bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interdecadal variations of surface wind direction in Lund, southern Sweden, 1741–1990
Authors: Jönsson Peter , Fortuniak Krzysztof 
Published: February 2007

AbstractBy uni‐ and bimodal mean vector analysis it is concluded that the decadal pattern of surface‐wind‐direction frequencies in Lund, southern Sweden, has changed substantially between 1741 and 1990. Trend analysis shows that statistically significant decreasing trends for north and north‐east winds are present during all seasons, whereas a decline in easterly wind is most prominent in July‐September. These trends are paralleled by increases of south‐east (January‐May and August‐November) and south‐west winds (April‐September and November‐January). These trends promote milder autumns, winters, and springs and a somewhat cooler summer.The investigation period is divided into three phases on the basis of similar flow patterns, which in general terms agree with Scandinavian temperature records: (i) 1741–1840‐a continental low‐zonality period featuring extreme bimodal flow of wind with relatively high frequencies of east winds, which indicate a continental climate. Warm summers and cold winters are produced by this flow pattern. The severity of winters was enhanced by a high frequency of north and north‐east winds. (ii) 1841–1910‐a transition period with decreased continentality and low yearly temperatures. This circulation type caused a temperature drop except during winter. (iii) 1911–1990‐a maritime high‐zonality period featuring further strengthening of the westerly flow. A warm maritime phase with least expressed warming in summer. Severe winters are further counteracted by low frequencies of north and north‐east winds.
Maximum entropy spectral analysis of the Duero Basin
Authors: Leite Solange Mendonça , Peixoto José Pinto 
Published: February 2007

AbstractMaximum entropy spectral analysis for the estimation of power spectra is used to study monthly and annual spectra of air temperature and precipitation at 63 weather stations in Duero Hydrographic Basin. Annual data are first submitted to the maximum entropy method (MEM) and the resulting power found are analysed. These spectra were then stratified according to the spectral peaks and on this basis several climatic regions were defined for the Duero Basin. The MEM spectral estimates of monthly values clearly show the annual and semi‐annual cycle.
Towards a consistent global climatological rawinsonde data‐base
Authors: Parker D. E. , Cox D. I. 
Published: February 2007

AbstractAn archive of monthly temperatures, dew points, geopotentials, and winds at standard tropospheric and stratospheric levels from about 800 rawinsonde stations has been developed from routinely transmitted monthly data, and supplemented with published or national archive data. Many stations' data commence in the 1950s and the archive is continually updated. The raw data, however, contain both random and systematic errors. Quality control of random errors includes hydrostatic, wind‐shear, and climatological checks, and comparisons with neighbouring stations and operational model analyses. Systematic errors in the wind speeds have resulted from the inadequately documented use of knots by some nations and metres per second by others in monthly messages. These errors are being amended by using geopotential height gradients, by comparing wind speeds reported from opposite sides of national borders, by averaging independently coded and transmitted daily data, and by the acquisition of original data from national archives. Other systematic errors result from changes of rawinsonde instrumentation, evolving operationally applied radiation and lag corrections, and changes of ascent times. Accordingly, the archive includes station histories where available, but these are far from complete. If the data are to be used in trustworthy analyses of interannual and longer term climatic variations, adjustments will need to be applied, using fully documented station histories and a knowledge of the effects of instrumental and other changes. Techniques for estimation of systematic adjustments include comparisons between neighbouring stations, comparisons with operational model analyses, the use of extended international radiosonde comparisons, and models of the thermodynamics of radiosonde instruments.
Relationships between 700 hPa height anomalies and 1 April snowpack accumulations in the western USA
Authors: McCabe Gregory J. , Legates David R. 
Published: February 2007

AbstractRelationships between atmospheric circulation and the temporal and spatial distributions of snowpack accumulations in the western USA are examined. Winter mean 700 hPa height anomalies, representing the average atmospheric circulation during the snow season, are compared with snowpack measurements made on or about 1 April at 311 snowcourse 7stations in the western USA during the winters of 1947–1948 through 1986–1987. Correlation and anomaly pattern analysis are used to identify relations between atmospheric circulation and the temporal and spatial distributions of snowpack accumulations, and to quantify the degree to which the temporal and spatial variability in snowpack accumulations can be attributed to variations in atmospheric circulation.Results indicate that winter mean 700 hPa height anomalies account for a statistically significant portion of both the temporal and spatial variability in the snowpack accumulations. In general, above‐average snowpack accumulations are associated with negative 700 hPa height anomalies over the eastern North Pacific Ocean and the western USA. These anomalies are indicative of anomalous cyclonic circulation, which produces an anomalous westerly flow of moist air from the eastern North Pacific Ocean into the western USA and increases winter precipitation and snowpack accumulations. Below‐average snowpack accumulations at most of the snowcourse stations are associated with positive 700 hPa height anomalies over the western USA. These positive anomalies indicate anomalous anticyclonic circulation which prevents the intrusion of moist air from the eastern North Pacific Ocean into the western USA, increases subsidence, and decreases winter precipitation. Five winter mean 700 hPa height anomaly patterns also were identified that explain the spatial variability in snowpack accumulations.
Precipitation over Scotland, 1757–1992: Some aspects of temporal variability
Authors: Smith Keith 
Published: February 2007

AbstractA 236‐year time series (1757–1992) of monthly areal average precipitation for Scotland is produced using the ‘official’ record compiled by the Meteorological Office (UKMO) from 1869 onwards, corrected for known inhomogeneities, and extended back to 1757 using previously unpublished data from the UKMO. The complete series is evaluated and examined for fluctuations and extreme values with particular reference to observed precipitation increases over the last two decades. Recent increases in annual precipitation, and associated seasonal variations, are judged to be unusual despite the recognition of a longer term trend to higher annual and winter values. Correlations of precipitation since 1869 with Lamb weather types show differences within the record and from other work, which suggest that this index does not fully capture the synoptic conditions relevant to precipitation over Scotland as a whole. The series since 1869 was also used to test the predictive value of climatic normals for 3, 5, 10, 15, 20, and 25 years alongside the standard 30‐year averages of precipitation. It is suggested that the best estimate of seasonal and annual precipitation totals for the following year can be achieved by the application of 3‐ and 5‐year normals, rather than by using precipitation averages of longer duration.
Universal spectrum for interannual variability in COADS global air and sea‐surface temperatures
Authors: Selvam A. Mary , Joshi R. R. 
Published: February 2007

AbstractContinuous periodogram spectral analyses of 28 years (1961–1988) of seasonal (September‐November) mean COADS global surface (air and sea) temperature time‐series show that the power spectra follow the universal inverse power law form of the statistical normal distribution. An inverse power law form for power spectra of temporal fluctuations implies long‐range temporal correlation and is a signature of self‐organized criticality. Universal quantification for self‐organized criticality presented in this paper is consistent with a recently developed cell dynamical system model for atmospheric flows, which predicts such non‐local connections as intrinsic to quantum‐like mechanics governing flow dynamics. The universal spectrum for interannual variabiality rules out linear secular trends in global surface (air and sea) temperatures.
Relations between winter precipitation and atmospheric circulation simulated by the geophysical fluid dynamics laboratory general circulation model
Authors: McCabe Gregory J. , Dettinger Michael D. 
Published: February 2007

AbstractGeneral circulation model (GCM) simulations of atmospheric circulation are more reliable than GCM simulations of temperature and precipitation. Thus, some researchers are developing empirical relations between observed atmospheric circulation and observed temperature and precipitation to translate GCM estimates of future atmospheric circulation into estimates of future regional temperature and precipitation. Developing climate‐change scenarios in this manner assumes, at least, that relationships between atmospheric circulation and surface climate variables, such as temperature and precipitation, are properly simulated by GCMs.In this study, temporal correlations between 700 hPa height anomalies (700 hPa anomalies) over North America simulated by the Geophysical Fluid Dynamics Laboratory (GFDL) GCM and GFDL‐GCM‐simulated (GFDL‐simulated) winter precipitation at eight locations in the conterminous United States are compared with corresponding correlations in observations. The objectives are to (i) characterize the relations between atmospheric circulation and winter precipitation simulated by the GFDL GCM for selected locations in the conterminous USA, (ii) determine whether these relations are similar to those found in observations of the actual climate system, and (iii) determine if GFDL‐simulated precipitation is forced by the same circulation patterns as in the real atmosphere.Results indicate that the GFDL GCM simulates relations between 700 hPa anomalies and local winter precipitation that are similar to relations found in observed data for most of the locations analysed in this study. Results also indicate that at regional scales GFDL GCM simulations of the relations between 700 hPa anomalies and winter precipitation are most similar to observed relations for locations near oceanic sources of atmospheric moisture. These results suggest that the GFDL GCM may not adequately simulate variations in advection of atmospheric moisture into the interior parts of the USA and/or that this moisture is not adequately converted into precipitation in the interior parts of the country. This problem may be due, in part, to (i) the inadequate representation of topography in the GFDL GCM, (ii) stronger‐than‐observed mean winter zonal winds simulated by the GFDL GCM and the consequent more west‐to‐east paths of air flow and storm systems across North America, (iii) the relative weakness of important synoptic patterns in GFDL simulations, such as the Pacific North American circulation pattern, and (iv) the occurrence of ‘spectral rain’.In addition, for some locations, the GFDL‐simulated relationships between precipitation and 700 hPa anomalies can be quite different from observed relations. The differing relationships suggest that GFDL‐simulated changes in regional precipitation in response to changes in atmospheric circulation could differ from changes that would occur in the actual climate system.
Seasonal phase lag between rainfall and vegetation activity in tropical Africa as revealed by NOAA satellite data
Authors: Shinoda Masato 
Published: February 2007

AbstractA seasonal phase lag in the response of vegetation to rainfall and its dependence on the type of vegetation in tropical Africa have been investigated, using weekly‐basis data of the NOAA/AVHRR‐derived NDVI (normalized difference vegetation index) and OLR (outgoing longwave radiation) for April 1985 to September 1987.The lag‐correlation analysis of the NDVI and OLR data demonstrates that the seasonal phase lag, by which the NDVI responds most markedly to the OLR, tends to increase from the Equator to the pole in the Northern and Southern Hemispheres. The lag ranges from 1–3 weeks in the equatorial rain forest to about 2–6 weeks in the wet savanna and about 6–9 weeks in the dry savanna.The strongest negative lag‐correlation coefficients at the above lags are characterized by a spatial pattern which has a maximum absolute value near the latitudes 7.5°–10° in the savanna areas of both hemispheres. The equatorial rain forest, especially its north‐eastern part, shows the weakest correlation. The results suggest that the response of vegetation to rainfall is more pronounced and has a longer lag in the savanna than in the equatorial rain forest. A regional analysis of the NDVI‐rainfall relationship for Cameroon confirms the above NDVI‐OLR lag‐correlation on the continental scale.
Variability of the summer monsoon rainfall over Thailand—comparison with features over India
Authors: Kripalani R. H. , Singh S. V. , Panchawagh Nalini , Brikshavana M. 
Published: February 2007

AbstractIn this study, 20 years (1961–1980) of rainfall data for 34 stations over Thailand are used to investigate and understand the intraseasonal and interannual variability of the summer monsoon. Dominant structures of 5‐day and seasonal rainfall are determined through empirical orthogonal functions (EOFs). Monthly and seasonal spatial patterns and a map showing the coefficient of variation are also presented.On an intraseasonal time‐scale regions with high 30‐60‐day variances (Madden Julian oscillations—MJOs) and 10‐20‐day variances (Quasi‐biweekly oscillations—QBWOs) are identified using a band‐pass Butterworth filter for 5‐day rainfall. It is seen that the MJOs are dominant over the Indian region and the QBWOs are dominant over the Thailand region. Extended EOFs (EEOFs) have shown that the most important evolutionary feature over India is the northward propagation associated with the MJOs, whereas over the Thailand region it is westward, associated with the QBWOs. Northward propagation of rainfall anomalies is not observed over the Thailand region.On the interannual scale the area over north‐west Thailand is related well with rainfall variation over west‐central India. The Darwin pressure tendency (DPT) and the subtropical ridge over India shows significant relation with rainfall over northwest Thailand. However, the Northern Hemisphere surface temperature (NHST), Quasi‐biennial Oscillation (QBO), and West Pacific ridge (WPR) show no significant relation.
The impact of surface circulation on significant daily rainfall patterns over Mallorca
Authors: Sumner Graham , Guijarro José A. , Ramis Clemente 
Published: February 2007

AbstractThis study is a preliminary attempt to associate the distribution of significant rainfalls over the island of Mallorca with recognized dominant surface circulation types. Based on the extraction of five prominent PCs from a principal components analysis using a T‐mode (time) correlation matrix, six dominant daily rainfall spatial patterns have been isolated using cluster analysis for significant rainfall days (area mean ⩾ 5–0 mm) for the island of Mallorca in the western Mediterranean. These six ‘pattern groups’, and a number of important subgroups, are linked closely to the prevailing near‐surface circulation. Seven dominant circulation types have been identified, which are closely, although not perfectly, associated with rainfall distribution, so that a conceptual spatial rainfall model for the island seems possible. Such a model would be most useful if used in conjunction with NWP forecasts of probable rainfall amount issued for the area, and would provide valuable local information on likely heavy rainfall occurrence.
On the severe drought of 1993 in north‐east Brazil
Authors: Rao V. Brahmananda , Hada Kioshi , Herdies Dirceu L. 
Published: February 2007

AbstractDuring the period 1990 through to 1993 a dry spell occurred over north‐east Brazil. The drought of 1993 was very severe. Rainfall series for north‐east Brazil are updated to 1993 and the drought conditions during 1993 are discussed. The 1993 drought seems to be connected at least partially to the unusual ENSO conditions during that year.
Prediction of the dry and wet spell of the Australian monsoon
Authors: Krishnamurti T. N. , Han Sang‐Ok , Misra Vasubandhu 
Published: February 2007

AbstractThis study is a sequel to two recent studies on the monsoonal dry and wet spells. The previous studies addressed the dry and wet spells of the monsoon over India and China on the intraseasonal time‐scales. The present study is intended to provide an outlook for the occurrence of dry and wet spells in reference to the Australian monsoon, within roughly a 1 ‐month period from the time of start of the forecast with a global model. In the global model, the definition of a time mean state and an intraseasonal component are retained. The high‐frequency component is viewed as one where inclusion in the initial state can contribute to a degradation of month long forecasts and hence is excluded initially. Sea‐surface temperature anomalies on intraseasonal time‐scales are included in this analysis. The prediction of the wet spells of the monsoon is assessed from the superposition of the predicted intraseasonal cyclonic circulation anomaly on top of the climatological cyclonic anomaly. The dry spell is assessed from an inverse superposition. We consider here a specific period, i.e. March 1992. The early part of this month was characterized by a wet spell over Northern Australia. A dry spell prevailed during the middle of this month and was followed by a wet spell during the latter part of the month. The prediction experiments with a prescribed and a modelled sea‐surface temperature anomaly successfully demonstrated the passage of the intraseasonal anomaly, with the superposition of the geometries of the intraseasonal and the climatic components favouring the wet and the dry spell during different periods of the month.
June‐september rainfall in north‐eastern Africa and atmospheric signals over the tropics: A zonal perspective
Authors: Camberlin Pierre 
Published: February 2007

AbstractThe connection between rainfall in northeast Africa (Djibouti, Eritrea, Ethiopia, Kenya, Somalia, Sudan, and Uganda) and various atmospheric indicators from the tropics have been investigated for the northern summer season. Variables used include zonal wind at 700 hPa and 200 hPa, sea‐level pressure, and rainfall over other tropical areas, for the period 1951–1988.Strong significant correlations are shown with the Southern Oscillation and the components of the Walker cell in the Pacific Ocean. Droughts in the Ethiopia‐Uganda area are associated with El Niño events and, moreover, with above normal pressure and droughts over India. Other significant relationships exist with the African monsoon. Westerly (easterly) anomalies in the lower (upper) levels are associated with abundant summer rainfall years in north‐east Africa.These results are all consistent with the previously defined Walker‐type circulations over the tropics, particularly as far as the Indo‐Pacific and African cells are concerned. Although the Southern Oscillation has a dominant impact in this respect, the specific coherence of the African cell is further evidenced. Preliminary findings suggest that the summer rainfall areas of East Africa could qualify as a location for the rising branch of this cell.
A study of sea and land breezes in an archipelago on the west coast of Sweden
Authors: Gustavsson T. , Lindqvist S. , Borne K. , Bogren J. 
Published: February 2007

AbstractThis paper reports analyses of recordings made on three tower masts in order to study the dynamics of sea and land breezes as well as the development of these systems in an archipelago along the west coast of Sweden. Intensive studies have focused on the duration and strength of sea and land breezes and the development of small‐scale systems controlled by the irregular coastline in the study area. The internal dynamics of the land breeze and the occurrence of temperature variations in the coastal area are discussed as well as the interrelationship between these factors.The studies show that the sea and land breezes are well developed when the synoptic‐scale pressure gradient is relatively weak. However, a division into smaller systems has been observed, i.e. small islands outside the coastline develop their own wind systems. In the archipelago, a primary sea breeze with no interaction with the main coastline develops during the first hours after sunrise. The primary sea breeze continues to act until a stronger sea breeze, developed in interaction with the main coastline, begins to blow. This phenomenon was not observed for the land breeze. Here, no general land breeze develops, instead a breeze was recorded which always blew towards the coastline.
Long‐term variability of sea—air heat transfer in the North Atlantic ocean
Authors: Gulev Sergey K. 
Published: February 2007

AbstractThere is evidence that climatological variations of the ocean‐atmosphere fluxes in the North Atlantic are significant with respect to long‐term climate changes. To study year‐to‐year changes of ocean‐atmosphere interaction processes in the North Atlantic Ocean, two meteorological data sets were used: the Comprehensive Ocean‐Atmosphere Data Set (COADS) and the Soviet National Meteorological Centre (SNMC) data set for the period from 1957 to 1990. Data sets were compared with each other in order to find out set‐to‐set variations of ocean‐atmosphere interaction parameters. The next step was to calculate sea‐air interaction characteristics on the basis of one data set, but with the use of different schemes for the parameterization fluxes. Both set‐to‐set and scheme‐to‐scheme variations are significant, but at the same time annual and interannual changes in radiation and heat fluxes indicate that variability patterns are close to each other. Differences obtained in the parameters of variability were taken to determine the confidence level for future consideration of climatological variability. Long‐term changes in net air‐sea heat fluxes were explored for the period from 1950 to 1990. Results demonstrate the different character of variations in the tropics, mid‐latitudes and high latitudes. Meridional heat transport for different climatological periods has been calculated in order to discuss the variations obtained in terms of ocean circulation. Two significantly different regimes of meridional heat transport were obtained. The first regime is characterized by high values in the tropics and a sharp decrease in mid‐latitudes. The second regime is connected with relatively high values of heat transport in mid‐latitudes.