bluuebunny/crossref_metadata_2025_split huggingface dataset:
Links between Tropical Pacific SST and Cholera Incidence in Bangladesh: Role of the Eastern and Central Tropical Pacific
Authors: Cash Benjamin A. , Rodó Xavier , Kinter James L. 
Published: September 2008

AbstractRecent studies arising from both statistical analysis and dynamical disease models indicate that there is a link between incidence of cholera, a paradigmatic waterborne bacterial disease (WBD) endemic to Bangladesh, and the El Niño–Southern Oscillation (ENSO). However, a physical mechanism explaining this relationship has not yet been established. A regionally coupled, or “pacemaker,” configuration of the Center for Ocean–Land–Atmosphere Studies atmospheric general circulation model is used to investigate links between sea surface temperature in the central and eastern tropical Pacific and the regional climate of Bangladesh. It is found that enhanced precipitation tends to follow winter El Niño events in both the model and observations, providing a plausible physical mechanism by which ENSO could influence cholera in Bangladesh.The enhanced precipitation in the model arises from a modification of the summer monsoon circulation over India and Bangladesh. Westerly wind anomalies over land to the west of Bangladesh lead to increased convergence in the zonal wind field and hence increased moisture convergence and rainfall. This change in circulation results from the tropics-wide warming in the model following a winter El Niño event. These results suggest that improved forecasting of cholera incidence may be possible through the use of climate predictions.
Trends in Extreme Temperatures in Relation to Urbanization in the Twin Cities Metropolitan Area, Minnesota
Authors: Sen Roy Shouraseni , Yuan Fei 
Published: September 2008

Abstract
The long-term trends in extreme summer season temperatures across the Twin Cities Metropolitan Area (TCMA) associated with urbanization are examined. To assess trends in extreme temperature data, maximum and minimum temperatures from 1975 to 2002 were assembled for seven stations located in both rural and urban areas. Furthermore, urbanization since 1975 was assessed by estimating the percentage of impervious surfaces from Landsat images acquired for various years. The results of this study indicated a greater rate of increase in overall minimum temperatures, resulting in a slightly declining trend in diurnal temperature range for all of the stations. In the case of extreme temperatures, most of the peripheral urban and rural stations experienced negative trends in extreme maximum temperatures, accompanied by positive trends in extreme minimum temperatures. This was also validated by the simultaneous increase in the percentage of impervious surfaces in those locations. The greatest changes were observed for Stillwater, which is located relatively close to the heart of the TCMA but has undergone a faster rate of urbanization.
Summer Moisture and Wildfire Risks across Canada
Authors: Girardin Martin P. , Wotton B. Mike 
Published: September 2008

Abstract
The Fire Weather Index System has been in use across Canada for the past 30 years in the daily operations of fire management agencies. As part of this system, the Drought Code (DC) was developed to act as a daily index of water stored in the soil. A major obstacle to the completion of climate risk analyses on the DC is that lengthy series of daily temperature and precipitation are not available for large portions of the circumboreal forest. Here the authors present a methodological modification to the daily DC to allow its approximation using monthly data. This new Monthly Drought Code (MDC) still retains its ability to capture moisture trends in deep organic layers. On the basis of high-resolution temperature and precipitation data, an analysis of summer moisture availability across Canada over 1901–2002 is presented. The driest periods on record were from the 1920s to the early 1960s, with the driest years being 1955, 1958, and 1961. The wettest period was from the mid-1960s to the 1980s. For the century-long period, drying was statistically significant in northern Canada. Locations south of the Hudson Bay, in the eastern Maritimes, and in western Canada recorded a trend toward decreasing dryness. When analyzed over 1951–2002, trends could hardly be distinguished from the (multi) decadal variability. Annual values of a spatial average of all July MDC grid cells showed an excellent fit against fire statistics: 63% of the variance in the Canada-wide annual area burned from 1959 to 1999 was explained by summer moisture availability.
Anomalies of Central England Temperature Classified by Air Source
Authors: Parker David E. 
Published: September 2008

Abstract
Daily anomalies of mean central England temperature (CET), relative to daily 1961–90 climatology, are analyzed in terms of the source of the air estimated from fields of mean sea level pressure. The average CET anomaly for a given source and calendar month during 1961–90 is taken as an estimate of the influence of atmospheric circulation for that source and calendar month, and the uncertainty in this influence is provided by the associated standard error. The atmospheric circulation influences are subtracted from the daily CET anomalies since the late nineteenth century to yield “residual anomalies,” which represent the influence of forcings other than atmospheric circulation. The use of air sources captures more circulation-related daily CET variance than the airflow indices used in previous studies. The warming in central England since the 1970s is not predominantly a result of atmospheric circulation changes, and the long-term changes of CET for air from major source regions are on the whole very similar to each other and to the overall long-term changes.
Reconciling Non-Gaussian Climate Statistics with Linear Dynamics
Authors: Sardeshmukh Prashant D. , Sura Philip 
Published: September 2008

Abstract
Linear stochastically forced models have been found to be competitive with comprehensive nonlinear weather and climate models at representing many features of the observed covariance statistics and at predictions beyond a week. Their success seems at odds with the fact that the observed statistics can be significantly non-Gaussian, which is often attributed to nonlinear dynamics. The stochastic noise in the linear models can be a mixture of state-independent (“additive”) and linearly state-dependent (“multiplicative”) Gaussian white noises. It is shown here that such mixtures can produce not only symmetric but also skewed non-Gaussian probability distributions if the additive and multiplicative noises are correlated. Such correlations are readily anticipated from first principles. A generic stochastically generated skewed (SGS) distribution can be analytically derived from the Fokker–Planck equation for a single-component system. In addition to skew, all such SGS distributions have power-law tails, as well as a striking property that the (excess) kurtosis K is always greater than 1.5 times the square of the skew S. Remarkably, this K–S inequality is found to be satisfied by circulation variables even in the observed multicomponent climate system. A principle of “diagonal dominance” in the multicomponent moment equations is introduced to understand this behavior.
To clarify the nature of the stochastic noises (turbulent adiabatic versus diabatic fluctuations) responsible for the observed non-Gaussian statistics, a long 1200-winter simulation of the northern winter climate is generated using a dry adiabatic atmospheric general circulation model forced only with the observed long-term winter-mean diabatic forcing as a constant forcing. Despite the complete neglect of diabatic variations, the model reproduces the observed K–S relationships and also the spatial patterns of the skew and kurtosis of the daily tropospheric circulation anomalies. This suggests that the stochastic generators of these higher moments are mostly associated with local adiabatic turbulent fluxes. The model also simulates fifth moments that are approximately 10 times the skew, and probability densities with power-law tails, as predicted by the linear theory.
Examining the Interaction of Growing Crops with Local Climate Using a Coupled Crop–Climate Model
Authors: Osborne Tom , Slingo Julia , Lawrence David , Wheeler Tim 
Published: September 2008

Abstract
This paper examines to what extent crops and their environment should be viewed as a coupled system. Crop impact assessments currently use climate model output offline to drive process-based crop models. However, in regions where local climate is sensitive to land surface conditions more consistent assessments may be produced with the crop model embedded within the land surface scheme of the climate model. Using a recently developed coupled crop–climate model, the sensitivity of local climate, in particular climate variability, to climatically forced variations in crop growth throughout the tropics is examined by comparing climates simulated with dynamic and prescribed seasonal growth of croplands.
Interannual variations in land surface properties associated with variations in crop growth and development were found to have significant impacts on near-surface fluxes and climate; for example, growing season temperature variability was increased by up to 40% by the inclusion of dynamic crops. The impact was greatest in dry years where the response of crop growth to soil moisture deficits enhanced the associated warming via a reduction in evaporation. Parts of the Sahel, India, Brazil, and southern Africa were identified where local climate variability is sensitive to variations in crop growth, and where crop yield is sensitive to variations in surface temperature. Therefore, offline seasonal forecasting methodologies in these regions may underestimate crop yield variability. The inclusion of dynamic crops also altered the mean climate of the humid tropics, highlighting the importance of including dynamical vegetation within climate models.
Impact of the Stratosphere on the Winter Tropospheric Teleconnections between ENSO and the North Atlantic and European Region
Authors: Cagnazzo Chiara , Manzini Elisa 
Published: September 2008

Abstract
The possible role of stratospheric variability on the tropospheric teleconnection between El Niño–Southern Oscillation (ENSO) and the North Atlantic and European (NAE) region is addressed by comparing results from two ensembles of simulations performed with an atmosphere general circulation model fully resolving the stratosphere (with the top at 0.01 hPa) and its low-top version (with the top at 10 hPa). Both ensembles of simulations consist of nine members, covering the 1980–99 period and are forced with prescribed observed sea surface temperatures. It is found that both models capture the sensitivity of the averaged polar winter lower stratosphere to ENSO in the Northern Hemisphere, although with a reduced amplitude for the low-top model. In late winter and spring, the ENSO response at the surface is instead different in the two models. A large-scale coherent pattern in sea level pressure, with high pressures over the Arctic and low pressures over western and central Europe and the North Pacific, is found in the February–March mean of the high-top model. In the low-top model, the Arctic high pressure and the western and central Europe low pressure are very much reduced. The high-top minus low-top model difference in the ENSO temperature and precipitation anomalies is that North Europe is colder and the Northern Atlantic storm track is shifted southward in the high-top model. In addition, it has been found that major sudden stratospheric warming events are virtually lacking in the low-top model, while their frequency of occurrence is broadly realistic in the high-top model. Given that this is a major difference in the dynamical behavior of the stratosphere of the two models and that these events are favored by ENSO, it is concluded that the occurrence of sudden stratospheric warming events affects the reported differences in the tropospheric ENSO–NAE teleconnection. Given that the essence of the high-top minus low-top model difference is a more annular (or zonal) pattern of the anomaly in sea level pressure, relatively larger over the Arctic and the NAE regions, this interpretation is consistent with the observational evidence that sudden stratospheric warmings play a role in giving rise to persistent Arctic Oscillation anomalies at the surface.
Sea Surface Height Signals as Indicators for Oceanic Meridional Mass Transports
Authors: Hirschi Joël J-M. , Killworth Peter D. , Blundell Jeffrey R. , Cromwell David 
Published: September 2008

Abstract
Numerical models are used to test whether the sea surface height (SSH) can be used as an indicator for the variability of Atlantic meridional oceanic mass transports. The results suggest that if the transports over the western boundary current region and those in the eastern part of the basin are considered separately, significant correlations (0.3–0.9) are found between zonal SSH differences and the meridional transports in the top 1100 m. Much weaker correlations are found for the basinwide transport, which corresponds to the surface branch of the meridional overturning circulation (MOC). For the eastern and western branches of the meridional transport, combining the SSH signal with the baroclinic structure obtained from Rossby wave theory enables calculation of a quantitative estimate of the transport variability in the top 1100 m. The results of the method are less convincing for the variability of the MOC. The reason for this is that even small relative errors in the variability of the eastern and western branches can be large compared with the MOC variability. These errors project onto the sum of the eastern and western transports and therefore onto the surface branch of the MOC. Nevertheless, being able to infer transport anomalies from SSH signals in the eastern and western parts of the Atlantic might prove useful in interpreting MOC observations from the U.K. Natural Environment Research Council Rapid Climate Change (RAPID) mooring array at 26°N, which show a large subannual variability that is mainly due to changes at the western boundary. Transports inferred from the SSH could help to identify the origin of this variability and whether transport anomalies propagate into the western boundary region from the basin interior or from other latitudes.
Multifrequency Decoding of a Phased Array Doppler Sodar
Authors: Rao I. Srinivasa , Anandan V. K. , Kumar M. Shravan 
Published: September 2008

Abstract
Doppler sodar is being used for studying the lower part of atmospheric boundary layer (ABL) and wind profiling. To obtain maximum altitude coverage multifrequency transmission has been used along with more transmitted power. In this article, the implementation of multifrequency transmission of a Doppler sodar and its decoding to extract the atmospheric parameters are presented. This article also shows the advantage of profiling using multifrequency sodar operation. The range of frequency used for transmission is between 1700 and 2100 Hz. The decoded Doppler spectra have shown significant improvement in signal-to-noise ratio (SNR) as well as higher altitude coverage compared to single-frequency transmission and reception. Wind profiles obtained from sodar have been compared with data obtained from high-resolution GPS sonde balloons, which were launched from a place close to the sodar system. The authors observed that 30% more wind data height coverage in when transmission is in multifrequency mode; the consistency in wind estimate is also improved compared to the single-frequency transmission.
Inferring Propagation Direction of Nonlinear Internal Waves in a Vertically Sheared Background Flow
Authors: Mirshak Ramzi , Kelley Daniel E. 
Published: September 2008

Abstract
Internal waves heave the background flow through which they propagate. If the background flow is vertically sheared, the high-pass-filtered velocity field will thus contain signals of both the wave velocity and the heaved flow. Under conditions of large wave amplitude and large background shear—a common situation for nonlinear internal waves in coastal waters—the velocity fluctuations caused by wave heaving of the background flow can be comparable to the wave velocity itself. This complicates the inference of wave properties such as energy flux and propagation direction. The present study deals with methods to infer propagation direction in such situations. Attention is given to three methods that may be applied to acoustic Doppler current profiler measurements: a “filtering” method that estimates wave signals from high-pass-filtered time series, a “beamwise” method that infers wave direction from lagged correlations of echo intensity between the spatially separated acoustic beams of the profiler, and a “modal” method that separates background and wave signals by regressing the high-pass-filtered velocity field onto a normal-mode wave model. The methods are tested using synthetic datasets. The results suggest that the filtering method is biased by wave heaving of the background shear, while the beamwise and modal methods are resistant to heaving. The beamwise method provides accurate predictions of wave propagation angle for cases in which the measurements have high temporal resolution and the environment exhibits no depth-averaged background flow. The limitation on depth-averaged flow is relaxed for the modal method, but it requires the measurement of stratification. These issues are illustrated, and the applicability of these methods is explored with a series of sensitivity tests, and it is found that the different methods perform well under different circumstances.
Mesoscale Convective Systems over Western Equatorial Africa and Their Relationship to Large-Scale Circulation
Authors: Jackson Brian , Nicholson Sharon E. , Klotter Douglas 
Published: September 2008

Abstract
This study examines mesoscale convective systems (MCSs) over western equatorial Africa using data from the Tropical Rainfall Measuring Mission (TRMM) satellite. This region experiences some of the world’s most intense thunderstorms and highest lightning frequency, but has low rainfall relative to other equatorial regions. The analyses of MCS activity include the frequency of occurrence, diurnal and annual cycles, and associated volumetric and convective rainfall. Also evaluated is the lightning activity associated with the MCSs. Emphasis is placed on the diurnal cycle and on the continental-scale motion fields in this region. The diurnal cycle shows a maximum in MCS count around 1500–1800 LT, a morning minimum, and substantial activity during the night; there is little seasonal variation in the diurnal cycle, suggesting stationary influences such as orography. Our analysis shows four maxima in MCS activity, three of which are related to local geography (two orographic and one over Lake Victoria). The fourth coincides with a midtropospheric convergence maximum in the right entrance quadrant of the African easterly jet of the Southern Hemisphere (AEJ-S). This maximum is substantially stronger in the September–November rainy season, when the jet is well developed, than in the March–May rainy season, when the jet is absent. Lightning frequency and flashes per MCS are also greatest during September–November; maxima occur in the right entrance quadrant of the AEJ-S. The lightning maximum is somewhat south of the MCS maximum and coincides with the low-lying areas of central Africa. Overall, the results of this study suggest that large-scale topography plays a critical role in the spatial and diurnal patterns of convection, lightning, and rainfall in this region. More speculative is the role of the AEJ-S, but this preliminary analysis suggests that it does play a role in the anomalous intensity of convection in western equatorial Africa.
Dynamical and Precipitation Structures of Poleward-Moving Tropical Cyclones in Eastern Canada, 1979–2005
Authors: Milrad Shawn M. , Atallah Eyad H. , Gyakum John R. 
Published: September 2008

Abstract
Tropical cyclones in the western North Atlantic basin are a persistent threat to human interests along the east coast of North America. Occurring mainly during the late summer and early autumn, these storms often cause strong winds and extreme rainfall and can have a large impact on the weather of eastern Canada. From 1979 to 2005, 40 named (by the National Hurricane Center) tropical cyclones tracked over eastern Canada. Based on the time tendency of the low-level (850–700 hPa) vorticity, the storms are partitioned into two groups: “intensifying” and “decaying.” The 16 intensifying and 12 decaying cases are then analyzed using data from both the National Centers for Environmental Prediction (NCEP) North American Regional Reanalysis (NARR) and the NCEP global reanalysis. Composite dynamical structures are presented for both partitioned groups, utilizing both quasigeostrophic (QG) and potential vorticity (PV) perspectives. It is found that the proximity to the tropical cyclone and subsequent negative tilt (or lack thereof) of a precursor trough over the Great Lakes region is crucial to whether a storm “intensifies” or “decays.” Heavy precipitation is often the main concern when tropical cyclones move northward into the midlatitudes. Therefore, analyses of storm-relative precipitation distributions show that storms intensifying (decaying) as they move into the midlatitudes often exhibit a counterclockwise (clockwise) rotation of precipitation around the storm center.
Intraoperative Acoustic Evaluation of Living Human Cartilage of the Elbow and Knee during Mosaicplasty for Osteochondritis Dissecans of the Elbow
Authors: Nishitani Kohei , Nakagawa Yasuaki , Gotoh Tadashi , Kobayashi Masahiko , Nakamura Takashi 
Published: September 2008

Background Autologous osteochondral mosaicplasty for osteochondritis dissecans of the capitellum is being used increasingly In adolescent patients. Little research has been published on the material properties of living human cartilage of the elbow and knee. Hypothesis The cartilage of the osteochondritis dissecans lesion is detected as degenerated by ultrasound. The material properties of the cartilage of the intact part of the elbow are not different from those of the intact knee except in thickness. Study Design Descriptive laboratory study. Methods The authors studied 10 young male athletes with osteochondritis dissecans of the capitellum who underwent mosaicplasty. An acoustic probe was used for measurement, and the wavelet transform method was used. Three parameters were used: signal intensity (Index of cartilage stiffness), signal duration (index of roughness), and signal interval (index of thickness). Results The cartilage of the osteochondritis dissecans lesion had lower signal intensity than did the intact part of the capitellum. The cartilage of the radial head opposite the capitellum had significantly lower signal intensity and higher signal duration than did other sites. The signal intensity of the radial head was significantly higher in early-stage patients than in late-stage Patients, although the macroscopic view was almost all intact. The signal intensity of the plug was decreased significantly after 9rafting. Conclusion The osteochondritis dissecans lesion had lower signal intensity than did the intact part of the capitellum. Although the macroscopic view looked intact, the radial head cartilage was degenerated as measured acoustically. Clinical Relevance Not only the cartilage of the capitellum but the cartilage of the radial head are acoustically degenerated in osteochondritis dissecans patients. Plugs might be damaged in the transplanting procedure, and further follow-up is necessary.