洋上层热含量在秋季的分布特征和年际变化。结果表明:(1)热含量呈南高北低分布,在7.5-22.1°N范围内。以130°E断面为代表,热含量的平均递减率为0.179(℃/纬度);(2)热含量的分布主要取决于环流系统,其等值线因受黑潮和棉兰老海流的影响而由纬向分布转向经向分布。某些区域因受暖涡及冷涡的影响而呈封闭状分布;(3)热含量的年际变化与E1Nino事件存在着很好的相关性,在E1Nino事件发生期间,热含量变得很低,高热含量(大于26.5℃)海区的分布范围明显缩小。 相似文献
25.
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27.
L.A. Cifuentes R.B. Coffin L. Solorzano W. Cardenas J. Espinoza R.R. Twilley 《Estuarine, Coastal and Shelf Science》1996,43(6):781-800
Variations in elemental and isotopic ratios of suspended particulate matter (SPM) were investigated in the Guayas River Estuary Ecosystem (GREE) that empties into the Gulf of Guayaquil, Ecuador. Detritus in the system was identified on the basis of extremely high carbon:chlorophyll aratios (>1000). This material had mean δ13C of −26·4±0·3, δ15N of +4·8±0·2, and (C:N)atomicof 14·1±0·9. The isotopic data were comparable to measurements reported for fresh and degrading mangrove leaves, whereas the elemental ratio was comparatively enriched in nitrogen. Isotope measurements of SPM throughout the GREE were more similar to values for riverine material and detritus compared with that for the coastal end-member. Values indicative ofin situproduced algae, sewage and shrimp pond effluent were only found at selected sites. Bacterial bioassays, which were used to document potential sources of dissolved organic matter in the GREE, were isotopically similar to SPM. This correspondence coupled with the relatively low (C:N)aof SPM could be explained by bacterial immobolization of nitrogen onto detritus. Finally, tidal variations of (C:N)aand δ13C at a brackish mangrove site were similar in magnitude to spatial variations encountered throughout the GREE. Based on these results, the authors caution that care must be taken when samples are taken for food-web studies in these systems. 相似文献
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29.
Spatial and temporal variability of heat content above the thermocline in the tropical Pacific Ocean 总被引:1,自引:0,他引:1
Abstract-Heat content of the upper layer above the 20℃ isotherm in the tropical Pacific Ocean isestimated by using the sea temperature data set with a resolution 2°latitude×5°longitude (1980~1993)for the water depths (every 10 m) from 0 m to 400 m, and its temporal and spatial variabilities are an-alyzed. (1) The temporal variability indicates that the total heat in the upper layer of the equatorial Pa-cific Ocean is charcterized by the interannual variability. The time series of the equatorial heat anomaly5 months lead that of the El Nino index at the best positive lag correlation between the two, and theformer 13 months lag behind the latter at their best negative lag correlation. Therefore the equatorialheat content can be used as a better predictor than the El Nino index for a warm or cold event. In addi-tion, it is also found that less heat anomaly in the equator corresponds to the stronger warm events inthe period (1980~1993) and much more heat was accumulated in the 4 years including 1992/1 相似文献
30.
山东省9216号强热带气旋风暴期间的海岸侵蚀灾害 总被引:14,自引:0,他引:14
本文比较详细地报导了山东省沿岸在9216号强热带气旋风暴潮期间的海岸侵蚀灾害情况,分析了灾害的形成原因、特点。最后讨论了与之有关的问题。 相似文献