bluuebunny/crossref_metadata_2025 huggingface dataset:
Production of nisin‐like bacteriocins by Lactococcus lactis strains isolated from vegetables
Authors: Franz C. M. A. P. , Du Toit M. , von Holy A. , Schillinger U. , Holzapfel W. H.
Published: February 2007

Four bacteriocin producing lactic acid bacteria isolated from vegetables were identified as Lactococcus lactis strains on the basis of physiological and biochemical characteristics, carbohydrate fermentation patterns and analysis of total soluble protein pattern by SDS PAGE. The bacteriocins had a wide spectrum of activity as antagonism was detected not only towards a variety of lactic acid bacteria, but also to Staphylococcus aureus and Listeria monocytogenes. These bacteriocins were resistant to heating at 121 °C for 15 minutes and showed highest activity at low pH (<5.0). They were inactivated by the proteolytic enzymes α‐chymotrypsin and proteinase K, but not by lipase, α‐amylase, catalase or lysozyme. These bacteriocinogenic Lactococcus strains were all immune to the bacteriocins produced as well as to commerical nisin. Bacteriocin producer culture supernatants showed a high degree (70 or 100%) of cross‐reactivity in the nisin ELISA, suggesting similarity of the produced bacteriocins to nisin. The potential application of bacteriocin producing lactococci of vegetable origin for safety assurance of vegetable foods and controlling vegetable fermentations is discussed.
The role of pigments in the assembly of photosynthetic complexes in Rhodobacter capsulatus
Authors: Brand Matthias , Drews Gerhart
Published: February 2007

Mutants of Rhodobacter capsulatus, blocked at different steps of bacteriochlorophyll a (BChl) synthesis between protoporphyrin IX and 2‐hydroxyethyl bacteriochlorophyllide a, were induced to synthesize the photosynthetic apparatus by lowering of oxygen tension in dark cultures. The cells were pulse‐labeled with [35S]methionine and the radioactivity chased after dilution of [35S]. The specific radioactivity in the pigment‐binding proteins of light‐harvesting and reaction center proteins of the wild‐type strain was not lowered during the chase period of three hours but in the BChl‐free mutants the label disappeared within five to thirty minutes. The polypeptides were inserted into the membrane but did not remain stably incorporated. In the mutant strain NK9 the synthesis of the carotenoid spheroidenone/spheroidene was inhibited by insertion of Tn5 in the crtI gene (phytoene desaturase), which blocked completely the formation of the light‐harvesting (LH) complex II (B800–850) but not of the LHI (B870) complex. In this mutant the polypeptides of the LH complexes were synthesized in a lower amount than in the wild‐type cells and were inserted into the membrane. The LHIIα poly‐peptide disappeared after 60 min of chase while the LHIIβ was more stable. It was concluded that the pigments are not only necessary for absorption of photons and efficient transfer of excitation energy but have a structural role by stabilizing the oligomeric LH complexes. This is in accordance with the crystal structure data of LHII complexes.
Trehalases from spores and vegetative cells of yeast Saccharomyces cerevisiae
Authors: Wolska‐Mitaszko Barbara
Published: February 2007

Trehalase (THA) activity from S. cerevisiae spores and vegetative cells could be differentiated in cell‐free extracts. THA from the vegetative cells has an optimal activity at neutral pH whereas biphase pH optimum in the spores was observed. The enzyme from the spores exhibited higher thermostability than that from the vegetative cells. The presence of magnesium ions was necessary mainly for THA activity from the vegetative cells. The effect of the other metal ions studied: Hg2+, Ag2+, Cu2+, Fe3+, Ni2+, Cd2+ etc. (Table II), on THA from both sources was almost the same, however, the spores THA was resistant to Pb2+ and especially to Zn2+. Moreover, the influence of inorganic polyphosphates and polyamines was also quite dissimilar. Polyphosphates inhibited THA from the vegetative cells and to a smaller extent from the spores. On the other hand, polyamines stimulated highly THA activity from vegetative yeast cells in contrast to spores one. The effect of these ions modulators would facilitate differentiating of THA activity in the cell‐free extracts from both sources. These data could be interpreted as phenotypic reflections of trehalase genes expression in the S. cerevisiae cells.
Thermostable, salt‐tolerant α‐amylase from Bacillus sp. MD 124
Authors: Jana M. , Pati B.
Published: February 2007

A bacterial strain (MD 124) isolated from municipal garbage and identified as Bacillus sp. was found to be capable of producing salt tolerant and thermostable α‐amylase. Rhamnose and peptone were found to be the best carbon and nitrogen source for the production of enzyme. The pH and temperature optima for the enzyme activity were found to be at 6 and 90 °C. Seventy five per cent enzyme activity was retained in 5 M NaCl over 24 hrs.
Isolation and screening for alkaline thermostable xylanases
Authors: Subramaniyan S. , Prema P. , Ramakrishna S. V.
Published: February 2007

Screening of xylanase producing microorganisms from soil samples and hemicellulosic materials were carried out in three stages using wheat bran extract agar medium, xylan agar medium and liquid medium with xylan. One of the isolates, identified as Bacillus SSP‐34 produced 100 times more xylanase activity than the other isolates. Maximum enzyme production by this isolate was observed after 102 hours of growth. The optimum pH for the crude xylanase preparation range from 6–8 and optimum temperature was at 50 °C. The enzyme was stable up to 20 minutes at 50 °C and at pH range 4.5–9.0 for more than 2 hours.
Arctic Oscillation and ice severity in the Bohai Sea, East Asia
Authors: Gong Dao‐Yi , Kim Seong‐Joong , Ho Chang‐Hoi
Published: February 2007

The Bohai Sea is the southernmost sea in the Northern Hemisphere where seasonal freezing takes place in winter. Climate and ice conditions there are very sensitive to large‐scale climatic variations. In the present study, the authors investigated the relationships of ice severity in the Bohai Sea to the planetary Arctic Oscillation (AO) during the period 1954/55–2001/02. It has been found that during low‐AO winters the regional mean temperature around the Bohai Sea is evidently lower, and the number of freezing days, freezing degree days and the length of freezing duration all change significantly. Daily temperature distribution shows a significant difference in both mean and variance between high‐AO and low‐AO phases, and the changes in the temperature means dominate over that of the variance in the context of sea ice severity. The temperature‐AO relation is well supported by the corresponding features of the large‐scale atmospheric circulation system. AO‐related changes in the Siberian High and East Asian Trough cause remarkable changes to the thermal conditions at the surface and to the dynamical conditions in the middle troposphere, consequently affecting the air temperature over the Bohai Sea and ice severity. The AO‐sea ice severity relation has been generally stationary over time during the last one hundred years. Analysis of cross‐power coherency between the AO and ice indices for the last century shows that the highest and significant covariance stands at periods of about 2.1, 3, and 7.5–14 years. The Bohai Sea ice severity has declined rapidly since the 1970s, which is unprecedented since 1880, and this feature is in agreement with the positively upward trend in the AO and the associated changes in the Siberian sea level pressure, East Asian Trough, and the regional temperature. Copyright © 2007 Royal Meteorological Society
Synoptic climatology of the Western United States in relation to climatic fluctuations during the twentieth century
Authors: Barry R. G. , Kiladis G. , Bradley R. S.
Published: February 2007

An objectively derived catalogue of daily pressure patterns for 1899‐1974 has been prepared for the western United States. The temperature and precipitation characteristics of the major types are described and a more detailed analysis for Colorado in extreme cold and warm months shows that the sign of the anomalies for each type is generally consistent with expectation based on the probable airflow patterns. A regression analysis of type frequencies versus temperature and precipitation anomalies for 1899‐1970 at stations east and west of the Continental Divide in the Rocky Mountain states shows that useful explanation of variance is obtained only for temperatures in the transition seasons and for precipitation west of the Divide in winter and east of the Divide in spring. Within‐type variability of the climatic characteristics is one source of the discrepancy. The results underline the problems encountered in trying to link climatic anomalies with atmospheric circulation characteristics.
The nature and development of rainstorms in Coastal East Africa
Authors: Sumner G. N.
Published: February 2007

Using data for a 29‐month period from an intense network of extended scale autographic raingauges at Dar es Salaam, various different storm types are identified, which are thought to be representative of the East African coast as a whole. The primary means of identification of storm types were storm morphology, mode of development and movement. Three major storm groups are proposed: (i) linear storms which develop parallel to the coast along sea or land‐breeze fronts, (ii) smaller elliptical outbreaks developing in situ, and (iii) small, moving elliptical ‘air mass’ storms apparently associated with the prevailing trade wind circulation. A fourth but far less numerous group is composed of large, often heavy, amorphous storms whose origins probably lie with larger‐scale tropospheric perturbations, rather than with local causes.
Annual rain‐water over India, its variability and impact on the economy
Authors: Mooley D. A. , Parthasarathy B. , Sontakke N. A. , Munot A. A.
Published: February 2007

The total volume of rain‐water over India has been computed for each of the years during the period 1871‐1978 on the basis of the rainfall data for a fixed network of 306 raingauges. The mean, the standard deviation and the coefficient of variation of the series of annual rain‐water volume are 3143 km3, 300 km3 and 9.5 per cent, respectively. The series is homogeneous and random. The serial correlation is 0.013 which is too low to suggest any relationship between successive terms. Gaussian distribution gives a good fit to the series.

The series giving the percentage area of the country with a deficiency of 20 per cent or more, as well as the percentage area with an excess of 20 per cent or more have been obtained. These bring out the variability in the deficiency and excess of rain‐water over the country during the period. The years of well‐marked rain‐water deficiency/excess over India have been identified by utilizing the criterion of 40 per cent or more area under rain‐water deficiency/excess. The occurrence of such years has been found to be random and the number of such years in five‐year periods appears to be distributed in accordance with the Binomial and the Poisson Probability models.

The impact of marked deficiency/excess on the All India Index of food grain prices and All India Index of food grain production has been examined. It is found that the impact of well‐marked deficiency can generally be seen clearly but that of well‐marked excess is seen clearly in some cases only. This is understandable. Overall excess in a year may or may not result in floods which have the potentiality to damage crops. The impact of the well‐marked deficiency of 1918 has been maximum.

Remedial measures which would make the economy of the country less dependent on the variability of the annual rain‐water have been discussed.
The nature and impact of Hurricane Allen—August 1980
Authors: Oliver J.
Published: February 2007

Hurricane Allen threatened to be a storm of devastating potential in the Caribbean and on the Gulf coast of Texas or Louisiana. Although it deepened on three occasions to the intensity of a category 5 storm on the Saffir‐Simpson Scale, its track was such that the islands escaped the worst possible effects. By the time it had reached close to the Texas coast the storm had started to fill. Storm surge damage was the major cause of damage, though locally in the Caribbean islands and to some extent in Texas, this was compounded by wind and/or rain effects. The forecasts gave a clear indication of the magnitude of the impending threat and, except in Haiti, the loss of life was fortunately very small. The track, the variations in intensity and the landfall were predicted efficiently and errors in track positions were smaller than the longer period averages for different forecast periods for other tropical cyclones.
The third correlative equation concerning heat and water balance on the land
Authors: Qiwu Cui
Published: February 2007

This paper derives a new equation from a knowledge of evaporation on land. Along with the heat balance equation and the water balance equation, it can be used in a wide range of climatological calculations and hydrologjcal calculations.
Nature and possible causes of droughts on the canadian prairies‐case studies
Authors: Dey B.
Published: February 2007

There has been increasing interest in recent years in the study of droughts because of their economic, social and political impacts on society. Two summer droughts that affected the Canadian Prairies in 1961 and 1967 are examined. Based on a synoptic climatological approach, the investigation reveals that droughts occurred when the weather type WR (mid‐tropospheric ridge dominant) was persistent with a ridge over western Canada. A study of the 1976–1977 winter drought supports this interpretation. In all three cases, a quaststationary mid‐tropospheric ridge over western Canada acted as a block which displaced the jet stream, cyclones and moist air masses to a location north of the Canadian Prairies, while anticyclonic circulation under the high pressure ridge gave atmospheric stability and dry conditions on the Canadian Prairies.
The southern oscillation: Sea surface temperature and wind relationships in a 100‐year data set
Authors: Newell Reginald E. , Selkirk Rennie , Ebisuzaki Wesley
Published: February 2007

The development of sea surface temperature (SST) and surface wind anomalies during the course of the Southern Oscillation is examined with a 100‐year data set covering most of the Pacific Ocean region. Correlation coefficients of SST and winds with Wright's (1975) Southern Oscillation Index (SOI) are presented for lags and leads up to four seasons relative to the Index. The primary SST response is in the eastern and central equatorial ocean, the regions usually associated with the El Nino phenomenon, but there are important SST and wind changes elsewhere in the Pacific. Significant precursors in the SST include warming (cooling) in the northwest subtropical Pacific up to one year preceding positive (negative) SOI and like‐signed anomalies near New Guinea one season later, in addition to the cooling (warming) along the Chilean coast and in the eastern equatorial region beginning 3 seasons before positive (negative) SOI. (Positive SOI corresponds to pressures higher than average over the south‐east Pacific and lower than average over the western equatorial Pacific.) The major wind response is an area of easterly (westerly) anomalies in the central and western equatorial ocean beginning (in the latter portion) north of the equator 2 seasons before positive (negative) SOI. There is evidence for increased (decreased) westerlies in the southern mid‐latitudes as well as easterly and southerly (westerly and northerly) anomalies in the southeast subtropics 1‐3 seasons before positive (negative) SOI. For both SST and surface winds, little seasonal dependence of the correlation results is found for the equatorial anomalies, but in the Indonesian‐New Guinea region positive correlations are found in the latter portion of the year; mid‐latitude SST anomalies in both hemispheres are restricted to June to August.

The mechanisms that determine the response of the SST and winds to the SOI are examined and compared with the factors that control the seasonal cycle in selected regions. Subtropical precursors to positive SOI are consistent with enhanced subsidence, higher anticyclonic vorticity and stronger oceanic gyres. Advection seems to account for the spreading of the SST anomalies westward along the equator. SST anomalies in the Indonesian region may be due to solar radiation changes accompanying cloud cover variations.
Spatial and temporal aspects of the surface wind regime on the canterbury plains, New Zealand
Authors: McKendry Ian G.
Published: February 2007

Seasonal and diurnal patterns produced by the interaction of synoptic scale winds and two thermo‐topographic systems, the land/sea breeze and mountain/plain winds, are investigated in a spatial context. Together with gradient winds and the shallow ‘lee trough’ north‐easterlies these local winds create a wind regime composed of several distinctive regional element, the boundaries of which are transitional in nature and dependent on time day and year and the strength of synoptic influences. The sea breeze maximum frequency by day in summer in coastal areas whereas katabatic flows are most frequent by night, in winter adjacent to the Alps. Banks Peninsula strongly influences the wind regime by funnelling north‐easterly airflow onto the plains and possibly creating a zone of sea breeze convergence extending inland. South of Banks Peninsula the interaction of onshore wind components with north‐easterly synoptic winds appears responsible for the diurnal rhythm in the synoptic wind, a phenomenon already observed north of Banks Peninsula in relation to south‐westerly gradient winds.

Practical and theoretical implications of the regional study are discussed.
Secular variations of surface temperature and precipitation patterns over the great lakes region
Authors: Brinkmann W. A. R.
Published: February 2007

Spatial patterns of surface temperature and precipitation variability over the Great Lakes region and their changes during the past 78 years are examined using eigenvector analysis. The results show that the region is homogeneous in terms of temperature variations. The most important regional temperature trends have been very similar to the trends in the average annual temperature for the Northern Hemisphere. In the case of precipitation, however, an important boundary divides the region into a north‐western and south‐eastern portion. Positive precipitation anomalies occurred over the south‐east during the early part of this century and again after about 1960. The north‐western portion, on the other hand, experienced wet conditions during most of the intervening years.
Estimation of the daily global solar irradiation at Corvallis, Oregon (U.S.A.) from the hours of bright sunshine, the daily temperature range and relative humidity
Authors: Rao C. R. Nagaraja , Bradley William A.
Published: February 2007

Simple empirical relationships based on the hours of bright sunshine, the daily temperature range and relative humidity have been developed to estimate the daily global solar irradiation at Corvallis, Oregon (U.S.A.). It is observed that the greater part of the variability in the daily solar radiation income at the surface is explained by changes in the available solar energy at the top of the atmosphere in the course of the year. The relationship based on the hours of bright sunshine yields estimates of the daily global solar irradiation which compare favorably with the measured values (coefficient of determination >0‐90).
The impact of wind circulation on the incidence and nature of rainstorms over Dar es Salaam, Tanzania
Authors: Sumner Graham N.
Published: February 2007

Using storm rainfall data from a dense network of autographic raingauges at Dar es Salaam, Tanzania, storm characteristics (morphology, alignment and time of occurrence) are related to prevailing gradient wind. There is a pronounced seasonal variation in the time of day at which storms generally occur, related to seasonal changes in the larger‐scale wind regime between the north‐easterly and south‐easterly trade winds. Many storms occur at times when there is a convergence between locally‐generated land‐ or sea‐breezes and the gradient wind, and their origin along these lines of convergence is further demonstrated by occurrence of both elliptical and linear morphology storms aligned along the coast. The trend of the coast is shown to control the alignment of storms, particularly by day, whereas by night gradient wind is more important. At this time, storms tend to form along the direction of the gradient wind. The most active storms form in the middle of the day, are linear in nature, aligned parallel to the coast, and occur when the gradient wind is either offshore or blows along the coast from the south‐south‐east.
Climatological contingency analysis and seasonal forecast skill in the United States
Authors: Lawson Merlin P. , Dewey Kenneth F. , Heim Richard
Published: February 2007

Tercile contingency tables were computed using 75 years (1895–1969) of state‐weighted monthly temperature and precipitation data. The data were grouped into 3‐month seasons and ranked for each state into three equally probable terciles. By comparing each season with the antecedent season, the magnitude of interseasonal persistence (or reversal) which exceeded chance was measured and mapped for the United States.

The patterns of interseasonal tendencies are quite varied and demonstrate that there are geographical regions with substantial persistence of climatic anomalies between seasons. There were also regions which reverse tendencies (for example, a wet spring tending to follow a dry winter). The average excess tendency over chance for all contingencies is approximately 9 per cent. Seasonal forecasts were then generated (for an independent data period of 1970–1978) using only these contingency relationships. Standard skill scores were calculated and it was determined that these climatological interseasonal tendencies could not alone produce seasonal forecasts exceeding chance.
What if increases in atmospheric CO2 have an inverse greenhouse effect? I. Energy balance considerations related to surface albedo
Authors: Idso S. B.
Published: February 2007

An analysis of northern, low and southern latitude temperature trends of the past century, along with available atmospheric CO2 concentration and industrial carbon production data, suggests that the true climatic effect of increasing the CO2 content of the atmosphere may be to cool the Earth and not warm it, contrary to most past analyses of this phenomenon. A physical mechanism is thus proposed to explain how CO2 may act as an inverse greenhouse gas in Earth's atmosphere. However, a negative feedback mechanism related to a lowering of the planet's mean surface albedo, due to the migration of more mesic‐adapted vegetation onto arid and semi‐arid lands as a result of the increased water use efficiency which most plants experience under high levels of atmospheric CO2, acts to counter this inverse greenhouse effect. Quantitative estimates of the magnitudes of both phenomena are made, and it is shown that they are probably compensatory. This finding suggests that we will not suffer any great climatic catastrophe but will instead reap great agricultural benefits from the rapid increase in atmospheric CO2 which we are currently experiencing and which is projected to continue for perhaps another century or two into the future.
Riverflow reconstruction from tree rings in southern Britain
Authors: Jones P. D. , Briffa K. R. , Pilcher J. R.
Published: February 2007

Ring widths of oak trees (Quercus petraea Liebl. and Quercus robur L.) from a network of seven sites in southern Britain and northern France are used to reconstruct riverflow for three river catchments in southern Britain. These dendrohydrological reconstructions, made using a principal components regression technique, are the first such reconstructions in Europe. The results are statistically significant, and the stability of the regression models is verified using independent data. The reconstructions are more reliable for low flow events; a finding which is potentially useful for water resource planning. The reconstructions indicate a possible increase in the frequency of extreme low flows over the period 1755–1859, compared to 1860–1979, which although not of conclusive statistical significance, warrants further investigation.
On the climate of dome C, antarctica, in relation to its geographical setting
Authors: Wendler G. , Kodama Y.
Published: February 2007

Automatic weather stations have been successfully deployed in the hostile climate of Antarctica, where temperatures can drop below −80°C and wind speeds are up to 100m.p.h. These stations use satellites for transmission of their data (Argos System). Three years of data had been collected at Dome C (3280m), East Antarctica, before breakdown of the equipment occurred in January 1983. These data were analysed and compared with data from other stations in Antarctica. Results show that the temperature at Dome C can drop very low (−84.6°C), a new absolute world minimum is not expected to be found, however. The annual course of the temperature displays the typical ‘coreless’ winter phenomenon, with no systematic temperature changes for 4 to 5 months, and mean temperatures of about −60°C during this time. This fits well into the picture found at other high altitude inland stations of Antarctica. The wind speeds observed at Dome C were the lightest, not only of all interior stations in Antarctica, but of all antarctic stations, including coastal and near‐coastal ones. This illustrates the well‐known dependence of the katabatic winds on slope angles and topography. Despite steep and deep surface inversions, katabatic winds generated at higher elevations on the continental slopes do not appear to override Dome C, but flow around it. By contrast, the winds observed in the coastal regions of Adelie Land, some 1000 km away from Dome C, belong to the strongest found anywhere on the earth. Another indication that Dome C is free from any gravity flow can be found in the fact that the winds display a diurnal maximum during the summer months around noon or early afternoon, at a time when the inversion strength is at a minimum. For gravity flow, one would expect a minimum in wind speed at that time, as observed in the coastal region.
The Southern Oscillation and its relation to the monsoon rainfall
Authors: Bhalme H. N. , Jadhav S. K.
Published: February 2007

The interannual fluctuations in the Southern Oscillation indices (Wright, 1975) and their relations to the Indian monsoon (June‐September) rainfall have been examined for the period of 106 years from 1875 to 1980. The monsoon rainfall is significantly (99.9 per cent level) correlated with the Southern Oscillation indices for the seasons: MJJ (0.59), ASO (0.67), NDJ (0.53), and FMA of the following year (0.38). The fluctuations in the Southern Oscillation index for the ASO season appear strongly related to the nearly simultaneous monsoon rainfall of India. This implies that the large positive (negative) value of the Southern Oscillation index, signifying strengthening (weakening) of the Walker circulation coincides with large excess (deficient) monsoon rainfall over India. The coherence spectrum reveals that the Southern Oscillation index and the monsoon rainfall are highly correlated in the period range of about 2–2.5 years and 4–6 years. The first of these periods corresponds with the Quasi‐Biennial Oscillation and the latter agrees with the features of the Southern Oscillation, suggesting a strong link between Indian monsoon rainfall and these two phenomena. The striking feature of the composites of the Southern Oscillation index averaged for all the drought years and for all the flood years is the simultaneous occurrence of low (high) Southern Oscillation index and droughts (floods) in India. However, this association has limited use in long‐range prediction. A preliminary study suggests that a nearly simultaneous occurrence of major climatic anomalies of the tropics, such as droughts in India and El Niño off the coast of Peru, are linked to the Southern Oscillation, indicating some kind of time dependent zonal east‐west circulation, i.e. Walker circulation.
A generalized classification of South African summer rain‐bearing synoptic systems
Authors: Harrison M. S. J.
Published: February 2007

S‐mode principal component analysis has been applied to standardized monthly South African rainfall fields and the synoptic systems represented on the higher eigenvectors identified by matching the spatial distribution of rainfall on each component with that of the various weather systems as revealed by satellite imagery. Summer systems identified include cloud bands connecting the tropical and temperate circulations, tropical and subtropical cyclones, coastal depressions, cyclones on the continental west coast and troughs associated with cold fronts on the east coast. The new classification is contrasted with earlier equivalent schemes. The uses of the results in terms of the search for geophysical controls on the development of each of the identified systems are discussed.
The atmospheric modulation of extended wet and dry spells over South Africa, 1958–1978
Authors: Tyson P. D.
Published: February 2007

Differences in annual geopotential heights at the 850 and 500 mb levels between 16 pairs of stations have been submitted to principal component analysis to identify the most important statistically uncorrelated pressure patterns accounting for the variance of the annual pressure field over South Africa and adjacent oceans. By correlating component scores for the period 1958/9 to 1977/8 with annual rainfall an attempt has been made to determine the regional rainfall responses to variations in different circulation types. Regional variations in annual rainfall are shown to be significantly linked to variations in both low latitude forcing, associated with tropical easterly airflow and cyclonic wave perturbations therein, and mid‐latitude forcing, associated with a variety of both cyclonic and anti‐cyclonic perturbations in the westerlies. It has been shown that it is primarily variations in the atmospheric field of motion at the 500 mb level that are responsible for year‐to‐year differences in annual rainfall totals.
Blocking signatures in the northern hemisphere: Frequency distribution and interpretation
Authors: Knox John L. , Hay John E.
Published: February 2007

In a companion paper (Knox and Hay, 1983) the authors developed objective identification criteria, adaptable to machine processing methods, by relating the blocking anticyclone to its associated positive anomaly of 5‐day mean 500 mb height. Anomalies meeting the criteria were called ‘blocking signatures’. Moreover, by using an empirically derived pentad displacement threshold, it was possible to identify ‘blocking signature sequences’ corresponding to the life history of blocking episodes.

In this paper we present and interpret the spatial and temporal distribution of blocking signatures during the 33 year period 1946 to 1978 inclusive. The frequency of occurrence is presented by area, and by longitude for each season and for the year. The results are, in general, in agreement with published studies for the oceans, but they also reveal a high frequency of blocking signatures over the North‐eastern Canadian Archipelago. This particular result, ‘the Baffin Island paradox’, is further investigated and rationalized.

The interannual variation of blocking signature frequency over the Northern Hemisphere showed substantial fluctuations, particularly with regard to the more persistent episodes. However, because of the small size of the sample (33 years) relative to the time scale of the fluctuations (order of one decade) it was not possible to draw statistical conclusions.
Urban and rural humidity distributions: Relationships to surface materials and land use
Authors: Henry James A. , Dicks Steven E. , Marotz Glen A.
Published: February 2007

Most weather elements are modified by urban areas. Humidity is among the least studied of the modified elements. Quantitative associations of urban and rural humidity variations with surface materials and land use in Lawrence, Kansas, a relatively small eastern Great Plains city are examined. Results are based on 45 dew point temperature distributions obtained in summer and autumn. Man‐made surface materials are consistently negatively correlated with humidity, whereas most natural surfaces are positively related. Residential and educational‐institutional land uses and undeveloped land are related positively to morning and afternoon humidity values; fewer significant relationships exist between evening humidity distributions and land use.
The dynamic climatology of the beaufort to laptev sea sector of the polar basin for the winters of 1975 and 1976
Authors: Ledrew Ellsworth F.
Published: February 2007

The dynamic climatology of the Asiatic and North American sectors of the Polar Basin is examined for the winter season using NMC grid data for 1975 and 1976. The relative contributions to the total vertical circulation field by the mechanisms of differential vorticity and thickness advection, the diabatic effects of latent heat release and surface heating, and the surface effects of friction and orography are evaluated for the major synoptic patterns of the region. From this analysis, the relative significance of advective versus local affects on synoptic development is determined. The results are compared with those from a similar study for the summer period.
The influence of the southern oscillation and volcanic eruptions on temperature in the tropical troposphere
Authors: Parker D. E.
Published: February 2007

Upper‐air data for a network of tropical stations have been used to create seasonal and annual time‐series of 850‐500 mb and 500‐200 mb thickness for the zone 20°N–20°S for 1950‐1983.

Linear regressions of thickness in each layer against a Southern Oscillation index show that in the northern winter about half the interannual variance of thickness is predicted by the Southern Oscillation index two seasons earlier. Similar but weaker results hold for the other seasons. Low Southern Oscillation index, implying low pressure in the southern tropical mid‐Pacific, is followed by a warm tropical troposphere.

The residuals of thickness after the regressions against the Southern Oscillation index were examined for evidence of the effects of major volcanic eruptions. The cooling in 1964‐1965 cannot be ascribed unambiguously to the March 1963 eruption of Agung, and there has been no significant cooling in the two years following the April 1982 eruption of El Chichón.
Time variation in solar radiation in the negev, israel and its possible relation to the el chichon volcanic dust cloud
Authors: Zangvil Abraham , Aviv Oran Einhorn
Published: February 2007

Extensive measurements of solar radiation at Sede Boqer, Israel revealed considerable changes in the direct and diffuse solar irradiance on clear days beginning in September 1982. The direct beam irradiance showed a consistent decrease of about 10 per cent compared to clear‐day values of the previous year. The diffuse irradiance data showed an increase of about 50 per cent and the ratio between diffuse and global irradiance increased by 63 per cent. The prominent effects were observed from autumn 1982 to spring 1983. Weak effects were still noticeable in winter 1983/1984 although a tendency of back to ‘normal’, though not quite, is evident in spring and summer 1984. Another interesting result of the analysis is that only very small changes in global irradiance were evident.

These observations may be attributed to the El Chichon dust cloud since they are in accord with various types of measurements made of the dust cloud in other areas of the world.
Impact of the southern oscillation on australian crops
Authors: Nicholls Neville
Published: February 2007

Climate plays a major role in determining variations in Australian crop production. The El Niño‐Southern Oscillation (ENSO) phenomenon is an important mode of climatic variation affecting the Australian region. Interannual fluctuations of Australian crop production and ENSO might thus be expected to be quite closely related. Analysis of the limited data available at present suggests that fluctuations in some Australian crops are in fact associated with ENSO and may be predictable, well in advance of harvest, from observed sea‐surface temperatures around northern Australia.
Solar radiation in Spain
Authors: Tena F. , Tinaut D.
Published: February 2007

In Spain there are only a few stations registering solar radiation, but by using correlations with other meteorological variables, an estimate of the solar radiation can be made in other areas throughout the country. The best results have been obtained using the correlation with hours of bright sunshine. Four linear expressions between the two variables have been obtained, corresponding to the four seasons of the year. Employing such expressions, monthly maps of solar radiation isolines have been plotted for the peninsular part of Spain. The mean deviation is not higher than 5 per cent.
Rainfall patterns in India
Authors: Vines R. G.
Published: February 2007

Indian rainfall figures from World Weather Records have been subjected to filter analysis and the results suggest substantial coherence of data for central and north‐west India. The analysis indicates that there is a long‐term fluctuation in rainfall of period c. 22 years—possibly linked to the double sunspot cycle—and another of period c. 16 years, with which the first interacts. There is also some suggestion of an 18 to 19 year rainfall fluctuation, which is geared to the lunar (MN) cycle as first proposed by Campbell, Blechman and Bryson, and later by Currie.

There is further evidence of a 10 to 11 year fluctuation (medium‐term) which is possibly connected with the single sunspot cycle, and an additional (short‐term) fluctuation of 6 to 7 years. Comparisons are made between these findings and those previously reported in analyses of rainfall records from both northern and southern hemispheres.
Some characteristics of storms on the transvaal highveld
Authors: Mader G. N. , Neishlos H. , Saunders M. M. , Carte A. E.
Published: February 2007

Storm climatological statistics were extracted from digitized weather radar records. The effects of using various definitions for storm cells were small for most attributes and data from 20 to 30 days spread over a few years gave representative results. Only a few per cent lasted for more than an hour and about half of all cells travelled slower than 25 km h−1. Cells defined by the 45 dBz contour at 5 to 8 km above mean sea level lasted on average 18 minutes and travelled at 26 km h−1, compared to 20 minutes and 23 to 31 km h−1 in north‐eastern Colorado. The distributions of speeds, lifetimes and areas for the Transvaal were also similar to those for Colorado and they were nearly log‐normal. There was a wide range of cell behaviour from day to day and for storms on individual days.
Economic use of weather and climate information: Concepts and an agricultural example
Authors: Sonka Steven T. , Lamb Peter J. , Hollinger Steven E. , Mjelde James W.
Published: February 2007

Although changing economic, conditions suggest a growing potential for the business application of weather and climate information, the actual use of that information will be affected by its suitability for decision‐making purposes. This article suggests the use of decision analytic techniques for evaluating the appropriatenesses and value of weather and climate information. The conceptual steps involved in this process are defined. The need for interdisciplinary modelling efforts to determine the economic use of weather and climate information is illustrated for an agricultural example.
The interaction of valley/mountain winds with A diurnally veering sea/land breeze
Authors: Goldreich Y. , Druyan L. M. , Berger H.
Published: February 2007

Summer‐time wind patterns have been monitored within and above a transverse valley of the Judaean Hills. Near surface anemograph records and pilot balloon observations have been analysed to identify three vertically separated wind regimes. Classical mountain/valley winds dominate the flow within the valley walls whereas the regional gradient flow is discerned above 400 m AGL or 700 m ASL. Sandwiched between these regimes is a breeze layer which reflects the diurnal rhythm of the coastal, mesoscale breezes which are driven by local sea‐land temperature contrasts under the influence of the inland hills and the Coriolis force.
The effect of the prescription of zonally‐uniform sea surface temperatures in a general circulation model
Authors: Simmonds Ian , Smith Ian N.
Published: February 2007

To assess the impact on the global atmospheric circulation of zonally‐varying sea surface temperature (SST), a general circulation model experiment has been run in which this variation has been removed for a January climate simulation. This results in an adjustment of the atmospheric parameters on a global scale, and particularly in the tropics. Surface pressure increases and rainfall decreases in the Australian‐Indonesian region and rainfall increases in the east Pacific and over Peru. Large changes occur in the Walker‐type circulations along the equator. Even though the mean meridional SST gradient is left unchanged in the experiment, the modelled Hadley cells are, perhaps surprisingly, weakened and the reduction in condensational heating leads to an equatorial troposphere which is cooler than the control run by up to 1°C. Outside the tropics the model response is predominantly barotropic. Our experiment demonstrates the fundamental role of the longitudinal variation of SST in determining the location of the subtropical highs in the Southern Hemisphere.

The observation that the SST ‘anomaly’ distribution used is similar in some respects to that observed during an El Niño (particularly the 1982–1983 event) led us to compare the model response to anomalies observed during that time. The change in the Walker circulation and the shift in the surface pressure and rainfall distributions bore considerable similarity to those observed. However, the weakening of the Hadley cells and the cooling of the tropical troposphere were rather different to what actually occurred. Our results suggest that regions of forcing other than, or taken in conjunction with, that in the ‘key region’ in the east Pacific can influence global response.
Droughts/floods in the summer monsoon season over different meteorological subdivisions of India for the period 1871–1984
Authors: Parthasarathy B. , Sontakke N. A. , Monot A. A. , Kothawale D. R.
Published: February 2007

Abnormalities in the performance of the Indian summer monsoon (June to September) rainfall, which provides 75–90 per cent of annual rainfall, have been studied during the period 1871 to 1984 over different meteorological subdivisions into which the country has been divided. Long homogeneous monsoon rainfall series of 29 subdivisions, prepared on the basis of a constant 306 rain gauges, have been tabulated for the users in view of their great importance. The criterion adopted in identification of drought/flood over a subdivision is the percentage of rainfall departures from normal, as officially used in the India Meteorological Department.

The worst drought years were 1877, 1899, 1911, 1918, 1920, 1951, 1965 and 1972 and the worst flood years were 1892, 1933, 1961 and 1983 when many subdivisions reported extremely low and excess rainfall, respectively. The probabilities of occurrence of droughts/floods are high in Haryana, Punjab, west Rajasthan, Gujarat and Saurashtra and Kutch subdivisions. The area of the country affected by drought conditions was at a maximum during the decade 1911–1920 and at a minimum during the decade 1881–1890. The decades 1971–1980 and 1921–1930 were characterized by maximum and minimum areas, respectively, under flood conditions. The percentage area of India which suffered from drought and flood was low during the continuous three decades 1921–1930, 1931–1940 and 1941–1950.
Northern hemisphere ice sheets and planetary waves: A strong feedback mechanism
Authors: Lindeman M. , Oerlemans J.
Published: February 2007

We carried out a statistical analysis of the relation between the net mass balance of high‐latitude glaciers and 500 mb height deviations of the seasonal mean atmosphere. Mass‐balance series of 23 glaciers and ice caps were used, ranging in length from 8 to 30 yr. Considering the sample as a whole, it appeared that the only significant predictor for mass balance variations is the summer anomaly of the 500mb height. Except for a few individual glaciers, correlations with mean vorticity and meridional wind component turned out to be insignificant.

To investigate the potential feedback between ice‐age ice sheets and planetary waves, we used a stationary two‐layer atmospheric model to calculate the response to the CLIMAP (1976) ice‐sheet topography for 18,000 YBP. Combining the result with the statistical analysis reveals that the feedback is important: the planetary‐wave pattern forced by the ice sheets leads to deviations of the equilibrium‐line altitude of about 500m.
Precipitation—temperature relationships in England and Wales summers
Authors: Tout D. G.
Published: February 2007

Using aggregate precipitation and the mean temperatures of July and August for 1766–1980 and seven 30 year periods, the relationships between precipitation and temperature in England and Wales summers are investigated. Wet summers tend to be cool and dry summers warm. The highest correlation coefficients are for the two most recent 30 year periods. In contrast to winter, there is no evidence of changed precipitation temperature relationships in recent years. Between 1766 and 1985 there were only two summers with precipitation above 200mm and temperature above 17°C.
Graphical estimation of sky view‐factors in urban environments
Authors: Watson I. D. , Johnson G. T.
Published: February 2007

A technique is described whereby sky view‐factors in urban locations can be estimated from graphs once azimuth and elevation angles of surrounding buildings are known. The graphs are easy to use and give results sufficiently accurate to enable their use when more elaborate computing or photographic equipment is unavailable.
Spatial patterns of daily rainfall in central Kenya: Application of principal component analysis, common factor analysis and spatial correlation
Authors: Bärring Lars
Published: February 2007

Spatial patterns of daily rainfall in central Kenya were investigated using principal component analysis {PCA) and common factor analysis (CFA) of covariance matrices, together with spatial correlation analysis. Data consisted of daily values from 42 stations for the period January 1971 to November 1979. All statistical analyses were made both on the whole data set, and by month.

The number of components/factors to retain for rotation could not be unambiguously determined by means of scree tests. Therefore, various numbers of components/factors were rotated, mainly by using the Direct Oblimin procedure. It was not possible to obtain simple structure solutions from the PCA, which explained 50–70 per cent of the total variance. CFA explained 30–40 per cent of the total variance and was easily rotated to simple structure. It is concluded that this difference is due to the large portion of unique variance in the data. Because of this, maximum likelihood CFA is judged superior. Also the scale‐independence of the method is considered advantageous.

The PCA and CFA correctly located the limit between the region of two pronounced rainy seasons, and the region of more complex and less distinct rainfall seasonality.

Spatial correlation analyses suggest two seasonal rainfall regimes, one of ‘random’ convection during December‐March, and another of rainfall organized in approximately NE‐SE direction. The latter is mainly attributed to orographic influence, but possible links to fluctuations in the general SE‐monsoonal flow and the East African low‐level jet are briefly discussed.