bluuebunny/crossref_metadata_2025_split huggingface dataset:
Climatology of tropical cyclone genesis in the Australian region
Authors: McBride J. L. , Keenan T. D. 
Published: February 2007

AbstractStatistics of tropical cyclone origin in the Australian region are presented for the period July 1959‐June 1979. Cyclone genesis is found to occur in preferred areas and to have a high incidence of coastline developments, often with the precursor system forming over land. There is an average of 1.3 occurrences per year of ‘regeneration’ whereby a cyclone develops from a pre‐existing cyclone which has lost intensity after crossing on to the continent.A synoptic analysis of individual developments over five years reveals that 84 per cent of the pre‐cyclone cloud clusters first appear on the gradient level monsoon shear line, whereas 97 per cent are on the shearline at the point of development. Statistical evidence is given for the enhancement of lower and upper level vorticity fields by mid‐latitude systems prior to cyclone genesis, but on a case by case basis the role of these systems is highly variable.The structure of the pre‐cyclone systems for individual cases and composites shows the upper level warm core and large scale cyclonic surrounding circulation in the middle and lower troposphere, known to exist for similar systems in other parts of the world. At upper levels the systems are surrounded by tangential winds in the anticyclonic sense beyond 6 degrees latitude radius.
Climate and energy balance on the arctic tundra
Authors: Ohmura Atsumu 
Published: February 2007

AbstractEnergy balance measurement on the arctic tundra on the midwest coast of Axel Heiberg Island, N.W.T., Canada, is summarized. The methods and the instruments as well as their difficulties in the arctic field conditions are described. The seasonal characteristics of the energy balance are presented for the dry snow, the melt and the postmelt periods. The diurnal variations of the energy balance for each of these periods are also presented.The climatic differences for the regions of the tundra, glaciers and the arctic seas become prominent during the three summer months of June, July and August. The energy balance at the present site is compared with that of Barrow, Alaska, revealing a high degree of similarity. The slight differences between them are more net radiation, more sensible and latent heat fluxes, larger Bowen ratio and less soil heat flux at Barrow. These differences are considered to be due to the larger distance of the present station from the coast.The energy balance on and in the dry snow cover is investigated. The stability of the snow cover is attributed to the high reflectivity as well as to the large absorptivity of its surface with respect to solar radiation. The absorption occurs mainly at the surface of the snow cover rather than its interior. This condition facilitates the efficient removal of the absorbed energy from the surface by the atmosphere.The energy balance on the tundra is compared with those on the Central Arctic Ocean, the ablation area of the polar glaciers, the accumulation area of the glaciers and the boreal forests. The surfaces of the tundra, ablation area of the glaciers and the Central Arctic Ocean are found to receive similar net radiation, despite the albedo differences. The fundamental difference among these surfaces is the magnitude of the latent heat of melt. This component on the ablation area of the glaciers and the Central Arctic Ocean is four to six times larger than on the tundra, which results in differential heating and evaporation in these regions. This difference is considered to be the basis of the milder climate in the tundra region in the Arctic.More substantial differences are found between these low altitude arctic surfaces and the accumulation areas of the glaciers and the boreal forests. The differences are due to the large variation in albedo for the former and to the difference in global radiation for the latter. These differences ultimately regulate the regional variations in net radiation, sensible and latent heat fluxes.
Studies of the indian summer monsoon with a coarse‐mesh general circulation model, part 1
Authors: Druyan Leonard M. 
Published: February 2007

AbstractA coarse‐mesh (8° latitude × 10° longitude), global domain climate model is shown to produce useful simulations of the sea‐level pressure and the precipitation distribution over south Asia during spring and early summer. Although the computations produce excessively fast development of the monsoon trough, the trend of increasing rainfall over the Indian subcontinent finds expression in the simulations. The model precipitation increases seasonally too early over southern India but the pattern by July correctly depicts a maximum south of the Tibetan plateau.Four pairs of simulations during the model onset month tested the sensitivity of the onset to small arbitary differences in atmospheric stale. The results suggest that the timing of Indian precipitation may not be predictable from consideration of antecedent measurable atmospheric parameters.
Principal component analysis of the lamb catalogue of daily weather types: Part 1, annual frequencies
Authors: Jones P. D. , Kelly P. M. 
Published: February 2007

AbstractPrincipal component analysis is applied to annual weather type frequencies for the British Isles. The results objectively define characteristic relationships between the different types, and are used to determine changes in the atmospheric circulation in the region of the British Isles over the period 1861 to 1980. It is shown that, as far as annual frequencies are concerned, only six (of the 27) weather types are needed to define and monitor changes in the atmospheric circulation.The component amplitudes are correlated with temperature and rainfall data, and physically reasonable relationships are identified. The analysis is extended to the period 1781 to 1785, and similarities are found between the extremes experienced during that period and during the 1970s.
Analysis of the spatial pattern of July temperature departures (1943–1972) over Canada and estimates of the 700 MB midsummer circulation during middle and late holocene
Authors: Diaz Henry F. , Andrews John T. 
Published: February 2007

AbstractThe pattern of July temperature variability over Canada north of ∼50°N for the period 1943–1972 has been analysed by means of principal component analysis. Our objective was to assess the spatial similarities between modern temperature fluctuations at the interannual scale and those derived from paieotempe nature records encompassing a period of the last 6000 14C years.A comparison of the first four principal components from each data set suggests that contemporary midsummer temperature variations offer a reasonable analogue to Holocene fluctuations on the order of a few centuries. The Keewatin‐Baffin Island‐Ungava Peninsula region appears to be within the area of maximum temperature response.
Drought in the United States: 1895–1981
Authors: Karl Thomas R. , Koscielny Albert J. 
Published: February 2007

AbstractStatewide averages of temperature and precipitation, from January 1895 to April 1981, were interpolated to a grid and Palmer Drought Severity Indices (PDSI) calculated for each of the grid points. Principal component (PC) analysis was performed on the gridded values of PDSI. By rotating the PC, nine readily identifiable patterns of drought are delineated. Each PC relates to different regions of the country, and is characterized by a distinct annual oscillation of monthly average precipitation. A high degree of confidence is placed in the state gridded data as patterns compare favourably to those derived using smaller averaging areas.Univariate and multivariate autoregressive spectral estimation procedures together with the traditional spectral estimation techniques were used to investigate the spectra and coherence of the PC scores. No significant cycles were found in the 86‐year (1036 months) data set. Coherence was very low (<0.30) for all frequencies between the various patterns depicted by the PC.Both the spectra of PC scores and drought duration statistics point to the major difference in droughts across the United States; droughts persist much longer in the interior portions of the country than in areas closer to the coasts. Sensitivity tests on the PDSI indicate that this is not directly attributable to the spatially varying available soil water capacity parameter used in the PDSI calculations. This is not to say that soil moisture evaporation does not indirectly influence drought duration, but merely that the differing lengths of droughts in the United States are real and not an artefact of the mechanics in the PDSI calculations.
Climate reconstruction from tree rings: Part 1, basic methodology and preliminary results for England
Authors: Briffa K. R. , Jones P. D. , Wigley T. M. L. , Pilcher J. R. , Baillie M. G. L. 
Published: February 2007

AbstractRing widths of oak trees (Quercus petraea Liebl. and Q. robor L.) from a network of 14 sites (13 in the British Isles and one in France) are used to reconstruct spatially‐averaged temperature and rainfall for England. A multiple linear regression technique is used, in which the regressors are orthogonal principal components of the ring widths. The multiple correlation coefficients are, statistically, highly significant, and the regression models' stability has been confirmed using independent data. These results demonstrate the usefulness of tree‐ring widths for climate reconstruction in temperate, maritime areas.
The spatial and temporal characteristics of northern Hemisphere surface air temperature variations
Authors: Jones P. D. , Kelly P. M. 
Published: February 2007

AbstractThe spatial and temporal characteristics of variations in surface air temperature over the Northern Hemisphere landmasses during the present century are determined. The spatial patterns of change accompanying major warming and cooling episodes are mapped. The spatial representativeness of the Northern Hemisphere average is assessed and implications for proxy climate studies are considered. Finally, the seasonal breakdown of trends and correlations between monthly and annual data for the Arctic and Northern Hemisphere is considered.It is shown that, although generally similar, significant differences in the spatial patterns of change accompanying warming and cooling in the Northern Hemisphere average have occurred. In particular, the early 20th century warming was more coherent spatially (as well as more rapid and stronger) then either the cooling that followed or the recent warming. Various regions tend to vary consistently with the Northern Hemisphere average but the relationships are not as marked or widespread as some investigators have claimed or assumed.The annual Northern Hemisphere average is shown to be more strongly correlated with late spring and summer temperatures than with winter temperatures (although in the latter season the variability is greatest). Trends in temperature over the Northern Hemisphere have been strongest in April and May, whereas over the Arctic they have been strongest in January. This seasonal distribution may give an indication of the physical mechanisms underlying these climatic variations.
An example of the climatological processing of the atmospheric landscape component
Authors: Prošek P , Brázdil R. 
Published: February 2007

AbstractThe paper describes the methods and main results of processing the atmospheric component of the landscape on the scale of the local climate in the surroundings of the towns of Rosice and Oslavany over an area of about 280 km2.The analysis of the local climate is based on the results of measurement of the authors' own network of 13 topoclimatic stations and on processing the material from 5 precipitation measuring stations from the network of the Czech Hydrometeorological Institute.For characterizing the local climate of the studied territory 9 characteristics of the diurnal regime of air temperature and humidity and the annual regime of precipitation were used, for which correlation and regression relations to the parameters of the relief (height above sea level, angle and. azimuth of slope) of the territory studied were determined. Finding the regression relations enabled the extension of point measurements of meteorological elements to the whole area of the territory studied and by means of statistically determined intervals of extremity of the characteristics employed to fill with them the basic information system‐a hexagonal network covering the territory under investigation. This in turn made it possible to outline partial climatomesochores in the territory of interest.By the summation of the values of selected characteristics of meteorological elements an overall characteristic of the local climate was determined, the so‐called relative climatic potential.
Independence of rainfalls through the rainy season and the implications for the estimation of rainfall probabilities
Authors: Dennett M. D. , Rodgers J. A. , Stern R. D. 
Published: February 2007

AbstractA detailed study of more than 50 years of daily rainfall records from three sites in seasonally arid West Africa revealed no dependence between rainfall at different times within the rainy season. Years were grouped on the basis of the date of the start of the rains and rainfall models fitted separately to early, medium and late start groups. Any differences between the groups in subsequent rainfall pattern bordered on statistical significance and were too small to be of practical significance. Thus, the best estimates of the probabilities of rainfall events are obtained by considering all years of the rainfall record. As rainfalls at different times of the season can be assumed to be independent, it is straightforward to calculate conditional distributions, for example, the probability distribution of the length of the rains given the actual starting date. The calculation and value of using conditional distributions are discussed.
Rainfall distribution, variability and probability in plateau state, Nigeria
Authors: Odumodu L. O. 
Published: February 2007

AbstractThe basic objective of this investigation is the determination of the spatial distribution of rainfall in Plateau State. Nigeria. The results show that the greatest amounts of rainfall are obtained in the southern and western parts of the State and on the southern and western margins of the high Plateau in particular. This pattern of rainfall distribution is explained partly by the movements and positions of the ITD (intertropical discontinuity) at various times of the year, and partly by the interplay of the direction of rainbearing south‐westerly winds with the physiographic features in the State.In general, also, the rainfall amounts are higher on the highland parts of the Stale than on the lowlands. Conversely, rainfall variabilities are higher on the lowlands of the State than on the high Plateau. Furthermore, rainfall variabilities are higher at the beginning and at the cessation of rainfalls than in the middle of the rainy season. Examples of implications of high rainfall variability and low probability of receiving certain given threshold amounts of rainfall at different phenological stages of crop developments, are given. These examples serve to substantiate the need for supplementary irrigation facilities in the Slate.
Monthly extreme air temperatures at Rothamsted
Authors: Challenor P. O. , Carter D. J. T. 
Published: February 2007

AbstractMonthly minimum and maximum air temperatures recorded at Rothamsted in Hertfordshire, England, from 1901‐1978 are analysed using the generalized extreme value distribution. Temperatures with return periods of 50 and 100 years, with their associated confidence limits, are produced for each month. The very low temperatures recorded in December 1981 and January 1982 are considered in the light of these results. The probability of air frost for each month is evaluated. From the distributions of monthly extremes the distributions of annual minima and maxima are derived. The assumptions implicit in the analysis, independence and stationarity, are examined. It is found that the data can be considered stationary in all cases except for the October minima, which appear to have been increasing over recent years. Correlations between monthly extremes are generally low with little discernible pattern, but confidence limits have not been determined.
Quasi‐periodic meteorological series and second‐order autoregressive processes
Authors: Jolliffe Ian T. 
Published: February 2007

AbstractQuasi‐periodic behaviour in meteorological or climatological series is a widespread phenomenon; various attempts have been made to explain such behaviour in physical terms, often invoking external influences in the explanations. While it is not disputed that external influences or feedback mechanisms may have a part to play, it is argued in the present note that a substantial part of quasi‐cyclic behaviour can often be explained by a simpler mechanism, namely second‐order dependence of a series on its own past. The plausibility of second‐order dependence is discussed, and the way in which such dependence leads to quasi‐periodic behaviour is described. Data on sunspots. Baltic ice area and a zonal circulation index are used to illustrate these ideas.
Water need in provence, Languedoc‐Roussillon (southern FRANCE)
Authors: Giles B. D. 
Published: February 2007

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 considered.
The influence of clouds on climate with A focus on high latitude interactions
Authors: Crane K. G. , Barry R. G. 
Published: February 2007

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 change.
The distance factor in the relationships between solar radiation and sunshine
Authors: Baker Donald G. , Skaggs R. H. 
Published: February 2007

AbstractThe effect that distance (d) has upon the correlation coefficient (r) obtained between paired radiation (R) and sunshine (S) stations was determined for the North Central region of the United States. Distances between stations varied from 0 to 608 km.In the regression of r against d three features of interest were found. First, the slope of the annual r values with distance is essentially linear from about 60 to 550 km and equals about −0.12/100 km. Secondly, from d = 0 to 60 km, the value of r remains constant at about 0–88, creating a ‘zone of indifference’ due to inherent differences between radiation and sunshine recording instruments and the insensitivity of the latter. Thirdly, beyond about 550 km the slope appears to reach a constant value, which varies with season but is about r = 0–30 on an annual basis.Seasonal and geographical differences in the degree of correlation between r and d are noted and discussed briefly.
On the homogeneity of the annual temperature of central England since 1659
Authors: Probert‐Jones J. R. 
Published: February 2007

AbstractTwo statistical models are developed to represent the annual temperature of central England from 1659 to 1973, and two similar models to represent the annual standard error (continentality). From these models, 95 per cent confidence intervals are obtained for the highest and lowest means over periods of 10, 30 and 50 years in a sequence of 315 years. Within the limits of accuracy of both the data and the models, no mean lies outside the confidence intervals, and it is concluded that in terms of both annual temperature and annual standard error the climate of central England is statistically homogeneous over these 315 years. Nevertheless, the 25 year period 1674–1698 was particularly cold, and may possibly represent the end of the ‘little ice age’ if it existed.
Synoptic consideration of snowfall in Athens
Authors: Prezerakos N. G. , Angouridakis V. E. 
Published: February 2007

AbstractIn this paper an attempt is made to study the synoptic evolution of the barometric systems which cause snowfall in Athens. Some simple statistical characteristics of the snowfall in Athens were found and related to the synoptic evolution.The study is based on the synoptic observations at the Hellinikon Meteorological Station for the period 1956–1973 and upon the mean charts and their anomalies, of 500 mb height, 500–1000 mb thickness and mean sea level (M.S.L.) pressure.Specifically, we examine the annual and monthly variations of snow days in Athens and their relation to the synoptic evolution of two synoptic types, A and B.In type A, the centre of action seems to be a quasi‐stationary wedge of a meridional block which, on the 500 mb charts, is located over the British Isles and NW Europe. This wedge is accompanied by a maximum of positive height anomalies and it steers, on its eastern flank, smaller perturbations which reach Greece accompanied by polar or arctic air.In type B, the centre of action is located over the north of Scandinavia with the form of an Omega block on the 500 mb charts. On the eastern flank of this system, a maximum of vorticity is created moving south‐south‐westwards, arriving over Greece from the northeast.
The influence of weather variability on evaporation leeward of A medium porous barrier
Authors: Rollin E. M. 
Published: February 2007

AbstractBlack porous disc atmometers were used to measure daily evaporation (E) at a distance of 4H (where H is barrier height) leeward of a medium porous hedge and in the open. The modification of E at the sheltered position was defined, in relative terms, as the percentage of the sheltered E to that in the open (relative E) and in absolute terms as the difference between the open and sheltered E totals. Although relative E was found to vary as a linear function of the relative wind (RW), E differences varied also with the meteorological conditions influencing the ‘evaporative climate’, identified here by the weather parameters: cloud cover, relative humidity and wind speed. For a particular value of relative E, the E differences were greatest on days with no cloud, low humidity and moderate wind speed and least on cloudy, humid days with low wind speed.