摘要:

AbstractIt is generally believed that the increasing CO2content of the atmosphere will lead to a substantial climatic warming in the polar regions. In this study the effect of consequent changes in the ice accumulation rate over the Antarctic Ice Sheet is investigated by means of a numerical ice flow model. In the model runs, temperature increases linearly with time during 100 years, and is kept constant afterwards.The results indicate that a climatic warming will probably lead to a sea‐level lowering of some tens of centimetres in the next centuries. This is because for Antarctic conditions the increase in snow accumulation exceeds the increase in melting. This estimate does not take into account the effects of possible surging of parts of the Antarctic Ice Sheet and the response of the Greenland Ice Sheet (which may be quite different

ISSN:0196-1748    

DOI:10.1002/joc.3370020102

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractStatistics of tropical cyclone origin in the Australian region are presented for the period July 1959‐June 1979. Cyclone genesis is found to occur in preferred areas and to have a high incidence of coastline developments, often with the precursor system forming over land. There is an average of 1.3 occurrences per year of ‘regeneration’ whereby a cyclone develops from a pre‐existing cyclone which has lost intensity after crossing on to the continent.A synoptic analysis of individual developments over five years reveals that 84 per cent of the pre‐cyclone cloud clusters first appear on the gradient level monsoon shear line, whereas 97 per cent are on the shearline at the point of development. Statistical evidence is given for the enhancement of lower and upper level vorticity fields by mid‐latitude systems prior to cyclone genesis, but on a case by case basis the role of these systems is highly variable.The structure of the pre‐cyclone systems for individual cases and composites shows the upper level warm core and large scale cyclonic surrounding circulation in the middle and lower troposphere, known to exist for similar systems in other parts of the world. At upper levels the systems are surrounded by tangential winds in the anticyclonic sense beyond 6 degrees la

ISSN:0196-1748    

DOI:10.1002/joc.3370020103

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractSurface wind and sea surface temperature data for the tropical Atlantic Ocean for the period 1911‐1972 are analysed in relation to the precipitation at Quixeramobim, Ceará in northeastern (NE) Brazil. Stratified correlations between the March‐April‐May Quixeramobim rainfall and the December, January, February, and March values of SST, andu‐ andv‐components of surface wind are presented for the tropical Atlantic. The implications of the correlations are that the months preceding an abnormally dry rainy season in NE Brazil are characterized by a strengthened South Atlantic trade flow and a North Atlantic circulation slightly weaker than normal. Cold SST anomalies are found in the South Atlantic and warm anomalies in the North Atlantic, suggesting a wind‐induced change in surface mixing or in evaporation from the surface. The divergence over the South Atlantic is seen to be stronger and more extensive preceding a dry season, and the equatorial convergence appears to be compressed northward and also strengthened. This northward compression is concluded to be responsible for the lack of rainf

ISSN:0196-1748    

DOI:10.1002/joc.3370020104

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe variation in intra‐annual variance in rainfall over Southern Africa is examined for evidence to support the contention that it has undergone a systematic upward change over the period 1921‐1974. A principal components analysis on the data shows that the time series of intra‐annual variances may be represented by four components. Although each of the four principal component time series possesses an oscillation in the region of the biennial wave, there is little evidence to suggest that the within‐year variation in rainfall is undergoing any type of upwar

ISSN:0196-1748    

DOI:10.1002/joc.3370020105

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractEnergy balance measurement on the arctic tundra on the midwest coast of Axel Heiberg Island, N.W.T., Canada, is summarized. The methods and the instruments as well as their difficulties in the arctic field conditions are described. The seasonal characteristics of the energy balance are presented for the dry snow, the melt and the postmelt periods. The diurnal variations of the energy balance for each of these periods are also presented.The climatic differences for the regions of the tundra, glaciers and the arctic seas become prominent during the three summer months of June, July and August. The energy balance at the present site is compared with that of Barrow, Alaska, revealing a high degree of similarity. The slight differences between them are more net radiation, more sensible and latent heat fluxes, larger Bowen ratio and less soil heat flux at Barrow. These differences are considered to be due to the larger distance of the present station from the coast.The energy balance on and in the dry snow cover is investigated. The stability of the snow cover is attributed to the high reflectivity as well as to the large absorptivity of its surface with respect to solar radiation. The absorption occurs mainly at the surface of the snow cover rather than its interior. This condition facilitates the efficient removal of the absorbed energy from the surface by the atmosphere.The energy balance on the tundra is compared with those on the Central Arctic Ocean, the ablation area of the polar glaciers, the accumulation area of the glaciers and the boreal forests. The surfaces of the tundra, ablation area of the glaciers and the Central Arctic Ocean are found to receive similar net radiation, despite the albedo differences. The fundamental difference among these surfaces is the magnitude of the latent heat of melt. This component on the ablation area of the glaciers and the Central Arctic Ocean is four to six times larger than on the tundra, which results in differential heating and evaporation in these regions. This difference is considered to be the basis of the milder climate in the tundra region in the Arctic.More substantial differences are found between these low altitude arctic surfaces and the accumulation areas of the glaciers and the boreal forests. The differences are due to the large variation in albedo for the former and to the difference in global radiation for the latter. These differences ultimately regulate the regional variations in net radiation, sensible and latent heat fluxes.

ISSN:0196-1748    

DOI:10.1002/joc.3370020106

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370020107

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370020109

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370020111

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370020112

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370020113

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY