990 resultados para climate trend
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A key to understanding the causes for climate variability lies in understanding how atmospheric circulation influences regional climate. The goal of this research is to investigate the long-term relationships between atmospheric circulation and winter climate in the southwestern United States. Patterns of atmospheric circulation are described by circulation indices, and winter climate is defined as number of days with precipitation and mean maximum temperature for the winter wet season, November through March. Records of both circulation indices and climate variables were reconstructed with tree-ring chronologies for the period 1702-1983. The years of the highest and lowest values of circulation indices and climate variables were compared in order to investigate possible spatial and temporal relationships between extremes in circulation and climate.
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EXTRACT (SEE PDF FOR FULL ABSTRACT): A varve chronology with annual resolution (AD 1117-1992) has been developed recently for Santa Barbara Basin. Varve thickness and water content show an exponential trend consistent with expected patterns in the presence of sediment compaction over time. Annual varve thickness was decomposed into orthogonal components using singular spectrum analysis (SSA) to identify and retrieve inter-decadal oscillations. ... This suggests a connection with global-scale decadal cycles identified in the subtropical Pacific gyre circulation and, possibly, with solar-driven phenomena. The near-1600 AD event coincides with (a) a similarly sudden change of state in nearby Santa Monica Basin that triggered the onset of anoxic conditions and the preservation of laminated sediments, (b) an extreme drought over the American Southwest, (c) a transformation of the age structure in a number of forest populations throughout Arizona and New Mexico. Total organic carbon burial flux in Santa Barbara Basin varves also shows a marked change after AD 1600. A possible climatic link is proposed that involves pathways for moisture transport in the Southwest at decadal and longer time scales.
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Recent papers provide detailed analyses of more than 40 high-resolution time series culled from the extensive paleoclimate literature that appear to define cyclical elements of the Solar-Insolation/Tidal-Resonance Climate Model. This model was earlier referred to as the Milankovitch/Pettersson Climatic Theory. This paper provides comparable analyses of an additional 20 or so, evidently supportive, climate and volcanic time series. The tree-ring, historical, pollen, cultural, time-frequency, and hydrologic records range in length from 400 to 90,000 years and spatially from Alaska to Tierra del Fuego.
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Abstracts of 24 oral presentations and 25 poster presentations.
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The appendices include the workshop agenda, a list of poster presentations, and a list of attendees.
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Mafia waters in the western Indian Ocean on the east coast of Africa is a natural attractive area for fishing. It has extensive coral beds which harbour good fish life and attracts sport fishery in the area. About 12 commercially important fishes listed are caught by sports fishermen. The data indicates that this area can become an attractive centre for sports fishery almost throughout the year with peak season from November to February. Long-term planning of the fishery is necessary. The conservation measures should be evolved and gan fishing, dynamiting or any other kind of distructive fishing should be prohibited. This area has natural potential to become a sports fishing centre in the future and a great attraction for tourists and anglers.
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Common carps are known for prolific breeding habits but they generally do not breed in water with temperature value less than 20 degree C. During winter months of 1985 when the temperature ranged from 15.5-20.5 degree C, the common carps were successfully bred by using ground water having temperature of 25-26 degree C and the results are discussed.
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城市增温的原因包括全球变暖和城市热岛效应两个方面,二者对城市环境、社会经济和市民健康均有相当程度的影响。本文的研究目的是:(1)通过比较处于不同气候带上同样规模城市的气温变化趋势和速率差异,探讨地理位置对城市增温现象的影响;(2)通过分析近期人类活动和城市发展规模与城市增温现象的相关性,搞清楚城市化发展过程中显著影响热岛效应的因素。了解城市增温的地理分异规律及其受城市化发展的影响,对全面认识城市增温现象、积极寻求应对城市增温所造成的环境危害的策略具有重要的科学和实践意义。 本文按照经纬度在全国范围内选取6个特大城市:济南、西安、兰州、广州、上海和北京为研究对象,按城市所处地理位置分为代表水分梯度的同纬度经向分布城市,近海到内陆依次为济南、西安和兰州,以及代表温度梯度的纬向分布城市,低纬度到高纬度依次为广州、上海和北京,借助统计学方法,对各城市分别进行了年均气温比较分析,并对近期人类活动对不同城市增温效应的影响进行了分析。结果表明: 1.各城市气温均呈上升趋势,其中年均最低气温上升幅度最大,年均气温上升幅度次之,年均最高温度上升幅度最小;温度普遍升高的前提下高纬度地区温度升幅较大,内陆地区增温比近海地区大,即城市增温幅度与水分梯度和温度梯度呈负相关关系;不同城市在不同年代冷暖变化的强度和峰谷相位不尽一致,北京、西安和广州从上世纪50年代到70年代气温整体趋势变冷,其他城市缓慢升温,进入80年代后6个城市均进入加速增温阶段。 2.城市热岛效应对最低气温影响最明显,即城市最低气温与参照站差值增长趋势最为显著,其次为年均温,市区最高气温与参照站差值增长趋势最缓慢;自1978年改革开放以来,6个城市年均最低气温和年均温城乡差值均达到极显著水平,兰州最高,达0.69℃/lOa和0.49℃/lOa;从近海到内陆随着年降水量减少,3个城市(依次为济南、西安和兰州)热岛效应依次增加,从高纬度到底纬度随着温度升高(北京、上海和广州),城市热岛效应有减小趋势。 3.不同城市增温均表现出与人口(包括市辖区年末总人口、市辖区人口密度)、市辖区地区生产总值、年末实有道路面积、建成区面积和第二产业占GDP比重等代表城市发展因素的指标呈显著正相关,与绿地有关的因素,包括园林绿地面积和年末耕地面积呈显著负相关,而同样的因素对同一个城市不同气候参数的影响也不相同,最低气温对增温因子的敏感度高于其他气温参数,而对降低增温效应因子的敏感度小于其他气候参数,同样的因素对不同城市气候参数也有不同效应。 本项研究的结果证实了城市增温是一个比较复杂的过程,其中即反映了全球气候变化的大背景,也受到了影响水热环境的地理因素的制约,同时又与城市化发展的进程密切相关。
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The paper reviews the production statistics of marine shrimps in the different maritime states of India from 1950 to 1962. It is pointed out that for a correct appraisal of the status of any fishery, it is necessary to have data on effort E and catch per unit effort in addition to the conventional data on catch C. A relationship between U and E has been developed and the status of the fishery of Metapenaeus dobsoni has been discussed in this connection with reference to the data on catch and effort obtained from trawler operations off Cochin.
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From the results of fishing operations during 3 years (from August 1963 to July 1966) attempts were made to study the extent of availability of prawns for bottom trawls. It was found that prawns formed 22.5% of the total catch on an average of the catch rate of 12.3 kg per trawling hour. The prawns were found to be abundant during two periods from November to February and again from April to July. The depth range of 11-15 m yielded better catch rate with best frequency of the optimum catch per hour.
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The countries and territories of the Pacific Islands face many challenges in building the three main pillars of food security: availability, access and appropriate use of nutritious food. These challenges arise from factors including rapid population growth and urbanization, shortages of arable land for farming and the availability of cheap, low-quality foods. As a result, many are now highly dependent on imported food, and the incidence of non-communicable diseases in the region is among the highest in the world. This report summarizes: 1) the projected effects of climate change on agriculture, fisheries and aquaculture in the Pacific region; 2) adaptations and supporting policies needed to reduce risks to food production; 3) gaps in knowledge that must be filled in order to implement the adaptations effectively; 4) recommendations to fill these knowledge gaps.
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CpG islands (CGIs) are often considered as gene markers, but the number of CGIs varies among mammalian genomes that have similar numbers of genes. In this study, we investigated the distribution of CGIs in the promoter regions of 3,197 human-mouse ortholo
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The distribution and landings of important varieties of prawns off Paradeep coast, Orissa, in relation to the climatic and hydrographic conditions from 1970-1976 are presented. The prawn fishery as a whole, showed a quadrennial cycle along the coast. The post-monsoon migration of all varieties of prawns along the coast directly depends on the annual precipitation. Temperature gradient, fluctuations in salinity and southerly wind in the Bay of Bengal influence the migration of the different species of prawns.