bluuebunny/crossref_metadata_2025 huggingface dataset:
The simultaneous production of both Hly‐ and Hpm‐like hemolysins is characteristic of the Proteus penneri species
Authors: Serwecinska L. , Pytlos M. , Łukomski S. , Jaworski A. , Rózalski A.
Published: February 2007

Clinical isolates of Proteus penneri were tested for the presence of genes encoding hemolytic activity. Strains possessing DNA sequences similar to the hlyCABD genes in Escherichia coli were found. Each secreted a 110 kDa protein which reacted with a specific anti‐HlyA antiserum. Southern blotting analysis revealed that the HindIII restriction fragment pattern for the hlyCABD genes of these strains was conserved. Similarly, the chromosomal location of these genes is relatively conserved based on the pattern of NotI digested DNA fragments separated by pulsed field gel electrophoresis. One strain carried an additional copy of the hlyCABD determinant which was mapped on a second NotI genomic fragment. All strains contained also chromosomally encoded sequences related to the hpmBA genes originally cloned from Proteus mirabilis. All strains produced a 166 kDa exoprotein detected in immunoblots with a specific antiserum raised against HpmA hemolysin. The hpmBA genes were located on other NotI fragments than hlyCABD genes. In contrast to the other Proteae, the simultaneus production of both hemolysins seems to be a common characteristics of Proteus penneri isolates.
A study of climatic variability of daily central england temperatures in relation to the lamb synoptic types
Authors: Sowden I. P. , Parker D. E.
Published: February 2007

Long‐term changes of temperature and of characteristic circulation patterns over the British Isles have been studied using catalogues of daily Central England temperature and daily Lamb circulation types for 1861 to date. Most inter‐decadal temperature variability appears to have been linked with fluctuations in circulation. For given Lamb circulation types much of the observed long‐term variability of temperature appears to derive from lack of precision in the circulation classifications.
The empirical relation between sunshine and radiation and its use in estimating evaporation in North East England
Authors: Hanna L. W. , Siam N.
Published: February 2007

The relation between the duration of sunshine hours and radiation derived from ten years of daily records at Eskdalemuir and Cawood differs significantly from formulae in general use with the Penman formula. When used in the Penman formula with meteorological data from North East England evaporation estimates were more satisfactory than those based on commonly used formulae. While winter months showed different relations between sunshine and radiation their use in estimating evaporation made no significant difference on cumulative evaporation over a year. The regression R/RA = 0.1894‐0.624(n/N) derived from Eskdalemuir is satisfactory for use in North East England.
The North Pacific Oscillation
Authors: Rogers Jeffery C.
Published: February 2007

A climatological study of the North Pacific Oscillation (NPO) during Januaries and winters (D‐J‐F) between 1906 and 1978 is presented. The NPO is defined in terms of opposition in sign of mean temperature anomaly between western Alaska‐eastern Siberia (as represented by the stations at Dutch Harbor and St. Paul, Alaska) and western Canada (as represented by Edmonton). The two oscillation modes, Aleutians below normal temperature (Edmonton above normal) and Aleutians above normal temperature (Edmonton below normal), are associated with variations in the strength of the zonal westerlies over the Pacific and North America which in turn result from longitudinal variations in the mean position of the Aleutian low. A westward location of the mean low. over the Sea of Okhotsk, is associated with the development of intense mean high pressure cells over western North America while zonal flow is associated with a more eastward location of the mean low over the Gulf of Alaska. Significant spatial correlations exist between the strength of the zonal component of the geostrophic wind over the Pacific Ocean and the zonal component of the polar and subtropical easterlies over the Pacific sector.

The NPO modes are associated with large regional variations in air temperature and precipitation over North America, sea surface temperatures in the North Pacific, and Bering Sea ice. The NPO is found to resemble the second eigenvector of January and winter sea level pressure anomalies. In contrast to its more frequently occurring counterpart, the North Atlantic Oscillation, the NPO is not clearly associated with hemispheric mean temperature trends and its modes occur randomly with time. The two oscillations represent separate patterns of teleconnections of sea level pressure and zonal geostrophic winds over the Northern Hemisphere.
The distribution in space of local rainfall in the Namib Desert
Authors: Sharon David
Published: February 2007

Spatial correlation analysis has been applied to Namib rainfall, in an attempt to identify possible patterns of the spatial organization of localized storms in this area. The utility of the above technique for areas with only sparse raingauge networks is explained. Results indicate that convective storms are not randomly scattered in space but, tend to form at preferred distances from each other, around 40‐50 and 80‐100 km, with no preferred locations of, or directions between, storms. Benard cells are mentioned as possibly imposing the inferred organization of convective storms in space.
The use of global circulation models in the study of the Indian monsoon
Authors: Druyan Leonard M.
Published: February 2007

The agricultural economy of India depends on the regularity of the summer monsoon rains although this climatic phenomenon exhibits a natural variability which often brings disaster. There exists much literature which discusses the physical mechanisms of the monsoon in its general aspects and some attention has been given to explanations of the variability of its main characteristics. Global circulation models afford an opportunity to examine the role of each of many physical components while allowing for interaction between the planetary circulation, sometimes even the oceanic circulation, and the monsoonal one over South Asia. Experiments to date have investigated the influence of Arabian Sea and Indian Ocean surface temperature anomalies, the influence of the Himalayan Mountains, of surface albedo and of the relative importance of sensible versus latent heating in maintaining the summertime regime. Armed with a greater understanding of the causes of monsoon variability, researchers will perhaps be able to begin developing techniques for seasonal forecasting.
Atmospheric circulation variations and the occurrence of extended wet and dry spells over Southern Africa
Authors: Tyson P. D.
Published: February 2007

Variations in rainfall over southern Africa are explained in terms of variations in pressure and circulation patterns. The extended wet spells of the quasi 18‐year oscillation in rainfall that have affected the subcontinent are shown to have occurred in association with increased pressures in the region where the subtropical ridge of the first zonal standing wave in the 500‐mb surface has its expression in the southern hemisphere, in association with the eastwards displacement or weakening of the Indian Ocean high and a probable lowering of pressure over the subcontinental interior. It is further suggested that the 10‐11 year rainfall oscillation of the southern Cape may be forced by longitudinal changes in the position of the first ridge of standing wave 3 which may oscillate with a similar quasi‐periodicity.
On the northward advance of the Itcz and the onset of the southwest monsoon rains over the southeast Bay of Bengal
Authors: Ananthakrishnan R. , Pathan J. M. , Aralikatti S. S.
Published: February 2007

The pentad rainfall data of six stations in the Andaman‐Nicobar group of islands for the period 1953‐1978 have been analysed to study the northward advance of the ITCZ and the onset of the summer monsoon rainfall over the southeast Bay of Bengal. It is found that at the island stations south of 10°N the summer monsoon rains set in on the average towards the end of April which is a month in advance of the onset of the monsoon over the south Kerala coast of peninsular India. At the island stations to the north of 10°N the onset occurs about the first week of May. These dates are ahead of those shown in the existing diagrams giving the average onset dates of the summer monsoon over the southeast Bay of Bengal. Examination of the frequency and latitude of formation of cyclonic disturbances in the Bay of Bengal and the progressive seasonal variations of the tropospheric winds over the aerological station of Port Blair during April‐May lend support to the earlier onset dates.
Canyon geometry and the nocturnal urban heat island: Comparison of scale model and field observations
Authors: Oke T. R.
Published: February 2007

A simple hardware scale model is used to simulate nocturnal cooling rates for rural and urban environments under calm and cloudless conditions. Comparison with field observations gathered under similar conditions shows the model capable of reproducing many of the features of the temporal development of urban heat islands and the long‐wave radiative exchange in urban canyons. The model is used to investigate the roles played by rural/urban differences in geometry and thermal admittance. The results of the experiments show that canyon geometry in the central portion of a city (as measured by the sky view factor) is a relevant variable in producing nocturnal urban heat islands due to its role in regulating long‐wave radiative heat loss. It is also demonstrated that this measure is central to the relationship between city size and heat island intensity. The importance of canyon geometry as a feature of urban design is discussed. Thermal admittance differences can also produce realistic heat island features but their magnitude requires quantification in the field.
On the stability of temperature eigenvector patterns
Authors: Gray B. M.
Published: February 2007

Eigenvector spatial patterns for European temperatures have been investigated for seven periods between 1761 and 1969. When the number of observations greatly exceeds the number of stations used in the analysis, the main patterns of anomaly are seen to be stable in time, appearing in the same position in the eigenvalue ranking order in each period. Patterns which are time‐invariant are concluded to have physical significance.
Synoptic controls over katabatic layer characteristics above a melting glacier
Authors: Stenntng Alison J. , Banfield Colin E. , Young Gordon J.
Published: February 2007

The objective was to demonstrate the degree of control exercised by synoptic‐scale meteorological conditions upon the development and characteristics of a katabatic layer above a melting glacier. Field measurements were undertaken at a point on the snout of a temperate‐alpine type valley glacier in Alberta during part of the 1979 ablation season. At this site vertical wind velocity profiles were recorded within a 7 m layer above the glacier surface, together with vertical air temperature difference over 1‐4 m and wind direction at 2 m. An hourly sampling period was chosen to facilitate investigation of the variation of near‐ice wind and temperature conditions under varying large‐scale synoptic weather patterns.

Five synoptic types were identified for the study period using a subjective classification. The greatest number of significant differences between pairs of types occurred for 700 mbar temperature and relative humidity, 500 mbar temperature, and local cloud‐cover and barometric pressure at the glacier site. Representative estimates of the glacier katabatic force and synoptic pressure‐gradient force indicated the former exceeded the latter by about 12:1 under strongly developed warm anticyclones and by about 3:1 during cool cyclonic situations.

Consequently under anticyclonic conditions a well developed katabatic layer was often observed with a wind velocity maximum below 5 m, whereas weaker katabatic layer development characterized cyclonic conditions. During anticyclonic influence increased deviation of ambient (700 mbar) winds from the down‐glacier direction produced significantly stronger katabatic layer inversion strength but had little impact on katabatic wind velocity or direction. Under cyclonic control across‐slope ambient winds were associated with weaker katabatic wind velocity and inversion strength, together with deflection of surface wind direction. An inverse relationship between katabatic layer wind velocity and inversion strength was significant for two synoptic types.
Monitoring a changing climatic series
Authors: Craddock J. M.
Published: February 2007

Formulae are developed for finding statistics to describe the latest state of a climatic time series without assuming that the character of the series will remain unchanged with time. The choice of formulae is discussed, and reasons given for the parameter settings which make the operations specific. Applications of the technique are illustrated by the extracts from analyses of British records covering most of the years 1821 to 1980, six being of rainfall and two of temperature.
Response of the antarctic ice sheet to a climatic warming: A model study
Authors: Oerlemans J.
Published: February 2007

It is generally believed that the increasing CO2 content of the atmosphere will lead to a substantial climatic warming in the polar regions. In this study the effect of consequent changes in the ice accumulation rate over the Antarctic Ice Sheet is investigated by means of a numerical ice flow model. In the model runs, temperature increases linearly with time during 100 years, and is kept constant afterwards.

The results indicate that a climatic warming will probably lead to a sea‐level lowering of some tens of centimetres in the next centuries. This is because for Antarctic conditions the increase in snow accumulation exceeds the increase in melting. This estimate does not take into account the effects of possible surging of parts of the Antarctic Ice Sheet and the response of the Greenland Ice Sheet (which may be quite different).
Snow cover conditions in the northern Hemisphere during the winter of 1981
Authors: Foster J. L. , Rango And A.
Published: February 2007

During the winter of 1981 the mean snow covered area in the Northern Hemisphere was less than any other year in the 15‐year record (1966‐1981) except 1970. For North America, the mean snow cover area was the lowest on record, and for Eurasia the mean snow cover area was the second lowest since records began in 1966. It has been observed that the average winter snow cover in both North America and Eurasia for both 1980 and 1981 decreased from that of the previous year, the first time this has been observed in the 15‐year period of record. Assessment of any long term climatic trends must wait extension of the snow cover data base.
A historical review of studies on the energy balance of arctic tundra
Authors: Ohmura Atsumu
Published: February 2007

The main field experiments and climatological calculations of the surface energy balance on the arctic tundra are reviewed, following the historical development of theories and instruments. The scientific significance and problem areas of individual studies are discussed and the present status of understanding the energy balance on the arctic tundra is described.
Snow and ice balance in britain at the present time, and during the last glacial maximum and late glacial periods
Authors: Lockwood J. G.
Published: February 2007

Simple parameterizations are used to estimate monthly mean ablation of snow and ice, and also the distribution of monthly mean precipitation in Britain. Together these enable estimates to be made of snow storage at various levels and the gradients of days with snow cover with elevation. Small semi‐permanent snow patches below the regional snow line are included in the discussion. The theoretical estimates fit the actual observations very closely. A similar approach is then used to estimate snow balances for the British Devensian ice sheets. Probable snow accumulation/elevation relationships are produced for 24,000 yr BP. Estimates suggest that the British ice sheet was just in balance at the lime of its maximum advance around 18,000 yr BP. The growth and decay of British ice sheets are considered and two stable states are suggested for ice‐age climates, one without an ice‐sheei and the other with a massive ice‐sheet.
Multiple interpolation in climatological spectra
Authors: Gray B. M.
Published: February 2007

The variable length record method of spectral analysis is considered as a composite of perturbations of a simple harmonic analysis. By smoothing over near neighbours, the composite spectrum can be made to approach the true spectrum. Since the method is computationally expensive, a less costly technique of multiple interpolation is considered and shown to produce equivalent results. This method is suitable for examining the low frequency end of cli ma to logical spectra.
Comparison of normal and below normal July precipitation patterns in central Iowa
Authors: White Gary R. , Vaughan Harry C.
Published: February 2007

Previous discussions of wet, dry and normal years in Iowa have been related primarily to the departure of rainfall from a climatological average. Rainfall during the month of July is examined because of its importance on the local cash crop, maize. The first section of the paper deals with the variability of areal precipitation patterns within the central Iowa climatological network (1000 km2/gauge) for the years 1930‐1978. Results of this study seemed to indicate that examination of a fine‐grid rain gauge network (1‐64 km2/gauge) was needed. Weather radar data also were used to provide a better data base to study the size and variability of July precipitation areas. In the second section, July 1976 (dry) and July 1977 (normal) were chosen to provide a comparision of precipitation patterns between a dry and normal precipitation year. The results show that, during a dry year (40 per cent below normal), there are nearly the same number of days with rain occurring as in a normal year. The most important factor in the comparison of the two years is that the size and number of individual precipitation echoes are both about 40 per cent less during 1976 than in 1977.
Studies of the Indian summer monsoon with a coarse‐mesh general circulation model, part II
Authors: Druyan Leonard M.
Published: February 2007

A previous paper (Part I) discussed the performance of a coarse‐mesh general circulation model in studies of the Indian summer monsoon. Part II herein describes impacts on the simulated monsoon climate due to prescribed changes in the lower boundary conditions: lowering and flattening of the Himalayan Mountains and cold and warm sea‐surface temperature (SST) anomalies in the Arabian Sea. Results indicate that it is the Himalayas that are responsible for the observed north‐westerly flow aloft over northern India before onset and the delay in precipitation onset there until late June or July. SST anomalies, which are held constant throughout four‐month simulations, affect local precipitation computations via changes in stability and cause impacts of the opposite sign immediately downwind. Neither of the two anomalies tested resulted in statistically significant precipitation impacts over India.
The effect of altitude on the daily range of temperature
Authors: Linacre Edward
Published: February 2007

Although it has been claimed that the daily range of screen temperature increases with altitude on a mountain, this appears not to be true generally. Data from sixteen sources indicate a confusion of evidence, though there appears to be some evidence of an increase of daily temperature range with height from 0‐200 m, and of a decrease between 750 m and 3400 m. The low‐altitude increase is attributed to the sea's moderating influence at the coast. The higher altitude decrease may be due to stronger winds or to more cloud. The evidence for a decrease may be confounded in some places by either peculiarities of locale or the increased daily fluctuation of radiation at highest altitudes.
Cave climate: Assessment of airflow and ventilation
Authors: De Freitas C. R. , Littlbjohn R. N. , Clarkson T. S. , Kristament I. S.
Published: February 2007

Study of cave climates is a neglected aspect of microclimatology. An understanding of the processes that control cave climate is required in the study of cave flora and fauna, thermodynamic conditions for karst processes underground, hydrogeologic features of speleothems as well as human use of caves for recreational and commercial purposes. An understanding of cave airflow is of central importance as the climate of a cave is a function of air exchange with the outside environment. The study site is the Glowworm Cave of New Zealand and is of particular interest because of its heavy visitor use and the presence of climate sensitive cave fauna on which the value of the cave as a tourist attraction depends.

The study examines airflow using conventional methods together with experimental procedures using SF6 and CCl2F2 tracer gases. The results show that the rate and direction of airflow are a direct response to a thermally induced disequilibrium in air density between the cave and outside air. Both diurnal and seasonal patterns in the direction of airflow were identified. Reversal of airflow occurs when the cave to outside air density gradient is zero rather than when thermal conditions of the cave and external air are the same. Major and minor airflow routes through the cave were identified. The results of the gas tracer experiments allowed estimation of rates of air change in different parts of the cave and confirm the marked difference in ventilation that occurs within the cave. Information of this type is important because of the relationship between natural ventilation and CO2 buildup. There is also the effect of ventilation on differences in climate within the cave as the thermal and moisture effects of outside air will not be as pronounced in parts of the cave where air change is limited.
A probability analysis of precipitation surplus or deficit
Authors: Takhar H. S. , Cook D. J.
Published: February 2007

The surplus or deficit of precipitation is of fundamental importance in hydrology. An analysis is presented which provides for the prediction of surplus or deficit conditions as far as six months ahead. Data from Yorkshire, together with thirteen years data from a station in Nottinghamshire, are used statistically to analyse problems in water supply, irrigation and drainage. This analysis is based upon a technique developed by Stol in which differences between evaporation and precipitation are analysed over different periods of time.
Extreme distributions of Australian annual rainfall in relation to sea surface temperature
Authors: Streten N. A.
Published: February 2007

Sea surface temperature (SST) measurements from 1950 to 1969 are analysed for an extensive region of the Southern Hemisphere for six years of very high and very low areal extent of above normal Australian continental rainfall. Years of extensive drought are found to be associated with a predominantly low SST persisting throughout the year over the eastern Indian Ocean and the south west Pacific in the Australasian region particularly at low latitudes; very wet years over the continent are associated with a persistently warm SST extending from the equator to mid latitudes in the same region. Although the extreme years tend to be related to extremes of a Southern Oscillation index this is not always the case. Examination of SST over the eastern Pacific for the same years indicates some evidence that its thermal anomalies are in general opposite to those in the Australasian region though this is not so in all cases. Eastern South Pacific SST data sequences for years preceding and following individual extreme rainfall years over Australia show rapid and differing changes so that their forecasting potential is very limited.
The value of climate information: A decision‐analytic approach
Authors: Winkler Robert L. , Murphy Allan H. , Katz Richard W.
Published: February 2007

A decision‐analytic approach to the problem of assessing the value of climate information is presented and an application of this methodology to a decision‐making problem involving the use of climate information is described. First, decision analysis is discussed briefly with emphasis on its informational aspects. Then a decision‐making situation is considered in which a farmer must decide which of two crops to plant in the face of uncertainty as to whether growing season precipitation will be above or below average. It is assumed that information concerning growing season precipitation is embodied in a climate forecast provided by a meteorologist and that this information constitutes the basis for the farmer's decision. Several probabilistic models for the climate forecasts are considered, including symmetric and asymmetric discrete distributions and a normal model. These models can provide reasonable descriptions of currently available climate forecasts. The analysis reveals that relatively uncertain climate information may be of value in some decision‐making situations, although the value of climate forecasts with skill levels commensurate with existing seasonal forecasts does not approach the value of perfect forecasts. Nevertheless, in the situations considered, once a minimum level of skill is achieved, further improvements in the forecasts result in steadily increasing benefits. Finally, it is indicated that decision analysis is also applicable to more complex situations in which climate information may play an important role.
Teleconnections and the siege of time
Authors: Ramaoe C. S.
Published: February 2007

The recent surge of interest in climate has resurrected correlation coefficients as tools for identifying ‘significant’ atmospheric teleconnections. Unfortunately, large coefficients may diminish and even change sign with time, suggesting absence of real physical relationships.

Some statistical evidence supports the view that higher than normal sea surface temperatures in the central and eastern Pacific ‘cause’ less than normal rainfall in the Indian summer monsoon. However, a study of individual Augusts uncovers major exceptions and at the same time fails to confirm that Indian summer rainfall influences central and eastern Pacific rainfall or that the Southern Oscillation Index can be consistently related to conditions in either region.

Around 1963‐1964 the apparent relationship between the Southern Oscillation Index and Indian rainfall reversed. At about the same time other global climatic relationships changed, raising the possibility of identifying and describing a major global climatic singularity separating two distinct statistical populations.
Fluctuations in the surface temperature and surface salinity of the north‐east Atlantic at frequencies of one cycle per year and below
Authors: Taylor A. H.
Published: February 2007

Time‐series of monthly sea surface temperature and salinity data (1951‐1974) from stations in the N.E. Atlantic were investigated by calculating cross‐spectra using the method of maximum entropy analysis. This new technique has not previously been applied to climatological problems. The temperature and salinity data were also compared with surface heat‐flux and evaporation time‐series and wind observations. The main features of the seasonal cycle are apparent in the results, in particular, the close synchronism of the temperature cycle across the region. In addition, the results show that: variations in the seasonal flux of low salinity water led to short period anomalous salinity values, salinity and temperature anomalies tended to drift with the surface currents, and salinity and temperature changes at the lowest frequencies were caused by displacements of water masses which do not seem to have been forced locally. Fluctuations in heat‐flux and evaporation contributed to variations on a timescale of about three years and it is shown that these gave rise to additional spectral peaks by interacting with the seasonal cycle.
Solar and net radiation in Peninsular Malaysia
Authors: Hu Hing Chong , Lim Joo Tick
Published: February 2007

Linear regression equations relating the global solar radiation and sunshine duration are derived for a total of 14 stations in Peninsular Malaysia. Mean monthly global solar radiation values for other stations which have only sunshine data are estimated using these regression equations. The intensities of global solar radiation during different times of the day and under different meteorological conditions are discussed. Maps of mean monthly global solar radiation are presented and discussed. It is found that the distribution pattern of global solar radiation follows somewhat with that of rainfall pattern.

Net radiation was estimated using empirical equations developed by Chang (1970), Davies (1967). Selirio et al. (1971) and Penman (cited by Chang, 1970). Comparison of the estimated net radiation with the limited net radiation record available shows that the Davies' formula gives the best estimates. Hence Davies' formula is used for the estimation of net radiation. Maps of estimated net radiation are similarly prepared and discussed.
The estimation of missing climatological data
Authors: Tabony R. C.
Published: February 2007

Various methods of estimating montly means and extremes of climatological data are examined. Any generalized method is likely to be based on a correlation matrix, but the incompleteness of the data introduces problems with this approach. These are illustrated by program BMDPAM of the BMDP suite, which produces estimates inferior to those using traditional methods based on single station comparisons. Principal component analysis is considered likely to be the best statistical technique for estimating missing values among highly correlated data. The high quality correlation matrix required as input can be obtained by using a simple estimating procedure to produce a preliminary set of complete data. A simple technique devised for estimating climatological data in the U.K. was found to give results similar to those obtained from an eigenvector scheme used for quality control purposes. The accuracy of the technique is such that it is suggested that satisfactory averages could be estimated for stations with only 10 years of data, and possibly less.
A statistical method for quality control of routine temperature observations in developing countries
Authors: Stigter C. J. , Hyera T. M. , Mjungu Y. B.
Published: February 2007

A simple statistical method is outlined to evaluate and improve routine temperature observations from meteorological stations in developing countries. This quality control achieves two things. It identifies anomalous data before storage or use. It also reveals whether thermograph, minimum thermometer, maximum thermometer and dry bulb thermometer have to be checked and/or how their data must be improved to be internally consistent. In addition this statistical approach assesses differences between averaging methods. It can be concluded that with this cost‐efficient method, temperature data accuracy obtained will be adequate for agricultural purposes and other climatological applications.
The spatial organisation of daily rainfall in eastern New South Wales
Authors: Sumner Graham N.
Published: February 2007

Product‐moment correlation are used to provide an estimate of the degree of association of daily rainfalls between a number of sited in eastern New South Wales. Completely dry days are omitted from the analysis so that the coefficients obtained represent the strength of association between sites for days on which rainfall occurs. Maps showing the strength of links between sites are used to illustrate general trends in the spatial organization of daily rainfall on a monthly basis. Certain very district seasonal changes in rainfall patterns emerge, principally distinguishing the summer (December to February) from the cooler part of the year (April to October) in terms of the nature of association and the separation of discrete rainfall areas. Many of these comprise groups of two or three Bureau of Meteorology forecasting areas. More widespread rainfall associated with lager‐scale atmospheric disturbance occurs in February, and in April and May, but during the April to October period the Divide is seen as a very important climate, as well as topographic, feature. At other times smaller topographic units apparently exert a control over rainfall occurrence. This is particularly true of the Hunter valley which is the center of rainfall development for a wide area in January. Sea breeze front effects are also seen as important enhancers of rainfall in the summer.
Sub‐saharan rainfall update for 1982; continued drought
Authors: Lamb Peter J.
Published: February 2007

The 1982 value of a sub‐Saharan rainfall index previously published for 1941‐1981 is given. This establishes that the drought which commenced in 1968 and persisted very strongly throughout the 1970s and 1980‐1981 continued into 1982. which was the third driest year of the period 1968‐1982, and also appears to have received substantially less rainfall than the drought years of the 1940s. Several meteorological and socioeconomic implications of this situation are discussed. The paper also provides a recomputation of the entire 1941‐1982 index time series that was permitted by the forward extension of the database since the original calculation for 1941‐1974.
Spatial patterns of precipitation in England and Wales and a revised, homogeneous England and Wales precipitation series
Authors: Wigley T. M. L. , Lough J. M. , Jones P. D.
Published: February 2007

The spatial patterns of precipitation variability over the United Kingdom are examined for the period 1861–1970 using principal components analysis. Most of the variance (around 50 per cent) is explained by the first component, which is characterized by uniform variability over the whole region. Higher‐order components isolate differential variability between different regions. The first four components are essentially the same for all months, all seasons and the annual total, highlighting the intra‐annual constancy of inter‐regional variability and pointing to strong geographical and topographical control. A subdivision of the analysis period into two halves produces no change in the component patterns, but changes in the variance explained by the first component imply that summer precipitation has become less spatially variable since 1915. On the basis of the principal components analysis the England and Wales region is divided into five coherent subregions. A regression technique is developed to produce a homogeneous area‐average precipitation series for England and Wales using the longest site precipitation records available and maintaining even spatial coverage. The method used allows changes in the reliability of the area‐average due to changes in the density of station coverage to be quantified. An empirical relationship between the standard error of estimate of area‐averaged precipitation and the number of recording sites is derived. Significant inhomogeneities in the Nicholas and Glasspoole England and Wales precipitation series at 1915 and 1957 are detected and quantified. The Nicholas and Glasspoole series as a whole is found to underestimate precipitation amounts noticeably in the late eighteenth and early nineteenth centuries.
A stochastic model to generate sequences of hourly mean wind speeds for different sites in the United Kingdom
Authors: Smith S. G.
Published: February 2007

A stochastic model has been developed to generate sequences of hourly mean wind speeds for different sites in the United Kingdom. A feature of its formulation is that three distinct wind speed regimes have been identified within a time series and each regime fitted separately. Sixteen stations providing data over a 15 year period have been used to develop and test the model. Results are encouraging, more especially for the higher speeds.
Indian rainfall in relation to the sunspot cycle: 1871–1978
Authors: Ananthakrishnan R. , Parthasarathy B.
Published: February 2007

The paper presents the results of a detailed study of the annual rainfall of India in relation to the sunspot cycle for the period 1871 to 1978. Rainfall time series of individual stations as well as of meteorological subdivisions have been examined for the full period (108 years) and for two half periods.

The correlation coefficients (CC) of 306 stations for the full period lie between 4–0–29 and −0–14 with a preponderance of positive over negative values in the ratio 4:1. Twenty‐six CC values are significant at the 5 per cent level. The CC values for the two subseries reveal appreciable temporal variations, the correlations being higher for the first half. Lag correlations between the rainfall and sunspot series indicate that the CC values tend to increase when the rainfall is correlated with sunspot numbers 1 to 3 years later and to decrease when correlated with sunspot numbers 1 to 3 years earlier.

Examination of the all‐India rainfall series and the sunspot series for the full period shows that excess rainfall years were significantly more during the ascending phase of alternate cycles. Superposed epoch analysis and the Student t test show that the rainfall around the maximum of even cycles characterized by high sunspot activity is significantly higher than the corresponding rainfall in the odd cycles with lesser spot activity. Correlation study with a 15‐year sliding window reveals large temporal variations in the CC values.

Although most of the variance in the rainfall time series is due to causes unconnected with the sunspot cycle, the present study suggests the existence of a weak positive association between Indian rainfall and sunspots on the 22‐year time scale, although the causal connection is unknown.
Riverflow reconstruction from precipitation data
Authors: Jones P. D.
Published: February 2007

In the United Kingdom few river catchments have overflow records longer than 35 years. The wealth of precipitation data in the United Kingdom enables long records of riverflow to be produced with a catchment model calibrated over the recent period. For most parts of England and Wales it is shown that monthly sequences of riverflow that account for 90–95 per cent of the variance of the measured riverflow can be produced back to 1860. Reconstructions are made on 10 catchments (size range 400–4500 km2) in both upland and lowland Britain. Reliable reconstructions are possible using as few as 4 rainguage records.

The reconstructions provide not only a valuable database for the study of the effect of climatic change on riverflow, but also allow stationarity, homoscedasticy and changes in the frequency of extreme events to be examined. It is shown that on the 10 catchments extreme droughts with a duration of 18 months are three times more likely to have occurred between 1925 and 1979 than between 1870 and 1924. The significance of this and other findings are discussed in the context of water resource analysis. The reconstructed riverflows, apart from their obvious use for water resource analysis, also provide a valuable climatological database for the possible further extension of riverflow using proxy climate indicators such as tree rings.
A Southern Hemisphere sea level pressure data set for use in climatic studies
Authors: Harnack Jeremi , Harnack Robert P.
Published: February 2007

A 25‐year (1956–1980) Southern Hemisphere sea level pressure (SLP) data set (G‐SLP) for the region 10°S–50°S was created by manually extracting interpolated grid point data from monthly SLP maps contained in the German publication Die Witterung in Übersee. Comparison of long term means with published means indicated that the major large‐scale circulation features on the original maps were retained through the extraction process. Comparison between a short term subset (1972–1979) of the data set and A‐SLP, derived from a SLP data set produced by the Australian National Meteorological Analysis Centre of the Australian Bureau of Meteorology, substantiated the reasonableness of the extraction process and suggested areas of possible data problems. The 50°S data was determined to be insufficient for statistical studies owing to missing data. Most areas of significant difference between G‐SLP and A‐SLP, as determined by a Student's t test, can probably be accounted for by the fact that A‐SLP includes satellite data not included in G‐SLP. Analysis of the informational content of the G‐SLP data set is presented, the results of which strongly suggest that the derived data set will be useful in large‐scale climatic studies involving interannual variability of Southern Hemisphere SLP.
The relationship of soil temperature to vegetation height
Authors: Green F. H. W. , Harding R. J. , Oliver H. R.
Published: February 2007

Using extensive observations of air and soil temperatures made under a variety of vegetated surfaces (forest, heather and grass) the influence of vegetation characteristics on the mean soil temperature is considered. It is demonstrated that the main influence is the height of the vegetation, with canopy density only a subsidiary factor. Consideration of the energy balance from two catchments in Wales (one forested and one grassland) strongly suggests that it is the aerodynamic resistance (itself related to vegetation height) which is the determining factor.
Graphical and statistical techniques to describe snow‐cover variations in mountain environments
Authors: Risser Vincent , Martin Serge
Published: February 2007

This paper attempts to provide some practical suggestions for graphical and statistical methods used to describe interannual and seasonal variations of the snow‐cover amount. Essentially two techniques are developed: (i) the ‘probability calendar’, which gives for each day of the cold season (December to May) information on the probabilities of observing some given thickness of the snow‐pack, and (ii) ‘probability charts of evolution’, which give probabilities for the evolution during the snow‐melt period of a snow‐pack having a given thickness at a given date. In order to build these charts we develop statistical models of the melting and compaction of snow using standard meteorological data.
Monthly estimates of wind speed and wind run for Australia
Authors: Hutchinson M. F. , Kalma J. D. , Johnson M. E.
Published: February 2007

This paper introduces the first comprehensive wind speed and wind run maps for Australia. Maps for January, April, July and October based on analyses for all twelve months are presented and discussed. They show, in turn, the distributions of mean 9 a.m. and mean 3 p.m. wind speed at a height of 10 m, the distribution of the ratio between mean daily wind speed and the mean of 9 a.m. and 3 p.m. wind speeds and, finally, the distribution of mean daily wind run at a height of 2 m. The wind speed and wind run maps have been produced from Laplacian smoothing spline surfaces fitted to wind speed observations and to wind run observations and estimates at approximately 500 Bureau of Meteorology stations. The ratio maps, which may be used to estimate wind run from 9 a.m. and 3 p.m. wind speeds, have been similarly produced from data at just 73 Bureau of Meteorology anemograph stations but with independent validation at 68 stations which record both wind speed and wind run. The fitted surfaces are functions of latitude, longitude and a suitable transformation of distance inland from the coast. The degree of data smoothing imposed by the surface fitting procedure has been chosen to minimize for each surface the mean square predictive error estimate as measured by generalized cross‐validation.
Seasonally stratified correlations of the 200 mb tropical wind field to the Southern Oscillation
Authors: Selkirk Rennie
Published: February 2007

The response of the 200 mb tropical wind field to the Southern Oscillation and central equatorial Pacific sea surface temperature is examined with correlation and regression analyses on a seasonally stratified basis. Although there are differences in magnitude, all seasons are found to exhibit the following set of responses: during periods of low Southern Oscillation Index and high equatorial sea surface temperature there are easterly anomalies of the equatorial zonal wind and westerly anomalies in the adjacent subtropics. These anomalies are consistent with the circulations in simple models of the Walker circulation in which the longitudinal scale of equatorial heating is increased, resulting in reduced zonal overturning at the equator (weakened Walker circulation) and increased meridional overturning and acceleration of the subtropical westerlies in a region slightly to the west of the anomalous heating centre. The correlation and regression results also show that central Pacific equatorial sea surface temperature is an excellent index of the heating anomalies.

Theoretical results have predicted that the importance of remote forcing from the tropics in higher latitudes is dependent upon the strength of the intervening zonal wind field. Season‐to‐season differences are particularly apparent in the northern hemisphere responses of the zonal wind field to the Southern Oscillation: remote responses are relatively strong when the mean zonal winds over the Pacific region and corresponding values of standing wave group velocity are relatively large and vice versa. A similar correspondence is not found south of the equator as the correlation results do not vary as strongly with season. This may be due to greater equatorial trapping of Southern Oscillation anomalies in the same season when subtropical winds are more favourable for meridional coupling.
The statistical effects of incomplete sampling of coherent data series
Authors: Parker D. E.
Published: February 2007

An expression is derived for the equivalent number of independent values obtained by partial sampling of a coherent, i.e. autocorrelated, time‐series or spatial series of data. The expression is a function of both the coherence of the data values and the coherence of the sampling, i.e. the non‐randomness of the distribution of available data. For a data series with high autocorrelation the distribution of the sampling in time or space is more important than for a relatively incoherent data series. Meteorological data are used as illustrative examples. The derived expression can be used in estimating the variance of sample means.
Air temperature variations in Greece. Part 2. Spectral analysis
Authors: Flocas A. A. , Giles B. D.
Published: February 2007

Power spectrum analysis is applied to annual and seasonal temperature data at three Greek stations. The results are tabulated and oscillations of 9, 4.8, 4.0, 2.7 and 2.2 years occur in most sets of data. The statistical importance of the results is indicated by 95 per cent, 90 per cent and null continuum levels. The quasi‐biennial oscillation is very clear but seems to be composed of individual cycles of 24, 26 and 32 months.
Estimating solar radiation in A tropical environment using satellite data
Authors: Nunez M. , Hart T. L. , Kalma J. D.
Published: February 2007

Daily values of satellite derived reflectivity and daily totals of incoming solar radiation were obtained over a six‐month period for a network of stations in tropical Queensland, Australia.

A definite linear relationship was observed between the reflectivity of the earth‐atmosphere system and the atmospheric transmissivity calculated as the portion of extraterrestrial radiation reaching the surface.

The scatter in the relationship was largely due to variation in the number of satellite scans available each day and to variations in aerosol absorption.

Using the regression model, the transmissivity of solar radiation has been calculated over the entire study region for the months of August 1982 and January 1983. The spatial variability of incoming solar radiation has been discussed. It was found that the spatial pattern is strongly dependent on topography and wind direction.