bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of rainfall time series over South Africa generated from real data and through principal component analysis
Authors: Harrison M. S. J. 
Published: February 2007

AbstractTime series (scores) of rainfall from cloud bands across South Africa, generated through S‐mode principal component analysis, are compared with equivalent estimated time series developed from satellite imagery and surface data. The cloud bands, which link the tropical and temperate circulations, accounted for the highest explained rainfall variance over the interior of South Africa in the principal component analysis. For most summer months the principal component scores are useful first approximations to the true time series.
Method of study and cartography of the potential Sunny periods in mountainous areas
Authors: Bocquet G. 
Published: February 2007

AbstractIn mountainous areas, the duration of sunny periods is an important but often unknown climatic parameter. The difference in amounts of sunshine between exposed and shade sides of mountains must be treated circumspectly, sometimes corrected, for it is dependent on the action of shadows and thus can sometimes reduce the amount of sunshine at a given spot quite considerably.By using a computerized calculation comparing the apparent movement of the sun and the positions of the summits surrounding a given point, the duration of sunshine at this given point can be calculated for a chosen period of the year.This same calculation repeated for frequent points within a same area is transferred to a grid. This grid can be used to draw maps of the potential amount of sunshine for that area at a precise date or between two given dates.This kind of study can be a valuable aid, not only in research into the environment (the amount of insolation is a determining factor in the melting of snow or ice, the evaporation of lakes, the development of vegetation etc.) but also in the planning of an area (solar energy, exposition of buildings in an urban setting, research into sites for new tourist resorts etc.).
Homogeneity analysis of rainfall series: An application of the use of A realistic rainfall model
Authors: Thompson C. S. 
Published: February 2007

AbstractOne approach in the stochastic modelling of rainfall is to derive a distribution function which has physically meaningful parameters. Such a distribution is derived from a Poisson process of rainfall occurrence with an independent exponentially distributed rainfall amount. The distribution appears to fit monthly precipitation totals extremely well.This type of model has many potential applications in climatology and hydrology. The homogenizing of long term rainfall sequences is one of these, and a methodology for this process is presented here. A 130 year record, from Auckland, New Zealand with three changes of site, is used to evaluate the procedure described.The significant advantage in the proposed method is that the homogeneity testing is done within the single rainfall record and the use of comparison stations is not required.
July‐August rainfall in West‐Central Kenya
Authors: Davies T. D. , Vincent C. E. , Beresford A. K. C. 
Published: February 2007

AbstractThe annual rainfall distribution in west‐central Kenya (34°−38°E, 1°N–1°S) exhibits marked spatial variation because of the complicated nature of the local topography. The annual distributions are classified into a number of types on the basis of ‘rainfall seasons’. Over parts of the area of study, precipitation falling in July and August makes an important contribution to the yearly total (up to 33 per cent). The spatial variation of the rainfall in this period, during the so‐called ‘dry season’ over much of Kenya (between the two main ‘monsoon’ rains) is examined in some detail, especially its relationship with altitude. The distribution of the July and August rainfall indicates that it is associated with a westerly airstream overlying the lowest layers of the atmosphere.
A statistical evaluation of the efficiency of the climatic normal as a predictor
Authors: Sabin Thomas E. , Shulman Mark D. 
Published: February 2007

AbstractMonthly and annual temperature and precipitation data were studied to determine the most efficient normal for predictive purposes using root mean square error. The number of years over which the normal was calculated was varied, and the value where the minimum error occurred was found to differ considerably from month to month, but there existed some conformity between stations within the same month.A Monte Carlo simulation was developed for the above procedure. The simulation of the station relocation for temperature data at Flemington, New Jersey suggested that the relocation could limit the most efficient length of the climatic normal to a shorter period. The results from a simulation of annual temperature trends at New Brunswick, New Jersey closely agreed with those found with actual data. Thus, the low value found for the most efficient normal is largely due to these trends. Relocations were found to have little effect on the most efficient normal for precipitation data.A modified procedure, varying the number of iterations, showed that RMSE was also dependent on the period of record selected. With this procedure the most efficient normal was found to be between 35 and 40 years for a station with minor relocations, and longer for a benchmark station. In most cases, however, there was little difference between a 10‐year normal and the most efficient normal.
The goodness of fit of the weibull and rayleigh distributions to the distributions of observed wind speeds in a topographically diverse area
Authors: Tuller Stanton E. , Brett Arthur C. 
Published: February 2007

AbstractThe goodness of fit of the Weibull and Rayleigh distributions to the observed wind speed distribution was investigated at seven coastal weather stations markedly influenced by local topography and possessing relatively long periods of record. Wind speeds will he Rayleigh or Weibull distributed if four conditions specifying the circular normal distribution for wind velocity are met. These conditions were not met at the seven stations because of the influences of local topography and storm systems. In all cases the null hypothesis that there is no difference between the Weibull or Rayleigh distributions and the observed distribution had to be rejected with the large sample sizes employed. The transformation of wind velocity involved in deriving the Weibull distribution helps make the distribution more circular normal and the Weibull distribution gave better fits than the Rayleigh distribution. The fits were generally best al those stations with the most circular normal wind velocity distributions and the lowest percentage of calms.
Review article wind climate studies for wecs siting
Authors: Druyan Leonard M. 
Published: February 2007

AbstractThe many considerations which come into play in the determination of sites for wind energy conversion systems (WECS) are synthesized from a cross‐section of the literature. Prevailing strategies select candidate regions from interpolations of existing wind data and narrow the selection according to local terrain and sometimes vegetative and/or geomorphological indicators. The economic success of a WECS project requires that wind characteristics prove better than certain minima so that planners are obliged to apply scrupulous observational and statistical procedures both in making preliminary estimates of the wind climate and, afterwards, in validating the estimates at the chosen final site(s).
Association between summer temperature and precipitation patterns over the great lakes region and water supplies to the great lakes
Authors: Brinkmann W. A. R. 
Published: February 2007

AbstractEmpirical orthogonal function (EOF) analysis was applied to the combined set of summer temperature precipitation over the Great Lake region, and water supplies to the Great Lakes. The purpose of this analysis to determine the association between these three variables. The results show that the predominant association between temperature and precipitation is a negative one, although a positive association is important central and eastern portions of the region. The water supplies to the lakes are more closely associated (positively) with precipitation than with temperature.Comparison between the results of the EOF analysis of the combined set of temperature, precipitation, water supplies (TPS) and the results of separate EOF analyses of temperature (T), precipitation ( P ), and supplies (S) shows that although the first loading patterns of T, P and S do appear in the combined loading of TPS, they do not appear together in the same pattern of TPS. This result provides further insight into the of the association between these variables.
The southern oscillation over the indian ocean
Authors: Cadet Daniel L. 
Published: February 2007

AbstractThe Southern Oscillation (SO) signal at the surface level over the Indian Ocean is studied during the period 1954‐1976‐ The data set consists of ship observations analysed on a grid mesh of 2 degrees to determine monthly mean fields of wind, pressure, SST. air temperature and cloud cover. Time series of the parameters over different areas show the evidence of an SO signal over the Indian Ocean. Warm and high pressure episodes occur during El Nino event years. High correlation exists between pressure, SST, air temperature fields and the SO index (SOI) north of 10cS. Significant correlation between SOI and cloudiness and zonal wind is mainly found in the eastern Indian Ocean. Composite analysis of he pressure, SST, cloud cover and zonal component of the wind suggests that minimum cloudiness occurs slightly ahead of maximum pressure whereas weaker westerlies over northern Indian Ocean are associated with higher SST a few months later. Power spectral analysis demonstrate the existence of a major periodicity at 40 months, Fields of percentage of variance in the spectral range between 30 and 50 months show a stronger SO signal in the eastern than in the western part of the Indian Ocean, From bandpass filtering and phase spectral analysis of the time series, the phase relationships between the different parameters are determined. Minimum cloudiness occurs with maximum pressure during a phase of decreasing westerlies which reduce the cooling of the ocean and induces an above normal SST and air temperature. The results also suggest the eastward propagation of zonal wind anomalies over the equatorial Indian Ocean. Warmings over the eastern Indian Ocean are occurring simultaneously with the warmings over the Central Pacific Ocean.
A 500 mb synoptic climatology of pacific north‐west coast winters in relation to climatic variability, 1948–1949 to 1977–1978
Authors: Yarnal Brent 
Published: February 2007

AbstractWithin the context of a 500 mb synoptic climatology, relationships between synoptic types and Pacific north‐west coast climatological regimes are investigated. Distinct fluctuations in thermal and moisture trends are identified for the winters of 1948‐1949 to 1977‐1978. Within any one of these climatological regimes, interannual variability in temperature and precipitation is related to the frequency of occurrence of synoptic types associated with warm and wet conditions, respectively. However, the analysis suggests that mixing of data from differing regimes may contribute to within‐type variation, often identified as a major methodological problem in synoptic climatological research.
Principal component analysis of mediterranean rainfall
Authors: Goossens Ch. R. 
Published: February 2007

AbstractPrincipal component analysis has been used to group the European Mediterranean stations into homogeneous regions. The annual rainfall records used were from 90 stations distributed all over the European Mediterranean countries.Major components were selected by a dominant‐variance selection rule, called rule N. The most important component corresponds to a fairly uniform field, the second marks the climatological distribution of cyclonic disturbances, the third shows a gradient from north‐east to south‐west and the fourth exhibits the existence of two centres of anomalies with a negative ridge and a positive value on each side.A cluster analysis based on these major eigenvectors shows the existence of five climatic regions. A subjective method, using the zero‐line characterizing the significant eigenvectors, shows similar results.
Canyon geometry, street temperatures and urban heat island in malmö, sweden
Authors: Bärring Lars , Mattsson Jan O. , Lindqvist Sven 
Published: February 2007

AbstractThe paper demonstrates the relevance of sky view factor analysis in urban canyons to thermal features of the surface and air in the urban canopy layer at night. The result of the study, made in the city of Malmö (population about 230,000) in southern Sweden, indicates, among other things, that the street geometry and its regional distribution within the city area plays a fundamental role in generating the street surface temperature pattern of the city, its 'surface heat island, The paper also demonstrates a digital image processing technique of determining the sky view factor from fish‐eye lens photographs.
Seasonal changes in heat flux and heat storage forth estuary, scotland in the intertidal mudflats of the forth estuary, scotland
Authors: Harrison S. J. , Phizacklea A. P. 
Published: February 2007

AbstractThe surface energy balance of intertidal sediments is complex. Heat is exchanged across sediment‐atmosphere and sediment‐water interfaces at differing states of the tide. This takes place within the context of seasonal changes in the temperature of the atmospheric boundary layer, and sea and river water. Subsurface heat flux in an intertidal mudflat near Grangemouth in the Forth Estuary, Scotland, was determined over a full seasonal range of ambient conditions during 1981. Measurements of temperature and weather variables were made from a 4.3m high instrument tower. Thermal properties of the muddy sediment were determined under laboratory conditions. Heat flux in and out of a 0.1 m deep surface layer of mud was calculated. Time of high water exerts a strong control over net heat flux in a 24 hour period. This is due to variation in heat exchange across the sediment‐water interface during tidal inundation, and across the sediment‐atmosphere interface at low water. The relationship between time of high water and net heat flux during inundation follows a broadly similar form at all seasons. Season, however, determines the magnitude of heat exchanges.
Climatic clusters in a small area
Authors: Galliani G. , Filippini F. 
Published: February 2007

AbstractThe optimization of agricultural productivity by means of numerical weather models requires a detailed analysis of historical daily weather data in order to determine which areas best meet the climatic requirements of a particular crop. The determination of the profiles of climatic factors, in order to identify climatologically similar and closely correlated zones, provides an adequate method of transferring locally tested numerical crop‐weather models from one area to others with the same agroclimatic conditions.This study was made on a small but meteorologically, orographically and agriculturally varied area. It is based on daily measurements of precipitation and of minimum and maximum temperatures, taken by 42 weather recording stations over the period 1961‐1977. The climatic profiles are made by analysing the spatial and temporal variability of meteorological parameters in order to select the similarity functions to be used in models of hierarchical clustering.
Relations between minimum temperature and topography in great britain
Authors: Tabony R. C. 
Published: February 2007

AbstractThe effects of topography on two measures of temperature, the daily minimum and the diurnal range, were investigated using the conventional network of climatological stations in the U.K. The effects of large bodies of water and buildings were minimized by restricting the analysis to data obtained from 145 inland rural sites.Topographic influences were considered to be mainly due to the effects of ‘local’ and ‘large‐scale’ shelter. Local shelter is associated with ‘height above the valley’ and is represented by the drop in altitude within 3 km, whereas large‐scale shelter is associated with nocturnal drainage of cold air, and is represented by the average height of the terrain above the valley over a radius of 10 km. The height above the valley is the most important variable and its maximum effect on diurnal range occurs in the early autumn, when the difference in soil moisture deficit between valleys and summits reaches its maximum. Large‐scale shelter is more important in winter than in summer, and for diurnal range, for rare rather than common events. This represents the increasing importance of nocturnal air drainage with the length of the night and suitable radiating conditions. For minimum temperatures in winter, however, the maximum impact of large‐scale shelter occurs for events with a return‐period around 2 years, and which are loosely associated with cold spells lasting a day or so. More extreme temperatures are usually attained at the end of cold spells lasting several days, when continued radiational cooling over level ground can produce temperatures as low as those attained through cold air drainage.
European rainfall patterns
Authors: Vines R. G. 
Published: February 2007

AbstractThis analysis suggests substantial coherence of rainfall data from Northern Europe, in a region from England to eastern Germany. Within this entire area, there appears to be a long‐term fluctuation in rainfall with a period of about 16 years. Further south, from Switzerland into northern Italy, a different long‐term fluctuation of about 20‐22 years is evident, which exhibits a possible relationship with the double sunspot cycle. Both rainfall variations are out of phase with corresponding fluctuations in North America, which have been reported previously.Other quasi‐periodic fluctuations in precipitation of 10‐12 years (medium term) and 6‐7 years (short term) are observed in the same parts of Europe. Comparisons are made between these systematic temporal rainfall variations and those similarly found in both the northern and southern hemispheres.
Cloudiness and sunshine in cracow, 1861‐1980, and its contemporary tendencies
Authors: Morawska‐horawska Maria 
Published: February 2007

AbstractThe averages of daytime cloudiness for each year from 1861‐1980, smoothed by taking 11‐year consecutive averages (in view of the 11‐year cycle of the sun's activity), closely resemble a sinusoid with minimum values occurring from 1903‐1906. Sunshine values, likewise smoothed, can also be compared to a sinusoid, that is a descending sinusoid. It is worth noting the coincidence of the descending tendency of both graphs in the last 25 years.The correlations between relative sunspot numbers and cloudiness showed a positive dependence with a time‐lag of 5‐7 years, and the strongest correlation, expressed by r = 0.32 (significance level 0.001), occurs with a lag of 6 years after the maximum sunspot number.Sunshine and relative sunspot number show a negative correlation with time‐lags of 6‐11 years, and the strongest correlations occur with a lag of 8 years after the maximum sunspot number, and are expressed by the value r = ‐0.34 (significance level 0.001).A harmonic analysis of detrended data for various periods of time in the space of 122 years, showed two periodicities of cloudiness: 14.3 and 3.6 years respectively. The first is very close to the known periodicity of precipitation and temperature in Cracow. As regards sunshine, the significant periodicities are as follows: 22.2, 10.3 and 3.6 years, respectively. The first two seem to be associated with the 11‐year cycle of solar activity. The 3.6‐year periodicity is probably connected with the identical periodicity in cloudiness.On the basis of the results obtained for Cracow, it cannot be ascertained whether the recorded cycle of sunshine and cloudiness is a regional phenomenon or one of wider consequence.A decline in cloudiness over the past 25 years is connected with rapid growth of Cracow which took place in that time. This caused the drying up of the air, and a decline in cloudiness.Despite the decline in cloudiness (at its highest at noon), there persists in Cracow a decline in sunshine which has existed since 1890 and which has steadily increased over the past 30 years. It has been caused by the industrialization of Cracow which took place after 1950, and is connected with increase in air pollution.
Rainfall analysis of the sahelian drought in the gambia
Authors: Hutchinson Peter 
Published: February 2007

AbstractUsing rainfall data from five stations in The Gambia, it is shown that there has been a very marked decrease in annual rainfall over the last thirty years. This decrease is thought to be due to a reduction in the number of rain‐producing synoptic situations rather than a decrease in intensity of rainfall.Using monthly data for the five stations and decadal and daily data for one station, it is demonstrated that the characteristics of the rainfall season have varied systematically over the years. Although the length of the season is virtually unaltered there is a marked reduction of rainfall in the middle of the season, so that there is a tendency towards bimodality, which could have serious consequences for rain‐fed agriculture.
Possible association between the climatic effects of stratospheric aerosols and sea surface temperatures in the Eastern tropical Pacific Ocean
Authors: Handler Paul 
Published: February 2007

AbstractRecent model calculations have suggested that the occurrence of ENSO (El Niño/Southern Oscillation) events may be related to the appearance of a stratospheric aerosol generated by volcanic eruptions. The association of sea surface temperature anomalies in the eastern tropical Pacific Ocean with the occurrence of major eruptions in investigated over the period 1866–1982. It is found that after the eruption of low latitude volcanoes (<20°) that the sea surface temperatures are significantly warmer than normal within the first nine months (>95 per cent confidence level). These results are consistent with the statistical dynamical model calculations of MacCracken and Luther (1984) for the El Chichon aerosol. A second unexpected result was that the sea surfaces temperatures are significantly cooler than normal nine to fifteen months after the eruption of a high latitude volcano (>20°). Additional data such asin situmeasurements in the stratosphere and acid concentrations in the Greenland ice core are discussed to support the observed association.