bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatio‐temporal patterns of drought in Morocco
Authors: Chbouki Nabil , Stockton Charles W. , Myers Donald E. 
Published: February 2007

AbstractPast climatic moisture anomalies can be reconstructed from climatically sensitive tree‐ring chronologies of Cedrus atlantica in Morocco. A map‐pattern technique was utilized to derive 10 patterns of variability for the period 1845–1974. The individual patterns were examined, in space using geostatistical techniques, and in time using correlation coefficients. The results indicate a clear alternation of favourable‐unfavourable climatic regimes lasting 20–25 years. The spatial extent of the climatic moisture anomalies can be explained by a combination of three factors of the atmospheric circulation related to the Azores High, local cyclogenesis, and north‐eastern perturbations.
Climatologically aided interpolation (CAI) of terrestrial air temperature
Authors: Willmott Cort J. , Robeson Scott M. 
Published: February 2007

AbstractA new and relatively straightforward approach to interpolating and spatially averaging air temperature from weather‐station observations is introduced and evaluated using yearly station averages taken from the Jones et al. archive. All available terrestrial station records over the period from 1881 through to 1988 are examined. Called climatologically aided interpolation, or CAI, our procedure makes combined use of (i) a spatially high‐resolution air‐temperature climatology recently compiled by Legates and Willmott, as well as (ii) spatially interpolated yearly temperature deviations (evaluated at the stations) from the climatology. Spherically based inverse‐distance‐weighting and triangular‐decomposition interpolation algorithms are used to interpolate yearly station temperatures and temperature deviations to the nodes of a regular, spherical lattice. Interpolation errors are estimated using a cross‐validation methodology.Interpolation errors associated with CAI estimates of annual‐average air temperatures over the terrestrial surface are quite low. On average, CAI errors are of the order of 0.8°C, whereas interpolations made directly (and only) from the yearly station temperatures exhibit average errors between 1.3°C and 1.9°C. Although both the high‐resolution climatology and the interpolated temperature‐deviation fields explain non‐trivial portions of the space‐time variability in terrestrial air temperature, most of CAI's accuracy can be attributed to the spatial variability captured by the high‐resolution (Legates and Willmott's) climatology. Our results suggest that raw air‐temperature fields as well as temperature anomaly fields can be interpolated reliably.
Comment on D. E. Parker, ‘effects of changing exposure of thermometers at land stations’
Authors: Hughes Warwick S. 
Published: February 2007

AbstractThis short note reviews the Minutes of two Intercolonial Meteorological Conferences, held at Melbourne, Australia in 1881 and 1888, where the transcripts refer to the use of the Stevenson screen. Additional historical and modern material is reviewed demonstrating the use of the Stevenson screen in late nineteenth century Australia and Fiji. Some possible implications for the climate change debate in Australia are considered.
Climate trends in the South‐west Pacific
Authors: Salinger M. J. , Basher R. E. , Fitzharris B. B. , Hay J. E. , Jones P. D. , Macveigh J. P. , Schmidely‐Leleu I. 
Published: February 2007

AbstractTemperature and precipitation trends are described for newly homogenized historical climate data sets for the South‐west Pacific. Regions that exhibit similar temperature and precipitation trends and variability are defined, and the temperature and precipitation time series aggregated according to these regions. Four temperature regions show distinctive trends: two regions south‐west of the South Pacific Convergence Zone (SPCZ), which display steady climate warming; two regions north‐east of the SPCZ, which cooled during the 1970s, and warmed in the 1980s. Annual anomalies differ in response to the El Niño‐Southern Oscillation (ENSO) phenomena, depending on the region's position with respect to a pivotal line along the SPCZ. The climate warming apparent throughout much of the south‐west Pacific comes from sites where there can be no question of any urban influence. Five main South‐west Pacific precipitation regions show distinctive trends that are connected to the main climatological features. Four New Zealand precipitation subregions relate to the interaction of the main climatological features with local orography. Annual precipitation anomalies show marked variability and are also affected by ENSO in most regions. The pivotal line for the response of precipitation regions lies just to the north‐east of the SPCZ. The ENSO relationships with precipitation appear consistent on both annual and interdecadal time‐scales. From these climatic trends four climatic response regions are recognized in the South‐west Pacific.
Seasonal variability of latent heat fluxes over the tropical Indian ocean using SSM/I and NOAA/AVHRR satellite data during 1988
Authors: Nair Nimmi , Pandey P. C. , Simon B. , Gautam N. 
Published: February 2007

AbstractThe monthly mean latent heat fluxes using Special Sensor Microwave Imager (SSM/I) and Advanced Very High Resolution Radiometer (AVHRR) data over the Indian Ocean have been estimated using a bulk parameterization technique for the year 1988. Liu's (1986) global relation between monthly mean precipitable water and surface‐level humidity has been applied to estimate surface‐level humidity from satellite‐derived precipitable water in this work. The month‐to‐month variation in latent heat fluxes have been studied along with oceanic and atmospheric parameters. The latent heat flux values were found to be higher over the Arabian Sea than those over the Bay of Bengal in the pre‐monsoon and monsoon months, and almost the same or less for the other months. The latent heat flux values over the Indian Ocean varies from 100 W m−2 in August near the Somali coast to 400 W m−2 in June. The latent heat flux associated with tropical systems are extremely high.
Missing data assessment in a solarimetric network
Authors: Ceballos Juan Carlos , Braga Célia Campos 
Published: February 2007

AbstractPrincipal components analysis was applied to solar irradiation (energy per unit area integrated over a daily period) in Paraiba State, north‐east Brazil, in order to find homogeneous subregions. The network data set included measurements of 19 solarimetric stations, generated by bimetallic Robitzsch‐type actinographs with associated daily errors not greater than 5 per cent. Two months were considered (February and August 1976).A simple procedure is developed for assessing missing data in time series of any station in the network, based on the remaining known data and on a small number of network eigenvectors. If applied over a homogeneous subregion, a specific new principal components analysis leads to a lower dimensioned system with even fewer eigenvectors used for proper assessment of missing data. Standard deviation of errors is lower than half the data standard deviation (the same order of expected instrumental errors). The method may be adapted easily in order to simulate (synthetize) time series of a site with no station, provided that time correlation fields vary smoothly within the region.
Daily precipitation maxima in Catalonia (north‐east Spain): Expected values and their spatial distribution
Authors: Lana X. , Mills G. Fernandez , Burgueño A. 
Published: February 2007

AbstractThe climatic diversity of Catalonia (north‐east Spain) is studied from the viewpoint of precipitation maxima. The spatial distribution of expected daily precipitation maxima is investigated for several return periods. The process is applied to the four traditional seasons and for the whole year by assuming the classical Gumbel theory of extremes (Gumbel I distribution), which is confirmed by the reasonable fit between predicted and empirical extremes. The analysis points towards a combination of several factors, such as the complex orography, the proximity of the Mediterranean Sea, the significant convective activity, and the dominant surface circulation, controlling the extreme daily amount distribution in Catalonia.
Luni‐solar 18.6‐ and solar cycle 10–11‐year signals in Chinese dryness‐wetness indices
Authors: Currie Robert G. 
Published: February 2007

AbstractPower spectrum analysis of 81 long and 202 short Chinese dryness‐wetness indices yields evidence for two peaks with periods near 18.6 and 10.5 years, both of which are statistically significant at confidence levels of 99.9 per cent. They are identified as induced by the 18.6‐year luni‐solar, Mn, constituent tide and a 10–11‐year solar cycle, Sc, variation in the Sun's luminosity of the order of 0.1 per cent. Amplitude and phase of Mn wavetrains are highly non‐stationary with respect to both time and geography; in particular, abrupt 180° phase changes in wave polarity are often observed. Amplitude and phase of Sc waves are also highly non‐stationary, with those in northern China out of phase with waves in the south since 1895 (they were in phase from 1815 to 1845). For the 202 short records variance contribution of the two signals to total variance in raw data varied from 6 per cent to 53 per cent, with a mean of 22 per cent, again demonstrating their extreme non‐stationarity. Construction of a dry and very dry drought index (DVDI) shows that since 1470 by far the most prolonged, continuous, and serious drought (due to constructive interference and concomitant high amplitudes of the two waves) occurred from 1633 to 1643; the Ming Dynasty collapsed in 1644 and, in agreement with Hameed and Gong (1990), it is concluded that this climatic disaster was a causal factor in the fall of the Ming Empire.
Long‐term trends of precipitation and runoff in Louisiana, USA
Authors: Keim Barry D. , Faiers Gregory E. , Muller Robert A. , Grymes John M. , Rohli Robert V. 
Published: February 2007

AbstractChanging precipitation patterns and their impact on surface water resources is an important climatic problem facing society today, especially as it relates to potential global change. Therefore, this paper analyses temporal variability and trends in the empirical precipitation record and modelled runoff in Louisiana, USA, during the past century. Long‐term trends in precipitation were identified and impacts on surface water resources were found. If general circulation model predictions for increasing precipitation in the south‐eastern US prove to be correct, surface water will likely increase at a disproportionately higher rate which should be of concern to water resource planners in the region.
Variations and trends in annual mean air temperatures in Turkey with respect to climatic variability
Authors: Türkeş Murat , Sümer Utku M. , Kiliç Gönül 
Published: February 2007

AbstractThe purpose of this study is to investigate the variations and trends in the long‐term annual mean air temperatures by using graphical and statistical time‐series methods. The study covers a 63‐year period starting from 1930 and uses temperature records from 85 climate stations. First, spatial distributions of the annual mean temperatures and coefficients of variation are studied in order to show normal conditions of the long‐term annual mean temperatures. Then variations and trends observed in the annual mean temperatures are investigated using temperature data from 71 climate stations and regional mean series. Various non‐parametric tests are used to detect abrupt changes and trends in the long‐term mean temperatures of both geographical regions within Turkey and individual stations. The analyses indicate some noticeable variations and significant trends in the long‐term annual mean temperatures. Among the geographical regions, only Eastern Anatolia appears to show similar behaviour to the global warming trends, except in the last 5 years. All the coastal regions, however, are characterized by cooling trends in the last two decades. Considering the results of the statistical tests applied to the 71 individual stations data, it could be concluded that annual mean temperatures are generally dominated by a cooling tendency in Turkey. The coldest years of the temperature records of the majority of the stations were 1933 and 1992, respectively.
Chaotic influences and the problem of deterministic seasonal predictions
Authors: Dix M. R. , Hunt B. G. 
Published: February 2007

AbstractAn analysis has been performed of three simulations made by forcing a global climatic model with observed sea‐surface temperature and sea‐ice distributions for the period 1979–1988. These simulations were started from different years of an extended control run, otherwise all conditions were identical. The analysis concentrates on the regional and local differences in the simulations caused by chaos attributable to the differing initial conditions interacting with the non‐linearities of the model climatic system. Of particular interest is whether the presence of sea‐surface temperature variations in individual years is able to overcome chaotic influences. This interest arises because of the increasing international appreciation that such temperature variations provide the basis for the development of multi‐seasonal prediction schemes.The analysis shows that between about 20°N and 20°S a coherent climatic reponse is obtainable owing to the boundary value forcing associated with the sea‐surface temperature field. At high latitudes the signal‐to‐noise ratio rapidly deteriorates. Even at low latitudes, in a sensitive variable such as rainfall, chaos creates substantial differences between the three simulations, except over the Pacific Ocean where a very coherent response is found. In general, over land areas, even those within recognized regions of ENSO (El Niño‐Southern Oscillation) influence, the impact of chaos is much higher. Examination of Pacific North American teleconnection patterns for 1988 reveals substantial differences between the three simulations, and the associated impact on rainfall and surface temperatures over the North American continent. Agreement with observations ranges from rather good to poor, indicating the need for multiple runs for any given situation. Overall the results establish that sea‐surface temperature variations can overwhelm chaos in appropriate circumstances and specific regions. Importantly, this indicates that given accurate predictions of sea‐surface temperature anomalies a few seasons in advance, then model‐based predictions will be possible over many regions of the world despite the omnipresence of chaos.
Zones of severe rainstorm activity over India—some refinements
Authors: Dhar O. N. , Nandargi Shobha 
Published: February 2007

AbstractAn examination of daily rainfall data and other rainstorm studies have shown that about 231 severe rainstorms affected India during the period 1880–1990. This study is an extension of the previous study made by Dhar and Nandargi. This study, with specified locations of frequent rain centres and a large sample of 231 severe rainstorms, has confirmed the existence of the four rainstorm zones found earlier and has also found small zones in south‐east Rajasthan and along the east and west coasts of India. It has also specified locations of frequent rain centres during severe rainstorms.
Climatic response of the Indian subcontinent to doubled CO2 concentrations
Authors: Bhaskaran B. , Mitchell J. F. B. , Lavery J. R. , Lal M. 
Published: February 2007

AbstractResults from the United Kingdom Meteorological Office (UKMO) coupled climate model have been analysed over the Indian subcontinent in order to validate the model's performance and to assess the changes in climate and its variability in a simulation with a 1 per cent increase per year in CO2 (compound).The model produces a reasonable simulation of present‐day climate over the Indian subcontinent. At the time of CO2 doubling, the model simulates temperature increases of the order of 1 K to 4 K over the Indian subcontinent during winter and monsoon seasons. The model‐simulated monsoon circulation shifts by 10° latitude towards the north and intensifies by approximately 10 per cent in the warmer atmosphere. The interannual variability of monsoon onset dates and intraseasonal variability of monsoon rainfall are not significantly different when the CO2 concentration doubles. However, the model simulates increased interannual variability of the monsoon rainfall and a greater number of heavy rainfall days during the monsoon.
Solar dimming and urban heating at Hong Kong
Authors: Stanhill G. , Kalma J. D. 
Published: February 2007

AbstractOver the last 35 years solar radiation in Hong Kong has decreased by more than one‐third. During the same period the population doubled and the total use of fossil fuels increased more than sevenfold. A surface energy balance model was used to demonstrate the opposing effects of the decline in irradiance and the increase in anthropogenic heat production on air temperature. Differences between air temperatures measured in the city and at an upwind, unpopulated island were used to verify the simulated decrease in the urban heat‐island by day and increase at night, leading to an unchanged mean air temperature difference. The implications of these results for climate change in the rapidly urbanizing Pacific Rim region are discussed briefly.
Growing season temperatures over the former Soviet Union
Authors: Jones P. D. , Briffa K. R. 
Published: February 2007

AbstractAnalyses of daily mean temperatures during the growing season (days >5°C) from about 200 stations over the former Soviet Union indicate that little change has taken place in a number of growing‐season‐related variables during the last 110 years. We have considered the start (STR), end (END), duration (DUR), and the number of degree‐days above 5°C (DD). Annual average temperatures in the region have warmed by about 1°C, but this increase has been confined to the October‐to‐April period. Time series of the variables at individual stations show that there is little correlation between the start and end dates of the growing season and between the duration and the number of degree‐days in the season. Mean May‐to‐September temperatures at individual stations are shown to be highly correlated with the number of degree‐days, implying that the average of an appropriate combination of monthly temperatures can be used as a proxy for the number of degree‐days when daily data are not available. The low correlation between degree‐day counts and growing season duration in time series at all the stations is surprising given the strong spatial dependence between the 1950–1989 averages of the variables at all the stations. The results have implications for studies concerned with the impacts on growing season temperatures of future climate change.
The tropical‐subtropical semi‐annual oscillation in the upper troposphere
Authors: Shea Dennis J. , Van Loon Harry , Hurrell James W. 
Published: February 2007

AbstractThe tropical‐subtropical semi‐annual oscillation (TSSAO) of the zonal wind and temperature in the upper troposphere has been described by van Loon and Jenne. Their description was based on analysis of 20 Southern Hemisphere (SH) radiosonde stations and on two SH climatological atlases. This note documents further the TSSAO's climatology and its' spatial and temporal variability. This is accomplished by (i) using more radiosonde stations, in which data records span longer time periods, and (ii) using analyses from the European Centre for Medium Range Weather Forecasts for a spatially coherent picture.
Impacts of model improvements on general circulation model sensitivity to sea‐surface temperature forcing
Authors: Druyan Leonard M. , Shah Kathryn P. , Lo Kwok‐Wai K. , Marengo Jose A. , Russell Gary 
Published: February 2007

AbstractThe sensitivity of the 4° × 5° resolution general circulation model of the Goddard Institute for Space Studies to some basic changes in model formulation was studied by comparing parallel simulations forced by global sea‐surface temperature of June‐August 1987 and 1988. The new modelling schemes were substituted for the control model's parameterizations of moist convection, planetary boundary layer, ground hydrology, and cloud optical thickness in a series of sensitivity experiments. In addition, linear and quadratic upstream schemes for advecting tracers were tried in place of second‐order differencing. Elimination of the vertical mixing of horizontal momentum by moist convection was also tested. Impacts of the new modelling schemes on simulated circulation, temperature, and precipitation rates were inferred from pairs of simulations made by model versions that differed with respect to a single change. No discernible positive impacts were found for the new ground hydrology scheme or for changes in the determination of cloud optical thickness. Profiles of zonal wind speeds and lower tropospheric circulation patterns, both in the tropics, were more realistic when the vertical mixing of horizontal momentum was included. Major improvements in modelling the interannual variability of the planetary circulation, mid‐tropospheric temperature, and precipitation can be attributed to the salutory effects of the new moist convection, new planetary boundary layer, and the quadratic upstream scheme for advecting tracers.
Trends in air temperature and precipitation for Canada and north‐eastern USA
Authors: Gan Thian Yew 
Published: February 2007

AbstractUsing the univariate, non‐parametric, Kendall's test for monotonic trends from the 1949 to 1989 period, monthly maximum, minimum, average temperature, and precipitation data of some carefully selected stations in Canada and north‐eastern USA, it is found that western Canada for the past 40 years has experienced significant warming in January and March, and to a limited extent in April, May, and June, but virtually no warming trend was detected in eastern Canada and north‐eastern USA. Instead, some cooling trends were found, particularly in October. The analysis on the annual cycle of temperature data also shows the seasonal and regional nature of warming and cooling trends. Unlike temperature, no obvious trend is found in the precipitation data, but on the whole there are more stations (up to 10 per cent) with upward trends (increase in precipitation) during springs and summers. A bivariate test was used to detect a shift in the mean of precipitation series with respect to maximum temperature series but no obvious indication of such a shift was detected.