bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coherent rainfall zones of the Indian region
Authors: Gadgil Sulochana , Yadumani  , Joshi N. V. 
Published: February 2007

AbstractWe have delineated rainfall zones for the Indian region that are coherent with respect to the variations of the summer monsoon rainfall. Within each zone, the time series of the summer monsoon rainfall at every pair of stations are significantly positively correlated, and the mean interseries correlation for each zone is high. The interseries correlation data set is analysed in order to delineate the rainfall zones, using an objective method specifically developed for the purpose. Each of the zonal averages are shown to be representative of the zone as a whole. We suggest that this regionalization is appropriate for study of the variation of the summer monsoon rainfall over the Indian region on interannual and larger scales.
Global cloud cover and cloud water path from ISCCP C2 data
Authors: Drake Frances 
Published: February 2007

AbstractThe International Satellite Cloud Climatology Project (ISCCP) C2 data from 1984 to 1987 are used to form average extreme season zonal means and global climatologies of cloud parameters. The total cloud amount, in general, agrees well with previous cloud climatologies. The level of agreement between the zonal total cloud climatology of Warren et al. and the ISCCP C2 data is extremely good. The main features of the general circulation of the atmosphere are observed in the global climatology, notably the equatorial maximum associated with the Inter Tropical Convergence Zone, the subtropical minima, and mid‐latitude maxima. The polar regions are areas of large disagreement with previous cloud climatologies. For both poles the ISCCP C2 data show that maximum cloudiness occurs in the winter, whereas most previous cloud climatologies indicate that maximum cloudiness occurs in summer. The ISCCP data indicate that Antarctica is an area of relatively small cloud amounts, which concurs with most previous climatologies. However, the amount and season of minimum cloudiness is in disagreement. Results from the amount of cloud types also show features that can be related to the general circulation of the atmosphere. Low clouds are found to be the most common cloud type over the ocean. Large amounts of low cloud are found on the west coasts of subtropical continents, consistent with the presence of marine stratocumulus. The subtropical high pressure zones are areas with small amounts of middle and high cloud types. The Indian south‐west monsoon is easily visible by an increase in the amount of high cloud in the region during Northern Hemisphere summer. The total water‐path results highlight the difficulties of cloud retrieval over permanent snow or ice cover. At present the water path results are unreliable.
The development of a satellite‐based insolation model for the tropical western Pacific Ocean
Authors: Nunez M. 
Published: February 2007

AbstractConcurrent pyranometer and GMS (Japanese Geostationary Meteorological Satellite) data were collected for the western tropical Pacific during a 21‐month period in 1987 and 1988. Data from 10 pyranometer stations in 1987 were used to build a satellite insolation model. Such processes as surface albedo, narrow band to broad band conversion, and depletion by water vapour and aerosols were taken into account. The model was then tested with an independent pyranometer data set comprising 9 months in 1988.Results show that aerosol depletion is site‐specific, with typical long‐term values ranging from 19·8 per cent of the extraterrestrial value for Kuala Lampur, to 4·8 per cent for Willis Island. Monthly insolation may be mapped over the oceanic regions of the study area assuming that the Willis Island aerosol depletion values apply. The model gave root‐mean‐square (RMS) errors of 14·08 W m−2 when tested against all monthly average pyranometer data for 1988. Corresponding RMS errors are 11·67 W m−2 when only Willis Island data are used. Sources of errors are discussed, as are suggestions for future research.
Arrival and withdrawal dates of the summer monsoon in Bangladesh
Authors: Ahmed Rafique , Karmakar Samarendra 
Published: February 2007

AbstractDaily data of (a) rainfall amount, (b) prevailing wind direction, (c) wind speed, (d) mean temperature, and (e) mean relative humidity of 19 stations in Bangladesh for the months May through to October, for the period 1958 through to 1987, have been analysed in order to determine various spatio‐temporal patterns of the arrival and withdrawal dates of the summer monsoon in the country. Statistical characteristics of these dates have been presented.The summer monsoon arrives first in the extreme south‐eastern part of the country, and initially moves towards the north. After being diverted by the Meghalaya Plateau, the flow turns towards the west. The mean arrival date of the summer monsoon in the extreme south‐eastern coastal part and in the extreme north‐western part are 2 June and 15 June, respectively. Withdrawal of the summer monsoon proceeds in the opposite direction to the arrival. Mean withdrawal dates of the summer monsoon from the extreme north‐western part and extreme south‐eastern part of the country are 30 September and 17 October, respectively. Standard deviations of both arrival and withdrawal dates in different parts of the country vary from 7 to 10 days.Probabilistic early dates of arrival of the summer monsoon in Cox's Bazar area in 1 year out of 4 years, 10 years, and 25 years are 28 May, 23 May, and 19 May, respectively. Probabilistic late dates of arrival in 1 year out of 4 years, 10 years, and 25 years are 8 June, 13 June, and 16 June, respectively.Probabilistic early dates of complete withdrawal of the summer monsoon from Bangladesh in 1 year out of 4 years, 10 years, and 25 years are 10 October, 5 October, and 1 October, respectively. Probabilistic late dates of complete withdrawal in 1 year out of 4 years, 10 years, and 25 years are 23 October, 28 October, and November 1, respectively.
A statistical approach towards a regionalization of daily rainfall in Sri Lanka
Authors: Domroes Manfred , Ranatunge Edmound 
Published: February 2007

AbstractRegionalization of daily rainfall in Sri Lanka was examined using orthogonal factor analysis (OFA) based on daily rainfall data of 42 stations for a 15‐year period (1971–1985). The number of potential rainy days was computed from the original data matrix and subjected to S‐mode OFA. The first 10 orthogonal factors were shown as highly significant, explaining 65.1 per cent of the total variance of the whole data matrix, where the level of eigenvalues represented was > 1.0. Noticeably, the 10 orthogonal factors clearly revealed the different homogeneous daily rainfall regions in Sri Lanka (labelled as A to J), according to the orthogonal factor high loadings matrix. Delimitation of the daily rainfall regions was carried out in accordance with the ‘variance boundaries’ resulting from the rotated factor loadings matrix. The number of potential rainy days has been identified for each region, showing an increasing trend with elevation. The probability of rainy days, wet spells and their mean length have been computed separately on a monthly and yearly basis in order to analyse the nature of the daily rainfall reliability in each region. The main factors for the daily rainfall fluctuation patterns in Sri Lanka are the typical monsoon rainfall, the dominant influence of the Inter Tropical Convergence Zone and topography.
Urban climate effects of artificial heat sources and ground shadowing by buildings
Authors: Swaid Hanna 
Published: February 2007

AbstractSimulations are presented for the effects of artificial heat sources and ground shading by buildings on air temperature variations in the urban canopy layer. An idealized urban cluster composed of repeated street canyons oriented east‐west with an aspect ratio of 0.5 is used to evaluate these effects. The simulations by the cluster thermal time constant model show that a daily mean artificial heat flux of 11 Wm−2 causes an almost invariant temperature rise of 0.7 K around‐the‐clock. Conversely, increasing the shade area in the streets by means of vertical screens fitted at the building roof‐level can produce a pronounced temperature lowering at midday.
ENSO phenomenon and 30–50 day variability in the Australian summer monsoon rainfall
Authors: Suppiah Ramasamy 
Published: February 2007

AbstractThe characteristics of 30–50 day variability in the Australian summer monsoon rainfall has been investigated by using station rainfall data. In particular, the influence of the El Niño/Southern Oscillation (ENSO) phenomenon on the Australian summer monsoon rainfall is analysed. Results of the power spectrum analysis indicate statistically significant peaks in the 30–50 day band during anti‐ENSO events in the north‐central, and north and east coast regions. The spectral analysis also reveals a statistically significant peak in this band during ENSO events in the inland desert and north and east coast regions. Filtered rainfall values show an eastward propagation pattern during anti‐ENSO events, whereas ENSO events demonstrate a pattern characteristic of a standing oscillation and sometimes a westward propagation pattern. The present study also suggests some tendency for the 30–50 day oscillation to be phase‐locked to the seasonal cycle of this region. The phase‐locking phenomenon is also observed in the daily mean sea‐level pressure at Darwin, which is very clear during the anti‐ENSO events.
Teleconnections between North Pacific SST anomalies and growing season extended dry spells on the canadian prairies
Authors: Bonsal B. R. , Chakravarti A. K. , Lawford R. G. 
Published: February 2007

AbstractThis investigation documents the relationships between anomalous North Pacific sea‐surface temperatures (SSTs) and the occurrence of growing season extended dry spells on the Canadian Prairies. Results show a significant correlation between extended dry spells and a positive SST anomaly gradient in the east‐central North Pacific. The gradient exists between an area of anomalously cold water in the east‐central North Pacific in the area 30°N–40°N latitude and 165°W‐135°W longitude, and an area of anomalously warm water along the central west coast of North America in the area 45°N–55°N latitude and 130°W‐125°W longitude. A probability model shows that the longer this positive gradient persists, the greater the probability of a major extended dry spell on the Canadian Prairies.
Climatological study of the total ozone field around the subtropical jet stream
Authors: Begum D. A. 
Published: February 2007

AbstractA study of the average distribution of total ozone was accomplished for the period from October 1982 to September 1983 in the area 20–50°N, 90–160°E, i.e. the entrance region of the East Asian subtropical jet stream. Total ozone data were obtained from the Total Ozone Mapping Spectrometer on the Nimbus‐7 satellite.Normally, the subtropical jet stream (STJ) marks a steep gradient in total ozone. From the monthly mean study of total ozone and wind fields at the 200 hPa surface, it was found that in winter the total ozone contours are almost parallel to the wind directions; the horizontal gradient in total ozone increases as the wind speed strengthens. In winter and spring, a sharp gradient in total ozone is found on the cyclonic side of the STJ because of the strong Hadley circulation. As the Hadley cell ceases in summer, the jet weakens and horizontal gradients in total ozone become much smaller, disappearing almost entirely by early autumn.
Noaa tovs‐derived moisture fields over the arabian sea and the bay of bengal and their association with the south‐west monsoon
Authors: Gautam N. , Kishtawal C. M. , Pandey P. C. 
Published: February 2007

AbstractMoisture fields derived from the Tiros‐N Operational Vertical Sounder (TOVS) data onboard previous National Oceanic and Atmospheric Administration (NOAA) series of satellites have been used to study monthly moisture fields over the Arabian Sea and the Bay of Bengal for the years 1979–1981. It is observed that monthly averaged moisture fields over the Bay of Bengal are always more than those over the Arabian Sea at a given latitudinal belt. Further, the monthly mean moisture flux divergence has been calculated using monthly mean winds from ship observations over the same areas of the Arabian Sea and the Bay of Bengal. It is found that net moisture flux divergence over the Arabian Sea is consistently higher than that over the Bay of Bengal for the years, 1979, 1980, and 1981, which are deficient, and excess monsoon rainfall years in terms of departure from long‐term climatological rainfall values. Moisture variability over the Arabian Sea and the Bay of Bengal on a monthly scale has also been studied for the months of June, July, and August for the years 1979–1981.A plot of the zonally averaged (at every 2° latitude) differential moisture signal (DMS) by latitude indicates the approximate position of the low‐level westerly jet. The overall differential signal between zonally averaged moisture fields over the Arabian Sea and the Bay of Bengal has also been found to be an indicator of total Indian rainfall excluding orographically influenced regions, although more data is needed to firmly establish the relationship quantitatively.
Comparison of global ultraviolet (290–385 nm) and global irradiation measured during the warm season in valencia, spain
Authors: Martinez‐Lozano J. A. , Casanovas A. J. , Utrillas M. P. 
Published: February 2007

AbstractThis paper studies data of ultraviolet (290–385 nm band) horizontal solar irradiation and global horizontal solar irradiation measured at Valencia (Spain) during the period March 1991 to September 1991. Analysis of error estimations and correlation coefficients show that the 10 minute, hourly, and daily values of ultraviolet (UV) and global irradiation are highly correlated. Improved figures and less dependence on location are achieved by defining a clearness index for the UV 290–385 nm band and relating it to the conventional whole‐band clearness index. The novel clearness index obtained from Valencia data is approximately half of the conventional clearness index. Considering solar elevation as an additional parameter, the correlation coefficients increase to values in the 0.94 to 0.96 interval for solar elevations greater than 55°, both for hourly and 10‐minute values.
Regional and temporal variations in heavy precipitation in south carolina
Authors: Changnon David 
Published: February 2007

AbstractDaily precipitation amounts greater than 50 mm from long‐term weather stations in South Carolina were analysed in order to determine their seasonal and annual frequencies and spatial variability. Year to year, the annual amount of precipitation produced by heavy rainfalls was not well correlated between stations ( –0.10≤r≤ + 0.65). The seasonal analysis detected three heavy precipitation regimes: (i) the mountainous region in western South Carolina with a winter maximum; (ii) the coastal plain with a distinct summer maximum; and (iii) the region in between with a summer‐autumn maximum. Such results indicate that site‐specific data should be used to examine large daily precipitation amounts rather than regionally averaged data because the primary four climatic and synoptic controls that create heavy precipitation vary considerably across South Carolina. Temporal analyses of the site‐specific, annual, large daily precipitation amounts and regional average annual precipitation showed generally weak to moderate correlations (+0.25 ≤r ≤0.57), indicating that interannual changes in annual precipitation are not well related to changes in annual contributions due to large daily precipitation amounts. Differences between regional wet and dry decadal periods were associated with significant changes in the annual large daily precipitation amounts at some but not all stations, indicating that similar long‐term changes cannot be assumed across a region as small as South Carolina. This information is useful to water managers and has potential utility for estimating conditions in a changing climate.
Surface conditions associated with anomalous rainfall in the guinea coastal region
Authors: Wagner Richard G. , da Silva Arlindo M. 
Published: February 2007

AbstractThis paper examines surface atmospheric and oceanic conditions associated with anomalous rainfall at the Guinea coast. For time‐scales shorter than 5 years, rainfall in the Guinea coast is practically not correlated with rainfall in the Sahel, although both time series show a well‐defined drying trend in the last 30 years or so. While interannual variability of Sahel rainfall is associated with a sea‐surface temperature (SST) pattern anti‐symmetric about the Equator, anomalous rainfall near the Guinea coast in associated with an SST pattern roughly symmetric about the Equator. During wet years near the Guinea coast this SST pattern corresponds to a less developed cold tougue in the boreal summer.Using the Comprehensive Ocean‐Atmosphere Data Set surface fields we examine key terms of the oceanic heat budget. Anomalous shortwave radiation and latent heat fluxes seem to play an important role in the decaying of the SST anomaly. During wet years anomalous atmospheric winds act to relax the trade winds, which probably reduces the equatorial thermocline slope and contributes to the observed warming of the equatorial waters in the east.We also investigate the relationship between the surface winds and the underlying SST using numerical and analytical solutions of a simple model. The anomalous winds are shown to be consistent with the hydrostatic adjustment of the tropical boundary layer.
An analysis of the circulation characteristics and energy budget of a dry, asymmetric, east‐west urban canyon. II. Energy budget
Authors: Arnfield A. John , Mills Gerald M. 
Published: February 2007

AbstractThis study presents partial energy budget evaluations for a dry east‐west oriented urban canyon in Columbus, Ohio, based on canyon‐top measurements of net radiation and the turbulent and circulation‐related components of the sensible heat flux. While net radiation data were similar to those reported in previous studies, the sensible heat exchanges were small in absolute magnitude, showed a “flat” diurnal regime and were uncorrelated with the net radiation. These results suggest a minimal degree of coupling by heat exchange between the canyon air space and the urban boundary layer above roof level. Speculations are offered on the nature of the unmeasured residual in the canyon energy budget. Evidence suggests that both a substrate heat flux and a significant advective term (through the canyon ends and top) may be instrumental in accounting for the residual. However, definitive conclusions were precluded by the absence of simultaneous evaluations of all the energy budget components. The need for such studies at canyon sites with diverse structures and fabrics is emphasized.
Towards a classification of tropical rainfall stations
Authors: Jackson I. J. , Weinand H. 
Published: February 2007

AbstractAs part of a long‐term project examining short‐period tropical rainfall characteristics, a preliminary classification of stations for a wide range of localities based on such characteristics is presented. The approach adopted, using principal component analysis and a clustering procedure, functioned well and the resulting classification would not have been anticipated simply by using general annual and seasonal variables alone. Interpretation of the components allowed the important characteristics of each group of stations to be described. Although the stations used did not represent every region of the tropics, the range of groups with a wide variety of characteristics suggests that they are indicative of conditions applicable to many areas. Although the data base was for varying periods and record lengths, it appeared to be adequate for the purpose of the analysis.
Relationships between the pacific/north american teleconnection patterns and precipitation events in the south‐eastern USA
Authors: Henderson Keith G. , Robinson Peter J. 
Published: February 2007

AbstractPrecipitation event attributes, defined as the amount, duration, and frequency of individual rainstorms, vary considerably from place to place and season to season. Event variability is caused by a combination of large‐scale and local climate processes. Correlations of seasonal time series show that the Pacific/North American (PNA) teleconnection pattern and local rainfall event attributes are significantly related in specific areas of the south‐eastern USA in some seasons. Shifts in the zonal/meridional flow over North America affect both the number of events and the event size. The total number of events in some regions changes by as many as 10 to 12 events per season with shifts in continental‐scale circulation. An analysis of attribute distributions shows that the percentage of total events falling into selected intensity categories may also change by as much as 10 per cent between flow regimes. Relationships have both temporal and spatial patterns. Shifts in continental‐scale circulation affect event attributes most strongly in winter, with more events occurring in zonal years. Events with greater amounts and durations are found east of the Appalachians in meridional years and west of the mountains in zonal years.
Exploring the possibility of forecasting monthly ‐ 700 hPa geopotential fields over india
Authors: Prasad K. D. , Singh S. V. 
Published: February 2007

AbstractThe principal component regression approach is used for forecasting the monthly 700 hPa geopotential fields over India, for July, from the geopotential fields observed during June. The data used are for the 23‐year period from 1958 to 1980. The multiple linear regression equations are developed on 22 years of data using the principal components as predictors and keeping one randomly selected year for independent testing. The forecasts and validation experiments are carried out for seven representative years. The results show some skill in forecasting the monthly height fields over India.
Spatial regression methods in dendroclimatology: A review and comparison of two techniques
Authors: Cook Edward R. , Briffa Keith R. , Jones Philip D. 
Published: February 2007

AbstractWe review and compare two alternative spatial regression methods used in dendroclimatology to reconstruct climate from tree rings. These methods are orthogonal spatial regression (OSR) and canonical regression (CR). Both the OSR and CR methods have a common foundation in least‐squares theory and converge to the same solution when all p candidate tree‐ring predictors of climate are forced into the model. However, the perfomance of OSR and CR may differ when only subsets p′ < p predictors are used. Theory cannot predict how either method is likely to perform when best‐subset selection is applied, especially with regards to reconstruction accuracy. Consequently, empirical comparisons of OSR and CR are made using three tree‐ring and climate networks from western Europe and eastern North America that have been used in previous dendroclimatic studies. These comparisons rely on a suite of regression model verification statistics to validate the accuracy of the climatic reconstructions produced by the best‐subset models. The results indicate little real difference between OSR and CR, with each performing equally good or bad depending on the amount of recoverable climatic information in the tree rings. Canonical regression may perform slightly better in high signal‐to‐noise cases; conversely, OSR may perform slightly better when the signal‐to‐noise ratio is low. None of these apparent differences are large enough to select one method in preference to the other, however, and many more comparisons would be needed to determine if such indications are generally valid.