bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatial and temporal analysis of the palmer drought severity index over the south‐eastern United States
Authors: Eder Brian. K. , Davis Jerry M. , Monahan John F. 
Published: February 2007

AbstractThe spatial and temporal variability of the Palmer drought severity index (PDSI) over the south‐eastern United States during the period 1931–1982 was examined through the use of principal component analysis. Spatial mapping of the component loadings identified six statistically significant modes of variability or PDSI anomaly patterns, which together account for 77.3 percent of the total variance. The first component, which represents the dominant pattern, accounted for 43.4 per cent of the total variance and identified an in‐phase oscillation across the entire study area, indicating a general tendency for all sections to experience either a drought or a wet spell concurrently. The remaining five components, which account for 33.9 per cent of the total variance, each identified an out‐of‐phase oscillation. Application of Kaiser's Varimax orthogonal rotation on the six retained principal components led to the identification of six contiguous subregions of nearly equal size, each of which displays unique drought characteristics.Examination of the time series derived from the principal component scores within each subregion revealed a general trend in which the occurrence of drought was much more prevalent during the first three decades of the study period, culminating during the mid 1950s when most of the subregions experienced their worst drought episode.After removal of the inherent ‘red noise’ persistence found in the monthly PDSI data, spectral and cross‐spectral density analysis performed on the time series indicated that no cyclical patterns or periodicities were present.
A regionalization of Austria's precipitation climate using principal component analysis
Authors: Ehrendorfer Martin 
Published: February 2007

AbstractS‐mode principal component analysis (PCA) is performed on correlation matrices of precipitation data of Austria for summer and winter half‐year totals for the period 1951–1980. Application of the dominant‐variance selection Rule N (Overland and Preisendorfer, 1982) proves two or three eigenvalues to be significant, where three principal components (PCs) on average account for 68.3 and 79.4 per cent of total variance in the summer and winter half‐years, respectively. The Varimax‐rotated PC loadings allow for a subdivision of Austria into three homogeneous (with respect to the underlying processes) regions.Intercomparison of the PC primary patterns, variances and time series of the principal components of three different networks confirms the spatial stability of these regions and turns attention towards seasonal differences. The three PCs are identified by assignment of large‐scale weather types to them which are known to be precipitation producing in the region wherein the respective PC is dominant.The results of this study and their wide variety of applicability reveal PCA and Rule N as useful tools in identifying homogeneous groups of variables which can be ascribed a physical meaning. The paper contains a short account of the analysis of empirical orthogonal functions, the theory of PCA and its connection to factor analysis.
On the estimation of annual and monthly mean values of sunshine duration over Greece
Authors: Flocas A. A. 
Published: February 2007

AbstractAnnual and monthly values of sunshine duration at thirty‐seven stations in Greece are examined with the three factors of latitude, longitude and altitude by means of stepwise multiple regression analysis. The validity of the assumption that there is a linear relationship between the mean values of sunshine duration and these three factors is examined. A seasonal variation is evident in all the computed gradients of the sunshine duration, with altitude effects being at a maximum in summer, whereas the effects of latitude were most pronounced during the cold season. The thirteen empirical formulae produced do not account completely for all the variability in the data, but the resultant correlation coefficients range from 0.830 to 0.906. The residuals (i.e. differences) between actual and calculated values of sunshine duration are shown on representative maps which may be used (with the regression equations) to estimate sunshine at any locality in Greece.
The energy balance in the coastal environment of James Bay and Hudson Bay during the growing season
Authors: Rouse Wayne R. , Hardill Steven G. , Lafleur Peter 
Published: February 2007

AbstractEnergy balance measurements were made simultaneously at a terrestrial site in southern James Bay (SJB) and one in central Hudson Bay (CHB) during the growing season of 1985. Both sites were located 1 km inland from east‐west trending coastlines and both were fully vegetated with sedge grasses growing in standing water. The SJB site is in a non‐permafrost environment, whereas the CHB site is underlain by continuous permafrost.The measurements indicate that the magnitudes of all components of the energy balance, except net radiation, are strongly dependent on wind direction. Onshore winds are dominant. With onshore winds, the ground heat flux, evaporative heat flux and air temperature are smaller than for offshore winds and the sensible heat flux is larger. These relationships are apparent when the wind is directionally persistent for a full day and when there is a major wind shift between onshore and offshore during the day.With colder air temperatures the Bowen ratio becomes much larger than would be expected under conditions of potential evapotranspiration. This appears to be caused by a rapid increase in the canopy resistance of sedge grasses which occurs when air temperatures drop below 16°C.Components of the energy balance are linearly correlated with air temperature. This could be useful in predicting the impact of human activities which result in long term temperature change in the Hudson Bay lowlands, which is a large area with a very sparse climate database.
Estimates of global radiation at the ground from the reduced data sets of the international satellite cloud climatology project
Authors: Raschke E. , Gratzki A. , Rieland M. 
Published: February 2007

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 irradiances.
The radiation climate of the dead sea
Authors: Stanhill G. 
Published: February 2007

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−2 per 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−2 annually. 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−2 annually. 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−2 annually.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 reduced radiation balance.
A study of climatic stress and physiological regions in Greece
Authors: Giles B. D. , Balafouti C. , Arseni‐Papadimitriou A. 
Published: February 2007

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.
Tropical Quasi‐Biennial Oscillation of the 10‐mb wind and Indian monsoon rainfall‐implications for forecasting
Authors: Bhalme H. N. , Rahalkar S. S. , Sikder A. B. 
Published: February 2007

AbstractThe interannual variability of the Indian monsoon (June–September) rainfall has been examined in relation to the monthly zonal wind anomaly for 10‐mb (30km) and 30‐mb (24km) at Balboa for the 28‐year period 1958–85. The fluctuations in the zonal wind anomalies in January at 10‐mb appear to be highly related to the monsoon rainfall, with rainfall tending to be less (more) than normal during easterly (westerly) anomaly, suggesting some predictive value for the Indian monsoon rainfall. The zonal wind anomalies at 10‐mb lead those at 30‐mb by 6 months. This lead time is consistent with the well‐known downward phase propagation with a speed of 1 km/month in the QBO of tropical stratospheric wind. Large‐scale flood never occurred during easterly wind anomalies, and drought almost never during westerly anomalies in January at 10‐mb. This suggests that useful probability forecasts of droughts or floods could be prepared.
Arctic cloudiness in spring from satellite imagery
Authors: Barry R. G. , Crane R. G. , Schweiger A. , Newell J. 
Published: February 2007

AbstractMaps of cloud cover over the Arctic have been prepared from manual interpretation of Defense Meteorological Satellite Program images at 3‐day intervals for April, May and June, 1979,1980. Additional maps were prepared for selected dates to give a 10‐day sample for each of eight synoptic MSL pressure pattern types over the same area. Synoptic and monthly cloud distributions are compared with previous estimates. A large bias in our low cloud estimates for April may be caused by springtime Arctic have layers. The identification of substantial geographical and interannual variability of cloud amounts suggests that synoptic controls are important at this season.
Variations of trough positions and precipitation patterns in the mediterranean area
Authors: Jacobeit J. 
Published: February 2007

AbstractRecent variations of circulation and climate can be studied by investigating even rather short periods of time as far as they display different modes or anomalies which may also act on larger timescales as more persistent ones. Thus a period of 10 years (September 1966 to August 1976) which could be covered by daily sets of 500hPa airflow data in the Atlantic‐European region and of precipitation data at 101 Mediterranean stations was chosen to examine the variable distribution patterns of upper troughs in the Mediterranean area and their corresponding patterns of precipitation anomalies. After the outline of trough axis distribution to eight successive longitudinal bands and of the different percentages of trough precipitation at various trough axis positions for the whole period of 10 years a subdivision into individual years was made to show some of the operative deviations both of the upper trough distribution and of the corresponding precipitation pattern in relation to the overall mean situation. Together with some circulation indices (zonal index, geopotential anomaly, measure of (he relative vorticity, specifications about the Westerlies' main branch) which have been calculated for the crucial upstream region of the North Atlantic, some basic tendencies concerning different circulation patterns and their consequences for the Mediterranean region could be outlined. Considering within‐type changes and the variations of further cyclonic elements this might serve for estimating climatological effects on larger time‐scales of more persistent anomalies of circulation.
Power spectra and coherence of drought in the interior plains
Authors: Oladipo E. Olukayode 
Published: February 2007

AbstractMean growing season (April‐September) precipitation series at 407 stations in the Interior Plains of North America, dating back to 1985 in some stations, are used to derive a Bhalme and Mooley‐type drought index for the region. Linear trend, representing first order non‐stationarity, is first removed from the drought series. Then the periodogram via the Fast Fourier Transform (FFT), Maximum Entropy (ME) and Non‐Integer (NI) spectral techniques are applied to search for significant periodicities in the temporal characteristics of the drought series. Cross‐spectral technique is also used to characterize the extent of spectral coherence in the drought series.It is found that no significant power in drought is present at periods greater than about 6 years. Spectra of drought in the Interior Plains are dominated by three peaks in the quasi‐biennial, quasi‐triennial and quasi‐5‐year oscillations. The periodic 186‐year lunar nodal cycle obtained by others for the Drought Area Index (DAI) for the region is completely absent in the spectra of the analysed drought index series. Also the well‐known 11‐year sunspot cycle is only evident in the drought index series for a few of the stations. In general there is an ill‐defined drought recurrence interval.Moreover the areal extent of peaks contained within these oscillations do not indicate any significant spatial coherence. These periodicities can be evident at one station while being absent at another a few hundred kilometres away. On the basis of the spectral results, it is concluded that obtained significant periodicities are only short‐lived time variabilities in drought as recorded by individual stations and do not represent any persistent drought characteristics over a broad geographical region. A cross‐spectral analysis of the drought series with sunspot numbers shows no evidence to indicate a significant relation between drought and the single sunspot cycle. In general, the growing season drought series in the Interior Plains displays only what appears to be a random variation, with the possible superimposition of the quasi‐biennial oscillation.
Rotation of principal components: Some comments
Authors: Jolliffe Ian T. 
Published: February 2007

AbstractA recent paper by Richman (1986) provides a very useful review of the ideas of rotation in principal component analysis, in the context of climatology. However, the paper also raises a number of points which are open to discussion. The present note comments on a number of these points, and aims to give a balanced view of the usefulness of principal component analysis, both with and without rotation, in climatology.
The variations of dry spells in marseilles from 1865 to 1984
Authors: Douguedroit Annick 
Published: February 2007

AbstractThe study of dry spells gives a better characterization of the structure of a dry season than the monthly totals or means of rainfall. The dry season is characterized by the mean lengths of all dry spells and of the long dry spells (≥ 30 days), and by their persistence during 19 overlapping 30‐years series. A model based on shifted negative binomial distributions which fits well most of the monthly distributions of the frequency of the observed dry spells allows us to compute the probability of occurrence of a dry spell ≥ n days.
The time scale of the soil hydrology using a simple water budget model
Authors: Serafini V. V. , Sud Y. C. 
Published: February 2007

AbstractA simple water budget model is used to get a characteristic time scale of the soil hydrology, which is defined as the time scale for the onset of agricultural droughts. Assuming that there is no rain, our estimation requires as input the knowledge of the initial soil moisture content and an evaluation of the potential evaporation. Two applications at a global scale are shown. In a first case an initially saturated soil is considered to get an estimation of the time needed by a climate model to adjust realistically to initial errors in the soil moisture distribution. In a second case climatological values are used as initial conditions to get a measure of the sensitivity of the hydrological cycle to the atmospheric forcing.
The impact of rapid urbanization on pan evaporation in phoenix. Arizona
Authors: Balling Robert C. , Brazel Sandra W. 
Published: February 2007

AbstractRapid urbanization in Phoenix, Arizona over the past few decades has been associated with large increases in local temperature and wind speed values, and decreases in local dew point and relative humidity levels. In this study, the impact of these urban‐induced climatic changes on long‐term pan evaporation rates is identified. The results indicate an increase from 1917 to 1985 in the local pan evaporation in all months of the year. Following a long period of generally increasing pan evaporation levels, a sharp jump in the pan measurements occurred in the late 1960s. This pronounced discontinuity in the long‐term record appears to be associated with the construction of a nearby regional shopping centre in 1968. Given widespread similar land‐use changes throughout this rapidly growing desert city, and given the well‐documented changes in local climatic conditions, potential evapotranspiration increases are probably occurring throughout much of the metropolitan area.
Diurnal variation of outgoing longwave radiation
Authors: Gruber Arnold , Chen T. S. 
Published: February 2007

AbstractThe global and monthly distribution of the diurnal variation of outgoing longwave radiation (OLR) has been calculated by compositing estimates of the planetary OLR obtained from polar orbiting satellites at different equator crossing times. These data include NOAA and NASA polar orbiting satellites for the year 1974 through 1983, giving a total of ten different local observations per day throughout the whole data period. A Fourier analysis was then applied to calculate the phase and amplitude of the diurnal cycle on a 2.5° latitude/longitude grid for each month of the year. Assumption was implicitly made that the first harmonic alone explains most of the diurnal variation.The results are represented on maps extending from 55° south to 55° north for four different seasons from which a large seasonal variability of the diurnal harmonic primarily experienced by the mid‐latitude continents was clearly depicted. Over land areas the amplitude of the diurnal variation was large. In desert and semi‐arid areas it seem to be clearly related to surface solar heating i.e. phases of maximum OLR generally occurring near noon during summer and afternoon during winter months. Over the oceans, the amplitude is generally small even in the convectively active regions, such as the ITCZ, and the diurnal cycle appears to be modulated primarily by clouds.Finally, a ‘harmonic dial’ was constructed to examine the most dramatic features of the diurnal variation representative of such areas as the ITCZ, deserts, tropical convective clouds regions and highly variable mid‐latitude areas. Results of this study are consistent with other studies of the diurnal variability of clouds and radiation budget parameters.
Relationships between seasonal rainfall in East Africa and the Southern Oscillation
Authors: Ogallo L. J. 
Published: February 2007

AbstractTeleconnections between the Southern Oscillation and seasonal rainfall over East Africa during the period 1923–1984 were investigated using correlation methods. The results from the study indicated significant negative zero lag correlations between Southern Oscillation and seasonal rainfall over parts of East Africa during the months of October—December. Maximum correlations were concentrated along the coast and over some western parts. Peak values in the range — 0.6 were, however, centred along central and northern coastal regions.During the months of July—September significant positive zero lag correlations in the range of 0.5 were observed over some western parts. Low zero lag correlations were, however, obtained over most of the regions with the January—May and annual rainfall records. The computed lagged correlation values displayed characteristics similar to those observed from the zero lag correlations. Highest month to month persistences were again centred within October/November when significant lag correlations persisted for time lags greater than 2 months at some locations.It was, however, noted that although there were some relationships between the Southern Oscillation and seasonal rainfall over parts of East Africa, some of the extreme wet and dry episodes were not related to the Southern Oscillation.
A detailed examination of the extratropical response to Tropical El Niño/Southern Oscillation events
Authors: Hamilton Kevin 
Published: February 2007

AbstractIt is now clear that conditions in the tropical Pacific Ocean and the overlying atmosphere can have significant associations with the seasonal—mean circulation of the mid‐latitude atmosphere, particularly in winter. Notable is a tendency for an intensification of the climatological standing wave pattern over the North Pacific and North America during the warm tropical conditions associated with El Niño/Southern Oscillation (ENSO) events. However, the actual mid‐latitutde circulation anomalies do show a great deal of variability among individual ENSO years. This paper addresses the question of whether the variability of the mid‐latitude response to ENSO events can be attributed to differences in the details of the tropical anomalies from event to event. The investigation embraced the period 1899–1982 and employed data on tropical sea surface temperatures (SSTs), tropical rainfall, and mid‐latitude atmospheric surface pressures and air temperatures.The results suggest that a major factor in determining the strength of the Northern Hemisphere extratropical response is the SST anomaly in the far western Pacific/Indonesian region. In particular, it appears that the strong extratropical teleconnections with ENSO events occur more frequently when the SST in the far western Pacific is anomalously warm (or at least not overly cold). This finding appears to be consistent with the results of at least some recent numerical experiments conducted with comprehensive general circulation models.