摘要:

AbstractA five year data set of satellite cloud cover observations and a thirty year data set of surface cloud cover observations were compared over Europe. There is good agreement between the general characteristics of these two cloud climatologies. Differences between monthly means (January, April, July and October) of the two data sets were formed in 5° × 5° grid cells. These differences, regarding all grid points and months are less than half of one tenth of sky cover in 46 per cent of all cases.The defining parameters (aandb) of the Beta distribution were calculated also for the months of January, April, July and October representing the four seasons. On the basis ofaandbvalues, different cloud cover regions were determined over Europe and these were characterized by averaged curves of the Beta probability density functions. These regions correspond well to distinct areas of geographical environments, as well as to the regimes of the general circulation. Thus, the character of cloud conditions within these regions can be expressed in a numerical way by means ofaandbparamete

ISSN:0196-1748    

DOI:10.1002/joc.3370080402

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractTwentieth century sea ice data from the Nordic Seas (the Atlantic Sector of the Arctic) are examined using a simple index of variations in sea ice extent. The index measures overall sea ice extent variations in the Nordic Seas between 1901 and 1977. Variations in the marginal ice zone during the melt season are shown to reflect regional air temperature changes. Reduction of the index data using principal component analysis highlights sub‐regional heterogeneity in melt season sea ice extent variations. An important spatial pattern of variation is one in which sea ice extent in the Barents Sea varies out of phase with that in the central Greenland Sea. This alternating pattern has a quasi‐periodicity of around three years. Time series analyses of other sea ice records indicate significant quasi‐periodicities in the region of between 3 and 4 years and 2.5 years. Three years may be a key time scale of variation in the Atlantic Sector of the Arctic seasonal sea ice

ISSN:0196-1748    

DOI:10.1002/joc.3370080403

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractUsing the principal component method, some characteristics of the precipitation pattern are established for an area from the Adriatic Sea to the Pannonian lowland (territory of Croatia). The data of monthly precipitation amounts for the 20‐year period (1961–1980) from 108 meteorological stations are used. The first four principal components (PCs), which describe 79‐4 per cent of the total precipitation field variance, are considered. It is shown, graphically and numerically, that the first PC is related to the frequency of cyclones on van Beber's paths IVb, Vb and Vc, the second one is related to their frequency on the paths Vd, Vd1 and Ve, the third to the anticyclonic and non‐gradient weather type and the fourth one is related to the frequency of cold fronts crossing Yugoslavian territory. Using the loadings of the PCs, four homogeneous precipitation sectors are determined and compared to those obtained by Koppen's scheme. Finally, some details of the annual pattern of precipitation for these sectors are di

ISSN:0196-1748    

DOI:10.1002/joc.3370080404

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractDaily rainfall data from 73 stations distributed throughout Kenya were subjected to maximum likelihood factor analysis. Data for the period January 1971 to December 1985 were used. A brief analysis of data quality and representativity and the problem of missing data are included. The data were transformed by natural logarithms. Scree and LEV plots together with the Kendall/North criterion for eigenvalue separation indicated break points at 5, 11 and 15 factors. The 11‐factor model was judged as being the most parsimonious, for both statistical and climatological reasons. It explained 38 per cent of the total variance.The general features of the regionalization are found to be reasonably consistent with other studies. The major regions (the coast, the Highlands, the Lake Victoria area, and the dry northern/eastern areas) appear in this regionalization but are divided into several subregions. It can be concluded that this subdivision is partly linked to physiographical regions and orographic influence. In addition, possible links to regional circulation patterns are discusse

ISSN:0196-1748    

DOI:10.1002/joc.3370080405

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractRainfall and temperature data during the period 1901–1982 are studied for the northwest Indian region consisting of the meteorological subdivisions of Punjab, Haryana, west Rajasthan, east Rajasthan and west Madhya Pradesh. The results indicate a decreasing trend in the mean annual surface air temperature, which is mainly contributed by the south‐west monsoon season (June through September), The mean annual and south‐west monsoon season rainfall series over most parts of the region indicate a conspicuous increasing trend. The increasing trend is significantly marked for the subdivisions constituting the peripheral areas of the Rajasthan desert. These trends in rainfall and temperature are examined in relation to the changing land use pattern of the region due to extensive irrigation. Earlier findings of Winstanley (1973) reporting a decreasing trend in rainfall are found to be unacceptable due to the unrealistic assumptions of his

ISSN:0196-1748    

DOI:10.1002/joc.3370080406

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper focuses primarily on the effect of El Niño on seasonal and annual precipitation at 26 locations in Arizona and western New Mexico for an 86‐year period from 1900 to 1985. Following Rasmusson (1984), each year is classified as either a non‐El Niño year (51) or an El Niño year (35), with the El Niños designated as being very weak (4), weak (8), moderate (12), or strong (11). Using the Mann‐Whitney U‐test for the 19 stations in Arizona, we find that, in the spring (March‐May) and in the autumn (September‐November), there is a positive relationship between precipitation in Arizona and both moderate and strong El Niños.These results are verified by correlating seasonal and annual precipitation for the complete 26‐station network with the pressure difference between Tahiti and Darwin. Plausible physical explanations for these

ISSN:0196-1748    

DOI:10.1002/joc.3370080407

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractSeasonal and annual patterns of potential wind erosion in Australia are mapped. Potential erosion is estimated by applying Fryberger's sand drift potential concept to 3 p.m. wind data from 732 stations. Contour maps for January, April, July and October show monthly total drift potential, resultant drift potential, and drift directionality. Stream line maps show resultant drift direction. Annual resultant drift potential and drift direction are also mapped.Monthly total drift potential is maximal in October and minimal in April. Highest values occur on the coast, in the Nullarbor Plain, and in Tasmania; lowest values are scattered across the northern inland. Monthly resultant drift potential is similarly distributed. Monthly drift directionality is higher in the north.Monthly drift direction stream lines mainly express the general circulation of the atmosphere. Some local disturbances occur over ranges; others have cyclonic form. Annual resultant drift potential stream lines are broadly confluent and have anticyclonic curvature.These maps of potential wind erosion, linked to measures of erodibility, provide a basis for studying wind erosion hazard in Australia.

ISSN:0196-1748    

DOI:10.1002/joc.3370080408

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370080410

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370080411

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370080412

出版商:John Wiley&Sons, Ltd.    

年代:1988

数据来源: WILEY