摘要:

AbstractThe spatial patterns of precipitation variability over the United Kingdom are examined for the period 1861–1970 using principal components analysis. Most of the variance (around 50 per cent) is explained by the first component, which is characterized by uniform variability over the whole region. Higher‐order components isolate differential variability between different regions. The first four components are essentially the same for all months, all seasons and the annual total, highlighting the intra‐annual constancy of inter‐regional variability and pointing to strong geographical and topographical control. A subdivision of the analysis period into two halves produces no change in the component patterns, but changes in the variance explained by the first component imply that summer precipitation has become less spatially variable since 1915. On the basis of the principal components analysis the England and Wales region is divided into five coherent subregions. A regression technique is developed to produce a homogeneous area‐average precipitation series for England and Wales using the longest site precipitation records available and maintaining even spatial coverage. The method used allows changes in the reliability of the area‐average due to changes in the density of station coverage to be quantified. An empirical relationship between the standard error of estimate of area‐averaged precipitation and the number of recording sites is derived. Significant inhomogeneities in the Nicholas and Glasspoole England and Wales precipitation series at 1915 and 1957 are detected and quantified. The Nicholas and Glasspoole series as a whole is found to underestimate precipitation amounts noticeably in the late eighteenth and early ninetee

ISSN:0196-1748    

DOI:10.1002/joc.3370040102

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractAfrican free air wind velocity data for wet and dry periods in the Sahel have been analysed objectively by the Cressman scheme and show that the lower troposphere easterly jet over west Africa is stronger in the dry period whereas the analogous easterly jet to the south of the equator exhibits greater vertical shear in the wet period. Two possible explanations, based on modulations of the meridional temperature gradients across the jet, are offered.

ISSN:0196-1748    

DOI:10.1002/joc.3370040103

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractUsing storm rainfall data from a dense network of autographic raingauges at Dar es Salaam, Tanzania, storm characteristics (morphology, alignment and time of occurrence) are related to prevailing gradient wind. There is a pronounced seasonal variation in the time of day at which storms generally occur, related to seasonal changes in the larger‐scale wind regime between the north‐easterly and south‐easterly trade winds. Many storms occur at times when there is a convergence between locally‐generated land‐ or sea‐breezes and the gradient wind, and their origin along these lines of convergence is further demonstrated by occurrence of both elliptical and linear morphology storms aligned along the coast. The trend of the coast is shown to control the alignment of storms, particularly by day, whereas by night gradient wind is more important. At this time, storms tend to form along the direction of the gradient wind. The most active storms form in the middle of the day, are linear in nature, aligned parallel to the coast, and occur when the gradient wind is either offshore or blows along the coast from the south

ISSN:0196-1748    

DOI:10.1002/joc.3370040104

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe paper considers the water requirements in the south of France. The historical development of water distribution schemes is described before a consideration of the general precipitation distribution in Provence and Languedoc‐Roussillon. The precipitation and potential evapotranspiration (calculated by the Thornihwaite/Mather bookkeeping method) data for 1931–1960 and for 1971–1980 are discussed and compared. A series of diagrams illustrates the monthly variation of surplus, deficit, use and recharge at seven stations over the latter ten‐year period. Maps showing wide variations in surplus or deficit in 1971, 1976 nad 1980 are presented. Finally, the implications of water provision for agriculture and tourism are con

ISSN:0196-1748    

DOI:10.1002/joc.3370040105

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe global cloud distribution is recognized as forming a major component of the Earth's climate through its influence on both the energy and moisture exchanges in the earth‐atmosphere system. This review concentrates on the radiative effects of clouds and examines a number of modelling and empirical studies that have addressed the possible significance of the role of cloud cover in climate change. This question is still not fully resolved. One reason for this is inadequate data and, therefore, some of the cloud climatologies available and the associated problems of data collection and interpretation are discussed. The review focuses specifically on interactions at high latitudes and describes recent studies which suggest that there may be a relationship between sea ice extent and cloud cover. Some possible consequences of this are discussed in the context of a high latitude response to climate chang

ISSN:0196-1748    

DOI:10.1002/joc.3370040106

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractNon‐linear chart traces can be digitized if the output is corrected by a mathematical function. A procedure is described which is advantageous if the recorder output may be regarded as symmetric about the mid‐point of the ch

ISSN:0196-1748    

DOI:10.1002/joc.3370040107

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe annual march of the mean monthly number of thunderstorm days at a station shows certain characteristics, depending on the prevailing climate. For example, the main maxima in continental and marine climates occur in summer and in autumn to winter, respectively. A gradation of such an annual march of thunderstorm activity is successfully used in delineating transitional climatic zones in Greece, and it might also be applied to other regions of the earth.

ISSN:0196-1748    

DOI:10.1002/joc.3370040108

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370040109

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370040110

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370040101

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY