摘要:

AbstractData from the Japanese geostationary meteorological satellite are used to map surface albedo in Tasmania, Australia. Satellite data are corrected for atmospheric depletion and the narrow spectral window of the satellite sensor. The effect of non‐Lambertian reflection is discussed.A composite albedo map is presented based on eight mostly cloudless images taken at 10.00 and 13.00 local time in a period spanning the end of January to the beginning of February, 1985. The map features a distinct east west gradient in the albedo, with lowest values measured in the rain‐forest environment of the western highlands. Highest values are observed among areas of cleared farmland in the eastern midla

ISSN:0196-1748    

DOI:10.1002/joc.3370070103

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractReversals in the usual monthly mean sea level pressure (SLP) gradient over the North Atlantic during winter—an extreme mode of the North Atlantic Oscillation—are documented back to 1867. Such events are typically associated with well‐below‐normal temperatures in north‐west Europe and above‐normal precipitation amounts in the western Mediterranean area. Also noted during these events is the tendency for above‐normal temperatures in western Greenland and below‐normal temperatures in the eastern United States.Temporal changes in the frequency of SLP reversals relate well to trends in the strength of the zonal wind and the frequency of blocking in the north‐east Atlantic area. Part of the fluctuations in temperature in western Europe during the last century can be explained by these changes in circulation. Nevertheless, major trends in winter temperature over this period, particularly the early 20th century rise in temperature, remain when adjustments are made to account for the effects of circulation changes during reversal winters. This suggests that mechanisms other than changes in the frequency of circulation regimes also play an important role in determining hemispheric temperature trends on

ISSN:0196-1748    

DOI:10.1002/joc.3370070104

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe spatial and temporal variability of the Palmer drought severity index (PDSI) over the south‐eastern United States during the period 1931–1982 was examined through the use of principal component analysis. Spatial mapping of the component loadings identified six statistically significant modes of variability or PDSI anomaly patterns, which together account for 77.3 percent of the total variance. The first component, which represents the dominant pattern, accounted for 43.4 per cent of the total variance and identified an in‐phase oscillation across the entire study area, indicating a general tendency for all sections to experience either a drought or a wet spell concurrently. The remaining five components, which account for 33.9 per cent of the total variance, each identified an out‐of‐phase oscillation. Application of Kaiser's Varimax orthogonal rotation on the six retained principal components led to the identification of six contiguous subregions of nearly equal size, each of which displays unique drought characteristics.Examination of the time series derived from the principal component scores within each subregion revealed a general trend in which the occurrence of drought was much more prevalent during the first three decades of the study period, culminating during the mid 1950s when most of the subregions experienced their worst drought episode.After removal of the inherent ‘red noise’ persistence found in the monthly PDSI data, spectral and cross‐spectral density analysis performed on the time series indicated that no cyclical patterns or periodiciti

ISSN:0196-1748    

DOI:10.1002/joc.3370070105

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractAbnormalities in the performance of the Indian summer monsoon (June to September) rainfall, which provides 75–90 per cent of annual rainfall, have been studied during the period 1871 to 1984 over different meteorological subdivisions into which the country has been divided. Long homogeneous monsoon rainfall series of 29 subdivisions, prepared on the basis of a constant 306 rain gauges, have been tabulated for the users in view of their great importance. The criterion adopted in identification of drought/flood over a subdivision is the percentage of rainfall departures from normal, as officially used in the India Meteorological Department.The worst drought years were 1877, 1899, 1911, 1918, 1920, 1951, 1965 and 1972 and the worst flood years were 1892, 1933, 1961 and 1983 when many subdivisions reported extremely low and excess rainfall, respectively. The probabilities of occurrence of droughts/floods are high in Haryana, Punjab, west Rajasthan, Gujarat and Saurashtra and Kutch subdivisions. The area of the country affected by drought conditions was at a maximum during the decade 1911–1920 and at a minimum during the decade 1881–1890. The decades 1971–1980 and 1921–1930 were characterized by maximum and minimum areas, respectively, under flood conditions. The percentage area of India which suffered from drought and flood was low during the continuous three decades 1921–1930, 1931–1940

ISSN:0196-1748    

DOI:10.1002/joc.3370070106

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractS‐mode principal component analysis (PCA) is performed on correlation matrices of precipitation data of Austria for summer and winter half‐year totals for the period 1951–1980. Application of the dominant‐variance selection Rule N (Overland and Preisendorfer, 1982) proves two or three eigenvalues to be significant, where three principal components (PCs) on average account for 68.3 and 79.4 per cent of total variance in the summer and winter half‐years, respectively. The Varimax‐rotated PC loadings allow for a subdivision of Austria into three homogeneous (with respect to the underlying processes) regions.Intercomparison of the PC primary patterns, variances and time series of the principal components of three different networks confirms the spatial stability of these regions and turns attention towards seasonal differences. The three PCs are identified by assignment of large‐scale weather types to them which are known to be precipitation producing in the region wherein the respective PC is dominant.The results of this study and their wide variety of applicability reveal PCA and Rule N as useful tools in identifying homogeneous groups of variables which can be ascribed a physical meaning. The paper contains a short account of the analysis of empirical orthogonal functions, the theory of PCA and its connection to fa

ISSN:0196-1748    

DOI:10.1002/joc.3370070107

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractAnnual and monthly values of sunshine duration at thirty‐seven stations in Greece are examined with the three factors of latitude, longitude and altitude by means of stepwise multiple regression analysis. The validity of the assumption that there is a linear relationship between the mean values of sunshine duration and these three factors is examined. A seasonal variation is evident in all the computed gradients of the sunshine duration, with altitude effects being at a maximum in summer, whereas the effects of latitude were most pronounced during the cold season. The thirteen empirical formulae produced do not account completely for all the variability in the data, but the resultant correlation coefficients range from 0.830 to 0.906. The residuals (i.e. differences) between actual and calculated values of sunshine duration are shown on representative maps which may be used (with the regression equations) to estimate sunshine at any locality in Greec

ISSN:0196-1748    

DOI:10.1002/joc.3370070108

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370070109

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370070111

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370070113

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370070114

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY