摘要:

AbstractSimple parameterizations are used to estimate monthly mean ablation of snow and ice, and also the distribution of monthly mean precipitation in Britain. Together these enable estimates to be made of snow storage at various levels and the gradients of days with snow cover with elevation. Small semi‐permanent snow patches below the regional snow line are included in the discussion. The theoretical estimates fit the actual observations very closely. A similar approach is then used to estimate snow balances for the British Devensian ice sheets. Probable snow accumulation/elevation relationships are produced for 24,000 yr BP. Estimates suggest that the British ice sheet was just in balance at the lime of its maximum advance around 18,000 yr BP. The growth and decay of British ice sheets are considered and two stable states are suggested for ice‐age climates, one without an ice‐sheei and the other with a massive ice

ISSN:0196-1748    

DOI:10.1002/joc.3370020302

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractThere has been increasing interest in recent years in the study of droughts because of their economic, social and political impacts on society. Two summer droughts that affected the Canadian Prairies in 1961 and 1967 are examined. Based on a synoptic climatological approach, the investigation reveals that droughts occurred when the weather type WR (mid‐tropospheric ridge dominant) was persistent with a ridge over western Canada. A study of the 1976–1977 winter drought supports this interpretation. In all three cases, a quaststationary mid‐tropospheric ridge over western Canada acted as a block which displaced the jet stream, cyclones and moist air masses to a location north of the Canadian Prairies, while anticyclonic circulation under the high pressure ridge gave atmospheric stability and dry conditions on the Canadian Pra

ISSN:0196-1748    

DOI:10.1002/joc.3370020303

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe pattern of July temperature variability over Canada north of ∼50°N for the period 1943–1972 has been analysed by means of principal component analysis. Our objective was to assess the spatial similarities between modern temperature fluctuations at the interannual scale and those derived from paieotempe nature records encompassing a period of the last 600014C years.A comparison of the first four principal components from each data set suggests that contemporary midsummer temperature variations offer a reasonable analogue to Holocene fluctuations on the order of a few centuries. The Keewatin‐Baffin Island‐Ungava Peninsula region appears to be within the area of maximum temperature

ISSN:0196-1748    

DOI:10.1002/joc.3370020304

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractAn empirical study was conducted examining associations between seasonal trade wind and sea surface temperature (SST) fields in the eastern half of the tropical Pacific Ocean for the period 1949‐1979. In addition, the tropical fields were statistically related to the extratropical circulation of the Northern Hemisphere (i.e. 700 mb heights). This study differs from most prior studies in that the trade wind field was examined primarily in terms of the horizontal trade wind divergence and seasonally stratified lag relationships were computed.Seasonally stratified autocorrelations of empirical orthogonal function (EOF) amplitudes (out to four seasons) indicated significant persistence of EOF1 of SST and divergence until spring‐summer for any initial season; accordingly, spring and summer (summer and autumn) EOF1 for SST (divergence) exhibited the greatest persistence. For divergence some tendency for a reversal of sign was seen from the autumn, winter, or spring seasons to the following autumn, which may imply negative air‐sea feedback mechanisms operating.Seasonally stratified cross correlations betwen the first EOF for SST and divergence indicated a significant contemporaneous relationship. When divergence leads SST, the relationship is significant at short lags (1‐3 seasons) until spring as a target season is reached. The same is true when SST leads divergence except that a significant relationship returns with opposite sign in the subsequent summer and auiumn. Winter SST and divergence, in particular, are well correlated with prior values of the other parameter.When the tropical parameters were related to the extratropical circulation through correlation with gridded 700 mb heights, significant patterns were found only when winter 700 mb heights were the target parameter (i.e. tropical parameter leading winter 700 mb heights). Summer through winter tropical SST and divergence (EOF1) displays a good association with subsequent winter extratropical circulation in the form of an expanded/contracted circumpolar vortex. The relationship between trade wind divergence and subsequent winter circulation is significant using the prior winter (4 season lag), vanishes during spring, and returns with the opposite sign for summer through winter (lags 0‐2). Using either SST or divergence, the observed relationships are stronger at lags 1 and 2 than

ISSN:0196-1748    

DOI:10.1002/joc.3370020305

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe variable length record method of spectral analysis is considered as a composite of perturbations of a simple harmonic analysis. By smoothing over near neighbours, the composite spectrum can be made to approach the true spectrum. Since the method is computationally expensive, a less costly technique of multiple interpolation is considered and shown to produce equivalent results. This method is suitable for examining the low frequency end of cli ma to logical spectra.

ISSN:0196-1748    

DOI:10.1002/joc.3370020306

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370020307

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370020308

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370020309

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370020310

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370020311

出版商:John Wiley&Sons, Ltd.    

年代:1982

数据来源: WILEY