bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparative performance analysis of three meteorological drought indices
Authors: Olukayode Oladipo E. 
Published: February 2007

AbstractThree indices for designating drought are examined and their comparative performance in depicting periods of different drought intensities is discussed. These indices are the rainfall anomaly index (RAI), Bhalme and Mooley drought index (BMDI) and the Palmer drought index (PDI). Using data from Nebraska state as an example, the three indices all appear to be effective in detecting drought periods. The results of the analysis suggest that precipitation is the most important climatic element as an input into meteorological drought. It can, therefore, be concluded that for meteorological purposes, and when undertaking single‐station analysis, simple indices with rainfall as the only input perform comparatively as well as the more complicated indices in depicting periods and intensity of drought.
Climate reconstruction from tree rings: Part 2, spatial reconstruction of summer mean sea‐level pressure patterns over Great Britain
Authors: Briffa K. R. , Jones P. D. , Wigley T. M. L. , Pilcher J. R. , Baillie M. G. L. 
Published: February 2007

AbstractWe present a methodology for the reconstruction of spatial climate patterns over the British Isles using tree rings. The predictands are mean sea‐level pressures averaged over May to July for a 16‐point grid centred over the British Isles. The predictors are ring widths from a network of 14 oak tree‐ring chronologies (Quercus petraea Liebl. and Q. robur L.) in Britain and northern France. Major spatial modes of variance in the climate data are linked directly with those of the ring‐width data via a series of principal component regressions. Reconstruction performance is assessed by examining calibration and verification statistics at individual grid points and for individual pressure principal component amplitudes. The reconstruction equations are examined in order to identify, region by region, which chronologies are most valuable. This diagnostic approach to reconstruction assessment, when coupled with information on the statistical quality of the chronologies themselves, can suggest areas where future field‐work would be most valuable. Though limited in scale, these pressure reconstructions are the first to have been made using trees from maritime sites, and are the first to be comprehensively verified using independent pressure data.
Precursors of the Southern Oscillation
Authors: Wright Peter B. 
Published: February 2007

AbstractEvidence is presented of the existence of three largely independent precursors of changes in the Southern Oscillation (SO). In a region of the south‐east Pacific, anomalously high SST, low pressure, low cloudiness and weak winds tend to occur in December‐February (DJF) prior to a year of low SO index. In the equatorial Atlantic, anomalously warm sea in DJF tends to follow a period of low SO index and precede a year of high index. Cold SST in a region near northern Australia is associated in every season with a trend towards warmer SST in the equatorial east Pacific, and in most months with anomalous westerly winds in the equatorial west Pacific. Plausible physical scenarios are proposed to explain the relationships.
Temporal fluctuations of daily rainburst and the cycle of the lunar year
Authors: Ghayoor Hassan Ali 
Published: February 2007

AbstractThe purpose of this research is to investigate climatic fluctuations connected with the cycles of the lunar year. The rainfall data belonging to the Balcombe station, Sussex, England, are used. From these data, variations in the frequency per year of daily rainfalls over 25 mm, which in this research are called daily rainbursts, are investigated, and the results show that there is a quasi‐regular fluctuation, connected with the cycles of the moon, in the number of daily rainbursts.
Factors affecting the isotopic composition of daily rainfall at Driby, Lincolnshire
Authors: Heathcote John Anthony , Lloyd John William 
Published: February 2007

AbstractTo further the understanding of the relationships between past climatic conditions and the hydrogen and oxygen isotope composition of old groundwaters, a study of the relationship between the composition of daily rainfall and meteorological parameters at a single site was made. The composition of daily rainfall was found to be extremely variable, with little seasonal dependence, and with no clear relationship to daily mean air temperature. This is typical of a maritime climate, although the site studied is located on the east coast of England. The most important control on composition is the origin of the precipitating air mass, whether Atlantic or Continental. The possibility of investigating past climates is discussed.
Relationships between raindays, mean daily intensity and monthly rainfall in the tropics
Authors: Jackson I. G. 
Published: February 2007

AbstractThere are limitations in using monthly rainfall totals in studies of rainfall climatology as well as in hydrological and agricultural investigations. Analysis of data for a range of tropical rainfall stations suggests that a better relationship exists between monthly rainfall and number of rain days than between monthly rainfall and mean daily rainfall intensity. In the former case, a logarithmic relationship is most appropriate, whereas for the latter a linear form is adopted. Deviations from the relationships show contrasts between stations and also within seasons at individual stations, suggesting the need for caution in attempting to generalize about tropical rainfall conditions. For some stations and at the start of rainy seasons, the two parameters examined suggest that the character of rainfall may create agricultural and hydrological problems greater than monthly totals suggest.
A geography of dust storms in South‐West Asia
Authors: Middleton N. J. 
Published: February 2007

AbstractMean annual dust storm frequencies are mapped for south‐west Asia (Iran, Afghanistan, Pakistan and India) showing areas of greatest activity in two regions: an area at the convergence of the borders of Iran, Afghanistan and Pakistan that comprises the Seistan Basin, Registan and north‐western Baluchistan; and the plains of Afghan Turkestan. The highest average annual number of dust storm days is 80.7 at Zabol in Iranian Seistan. Little dust‐raising activity occurs on the Indian peninsula. Dust storms occur principally during the dry season months of spring and summer.Local and regional meteorological conditions associated with dust storms are described, ranging from the short‐lived dust devil measuring tens of metres across to dust plumes visible on satellite imagery. Dust is transported from the region north to Asian states of the U.S.S.R., south over the Arabian Sea and east over south‐east Asia. The importance of soils in the wind erosion system is indicated. Dust storms commonly occur on fine‐grained material, particularly loess, alluvium, silt, clay and other outwash sediments. Dust storms have received a variety of names locally in the region.Dust storm frequency during the peak season in northern India is found to be poorly related to mean rainfall, mean wind speed and a climatic wind erosion factor,Cdeveloped by Chepilet al.(1962).
Relationships between extremes of the Southern oscillation and the winter climate of the Anglo‐American Pacific Coast
Authors: Yarnal Brent , Diaz Henry F. 
Published: February 2007

AbstractWarm and cold events in the central and eastern equatorial Pacific represent the two extreme climatic states of the Southern Oscillation and are related to pronounced winter climate anomalies along the Pacific coast of Anglo‐America. Previous research has demonstrated that the Pacific/North American (PNA) pattern may be the typical response of the northern hemisphere winter atmosphere to tropical forcing during warm events. In general, the anomalous flow associated with the PNA pattern raises winter temperatures along the entire length of the Anglo‐American west coast. Precipitation is enhanced in the vicinity of the Alaskan panhandle, but is suppressed to the south. During cold event winters, the dominant 700 mb anomaly strongly resembles the PNA pattern, but with a reversed polarity. Most cold event winters are associated with below normal temperatures along the west coast, while precipitation significantly decreases in the Alaskan panhandle and increases to the south. Thus, the climate anomalies experienced along the Anglo‐American west coast during cold events are in the opposite sense to those of warm events.Precipitation, and to a lesser extent temperature anomalies, are sensitive to minor fluctuations in the general placement and orientation of the PNA pattern, which in turn are related to shifts in the position of the polar front jet stream and associated storm track. Thus, a number of disparate climate anomalies are possible in the study area during warm event winters, depending upon the positioning of the long‐wave pattern over the north Pacific and North America.Although the PNA and ‘reverse PNA’ patterns can occur in any winter, they are significantly more frequent during warm and cold events, respectively, than in other winters. The west coast temperature and precipitation anomalies associated with the PNA (‘reverse PNA’) during warm event (cold event) winters can occur during any winter displaying the PNA (‘reverse PNA’) pattern, regardless of the presence of a warm (cold) event in the equatorial Pacific. A dynamical model is proposed to explain the observed teleconnection between the Anglo‐American west coast and cold Southern Oscillation events.
Simulation of time series of temperature and precipitation over Eastern England by an atmospheric general circulation model
Authors: Reed D. N. 
Published: February 2007

AbstractTime series of temperature and precipitation from a 3‐year integration of a 5‐level general circulation model (Corby et al., 1977) by the Dynamical Climatology branch of the U.K. Meteorological Office are studied. These are used to establish, and criticize, the ability of the model to simulate some aspects of the observed climate in a single grid box of the model (the eastern England grid box). Problems concerning the comparison of time series of model data with time series compiled from meteorological observations are discussed and some techniques for overcoming these problems developed.
The relationship of weather types to dust storm generation in Arizona (1965–1980)
Authors: Brazel A. J. , Nickling W. G. 
Published: February 2007

AbstractA general classification of dust weather types for Arizona first‐order stations was developed using synoptic data derived from surface, 850 mb, and 500 mb pressure and wind characteristics from daily weather maps for 321 observed dust storms during 1965–1980. Four major dust weather types were identified: (1) frontal, (2) thunderstorm/convective, (3) tropical disturbance and (4) upper level/cut‐off low. Frontal dust storms (Type 1) occur most frequently during the late autumn, winter and spring and can be divided into two subtypes; pre‐frontal dust and post‐frontal dust. Dust storms generated by thunderstorm or strong convective activity (Type 2) are most frequent during the summer months and are typified by large scale pressure pattern variability, particularly at the upper levels of the troposphere. Dust storms associated with tropical disturbances (Type 3) are infrequent at all stations but are typically very intense, long lasting events. The upper level/cut‐off low type (Type 4) dust storms usually occur during May and June and from September to November and are associated with upper level split flow, where high amplitude ridging to the north and troughing to the south occurs across the western U.S.A. Although dust storms can be traced to specific synoptic events, the interannual variability of dust storms shows a strong correspondence to antecedent winter moisture variability, probably reflecting an overriding control by surface crusting and vegetative effects on dust generation.
Rotation of principal components
Authors: Richman Michael B. 
Published: February 2007

AbstractRecent research has pointed to a number of inherent disadvantages of unrotated principal components and empirical orthogonal functions when these techniques are used to depict individual modes of variation of data matrices in exploratory analyses. The various pitfalls are outlined and illustrated with an alternative method introduced to minimize these problems via available linear transformations known as simple structure rotations. The rationale and theory behind simple structure rotation and Procrustes target rotation is examined in the context of meteorological/climatological applications. This includes a discussion of the six unique ways to decompose a rotated data set in order to maximize the physical interpretability of the rotated results.The various analytic simple structure rotations available are compared by a Monte Carlo simulation, which is a modification of a similar technique developed by Tucker (1983), revealing that the DAPPFR and Promax k = 2 rotations are the most accurate in recovering the input structure of the modes of variation over a wide range of conditions. Additionally, these results allow the investigator the opportunity to check the accuracy of the unrotated or rotated solution for specific types of data. This is important because, in the past, the decision of whether or not to apply a specific rotation has been a ‘blind decision’. In response to this, a methodology is presented herein by which the researcher can assess the degree of simple structure embedded within any meteorological data set and then apply known information about the data to the Monte Carlo results to optimize the likelihood of achieving physically meaningful results from a principal component analysis.
A comparison of synoptic classification schemes based on ‘objective’ procedures
Authors: Key Jeff , Crane Robert G. 
Published: February 2007

AbstractVarious ‘objective’ methods of classifying the atmospheric circulation are compared in order to determine whether the different methods result in similar groupings of circulation types, and also to examine the question of how much subjectivity is present in each of the typing schemes. The results indicate a high degree of subjectivity within each approach and that the different classification schemes do give rise to the production of different synoptic types. A method which groups days based on the sum of squares difference between cases (Kirchhofer method) gives the best overall classification, but only classifies 80 per cent of the days. A technique that clusters days based on principal component scores gives a larger mean sum of squares difference between the type patterns and the individual cases, but classifies all of the days.
Diurnal variation of planetary radiation budget parameters from geostationary satellites
Authors: Pinker R. T. , Ewing J. A. , Gruber A. 
Published: February 2007

AbstractStudies of diurnal variation in the planetary radiation budget parameters from space are possible only with observations from geosynchronous satellites. Such studies are necessary to establish possible bias in the radiation budget estimates derived currently from polar orbiting satellites. This paper outlines a preliminary approach to estimate the diurnal variation of the net radiation at the top of the atmosphere, using the Geostationary Operational Environmental Satellite (GOES) visible (0.55–0.75 μm) and IR window (10.5–12.5 μm) observations. Model development and analysis used GOES‐E data for the summer of 1982. This paper is the first to report monthly averaged diurnal variations in the planetary radiation budget parameters for several months. The possible error in the daily mean net radiation when derived from one observation per day instead of hourly observations, was also estimated. Computational experiments were conducted with different calibration techniques to assess the possible bias error in the quantities derived due to calibration.
A synoptic climatology of major avalanche winters in Norway
Authors: Fitzharris B. B. , Bakkehøi S. 
Published: February 2007

AbstractA near continuous record of avalanche deaths in Norway is compiled for 130 years from 1855, and shows a distinct downward trend, but large variations from winter to winter, with a periodicity of 12–13 years. Twelve major avalanche winters are selected, and their synoptic climatology examined using Grosswetterlagen, an index of atmospheric circulation over southern Norway, and monthly sea level pressure anomaly maps. More than one climatological pattern is needed to explain these winters. Major avalanche winters tend to be cold in December and/or January, and have more meridional and less mixed weather types compared with minor avalanche winters. Some have enhanced north or east circulations associated with large anomalies in the semi‐permanent pressure systems. Others display intense anticyclonic blocking near Britain that maintains sustained west to north‐west airflows onto Norway. A switch in circulation pattern from these to a more southerly regime is also important. These aspects of synoptic climatology are related to the mechanisms for producing big avalanches.
Specification of monthly mean surface temperature anomalies in Europe and Asia from concurrent 700 mb monthly mean height anomalies over the Northern Hemisphere
Authors: Klein William H. , Yang Runhua 
Published: February 2007

AbstractSpecification equations for the monthly mean air temperature anomalies at 115 surface stations in Eurasia are derived by applying a stepwise forward screening procedure to the simultaneous monthly mean 700 mb height anomalies at 134 grid points in the northern hemisphere and the previous month's local temperature. These equations explain about 65 per cent of the temperature variance by an average of only 4.7 variables, but with marked regional, seasonal and month‐to‐month variations. The main properties of the equations are highlighted by means of several maps and graphs that delineate important spatial and temporal variations.The average properties of the specification equations in the European sector closely resemble those derived previously for North America. However, the results are consistently poorer for stations in Asia, not only for the annual mean, but also during each of the four seasons. Furthermore, the phases of seasonal variation are opposite in Europe and Asia. In both sectors, however, the equations are better in winter than in summer at coastal stations, but the reverse is true at continental stations. The average error in specifying monthly average surface temperature from perfect 700 mb height forecasts should be less than 0.9°C in Europe and 1.2°C in Asia about two‐thirds of the time.
Persistence of anomalous moisture conditions in the interior plains of North America
Authors: Oladipo E. O. , Hare F. K. 
Published: February 2007

AbstractMean growing season (April‐September) climatic conditions in the Interior Plains of North America, as measured by the Bhalme and Mooley drought index, were subjected to the length of runs (Gold), chi‐squared and autocorrelation tests of dependence. Only a maximum of about 3 per cent of the total variation in the seasonal drought in any year is explained by the previous year. Based on the results from the three tests, it can be concluded that the mean seasonal moisture conditions during the growing season in the region can be considered to be an independent time process. In other words, the series of the seasonal drought index, statistically speaking, cannot be distinguished in its sequential pattern of occurrence from a random series.
Spatial patterns of drought in the interior plains of North America
Authors: Oladipo E. Olukayode 
Published: February 2007

AbstractA long‐period data set (1975–1978) of monthly growing season (April‐September) rainfall totals for over 400 stations in the Interior Plains of North America is used to derive a Bhalme‐and‐Mooley‐type drought index. A map‐pattern correlation technique is used to stratify the time period into distinct drought severity patterns, and maps of the mean drought patterns for each year are generated by SYMAP and examined for consistency.Based on the analyses, there are four patterns of moisture anomaly with distinct differences between the eastern, western, southern and extreme northern parts of the study region. In general, large‐scale droughts do not frequently cover the region as a whole. Indeed it seems to be the exception rather than the rule, with distinct spatial differences dominating the wet and dry years. The length and severity of drought varies from subarea to subarea, and although discrete areas do catch the brunt of drought on a year‐by‐year basis, drought occurrence in the region is largely spatially incoherent. It can therefore be concluded that drougth in the Interior Plains of North America is predominantly a non‐continental phenomenon.
Circulation and daily rainfall in the North Queensland wet seasons 1979–1982
Authors: Sumner Graham , Bonell Mike 
Published: February 2007

AbstractDaily rainfall data for 72 sites in tropical north Queensland have been analysed to yield indices of rainfall activity associated with ten identified surface circulation types which occur in the summer wet season (November to March). The influence on rainfall distribution of local topography and exposure to moist air flows emerges as an important determinant, so that the locations of larger scale rain‐producing systems relative to the area, and the direction of air flow, emerge as prime controls on rainfall presence and amount.
A homogeneity test applied to precipitation data
Authors: Alexandersson Hans 
Published: February 2007

AbstractIn climate research it is important to have access to reliable data which are free from artificial trends or changes. One way of checking the reliability of a climate series is to compare it with surrounding stations. This is the idea behind all tests of the relative homogeneity. Here we will present a simple homogeneity test and apply it to a precipitation data set from south‐western Sweden. More precisely we will apply it to ratios between station values and some reference values. The reference value is a form of a mean value from surrounding stations. It is found valuable to include short and incomplete series in the reference value. The test can be used as an instrument for quality control as far as the mean level of, for instance, precipitation is concerned. In practice it should be used along with the available station history. Several non‐homogeneities are present in these series and probably reflect a serious source of uncertainty in studies of climatic trends and climatic change all over the world. The significant breaks varied from 5 to 25 per cent for this data set. An example illustrates the importance of using relevant climatic normals that refer to the present measurement conditions in constructing maps of anomalies.