摘要:

AbstractThe global radiation at the ground is determined from monthly samples of imaging data from the geostationary satellites METEOSAT 2 and GMS 2 with a method which has earlier been developed by Möser and Raschke (1983). These radiance data are reduced to obtain resolutions of 30 to 40 km in space and 3 h in time according to the B3 format of the ISCCP procedures.If compared with simultaneous pyranometer measurements these results agree within an uncertainty of better than 8–10 per cent for monthly averages of daily sums and of better than 25 per cent for individual daily sums. Possible error sources are not only contained in the retrieval procedure but are also due to errors in navigation of satellite images. Further, local orographic effects can contribute to differences between calculated and measured downward irradianc

ISSN:0196-1748    

DOI:10.1002/joc.3370070302

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractGeneral circulation models (GCMs), which simulate the climate response to a doubling of the atmospheric carbon dioxide (CO2) concentration show a considerable variety of results even in respect to the globally averaged air temperature response near the ground. There is a need to verify the GCM results against an observational climatic data basis where noi only the global average but also the regional patterns and seasonal variations in the response are important. The statistical assessments described here are based on an annual time series 1851–1984 of the mean northern hemisphere surface air temperature and on corresponding monthly gridded data 1881–1980. The noise is reduced using a Gaussian 10 year low‐pass filter. Natural forcing is taken into account in terms of volcanic and solar forcing parameters. The sensitivity of the CO2‐induced temperature signal obtained from the statistical regression model is tested using different CO2time series and both a linear and a logarithmic CO2‐temperature relationship. The statistical CO2doubling simulations give results that are similar to most of the GCM experiments with respect to the zonal mean and seasonal response but not always with respect to the regional changes. Finally, the regional CO2induced signals are statistically compared with those due to volcani

ISSN:0196-1748    

DOI:10.1002/joc.3370070303

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractRecent changes in precipitation variability are examined for five regions of England and Wales. The only statistically significant changes that have occurred over the past 10 years have been an increase in the frequency of extreme dry summers and wet springs. The importance of large‐scale climate forcing factors, such as pressure gradients and weather types, in controlling precipitation variations is examined using simple correlation analyses. The homogenized England and Wales precipitation series is updated to 198

ISSN:0196-1748    

DOI:10.1002/joc.3370070304

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractThree years of continuous measurements on the NW coast of the Dead Sea, together with a series of shipborne observations made above its water surface, were used to characterize and analyze the radiation climate of the sea.Incident global radiation on the coast, averaged 6.64 GJm−2per year, less than values measured both at sea and at nearby pyranometer stations despite the greater cloud cover of the latter. The relatively low insolation was attributed to the considerable back scatter from the sky shown by the high values of diffuse sky radiation recorded even during cloudless conditions. Short‐wave radiation reflected from the sea was calculated, on the basis of a quadratic relationship between reflectivity and solar altitude, to total O50GJ m−2annually. Above a critical solar altitude of 45° reflectivity averaged 6 per cent. Monthly values of reflectivity from the Dead Sea agreed with those calculated for a standard sea surface.Atmospheric long wave radiation measured on the coast totalled ll.44 GJ m−2annually. Its seasonal and diurnal variations closely followed those in air temperature. Small variations in the apparent sky emissivity, which averaged 0.80, could be accounted for by reference to accompanying changes in the water content and transmissivity of the atmosphere.Midsummer and midwinter in situ determinations of the emissivity of the Dead Sea yielded near‐black body values which, with the high surface temperatures of the sea, resulted in a terrestrial radiation flux totalling 14.69 GJ m−2annually.Direct pyrradiometer measurements over the Dead Sea were used to establish the accuracy of long term estimates of the radiation balance of the sea and to develop a method of calculating it from routine, shore‐based measurements of global radiation.The radiation balance of the Dead Sea, normalized to the incident radiation, was 0.45,22 per cent less than the average for eight other non‐saline water bodies in comparable mid‐latitude climates. The relatively low radiation balance of the Dead Sea was attributed to the enhanced long‐wave radiation loss caused by the elevated surface temperature of its salt‐saturated waters.Thus the salinity of the Dead Sea reduces its evaporation loss by two mechanisms; the direct effect of the reduced vapour pressure of the water surface and the indirect effect of the red

ISSN:0196-1748    

DOI:10.1002/joc.3370070305

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractSpatial patterns of daily rainfall in central Kenya were investigated using principal component analysis {PCA) and common factor analysis (CFA) of covariance matrices, together with spatial correlation analysis. Data consisted of daily values from 42 stations for the period January 1971 to November 1979. All statistical analyses were made both on the whole data set, and by month.The number of components/factors to retain for rotation could not be unambiguously determined by means of scree tests. Therefore, various numbers of components/factors were rotated, mainly by using the Direct Oblimin procedure. It was not possible to obtain simple structure solutions from the PCA, which explained 50–70 per cent of the total variance. CFA explained 30–40 per cent of the total variance and was easily rotated to simple structure. It is concluded that this difference is due to the large portion of unique variance in the data. Because of this, maximum likelihood CFA is judged superior. Also the scale‐independence of the method is considered advantageous.The PCA and CFA correctly located the limit between the region of two pronounced rainy seasons, and the region of more complex and less distinct rainfall seasonality.Spatial correlation analyses suggest two seasonal rainfall regimes, one of ‘random’ convection during December‐March, and another of rainfall organized in approximately NE‐SE direction. The latter is mainly attributed to orographic influence, but possible links to fluctuations in the general SE‐monsoonal flow and the East African low‐level jet are

ISSN:0196-1748    

DOI:10.1002/joc.3370070306

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractRainfall on the Guyana coastal region is produced by mesoscale synoptic systems occurring throughout the year and by large‐scale systems associated with the seasonal movement of the ITCZ. Consequently, the rainfall is highly variable in time and space. This variability has often adversely affected crop production.Daily rainfall data are examined for a selected sample of stations in order to establish the onset dates of effective and persistent rainfall within the two major rainfall seasons. Onset dates show significant inter‐station and yearly variations for the winter (short wet) season while they vary only moderately for the summer (long wet) season.Correlation analysis has also been used to examine the spatial coherence of the rainfall. Seasonal differences have been found. Winter rains tend to be more localized and appears to be produced by a larger number of small‐scale systems. Summer rains appear to be more spatially coherent owing to the influence of energetic large‐scale systems associated with t

ISSN:0196-1748    

DOI:10.1002/joc.3370070307

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

摘要:

AbstractDaytime and nighttime mean temperature and humidity values are used to calculate a monthly Comfort Index for 41 stations in Greece. These indices are related to heat and cold stress using a psychrometric chart and combined to provide values of Annual Stress, Proportional Cumulative Stress, and Annual Physio climatic Regime following the methods proposed by Terjung (1966,1967). In addition alternative methods of showing the temporal and spatial distribution of the parameters are considered and illustrated.

ISSN:0196-1748    

DOI:10.1002/joc.3370070308

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370070309

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY

ISSN:0196-1748    

DOI:10.1002/joc.3370070301

出版商:John Wiley&Sons, Ltd.    

年代:1987

数据来源: WILEY