bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local and remote response to zonally uniform sea‐surface temperature in a July general circulation model
Authors: Simmonds Ian , Dix Martin , Rayner Peter , Trigg Glenn 
Published: February 2007

AbstractTo investigate the effect of longitudinal sea‐surface temperature gradients this paper reports on three experiments in which they were removed over the entire globe, and separately in the two hemispheres. The first of these is compared to an analogous experiment for January and the response is found to be generally greater.An almost‐hemispheric region of sea‐level pressure increase is simulated centred on Papua New Guinea with decreases centred on the Atlantic. In the anomalous upper level streamfunction there is an anticyclonic pair straddling the Equator in the Western Hemisphere with a corresponding cyclonic pair in the Eastern Hemisphere. The velocity potential is dominated by a wave 1 response. Precipitation anomalies tend to be confined to and follow the sea‐surface temperature anomalies and their magnitudes are much larger than evaporation changes. This highlights the role of moisture advection in maintaining these anomalies. The Hadley cell intensifies while the Walker circulation is weakened. The root‐mean‐square deviation of geopotential height waves generally decreases, particularly in the Southern Hemisphere, mainly due to reductions in the strength of wave 1.The experiments with hemispheric anomalies allow us to investigate the relative importance of local and remote forcing. It is found that most of the global response can be explained by the Northern Hemisphere forcing alone. This is true even in the Southern Hemisphere. The implications of this for cross‐equatorial propagation of information are discussed. The results highlight the importance of the meridional component of the wind in this connection.
Multiple reflections across a linear discontinuity in surface albedo
Authors: Barker Howard W. , Davies John A. 
Published: February 2007

AbstractSolar radiation received and absorbed at the surface beneath an overcast sky is calculated as a function of distance d from a linear discontinuity in surface albedo, cloud base altitude h, cloud optical thickness τ, surface albedo α, and precipitable water. Horizontal variation of multiple reflections between surface and cloud is accounted for. Cases of snow or ice surfaces adjacent to open water or snow‐free land surfaces are considered because of large albedo differences. Irradiance on all surfaces and absorptance on the darker surfaces are shown to depend on d, h, τ, α and water vapour beneath the cloud base. Absorption by snow and ice surfaces is less sensitive to changes in d, h and τ because of weak absorptance in the spectral region where multiple reflections are most prevalent; λ<0.7 μm. Ground‐based, radiometrically measured (point) surface albedo depends weakly on d and h but more strongly on τ. Estimates of cloud base albedo from surface measurements may be in error if surface irradiances are measured too close to large albedo discontinuities.
The walker circulation and atmospheric water vapour characteristics over the Pacific for two contrasting years
Authors: Kayano Mary Toshie , Rao Vadlamudi Brahmananda , Moura Antonio Divino 
Published: February 2007

AbstractThe Walker circulation for two contrasting years 1983 (ENSO year) and 1984 (non ENSO year) is determined. Principal changes in the upper level divergence are noted in the western and central Pacific regions. Thus, this part seems to form the principal branch of the Walker circulation, where a reversal takes place during the two contrasting years. Water vapour characteristics of the atmosphere over the western and central Pacific regions are determined using radiosonde data. During the ENSO event of 1983 an unusual accumulation of water vapour over the central Pacific and a depletion of it over the Indonesian region is noted. Further, the correlation coefficient between the SO index and water vapour variation showed significant values. Another aspect of the tropical atmosphere discussed here is the thermodynamic structure and its implications for the development of convection. Our study revealed a spectacular reversal of atmospheric properties such as the upper level divergence, water vapour, and thermodynamic structure during the two contrasting years.
Bivariate normal classification of North American air masses using the normix program
Authors: Epperson David L. , Davis Jerry M. , Watson Gerald F. , Monahan John F. 
Published: February 2007

AbstractThis preliminary study employs Wolfe's cluster analysis program (NORMIX) in the bivariate normal classification of North American air masses. Once‐daily observations of potential temperature and mixing ratio were classified by the NORMIX program into ‘types’ which represent different air masses. The cluster analysis was performed at the surface, at 850 mbar, at 700 mbar, and at 500 mbar for each of seven stations located along the 80th meridian. Individual data sets were composed of 10 years of observations taken during January or July at each level.Analyses derived from the NORMIX results showed more types at the middle latitudes than at source region latitudes. A different number of NORMIX types was found at each level above each station, except at Miami in July. Frequency tables for the Greensboro station showed that some NORMIX types at upper levels occurred in conjunction with two or more surface NORMIX types, thereby indicating the presence of overrunning. Synoptic analyses for the Greensboro station showed that each NORMIX type was associated with a specific synoptic air mass type.The NORMIX program generated discriminant functions which were used to objectively classify independent potential temperature and mixing ratio data for the Greensboro station. The results of the independent data classification compared favourably with synoptic air mass types and with the original NORMIX results.
Deterministic signals in precipitation records from the American corn belt
Authors: Currie Robert G. , O'Brien Douglas P. 
Published: February 2007

AbstractMaximum entropy spectrum analysis of 120 yearly total precipitation records in the Corn Belt (States of Illinois, Indiana, Iowa, and Missouri) yield evidence for the 18·6‐year luni‐solar term in 109 instances, while the 10‐ to 11‐year solar cycle signal was found in 100 records. For Illinois, minima in the 19‐year wavetrains were highly correlated with epochs 1898·9, 1917·5, and 1936·1. For eighteen stations wave minima were still correlated with the next epoch, epoch 1954·7; however, a bistable phase switch of 180° then occurred and wave maxima came into phase with epoch 1973·3. In two instances in northern Illinois the switch occurred a cycle earlier at epoch 1954·7, and in five instances a half cycle earlier at mid‐epoch 1964·0. O'Brien and Currie (1989) have provided a construct in mathematical physics that explains how bistability can occur at air‐pressure recording stations, and Currie (1987a) has provided many examples of bistability in air pressure and air temperature data from around the world.
Southern Oscillation influences on tropical cyclone activity in the Australian/south‐west Pacific region
Authors: Hastings Peter A. 
Published: February 2007

AbstractTropical cyclone activity within the Australian (105°–165°E) and south‐west Pacific (145°E–150°W approximately) regions is examined during seasons affected by contrasting extremes of the Southern Oscillation (SO). In the Australian region, the most pronounced and consistent contrast of tropical cyclone frequency variability was within the eastern Australian region (145°–165°E) where anti‐ENSO (ENSO) conditions were associated with a higher (lower) incidence of tropical cyclogenesis. This relationship appears to be a manifestation of tropical cyclone behaviour in the wider south‐west Pacific region, wherein tropical cyclone origin points exhibit distinct areal patterning associated with times of extreme SO states. Intra‐seasonal temporal distributions of the Australian region tropical cyclogenesis and the south‐west Pacific tropical cyclone incidence are also examined.
A climatological approach for estimations of hourly averages of global irradiation
Authors: Castro‐Diez Y. , Jimenez J. I. 
Published: February 2007

AbstractMonthly mean values of daily and hourly global solar irradiation at eight stations in Spain are analysed on the basis of the similarity between the shape of extraterrestrial irradiance during the day and the Gaussian curve. This shape is found to be the same on the Earth's surface after attenuation through the atmosphere whenever the averaged‐out period is long enough. Bearing this in mind, it is possible to obtain values for the ratio between the hourly irradiance and the daily global irradiation, from one parameter σ, with the normal distribution curve. This curve is found to fit closely with experimental results. The mean of the normal distribution is taken at solar noon and the parameter σ is determined for each month by matching the experimental and the theoretical values at this time. The σ‐values thus obtained are found to bear an excellent linear correlation with N (monthly mean of maximum sunshine duration). The close correlation of the regression constants with latitude, altitude, and relative bright sunshine duration provides a simple technique for estimating hourly irradiance from the daily values within a certain range of latitudes. This technique makes the estimation of global irradiation for any smaller time interval possible. The errors involved in the estimations obtained are less than 10 per cent in most cases.
Occurrence and characteristics of lower tropospheric ice crystals in the arctic
Authors: Curry J. A. , Meyer F. G. , Radke L. F. , Brock C. A. , Ebert E. E. 
Published: February 2007

AbstractThis paper discusses the occurrence and characteristics of small ice crystals that are encountered in the lower troposphere of the Arctic during the cold half of the year, when large reductions in visibility are present. Because of the difficulties in observing these ice crystals, both from surface and satellite observations, and owing to the ambiguities of cloud classification in the polar regions, these ice crystals are not included in current cloud climatologies. A summary is presented of what is known about the Arctic ice crystal climatology, formation mechanisms, and physical properties. Data obtained from the University of Washington Convair C‐131A research aircraft during April 1983 and 1986 are presented, including the frequency of occurrence of ice crystals as a function of height, temperature, and relative humidity. Radiative transfer calculations were made using the observed ice crystal size distributions. The radiative transfer through the ice crystal layers is inferred to have a substantial impact on visibility in the Arctic, the vertical temperature structure of the Arctic troposphere, and on the surface energy balance.
Deterministic signals in USA precipitation records: Part I
Authors: Currie Robert G. , O'Brien Douglas P. 
Published: February 2007

AbstractEvidence for the 18–6‐year luni‐solar MN signal is found in 220 out of 288 rain‐gauge records (76 per cent detection ratio) in the states of California, Colorado, Kansas, Missouri, North Carolina, Ohio. Oregon, Washington, and West Virginia, with a mean period of 18·4 ± 1·5 years. This detection ratio is less than that for the nation, which is 1015 out of 1219 records, or 83 per cent. The solar cycle Sc signal was found in 70 per cent of these records, with a period of 10·6 ± 0·5 years. For Colorado, and states directly to the east as far as Illinois, minima in most 19‐year Mn wavetrains were generally in phase with epochs 1898·9 through to 1954·7 (epochs are dates of maximum in tidal forcing). However, by 1973‐3 virtually all records east of Colorado had experienced a 180° phase switch and wave maxima were in phase with this epoch. In Oregon and Washington most MN waves recorded maxima in wetness at epoch 1898·9 through to 1973·3, and thus have historically been out of phase with the continental interior. California records displayed evidence for two 180° phase switches in the past 100 years. The apparent reason for this is that California is near the edge of a fairly stable continental interior cell that has historically been dry at epochs; and when the dry cell waxes or wanes in areal extent, frequent 180° phase switches are produced in areas adjacent to it. The phenomena described have been found in other regions of the USA, and in records of air temperature and air pressure world‐wide.
Signatures of A universal spectrum for atmospheric interannual variability in rainfall time series over the Indian region
Authors: Selvam A. Mary , Pethkar J. S. , Kulkarni M. K. 
Published: February 2007

AbstractA recently developed non‐deterministic cell dynamic system model for atmospheric flows is summarized in this paper. The model predicts quantum‐like mechanics for atmospheric flows with inherent long‐range spatiotemporal correlations, now identified as signatures of self‐organized criticality or deterministic chaos. The model enables quantification of the power spectrum of temporal fluctuations of atmospheric flows in terms of the universal and unique characteristics of the statistical normal distribution. The model predictions are in agreement with continuous periodogram analysis of three sets each of 30 years (1871–1900, 1901–1930, 1956–1985) and one set of 25 years (1931–1955) summer monsoon rainfall time series for 29 meteorological subdivisions in the Indian region. The important results of the present study are as follows. (i) The power spectrum of the temporal fluctuations of rainfall follows the universal inverse power law form of the statistical normal distribution, with the square of the eddy amplitude representing the eddy probability density corresponding to the normalized standard deviation t equal to (logλlogλ50)‐1; where λ is the period length in years and λ50 the period up to which the cumulative percentage contribution to total variance is equal to 50 and t=0. (ii) Periodicities in rainfall up to 3–4 years contribute to as much as 50 per cent of the total variance.A universal spectrum for interannual variability in summer monsoon rainfall indicates predictability of the overall pattern of rainfall fluctuations. A relatively recent and short period rainfall time series, such as the 30‐year period 1956–1985 in this study, enables identification of the universal structure of atmospheric variability. Further, short period fluctuations that are major contributors to interannual variability can be identified accurately in the 30‐year data sets and provide means for estimating the near future (up to 4 years) rainfall variation.
A procedure for removing the synoptic climate signal from environmental data
Authors: Comrie Andrew C. 
Published: February 2007

AbstractUsing weather‐type frequencies from a synoptic climatology, a technique is presented that discriminates between within‐type and between‐type variations in a time series of climate‐related environmental data. The removal of the synoptic climate signal, or declimatizing, is based on normalizing the data by the mean annual weather‐type frequencies for the study period. Declimatizing is illustrated symbolically and with a worked hypothetical example. An application of the procedure to visibility data from Pittsburgh, Pennsylvania demonstrates its utility in decomposing complex climate‐related environmental data into its component synoptic and non‐synoptic influences. The methodology can also distinguish the relative importance of between‐type and within‐type changes in a synoptic climatology.
Cellular convection over the north‐eastern Atlantic
Authors: Bakan S. , Schwarz E. 
Published: February 2007

AbstractConvective clouds over the ocean frequently exhibit organized meso‐scale patterns. A statistical evaluation of 4 years of NOAA satellite images over the north‐eastern Atlantic yields climatological data of the appearance of these patterns and shows that open cellular convection is most abundant. For this convection type, surface and radiosonde data from Weathership M have been analysed. Open convection cells appear at a wide range of positive sea‐air temperature differences up to 12°C and at wind speeds up to 25 m s−1. All diameters have been found to be less than 80 km (average 41 km). Larger diameters are, on average, associated with slightly larger convection heights and, thus, with larger aspect ratios.The scene‐averaged brightness temperature of AVHRR channel 4 exhibits a definite correlation with the sea‐air temperature difference and, less well expressed, with the sensible and latent heat flux. This, in turn, provides a possibility of estimating those quantities by using easily accessible AVHRR satellite data.
Monthly mean pressure model for Chile
Authors: Saavedra N. , Foppiano A. J. 
Published: February 2007

AbstractA simple empirical model to describe the latitudinal distributions of monthly mean surface pressure along the Chilean coast is proposed. Model hypotheses, such as regions into which latitude distributions are to be divided and latitude dependencies of pressure within these regions to be assumed, are discussed with reference to a climatic scenario that has been found of value in developing simple empirical climatic models for coastal stations in Chile. Equations are derived giving pressure at any latitude as a function of the latitude of the location of maximum monthly mean pressure in Chile (LMP) and of pressure at that location. It is concluded that the proposed model describes adequately the observed latitudinal distributions. Moreover, it is found that the coupling between the Pacific Anticyclone and the continent is particularly simple for locations north of the LMP's latitude, leading to a unified quantitative description of climate for those latitudes. Furthermore, the model allows qualitative inferences to be made regarding the interaction mechanisms between the main meteorological centres of action on a regional scale, which may prove of value to identify trends of regional climatic change.
Wind persistence in Croatia
Authors: Poje Dražken 
Published: February 2007

AbstractOn the basis of mean hourly wind direction and wind speed data from 11 anemograph stations in the eastern part of the Adriatic sea and seven inland stations in Croatia, and records of different length, the basic characteristics of wind persistence are discussed. In continuation of our earlier work, which dealt with wind persistence regardless of wind direction, this paper presents the results of investigation on wind persistence for wind groups of three combined directions. On the Adriatic three dominant winds are analysed: Bora, ‘Jugo’, and Etesian winds. The mean run length, run duration for 90 per cent and 95 per cent of all cases, as well as the longest recorded duration for run levels of v ⩽ 3m s−1, v 3 m s−1, v > 5 m s−1, v > 8 m s−1, v > 12 m s−1 and v > 18 m s−1, are elaborated. With regard to the potential utilization of wind, the most promising areas regarding wind persistence are the Velebit Channel in the northern Adriatic and the exposed islands in the southern Adriatic.The second part deals with different methods and analytical functions describing wind persistence depending on different parameters that could be assessed on the basis of observed wind runs or by using only the mean annual wind speed. The best results were achieved using the power exponential function, especially for long wind runs.The third part includes the testing of the methods used on the data for the station Sinj, with satisfactory results.
Temporal variation of relations between New South Wales rainfall and the Southern Oscillation
Authors: Opoku‐Ankomah Yaw , Cordery Ian 
Published: February 2007

AbstractPrincipal component analysis with varimax rotation was used to identify major spatial patterns of New South Wales (eastern Australia) district rainfalls in each season. Four spatial patterns of the principal components of rainfall, each dominant in a subregion of the State, were evident. Plots of correlation coefficients between the amplitudes of the spatial patterns and the Southern Oscillation Index (SOI) revealed temporal instability of the relationships. Results show that the relationships have changed dramatically with time and that they have changed differently from region to region. Over the 55 years (1933–1987) for which data were available, in some regions the correlation coefficients changed from being highly significant, to showing no relationship, in others the reverse was the case, and in some very little change occurred. This meant that over time the spatial pattern of relationships for a given season also changed quite dramatically.These findings have profound implications for studies based on assumptions of stationarity of geophysical phenomena and relationships and suggest there are other, as yet unrecognized, phenomena influencing rainfall in the long‐term.
Long‐term variations in regional rainfall in the south‐west of Western Australia and the difference between average and high intensity rainfalls
Authors: Yu B. , Neil D. T. 
Published: February 2007

AbstractThe south‐west of Western Australia is characterized by a ‘Mediterranean’ climate with dominantly winter rainfall. It is the only Australian region where the annual rainfall has significantly decreased during the period 1911–1990. Based on daily rainfall records from 70 stations in the area, high intensity rainfall (which is closely related to flooding, soil erosion, and gully formation) does not show a concurrent decrease. Reasons for this unconformable trend include a greater temporal variability of high intensity rainfall and an increase in the frequency of occurrence of rainfall events at high intensities during the summer. This tends to balance out a decrease during the winter months. While it is unwise to assume that there will be similar trends for average rainfall and high intensity rainfall for a given region, evidence from the instrumental records supports, to some extent, the notion that in a CO2‐warmed world, high intensity rainfall could occur more frequently irrespective of local change to average rainfall.
Comments on: ‘The effect of domain shape on principal components analyses’
Authors: Richman Michael B. 
Published: February 2007

AbstractIn a recent article claiming to deal with the effect of domain shape on principal component analysis, Legates attempts to use previously published research and analyses of two exploratory data sets to try to dismiss Buell's work on the topography of empirical orthogonal functions. Legates' logic and data sets suffer from a number of flaws, including omission of key results from Buell, neglect of dozens of published papers discussing domain dependence, misinterpreting and misrepresenting numerous references to Richman, and using data sets with inhomogeneities between land and water as well as very low temporal degrees of freedom. This Comment addresses some of these shortcomings by exploring what other researchers have concluded about Buell patterns and how they have minimized the problem. It also serves to provide a proper interpretation of PC loading fields consistent with Richman, and to point out several potential problems in the two data sets used by Legates, which might lead to inferior results.