摘要:

AbstractRing widths of oak trees (Quercus petraeaLiebl. andQuercus roburL.) from a network of seven sites in southern Britain and northern France are used to reconstruct riverflow for three river catchments in southern Britain. These dendrohydrological reconstructions, made using a principal components regression technique, are the first such reconstructions in Europe. The results are statistically significant, and the stability of the regression models is verified using independent data. The reconstructions are more reliable for low flow events; a finding which is potentially useful for water resource planning. The reconstructions indicate a possible increase in the frequency of extreme low flows over the period 1755–1859, compared to 1860–1979, which although not of conclusive statistical significance, warrants further investigat

ISSN:0196-1748    

DOI:10.1002/joc.3370040502

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractBlack porous disc atmometers were used to measure daily evaporation (E) at a distance of 4H(whereHis barrier height) leeward of a medium porous hedge and in the open. The modification ofEat the sheltered position was defined, in relative terms, as the percentage of the shelteredEto that in the open (relativeE) and in absolute terms as the difference between the open and shelteredEtotals. Although relativeEwas found to vary as a linear function of the relative wind (RW),Edifferences varied also with the meteorological conditions influencing the ‘evaporative climate’, identified here by the weather parameters: cloud cover, relative humidity and wind speed. For a particular value of relativeE, theEdifferences were greatest on days with no cloud, low humidity and moderate wind speed and least on cloudy, humid days with low wind sp

ISSN:0196-1748    

DOI:10.1002/joc.3370040503

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe results of an objective synoptic climatology of glacier mass balance in south‐western Canada are affected by the scale and degree of generality of the synoptic patterns used. Two scales of 500 mb daily weather maps are compared. Statistical analysis shows little direct relationship between the two scales: the smaller, high wave number patterns vary randomly within the more general flow of the larger circulation patterns. However, further analysis suggests that the smaller synoptic patterns control glacier mass balance in coastal British Columbia. Glacier accumulation in the Canadian Rockies is more closely related to larger‐scale atmospheric f

ISSN:0196-1748    

DOI:10.1002/joc.3370040504

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractAutomatic weather stations have been successfully deployed in the hostile climate of Antarctica, where temperatures can drop below −80°C and wind speeds are up to 100m.p.h. These stations use satellites for transmission of their data (Argos System). Three years of data had been collected at Dome C (3280m), East Antarctica, before breakdown of the equipment occurred in January 1983. These data were analysed and compared with data from other stations in Antarctica. Results show that the temperature at Dome C can drop very low (−84.6°C), a new absolute world minimum is not expected to be found, however. The annual course of the temperature displays the typical ‘coreless’ winter phenomenon, with no systematic temperature changes for 4 to 5 months, and mean temperatures of about −60°C during this time. This fits well into the picture found at other high altitude inland stations of Antarctica. The wind speeds observed at Dome C were the lightest, not only of all interior stations in Antarctica, but of all antarctic stations, including coastal and near‐coastal ones. This illustrates the well‐known dependence of the katabatic winds on slope angles and topography. Despite steep and deep surface inversions, katabatic winds generated at higher elevations on the continental slopes do not appear to override Dome C, but flow around it. By contrast, the winds observed in the coastal regions of Adelie Land, some 1000 km away from Dome C, belong to the strongest found anywhere on the earth. Another indication that Dome C is free from any gravity flow can be found in the fact that the winds display a diurnal maximum during the summer months around noon or early afternoon, at a time when the inversion strength is at a minimum. For gravity flow, one would expect a minimum in wind speed at that time, as observed in th

ISSN:0196-1748    

DOI:10.1002/joc.3370040505

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe interannual fluctuations in the Southern Oscillation indices (Wright, 1975) and their relations to the Indian monsoon (June‐September) rainfall have been examined for the period of 106 years from 1875 to 1980. The monsoon rainfall is significantly (99.9 per cent level) correlated with the Southern Oscillation indices for the seasons: MJJ (0.59), ASO (0.67), NDJ (0.53), and FMA of the following year (0.38). The fluctuations in the Southern Oscillation index for the ASO season appear strongly related to the nearly simultaneous monsoon rainfall of India. This implies that the large positive (negative) value of the Southern Oscillation index, signifying strengthening (weakening) of the Walker circulation coincides with large excess (deficient) monsoon rainfall over India. The coherence spectrum reveals that the Southern Oscillation index and the monsoon rainfall are highly correlated in the period range of about 2–2.5 years and 4–6 years. The first of these periods corresponds with the Quasi‐Biennial Oscillation and the latter agrees with the features of the Southern Oscillation, suggesting a strong link between Indian monsoon rainfall and these two phenomena. The striking feature of the composites of the Southern Oscillation index averaged for all the drought years and for all the flood years is the simultaneous occurrence of low (high) Southern Oscillation index and droughts (floods) in India. However, this association has limited use in long‐range prediction. A preliminary study suggests that a nearly simultaneous occurrence of major climatic anomalies of the tropics, such as droughts in India and El Niño off the coast of Peru, are linked to the Southern Oscillation, indicating some kind of time dependent zonal east‐west circulation, i.e. Walker

ISSN:0196-1748    

DOI:10.1002/joc.3370040506

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractIn July 1981, there occurred a comparatively severe flood and inundation in the Sichuan Basin. Before its occurrence, certain precursory phenomena appeared in the May 500 mb circulation field. The Western Pacific subtropical high apparently strengthened and extended westward, the mid‐latitudinal zonal circulation weakened, whereas the meridional circulation strengthened. At the same time, the astronomical background suggested a rainy period. All these precursory features unanimously indicated the probability of heavy precipitation and a tendency for flooding and inundation in July‐August, but especially in July, in the Basin. In this paper analysis and discussion emphasize the astronomical factors, the circulation factors and the prediction instrumentation which resulted in a successful predict

ISSN:0196-1748    

DOI:10.1002/joc.3370040507

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper considers annual and seasonal variations of temperatures at three stations in Greece with at least 80 years of records. The extent and nature of non‐random changes, such as persistence, trend and fluctuations, are investigated. There is statistical evidence of both Markov linear and non‐linear persistence in the data depending on stations and season. The trend analysis showed little of significance, probably because of the time periods chosen. The data were subjected to a ‘lowpass filter’ of a Gaussian type and the series of fluctuations which resulted are discussed. Finally the data for all three stations were combined and filtered in order to show changes that have occurred in the Greek region during the twentieth

ISSN:0196-1748    

DOI:10.1002/joc.3370040508

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractPower spectrum analysis is applied to annual and seasonal temperature data at three Greek stations. The results are tabulated and oscillations of 9, 4.8, 4.0, 2.7 and 2.2 years occur in most sets of data. The statistical importance of the results is indicated by 95 per cent, 90 per cent and null continuum levels. The quasi‐biennial oscillation is very clear but seems to be composed of individual cycles of 24, 26 and 32 month

ISSN:0196-1748    

DOI:10.1002/joc.3370040509

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractS‐mode principal component analysis has been applied to standardized monthly South African rainfall fields and the synoptic systems represented on the higher eigenvectors identified by matching the spatial distribution of rainfall on each component with that of the various weather systems as revealed by satellite imagery. Summer systems identified include cloud bands connecting the tropical and temperate circulations, tropical and subtropical cyclones, coastal depressions, cyclones on the continental west coast and troughs associated with cold fronts on the east coast. The new classification is contrasted with earlier equivalent schemes. The uses of the results in terms of the search for geophysical controls on the development of each of the identified systems are discusse

ISSN:0196-1748    

DOI:10.1002/joc.3370040510

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractTime series (scores) of rainfall from cloud bands across South Africa, generated through S‐mode principal component analysis, are compared with equivalent estimated time series developed from satellite imagery and surface data. The cloud bands, which link the tropical and temperate circulations, accounted for the highest explained rainfall variance over the interior of South Africa in the principal component analysis. For most summer months the principal component scores are useful first approximations to the true time serie

ISSN:0196-1748    

DOI:10.1002/joc.3370040511

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY