摘要:

AbstractA detailed examination of the variability of Australian district rainfall of seasonal time‐scales over the period 1950–1987 is described. In Part I, S‐ and T‐mode rotated principal component analysis (RPCA) was used to obtain a compressed representation of Australian district rainfall anomalies on seasonal time‐scales.In this paper, the temporal variability of these spatial patterns is examined, and their relationship to some large‐scale circulation indices, such as the Southern Oscillation (SO) and Pittock's L index. The S‐mode components show large intercomponent correlations as a result of the rotation of the principal components, although much of this is due to a common relationship to the SO. The T‐mode components are less strongly interrelated and only the first two show large correlations with the SO. The relationship with the SO and the L index are consistent with previous studies. Spectral analysis shows that most components do not have any dominant periodicity. Two distinct biennial tendencies are identified; in the north‐east associated with the SO, and in the south‐east associated with the L index.The large‐scale circulation anomalies associated with both the S‐ and T‐mode patterns are examined using the Comprehensive Ocean Atmosphere Data Set (COADS) and a network of rawindsonde stations over Australia and the South‐west Pacific. Three dominant teleconnection patterns are identified; the well‐known Southern Oscillation anomalies associated with the dominant T1 pattern of continental‐scale rainfall anomalies, a predominantly winter season Indonesian‐Indian Ocean pattern previously documented by Nicholls, and a spring/summer south Tasman Sea pattern. The evolution of these patterns is examined through composites, and the physical mechanisms for the initiation and maintenance of the anomaly patterns are discussed. In the latter two cases both the rainfall and SST anomalies appear to be driven by anomalies in the lar

ISSN:0899-8418    

DOI:10.1002/joc.3370130202

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractSouthern Africa is semi‐arid to arid, and the moisture that contributes to rainfall over the summer rainfall region is largely imported from other areas. Interseasonal and interannual variations in rainfall must result from changes in the circulation and in vapour fluxes over the subcontinent. It is shown that important changes in vapour fluxes occur between October (early summer) and January (late summer), with zonal fluxes being more important in October and meridional fluxes in January. Wet and dry months of October and January are characterized by enhanced zonal (meridional) flow in wet Octobers (Januaries), and reduced importance of these flows in the dry months. Adjustments in the areas of vapour flux convergence and divergence are as important as changes in the fluxes. The convergence and divergence changes between wet and dry months are confirmed by decreases in outgoing longwave radiation over central southern Africa in wet months and increases in dry months. Tropical zonal circulations, and tropical—subtropical meridional circulation cells, conform to the patterns of enhanced (reduced) convection over the central subcontinent in wet (dry) mon

ISSN:0899-8418    

DOI:10.1002/joc.3370130203

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractA classification of extratropical storms in the north‐western Atlantic Ocean is developed based upon the storm's origin, track, and intensification. All storms producing at least 1.6‐m deep‐water waves at Cape Hatteras, North Carolina from 1943 to 1984 are included. Eight distinct storm types are identified, and their seasonality, interannual variation, and relationship to a previously devised storm‐intensity scale are discussed. The most dangerous storms are cyclones which originate either over Florida or north of Cuba from October through to April, travel northward, and are blocked by a stagnating anticyclone over New England or the North Atlantic. Coastal storm frequencies declined from the mid‐1960s through to the mid‐1970s and increased through to 1984, but the frequency of potentially damaging storms has increased

ISSN:0899-8418    

DOI:10.1002/joc.3370130204

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe long‐term precipitation series (1926–1990) from a 10 rain gauge station network in the Marathon area, Greece, have been statistically examined for trends. Application of the Mann—Kendall rank statistic test to the annual time series revealed a significant decreasing trend in the precipitation over the area. Similar decreasing trends are observed in neighbouring regions to the Marathon area (Athens basin and Beotia). The differences in precipitation trends during the transitional seasons among the three areas seem to be caused by the urbanization process. The seasonal variations and the periodicities of precipitation in the study areas also are examined. Finally, the spatial distribution of precipitation and the relation of precipitation amounts to the station height in the Marathon area are disc

ISSN:0899-8418    

DOI:10.1002/joc.3370130205

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractIn a recent article claiming to deal with the effect of domain shape on principal component analysis, Legates attempts to use previously published research and analyses of two exploratory data sets to try to dismiss Buell's work on the topography of empirical orthogonal functions. Legates' logic and data sets suffer from a number of flaws, including omission of key results from Buell, neglect of dozens of published papers discussing domain dependence, misinterpreting and misrepresenting numerous references to Richman, and using data sets with inhomogeneities between land and water as well as very low temporal degrees of freedom. This Comment addresses some of these shortcomings by exploring what other researchers have concluded about Buell patterns and how they have minimized the problem. It also serves to provide a proper interpretation of PC loading fields consistent with Richman, and to point out several potential problems in the two data sets used by Legates, which might lead to inferior results.

ISSN:0899-8418    

DOI:10.1002/joc.3370130206

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractIn a previous paper, I reevaluated the domain shape dependence arguments of Buell and concluded that ‘unrotated’ principal components do represent, to a very large degree, the underlying structure represented in the dispersion matrix. Richman's comments are largely based as a defence of component rotation—a subject that was not addressed in my original paper. It is my thesis that much of the alleged uninterpretability of ‘unrotated’ components stems from an attempt to retrieve characteristic scenarios or ‘modes of the variation’ (which PCA does not purport to do) and not from an overdependence on the shape of the domain. This misapplication often results from a confusion of the goals of principal components analysis and common factor analysis as is evidenced in Richm

ISSN:0899-8418    

DOI:10.1002/joc.3370130207

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

ISSN:0899-8418    

DOI:10.1002/joc.3370130208

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

ISSN:0899-8418    

DOI:10.1002/joc.3370130201

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY