bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatial variations and trends in the Indian monsoon rainfall
Authors: Subbaramayya I. , Naidu C. V. 
Published: February 2007

AbstractThe spatial and temporal variations of the monsoon rainfall over India have been studied using the subdivisional rainfall data for the years 1871–1988. North‐west India and north peninsular India are found to constitute two homogeneous regions. North‐east India does not constitute a single homogeneous region since the rainfall variations in Bihar and Bengal are somewhat different from those in Assam and the Sub‐Himalayan region.Trends in the monsoon rainfall in different subdivisions and in the whole of India also have been examined. In the monsoon rainfall, decreasing trends during late nineteenth century and again in the 1960s are observed. The latter trend was reversed in the early 1970s. These trends are seen prominently in central and western Indian subdivisions, however, there are major differences in the epochs of changes in the trends in different subdivisions. The decreasing trend observed in the 1960s is still continuing in the central north Indian divisions, while in the adjoining divisions, the reversal took place in the early 1970s.
An observed poleward shift of the southern hemisphere subtropical wind maximum—a greenhouse symptom?
Authors: Gibson Timothy T. 
Published: February 2007

AbstractA 16–year (1976–1991) record of mean winter values of the zonally averaged latitude of the subtropical wind maximum (STWM) in the Southern Hemisphere is examined, and reveals a significant trend towards higher latitudes. This poleward shift of the STWM, which has a magnitude of 0.18° of latitude per year, is in agreement with the expected consequences of an enhanced greenhouse effect (EGE), and may indeed be regarded as a rather sensitive indicator of the reality of climatic impacts of the EGE, as it is a result of changes in temperaturegradients, rather than general increases in temperature.
Daily meso‐scale rainfall in the tropical wet/dry climate of the Townsville area, north‐east Queensland during the 1988–1989 wet season: Synoptic‐scale airflow considerations
Authors: Lyons W. F. , Bonell M. 
Published: February 2007

AbstractDaily rainfall during the 1988–1989 summer wet season, occurring at a dense meso‐scale network of 133 rain‐gauge sites in the Townsville region (3450 km2) of tropical north‐east Queensland, is analysed to yield indices of rainfall activity for 13 distinct synoptic circulations. Composite correlation field maps for the three most common synoptic circulations are also presented. The influence of topography and exposure to moisture sources emerges as the major control of rainfall distribution and amount, such that meso‐scale rainfall activity relates to synoptic‐scale wind vectors, which provide the steering of rainfall‐producing systems. In addition, the interaction between local winds, topography, and synoptic circulation is demonstrated, through the use of case studies, to be important for generating localized uplift and precipitation. This rainfall is then steered by the prevailing upper synoptic flow. Previous studies of rainfall in the tropics have not emphasized the importance of the interaction between local controls and the synoptic circulation for providing distinct meso‐scale rainfall patterns, and have rarely used a dense network of rain‐gauges.
Specification and prediction of monthly and seasonal precipitation amounts in California and Arizona river drainage basins
Authors: Klein William H. , Bloom Hal J. 
Published: February 2007

AbstractA forward selection procedure of stepwise regression is applied to 30 years of data to develop a set of multiple regression equations for percentiles of monthly and seasonal precipitation amounts (P) in high altitude river basins of California and Arizona during periods of 1–4 months in duration. Two main methods are used. The first is specification of P from simultaneous values of the field of 700 hPa mean height anomalies (H). The second is pure prediction, which uses only previous (observed) data as potential predictors. On average, 61 per cent of the monthly P variance is explained by specification equations containing about three concurrent values of H; seasonal specification equations explain about 2 per cent more of the variance by means of slightly fewer heights. In contrast, only 16 per cent of the prediction equations are significant at the 95 per cent level determined by a Monte Carlo test. All these equations select the local value of P observed during the month prior to the target period as the most important predictor.
Supplementing solar radiation network data by co‐Kriging with satellite images
Authors: D'Agostino V. , Zelenka A. 
Published: February 2007

AbstractObservations made in 1982 from the Swiss meteorological network are used to assess the precision of geostatistically predicted daily global horizontal insolation. Results of such predictions are compared with insolation estimates obtained from the imagery of the meteorological satellite METEOSAT.Application of Kriging to the network data yields cross‐validation results that are very close to the validation results of the satellite estimates, namely unbiased prediction with about 3 MJ m−2 root mean square error (RMSE) on a daily total measured mean (MM) of 18.9 MJ m−2. Co‐Kriging applied to both data sets helps to reduce the RMSE to about 2.5 MJ m−2. As the application occurs under simplifying assumptions to allow use of a PC, and that there is, therefore, much room for improvements, we conclude that co‐Kriging appears promising for detailed global insolation mapping.
Variations of sea‐surface temperatures off north‐eastern Australia and associations with rainfall in Queensland: 1956–1987
Authors: Lough J. M. 
Published: February 2007

AbstractSpatial, seasonal, and interannual variations of sea‐surface temperatures (SSTs) in the area 0.30°S, 130–180°E are examined for the period of 1956–1987. Sea‐surface temperatures in this region are high throughout the year with an annual range of only 0.5°C close to the Equator, increasing to 5.0°C, south of 24°S. Interannual variability of SSTs is highest and year‐to year persistence of anomalies is lowest in October‐November. Interannual variability is lowest and year‐to‐year persistence is highest in April‐May. Sea‐surface temperature anomalies developed in June‐July are more likely to persist through subsequent seasons than SST anomalies developed in December‐January. Interannual variations of SSTs are related more closely to Queensland rainfall variations in the winter season than in the summer season. In the summer season, SST‐rainfall linkages are dominated by co‐variations of these two variables with the Southern Oscillation. In the winter season, significant associations between SSTs and rainfall are present in the absence of large variations of the Southern Oscillation.
Numerical simulation of cut‐off lows on the Australian east coast: Sensitivity to sea‐surface temperature
Authors: McInnes Kathleen L. , Leslie Lance M. , McBride John L. 
Published: February 2007

AbstractThe occurrence and synoptic‐scale structure of cut‐off lows near the Australian east coast are documented. These systems are associated with severe weather in the south‐east Australian states of New South Wales and Victoria. Two types of cutoff low formation are identified, described here as coastal lows and blocking lows.Twenty‐four hour numerical simulations are performed for four systems in order to investigate the model‐reproduced structure of the large‐scale rainfall and gale‐force wind. The numerical experiments demonstrated that the regional‐scale model is capable of simulating the heavy rainfall and gale‐force winds associated with these systems. All systems are characterized by a major rain band curling around the south and east of the surface low. To the south of the system the rain band is paralleled by a curved band of gale‐strength winds. The sensitivity of these parameters and of mean sea‐level pressure to underlying sea‐surface temperature (SST) fields also is investigated through numerical experimentation.When the SSTs were increased by between 2° and 3°, the simulated cut‐off lows had deeper central pressures, usually of 1–2 hPa. In one case the extra deepening was dramatic, being 7 hPa at 24 h. The impact on rainfall was considerable, especially on the peak values, which were increased by between 45 per cent and 80 per cent, and on the areal mean values in ‘catchment size’ areas surrounding the peak value. In contrast the peak surface winds were increased only by about 10 per cent, but the areal extent of gale‐force winds increased greatly, by between 50 per cent and 70 per cent.The large sensitivity of these weather elements to SST is discussed in terms of possible implications for both short‐term operational forecasting and for regional effects of enhanced greenhouse climate change.
Australian runoff scenarios from A runoff‐climate model
Authors: Morassutti M. P. 
Published: February 2007

AbstractData of changes in precipitation and evaporation as computed from the GISS GCM for three scenarios of transient levels in trace gas concentration were used as input into the runoff‐climate model of Wigley and Jones to estimate changes in annual runoff regimes for three regions in Australia: Murray‐Darling (south‐east), Lake Eyre (central), and Timor Sea (northern) Drainage Divisions. All regions were calculated to have significant increases in mean annual runoff regardless of the GISS scenarios, due chiefly to the combination of intense aridity (e.g. low runoff ratios) and substantial changes in precipitation and evaporation as predicted by the GISS GCM. Also, attributes of the runoff‐climate model are related to their applicability and accuracy in runoff prediction.
Temporal characteristics of USA snowfall 1945–1946 through to 1984–1985
Authors: Leathers Daniel J. , Mote Thomas L. , Kuivinen Karl C. , McFeeters Stuart , Kluck Douglas R. 
Published: February 2007

AbstractThe temporal variability of USA snowfall is investigated for the period 1945–1946 through to 1984–1985 using linear trend and principal components analyses. The results of the linear trend analysis indicate that two regions of the USA evidence significant changes in monthly snowfall over the period. These areas include the Great Lakes/upper mid‐west and high plains regions of the USA. In the Great Lakes/upper mid‐west sector, positive linear trends are found in monthly snowfall totals for the mid‐winter months (December, January, February). For the high plains region, positive linear trends are found for the month of December. Principal components analysis (PCA) is used with seasonal snowfall data in order to better understand the spatial and temporal nature of seasonal snowfall variations across the USA. The PCA isolates six spatially coherent regions in which seasonal snowfall varied similarly over the 40‐year period. Only one of these regions, centred on the Great Lakes and upper mid‐west, displays any long‐term change in seasonal snowfall, a positive trend during the period 1945–1946 through to 1984–1985. These results are discussed in the context of man‐induced and natural environmental changes.
Water vapour transport over Southern Africa during wet and dry early and late summer months
Authors: D'Abreton P. C. , Lindesay J. A. 
Published: February 2007

AbstractSouthern Africa is semi‐arid to arid, and the moisture that contributes to rainfall over the summer rainfall region is largely imported from other areas. Interseasonal and interannual variations in rainfall must result from changes in the circulation and in vapour fluxes over the subcontinent. It is shown that important changes in vapour fluxes occur between October (early summer) and January (late summer), with zonal fluxes being more important in October and meridional fluxes in January. Wet and dry months of October and January are characterized by enhanced zonal (meridional) flow in wet Octobers (Januaries), and reduced importance of these flows in the dry months. Adjustments in the areas of vapour flux convergence and divergence are as important as changes in the fluxes. The convergence and divergence changes between wet and dry months are confirmed by decreases in outgoing longwave radiation over central southern Africa in wet months and increases in dry months. Tropical zonal circulations, and tropical—subtropical meridional circulation cells, conform to the patterns of enhanced (reduced) convection over the central subcontinent in wet (dry) months.
Satellite OLR and microwave data as a proxy for summer rainfall over sub‐equatorial Africa and adjacent oceans
Authors: Jury Mark R. , Pathack Beenay , Waliser Duane 
Published: February 2007

AbstractThe potential for using satellite outgoing longwave radiation (OLR) and passive microwave data as a proxy for rainfall over sub‐equatorial Africa and adjacent oceans is explored. Correlations between anomalies of field OLR and a summer rainfall index are −0.67 to −0.93 over central southern Africa, where the amplitude of interannual fluctuation in the decade 1975–1984 is largest. OLR‐rainfall correlations decline to −0.42 over Madagascar owing to a less homogeneous distribution of rainfall. Over South Africa during the winter dry season the correlation becomes positive except over the eastern seaboard where sea‐surface temperatures remain high.Satellite microwave estimates of cloud liquid water (LW) over the oceans surrounding southern Africa are presented for selected months during 1988 and 1989. Agreement is found between coastal rainfall and adjacent oceanic LW patterns. Contrasting distributions of interior and coastal rains in January and October 1989, respectively, are associated with the positioning of standing troughs evident in concentrated areas of high LW values in the mid‐latitudes. The advance and structure of the Inter Tropical Convergence Zone (ITCZ) over the tropical South‐west Indian Ocean is illustrated in monthly composites.
West African rainfall deficits and sea surface temperatures
Authors: Fontaine Bernard , Bigot Sylvain 
Published: February 2007

AbstractComparisons between years of below average rainfall over West Africa, sea‐surface temperatures (SST) over the Atlantic Ocean and the world ocean, and latitudinal positions of the Inter Tropical Convergence Zone (ITCZ) over the Atlantic Ocean show that the relationships depend mainly on the rainfall anomaly patterns. The well‐known SST dipole (cold northern ocean and warm equatorial and southern ocean) is only apparent during those August months with below average Sudano‐Sahelian rainfall and above average Guinean rainfall (rainfall type ‘−/+’) and an abnormal southward position of the ITCZ. In contrast, those August months that experience rainfall deficits over the whole of West Africa (rainfall type ‘−/−’) are associated with warm SST anomalies over the eastern Pacific Ocean, cold persistant SST anomalies over the equatorial Atlantic Ocean and a more northward position of the ITCZ. Those patterns first appear in northern spring before the Sahelian rainy season.The composite SST differences for the ‘−/+’ and ‘−/+’ rainfall types computed with August or July‐September amounts have a good resemblance with each other. Comparison of results related to the reverse July‐September rainfall patterns (the ‘+/−’ and ‘+/+’ patterns) during the 1950s shows that the SST anomalies were globally colder when, on average, the Sahelian rainy seasons experienced significant excesses while the Guinean little dry seasons were more marked.
Comparison of coastal wind and pressure trends over the tropical atlantic: 1946–1987
Authors: Bigg Grant R. 
Published: February 2007

AbstractStrengthening of the Atlantic Trade Winds since 1946 has been documented by several workers. This is broadly consistent with changes in the atmospheric pressure patterns over the tropical Atlantic. Here ship‐recorded pressures are compared with sea‐level pressures recorded from 49 coastal sites in order to validate the trends in the pressure patterns. Good correlation is found between the two independent sets of pressure measurements; a comparison of trends reveals statistically significant agreement along the African coast but disagreement in the western Atlantic and Caribbean. Island stations generally show poorer correlation with adjacent marine pressures than do continental stations. A degree of support for the observed marine trends is therefore provided by this analysis but it appears that, particularly for islands, marine and adjacent land areas are not always strongly coupled meteorologically.
A connection between mean wave height and atmospheric pressure gradient in the North Atlantic
Authors: Bacon S. , Carter D. J. T. 
Published: February 2007

AbstractComparison of long‐term trends in mean wave height in the North Atlantic with values of annual mean atmospheric pressure gradient in the North Atlantic measured between the Iceland Low and the Azores High suggests, for the period of overlap between the data set of Bacon and Carter and of Sahsamanoglou (early 1950s to 1980), a correlation between these two measures. This paper, using monthly mean values of significant wave height (HS) derived from measurements at two sites, one oceanic (Ocean Weather Station Lima) and one coastal (Seven Stones Light Vessel), covering the period 1962–1988, investigates correlation between (firstly) annual mean values and (secondly) monthly mean values of HS and of pressure gradient. The annual mean values of pressure gradient are shown to be linked to the long‐term changes in wave climate described by Bacon and Carter. The large annual cycles in the monthly mean values of both variates are found to be in phase; furthermore, correlation between the two variates independent of the annual cycle is found. Finally, the correlation between the annual means is used to generate a hindcast mean wave climate for Seven Stones Light Vessel (and also, tentatively, for the whole north‐east Atlantic) from 1873 to the present, which suggests that present conditions are as high as have been observed since 1873.
Temporal variations of the vertical profile of temperatures of Argentina
Authors: Duarte Maria Luz 
Published: February 2007

AbstractCharacteristics of the spatial and temporal variability of tropospheric and low stratospheric temperatures of Argentina during the period 1965–1982 are investigated.Empirical orthogonal functions (EOFs) were used to obtain the main characteristics of the vertical profile of temperature in three climatic regions, and time series of the temporal coefficients are analysed as indicators of temporal variations. The results indicate that there was an almost homogeneous upward trend in summer of the tropospheric temperatures (downward for stratospheric temperatures) in tropical and mid‐latitude regions.
The influence of variable weather patterns on river water quantity and quality regimes
Authors: Wilby R. L. 
Published: February 2007

AbstractThere is growing awareness as to the potential sensitivity of hydrological systems to climate change. In particular long‐term changes in precipitation variability will have consequences for runoff regimes and thence solute transport. By utilizing the Lamb's Weather Type register in conjunction with observed 24 h rainfall totals it was possible to determine daily precipitation event probabilities and magnitudes for eight dominant synoptic classes. The stochastic rainfall series thus generated were then used to drive a robust hydrochemical model of an experimental catchment in the East Midlands, UK. The model results indicate that the frequencies of flood and drought are dependent upon the synoptic scenario, and especially the historical prevalence of both the anticyclonic and cyclonic patterns. Given that there have been marked fluctuations in the annual frequencies of these classes since the mid‐nineteenth century, long‐term variations in the severity and incidence of extreme flows may be anticipated. Clearly this will have major implications for the episodic export and dilution of solutes, sediments and microorganisms originating from both pristine and polluted hydrosystems.
Global land‐surface albedo modelling
Authors: Rowe Clinton M. 
Published: February 2007

AbstractThe climatic impact of changes in terrestrial albedo has been studied using numerous climate models, ranging from simple, one‐dimensional energy balance climate models to the most complex, three‐dimensional general circulation models of the atmosphere. In the majority of these studies, the land‐surface albedos have been prescribed both spatially and temporally from albedo observations. The effects of variations in albedo, due to such factors as the angular distribution of incident radiation and plant phenology (especially leaf emergence, senescence, and drop), cannot be deduced from these observation‐based albedos.To overcome the limitations of using observed land‐surface albedos in climate models, a model of radiation transfer in plant canopies was used to predict vegetation albedo. This model incorporates the optical properties of the vegetation and soil surface as well as the micro and macrostructure of the canopy. Because of the model's reliance on these physical properties of the land‐surface cover, it is able to account explicitly for albedo variations caused by factors both internal and external to the vegetation canopy.Using the physiognomic classification of natural vegetation developed by Küchler, representative canopy architectures for each of 31 vegetation types were developed for each month of the year. Monthly albedos were then simulated for each vegetation type under a range of irradiance distributions. When these results are compared with existing observations of plant canopy albedo, the degree of correspondence is, in many cases, quite good. Moreover, the dependence of albedo on irradiance distribution predicted by the model agrees well with established theory.Global maps of land‐surface albedo are produced for both clear‐sky and overcast conditions in January, April, July, and October using a simple solar radiation model to determine the incident radiation field. These maps are compared with previously compiled maps of land‐surface albedo. Large differences between the model‐ and observation‐based global albedo maps occur for each of the four months. However, the model reproduces many of the large‐scale features and seasonal trends evident in albedo observations.
Cyclone tracks and wintertime climate in the mid‐atlantic region of the USA
Authors: Knappenberger Paul C. , Michaels Patrick J. 
Published: February 2007

AbstractThe relationship between cyclone tracks and the climate has been studied for over two centuries. Most studies, however, describe only qualitatively the link between these phenomena. Thus, the understanding of the true nature of this relationship is not complete. The goal of this work is to help fill this lack of understanding by describing quantitatively the relationship between cyclone tracks and wintertime climate in the mid‐Atlantic region of the USA.Canonical correlation analysis (CCA), which is used to help achieve this goal, is a statistical technique that finds the optimum correlation between two fields of data. Canonical correlation analyses are performed to relate a gridded cyclone frequency data set to precipitation, snowfall, and temperature data sets for the winter seasons from 1930 to 1989.The results of these analyses reveal a strong correlation between an abundance of cyclones in the Ohio Valley, and below normal precipitation and snowfall amounts, and above normal temperatures across most of the mid‐Atlantic region. Conversely, an abundance of storms along the southeastern Atlantic coast is associated with above normal precipitation and snowfall amounts, and lower than normal temperatures over the region. Since these relations are described by the first canonical variable pair in each analysis, they represent the strongest relationship between the data fields. Therefore, these results indicate that the oscillation between the frequency of Ohio Valley cyclones and the frequency of Atlantic coastal cyclones plays an important role in the year‐to‐year patterns of wintertime climate in the US mid‐Atlantic region.