bluuebunny/crossref_metadata_2025 huggingface dataset:
Summertime Cloud-to-Ground Lightning Activity around Major Midwestern Urban Areas
Authors: Westcott Nancy E.
Published: August 2010

Cloud-to-ground lightning flash data collected by the National Lightning Detection Network were analysed in and around 16 central U.S. cities for the period 1989–92. Lightning data are well suited to study storm activity in and around large urban areas since their continuity and coverage in space and time is superior to historical, spatially limited records of thunderstorm activity. Frequency of cloud-to-ground lightning flashes (of negative and positive polarity) in the area immediately upwind, within, and immediately downwind of the cities were compared. An enhancement of lightning frequency on the order of 40%–85% was found over and downwind of many of these cities.

A number of possible urban-related causal factors were examined including effects of increased urban concentrations of cloud condensation nuclei, urban population and size, and the presence of distinct topographic features in and around the cities. Various factors, physical and anthropogenic, appeared to interact in diverse ways to account for changes in lightning flash frequency. The enhancement of lightning activity was largest during the afternoon hours when the urban–rural temperature differences are usually smallest, but when the atmosphere is generally the most unstable and when there is often a maximum in convective activity. The spatial distribution of the first 50 lightning flashes from each storm suggested that the urban area did not initiate new lightning storms. Thus, the overall results suggested that existing thunderstorms were the most strongly affected.
Evaluation of the Effect of Horizontal Diffusion on the Long-Range Atmospheric Transport Simulation with Chernobyl Data
Authors: Ishikawa Hirohiko
Published: August 2010

The effect of horizontal diffusion on the long-range transport simulation is examined with a Lagrangian particle transport model. The transport of radioactivity released from Chernobyl is simulated by the model with different values of horizontal diffusivity. The computed concentrations are statistically compared with measured concentration. The best simulation is found when the magnitude of the horizontal diffusivity is between 3.3 × 104 and 1.0 × 105 m2 s−1. The performance of empirical formulas of horizontal diffusion, in which mean-square displacement σy is specified as a function of time, is also examined.

A part of measured concentrations, which are relatively low concentrations, cannot be explained by transport and diffusion only. It is shown that these measured concentrations can be explained by resuspension of deposited radioactivity.
A Simple Method for Spatial Interpolation of the Wind in Complex Terrain
Authors: Palomino I. , Martín F.
Published: August 2010

The topographical elevation difference is proposed as a new variable for spatial interpolation of the sparse surface wind measurements to a finer mesh in a complex terrain area. The most used method for the initialization of diagnostic wind field models is based on the inverse-distance-squared weighted averaging interpolation technique regardless of the topographical elevation. Analysis of experimental data obtained from six meteorological towers deployed at several heights on the slopes along a valley in the South of Spain has shown a good correlation between wind speed and elevation above valley bottom. The efficiency of the inverse absolute elevation difference and the inverse distance squared as averaging weights for interpolation of the wind vector at several locations is checked; this is done for two meteorological synoptic weather types: strong synoptic winds, and thermal low over the Iberian Peninsula. For the latter weather type, the formation of nocturnal thermal inversion and the drainage flows are taken into account. Wind fields in the valley resulting from the two interpolation methods are compared. The elevation difference between meteorological station and grid point seems to be an important variable to be included in the wind field initialization process, that is, interpolation of the wind vector to a grid, when complex terrain areas are considered.
Simulated Urban Climate Response to Modifications in Surface Albedo and Vegetative Cover
Authors: Sailor David J.
Published: August 2010

Three-dimensional meteorological simulations have been conducted to investigate the potential impact of urban surface characteristic modifications on local climate. Results for a base case simulation for the Los Angeles basin are compared to results from cases in which urban albedo or vegetative cover are increased. The methodology for determining the distribution and magnitude of these simulated surface modifications is presented. Increasing albedo over downtown Los Angeles by 0.14 and over the entire basin by an average of 0.08 decreased peak summertime temperatures by as much as 1.5°C. This level of albedo augmentation also lowered boundary layer heights by more than 50 m and reduced the magnitude and penetration of the sea breeze. A second simulation, in which vegetative cover was increased, showed qualitatively similar impacts. The results from these simulations indicate a potential to reduce urban energy demand and atmospheric pollution by 5%–10% through application of reasonable surface modification strategies.
Some Recent Long-Range Diffusion Observations
Authors: Gifford F. A.
Published: August 2010

Recent atmospheric cloud-spreading (relative diffusion) data from a variety of sources are combined to show that the horizontal spreading rate is approximately linear over a time range from 1 to 10 or more hours (20–200 or more km) of downwind cloud travel. This result agrees with earlier observational studies, in which the horizontal cloud standard deviation σy has consistently been found to vary as tp, where t is the downwind travel time and p is in the range 1–1.2. For the present dataset, σy is found to vary as t1.1. A recent theoretical prediction, p = 7/6, valid over the entire range of t, is very close to these observed values.
Variability of Microphysical Parameters in High-Altitude Ice Clouds: Results of the Remote Sensing Method
Authors: Matrosov Sergey Y.
Published: August 2010

The remote sensing method for retrieving vertical profiles of microphysical parameters in ice clouds from ground-based measurements taken by the Doppler radar and IR radiometer was applied to several cloud cases observed during different field experiments including FIRE-II, ASTEX, and the Arizona Program. The measurements were performed with the NOAA Environmental Technology Laboratory instrumentation. The observed ice clouds were mostly cirrus clouds located in the upper troposphere above 5.6 km. Their geometrical thicknesses varied from a few hundred meters to 3 km. Characteristic cloud particle sizes expressed in median mass diameters of equal-volume spheres varied from about 25 μm to more than 400 μm. Typically, characteristic particle sizes were increasing toward the cloud base, with the exception of the lowest range gates where particles were quickly sublimating. Highest particle concentrations were usually observed near the cloud tops. The vertical variability of particle sizes inside an individual cloud could reach one order of magnitude. The standard deviation of the mean profile for a typical cloud is usually factor of 2 or 3 smaller than mean values of particle characteristic size. Typical values of retrieved cloud ice water content varied from 1 to 100 mg m−3; however, individual variations were as high as four orders of magnitude. There was no consistent pattern in the vertical distribution of ice water content except for the rapid decrease in the vicinity of the cloud base. The relationships between retrieved cloud parameters and measured radar reflectivities were considered. The uncertainty of estimating cloud parameters from the power-law regressions is discussed. The parameters of these regressions varied from cloud to cloud and were comparable to the parameters in corresponding regressions obtained from direct particle sampling in other experiments. Relationships between cloud microphysical parameters and reflectivity can vary even for the same observational case. The variability diminishes if stronger reflectivities are considered. A procedure of “tuning” cloud microphysics–reflectivity regressions for individual profiles is suggested. Such a procedure can simplify the radar–radiometer method and make it applicable for a broader range of clouds.
Differential Doppler Velocity: A Radar Parameter for Characterizing Hydrometeor Size Distributions
Authors: Wilson Damian R. , Illingworth Anthony J. , Blackman T. Mark
Published: August 2010

Observations of Doppler-resolved spectra of differential radar reflectivity provide estimates of particle shapes as a function of their terminal velocity, and they can be derived by having the antenna at a significant elevation angle. Turbulence tends to smear out the details of the actual spectra observed, but the difference in the mean values of velocity using horizontal and vertical polarizations, which the authors call the “differential Doppler velocity” (DDV), is unaffected. Larger raindrops fall faster and are oblate, so values of DDV are positive. If a gamma function is used for the raindrop size spectrum, then the observed DDV and ZDR correspond to particular values of median drop diameter D0 and the dispersion index m. The scaling parameter N0 is derived from Z. Estimates of m have a mean value of 5 but vary substantially. An error in rainfall rate of up to ±15% results if the rainfall rate is computed from Z and ZDR alone, and m is assumed constant at 5. An overestimation of more than 30% occurs if m is assumed to be 0. DDV values in stratiform ice are slightly negative. The values in ice are explicable in terms of a mixture of slowly falling oblate crystals and faster-falling spherical aggregates. In the bright band, DDV is consistent with the coexistence of oblate snowflakes and faster-falling raindrops.
Large-Scale Analysis of Cirrus Clouds from AVHRR Data: Assessment of Both a Microphysical Index and the Cloud-Top Temperature
Authors: Giraud V. , Buriez J. C. , Fouquart Y. , Parol F. , Seze G.
Published: August 2010

An algorithm that allows an automatic analysis of cirrus properties from Advanced Very High Resolution Radiometer (AVHRR) observations is presented. Further investigations of the information content and physical meaning of the brightness temperature differences (BTD) between channels 4 (11 μm) and 5 (12 μm) of the radiometer have led to the development of an automatic procedure to provide global estimates both of the cirrus cloud temperature and of the ratio of the equivalent absorption coefficients in the two channels, accounting for scattering effects. The ratio is useful since its variations are related to differences in microphysical properties. Assuming that cirrus clouds are composed of ice spheres, the effective diameter of the particle size distribution can be deduced from this microphysical index.

The automatic procedure includes first, a cloud classification and a selection of the pixels corresponding to the envelope of the BTD diagram observed at a scale of typically 100 × 100 pixels. The classification, which uses dynamic cluster analysis, takes into account spectral and spatial properties of the AVHRR pixels. The selection is made through a series of tests, which also guarantees that the BTD diagram contains the necessary information, such as the presence of both cirrus-free pixels and pixels totally covered by opaque cirrus in the same area. Finally, the cloud temperature and the equivalent absorption coefficient ratio are found by fitting the envelope of the BTD diagram with a theoretical curve. Note that the method leads to the retrieval of the maximum value of the equivalent absorption coefficient ratio in the scene under consideration. This, in turn, corresponds to the minimum value of the effective diameter of the size distribution of equivalent Mie particles.

The automatic analysis has been applied to a series of 21 AVHRR images acquired during the International Cirrus Experiment (ICE’89). Although the dataset is obviously much too limited to draw any conclusion at the global scale, it is large enough to permit derivation of cirrus properties that are statistically representative of the cirrus systems contained therein. The authors found that on average, the maximum equivalent absorption coefficient ratio increases with the cloud-top temperature with a jump between 235 and 240 K. More precisely, for cloud temperatures warmer than 235 K, the retrieved equivalent absorption coefficient ratio sometimes corresponds to very small equivalent spheres (diameter smaller than 20 μm). This is never observed for lower cloud temperatures. This change in cirrus microphysical properties points out that ice crystal habits may vary from one temperature regime toanother. It may be attributed to a modification of the size and/or shape of the particles.
The Potential of a Spaceborne Cloud Radar for the Detection of Stratocumulus Clouds
Authors: Fox Neil I. , Illingworth Anthony J.
Published: August 2010

The radar reflectivity and liquid water content of stratocumulus clouds have been computed from cloud droplet spectra recorded during more than 4000 km of cloud penetrations by an aircraft, and the probability of detecting various values of liquid water content as a function of the radar sensitivity threshold has been derived. The goal of the study is to specify the sensitivity required for any future spaceborne cloud radar. In extensive marine stratocumulus deeper than about 200 m, occasional but ubiquitous drizzle-sized droplets of up to 200 μm dominate the radar return and increase it by between 10 and 20 dB above the cloud droplet contribution to the return, making radar detection easier, although the concentration of the drizzle drops is so low that they have no effect on the liquid water content or effective radius. These occasional drizzle-sized droplets are present throughout the vertical and horizontal extent of such clouds but should evaporate within 200 m of cloud base. On occasion, the drizzle can fall farther and may yield a false measurement of cloud-base altitude, but such cases can be recognized by examining the vertical profile of reflectivity. A radar sensitivity threshold of −30 dBZ would detect 80%, 85%, and 90% of the marine stratocumulus, with a liquid water content above 0.025, 0.05, and 0.075 g m−3, respectively. Because nonprecipitating drizzle droplets are rare in continental stratocumulus, the equivalent figures are reduced to 38%, 33%, and 25%. Improving the sensitivity to −40 dBZ increases detection probability to nearly 100% for both types of cloud. These figures are based on the assumption that the cloud is deep enough to fill the radar pulse volume.
Model-Simulated Influences of Shelterbelt Shape on Wind-Sheltering Efficiency
Authors: Wang Hao , Takle E. S.
Published: August 2010

The authors report results of a numerical model used to simulate wind and turbulence fields for porous, living shelterbelts with seven different cross-sectional shapes. The simulations are consistent with results of Woodruff and Zingg whose wind-tunnel study demonstrated that all shelterbelts with very different shapes have nearly identical reduction of wind and turbulence. The simulations also showed that the pressure-loss (resistance) coefficient for smooth-shaped or streamlined shelterbelts is significantly smaller than that for rectangle-shaped or triangle-shaped shelterbelts with a windward vertical side. However, the shelter effects are not proportional to the pressure-loss coefficient (drag). Analysis of the momentum budget demonstrated that in the near lee and in the far lee, both vertical advection and pressure gradient have opposite roles in the recovery of wind speed. This behavior, combined with differences in permeability, is the likely cause of reduced sensitivity of shelter effects to shelterbelt shape.
Validation of a Long-Range Trajectory Model Using Gas Balloon Tracks from the Gordon Bennett Cup 95
Authors: Baumann Kathrin , Stohl Andreas
Published: August 2010

In September 1995, 18 gas balloon teams competed at the Gordon Bennett Cup, a long-distance ballooning event. The landing positions, travel times of all teams, and detailed information on the tracks of four teams are available. A special version of the trajectory model FLEXTRA (flexible trajectories) is used that allows the heights of calculated trajectories to be adjusted to the respective balloon heights at every computation time step. The comparison of calculated and observed balloon trajectories allows a validation of the trajectory model. In this case study, the agreement between calculated and balloon trajectories was good, with average relative transport errors of less than 20% of the travel distance after 46 h of travel time. Most of the trajectory errors originate from interpolation errors and from amplifications of small position disturbances in divergent wind fields. Trajectory ensembles, taking into account stochastic errors occurring during the trajectory calculations, are shown to be very reliable in assessing the uncertainties of the computed trajectories. In the present study, the balloon tracks were enveloped by the ensemble trajectories most of the time, suggesting that errors in the analyzed wind fields were relatively small.
Radar Rainfall Estimation for Ground Validation Studies of the Tropical Rainfall Measuring Mission
Authors: Ciach Grzegorz J. , Krajewski Witold F. , Anagnostou Emmanouil N. , Baeck Mary L. , Smith James A. , McCollum Jeffrey R. , Kruger Anton
Published: August 2010

This study presents a multicomponent rainfall estimation algorithm, based on weather radar and rain gauge network, that can be used as a ground-based reference in the satellite Tropical Rainfall Measuring Mission (TRMM). The essential steps are constructing a radar observable, its nonlinear transformation to rainfall, interpolation to rectangular grid, constructing several timescale accumulations, bias adjustment, and merging of the radar rainfall estimates and rain gauge data. Observations from a C-band radar in Darwin, Australia, and a local network of 54 rain gauges were used to calibrate and test the algorithm. A period of 25 days was selected, and the rain gauges were split into two subsamples to apply cross-validation techniques.

A Z–R relationship with continuous range dependence and a temporal interpolation scheme that accounts for the advection effects is applied. An innovative methodology was used to estimate the algorithm controlling parameters. The model was globally optimized by using an objective function on the level of the final products. This is equivalent to comparing hundreds of Z–R relationships using a uniform and representative performance criterion. The algorithm performance is fairly insensitive to the parameter variations around the optimum. This suggests that the accuracy limit of the radar rainfall estimation based on power-law Z–R relationships has been reached. No improvement was achieved by using rain regime classification prior to estimation.
Inference of Marine Atmospheric Boundary Layer Moisture and Temperature Structure Using Airborne Lidar and Infrared Radiometer Data
Authors: Palm Stephen P. , Hagan Denise , Schwemmer Geary , Melfi S. H.
Published: August 2010

A new technique for retrieving near-surface moisture and profiles of mixing ratio and potential temperature through the depth of the marine atmospheric boundary layer (MABL) using airborne lidar and multichannel infrared radiometer data is presented. Data gathered during an extended field campaign over the Atlantic Ocean in support of the Lidar In-space Technology Experiment are used to generate 16 moisture and temperature retrievals that are then compared with dropsonde measurements. The technique utilizes lidar-derived statistics on the height of cumulus clouds that frequently cap the MABL to estimate the lifting condensation level. Combining this information with radiometer-derived sea surface temperature measurements, an estimate of the near-surface moisture can be obtained to an accuracy of about 0.8 g kg−1. Lidar-derived statistics on convective plume height and coverage within the MABL are then used to infer the profiles of potential temperature and moisture with a vertical resolution of 20 m. The rms accuracy of derived MABL average moisture and potential temperature is better than 1 g kg−1 and 1°C, respectively. The method relies on the presence of a cumulus-capped MABL, and it was found that the conditions necessary for use of the technique occurred roughly 75% of the time. The synergy of simple aerosol backscatter lidar and infrared radiometer data also shows promise for the retrieval of MABL moisture and temperature from space.
A Semianalytical Solution to a Diffusion–Deposition–Resuspension Model of Local Contamination
Authors: Zhuang Yahui
Published: August 2010

This note describes a semianalytical solution to a diffusion–deposition–resuspension model. Calculations of the fate of a point contaminant show that the model performs well in representing the individual effects of advection, deposition, and resuspension. Within uncertainties inherent to the model parameters, this model solution can be used for assessing the environmental impact of an initially localized source of contamination.
Modeling Surface Sensible Heat Flux Using Surface Radiative Temperatures in a Simple Urban Area
Authors: Voogt J. A. , Grimmond C. S. B.
Published: August 2010

Sensible heat fluxes over a light industrial area in Vancouver, British Columbia, Canada, are analyzed from observed tower fluxes and modeled using a bulk heat transfer approach. The bulk transfer models are initialized using remotely sensed surface temperatures from both airborne and ground-based observing platforms. The remotely sensed surface temperature, in conjunction with a surface database, is used to create area-weighted temperature estimates representative of the complete urban surface. Sensitivity analyses of the various surface temperature estimates are performed. Estimates of kB−1, the ratio of roughness length of momentum to heat, for this area are in general agreement with theoretical estimates for bluff-rough surfaces and are larger than those documented for vegetated and agricultural surfaces. Back-calculated values do vary depending on the method used to determine surface temperature but vary more with the time of day. Empirical relations derived previously for vegetated surfaces are shown to agree well with the results for a dry urban environment. Approaches based on microscale variability in temperature fields are problematic.
Alongwind Dispersion—A Simple Similarity Formula Compared with Observations at 11 Field Sites and in One Wind Tunnel
Authors: Hanna Steven R. , Franzese Pasquale
Published: August 2010

Observations of alongwind dispersion of clouds were collected from 11 field sites and from one wind tunnel and were used to test simple similarity relations. Because most of the observations consist of concentration time series from fixed monitors, the basic observed variable is σt, the standard deviation of the concentration time series. The observed σts range from 0.3 to 9000 s. The concentration time series observations also allow the travel time t from source to receptor to be estimated, from which the cloud advective speed ue can be determined. Observed ts range from 2 to 40 000 s, and observed ues range from 0.5 to 16 m s−1. The alongwind dispersion coefficient σx is then calculated from ueσt. The resulting σt and σx observations support the similarity relations σt = 0.1t and σx = 2u∗t, where u∗ is friction velocity. About 50% of the observations are within a factor of 2 of these similarity relations.
Parameterization of the Two-Point Velocity Correlation Function in a Two-Particle Lagrangian Stochastic Model and Its Effect on the Prediction of Concentration Variances due to a Line Source
Authors: Cohen J. E. , Reynolds A. M.
Published: August 2010

A Lagrangian stochastic model, in which a new parameterization of the two-point velocity correlation function is included, is investigated. Model simulations of temperature variances caused by a line source in an inhomogeneous wind-tunnel boundary layer are shown to be in good agreement with experimental data. A special limit of the new parameterization that is useful at large distances from the source is discussed in detail. A new technique is introduced that greatly enhances the computational efficiency of an implementation of this limit of the model and that renders long-distance simulations of concentration variances of tracers dispersing from line sources computationally treatable.
Estimating the Refractive Index Structure Parameter () over the Ocean Using Bulk Methods
Authors: Frederickson Paul A. , Davidson Kenneth L. , Zeisse Carl R. , Bendall Charles S.
Published: August 2010

Infrared scintillation measurements were obtained along a 7-km path over San Diego Bay concurrently with meteorological measurements obtained from a buoy at the midpoint of the path. Bulk estimates of the refractive index structure parameter were computed from the buoy data and compared with scintillation-derived values. The bulk estimates agreed well with the scintillation measurements in unstable conditions. In stable conditions the bulk estimates became increasingly higher than the scintillation values as the air–sea temperature difference increased. This disagreement may be due to enhanced wave-induced mixing of the lower atmosphere that decreases the vertical temperature and humidity gradients in stable conditions from the assumed Monin–Obukhov similarity (MOS) theory forms, resulting in bulk values that are too high. The bulk estimates decrease rapidly when the absolute air–sea temperature difference approaches small positive values. These predicted decreases in were not observed in either the path-averaged scintillation measurements or in single-point turbulence measurements, indicating that bulk models for estimating scalar structure parameters based on mean air–sea scalar differences are not valid when the mean air–sea difference approaches zero. The authors believe that the most promising means toward improving the bulk model is to obtain a better understanding of the MOS functions over the ocean for a wide stability range, and particularly of the role of ocean waves in modifying near-surface vertical gradients and turbulence characteristics.
Fuzzy Categorization of Weather Conditions for Thermal Mapping
Authors: Shao J.
Published: August 2010

Thermal mapping is a technique that uses a vehicle-mounted infrared radiometer to measure the variation of road surface temperature (RST). Conventionally, the technique is conducted under three qualitatively categorized weather conditions: extreme, intermediate, and damped. These three categories represent basic weather patterns and are widely used in thermal mapping. In real-time operation, however, determination of the weather category is hampered by the lack of systematic classification. Furthermore, certain skills and knowledge of both thermal mapping and meteorology are required. As the thermal mapping technique develops in the direction of providing a platform for automatic and dynamic forecasting of RST over an entire road network, it is necessary to have some kind of hands-off, quantitative, systematic, accurate, and fast categorization of weather conditions for thermal mapping. For this purpose, the relationship between the change of weather conditions and variation of RST was analyzed to define a time domain for application of a reliable categorization algorithm. Fuzzy membership functions were then established, based on cloud amount, cloud type, wind speed, and relative humidity, to compose a fuzzy function of weather categorization for thermal mapping. The results of validation for the fuzzy categorization show that the algorithm can become a useful tool for thermal mapping.
An Extended Version of the Richardson Model for Simulating Daily Weather Variables
Authors: Parlange Marc B. , Katz Richard W.
Published: August 2010

The Richardson model is a popular technique for stochastic simulation of daily weather variables, including precipitation amount, maximum and minimum temperature, and solar radiation. This model is extended to include two additional variables, daily mean wind speed and dewpoint, because these variables (or related quantities such as relative humidity) are required as inputs for certain ecological/vegetation response and agricultural management models. To allow for the positively skewed distribution of wind speed, a power transformation is applied. Solar radiation also is transformed to make the shape of its modeled distribution more realistic. A model identification criterion is used as an aid in determining whether the distributions of these two variables depend on precipitation occurrence. The approach can be viewed as an integration of what is known about the statistical properties of individual weather variables into a single multivariate model.

As an application, this extended model is fitted to weather data in the Pacific Northwest. To aid in understanding how such a stochastic weather generator works, considerable attention is devoted to its statistical properties. In particular, marginal and conditional distributions of wind speed and solar radiation are examined, with the model being capable of representing relationships between variables in which the variance is not constant, as well as certain forms of nonlinearity.
A Novel Ice-Cloud Retrieval Algorithm Based on the Millimeter-Wave Imaging Radiometer (MIR) 150- and 220-GHz Channels
Authors: Deeter Merritt N. , Evans K. Franklin
Published: August 2010

A novel microwave technique for simultaneously retrieving cirrus ice water path (IWP) and characteristic ice particle size is described. The retrieval algorithm exploits radiance measurements made at 150 and 220 GHz by the airborne Millimeter-Wave Imaging Radiometer (MIR). Other MIR channels additionally are used to test for the presence of liquid clouds and precipitation, which otherwise would have a contaminating effect on the retrievals. Forward radiative transfer modeling was used to generate a two-dimensional retrieval table in which brightness-temperature depressions (relative to clear-sky values) for both microwave channels were recorded as functions of IWP and characteristic particle size for gamma distributions of ice particles. Retrieval errors due to particle shape, size distribution, clear-sky water vapor variability, cirrus-cloud altitude variability, and instrument noise were estimated using Monte Carlo analysis. Particle shape uncertainty is believed to be the dominant source of retrieval error. The technique is demonstrated using MIR data recorded on the National Aeronautics and Space Administration ER-2 aircraft during the Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment experiment in the tropical western Pacific Ocean in 1993. The retrieval technique with MIR data is suited only to high-IWP clouds with large ice particles, such as thick frontal cirrus and convective anvils. The general methodology, however, is applicable to higher frequencies that have greatly increased sensitivity to thinner cirrus.
Discrepancy between Gauges and Satellite Estimates of Rainfall in Equatorial Africa
Authors: McCollum Jeffrey R. , Gruber Arnold , Ba Mamoudou B.
Published: August 2010

The Global Precipitation Climatology Project (GPCP) satellite estimates have approximately twice the magnitude of estimates produced from the rain gauges used by the GPCP in central equatorial Africa. Different possible explanations are identified and investigated. The first is that there may not be enough GPCP rain gauges in the area to provide accurate estimates of rainfall for comparisons with satellite estimates. A comparison of the time-averaged GPCP rain gauge estimate with a long-term (over 40 yr) climatology indicates that the GPCP gauge estimates are similar to long-term rainfall averages, suggesting that the GPCP rain gauge analysis is not underestimating rainfall. Two other possible explanations related to the physical properties of the air masses in this region are studied. Evidence from the literature and from estimates of the effective radii of cloud droplets suggests that there may be an abundance of aerosols in central Africa, resulting in an abundance of cloud condensation nuclei, small drops, and inefficient rain processes. The second explanation is that convective clouds forming under dry conditions generally have cloud bases considerably higher than those of clouds forming in moist environments. This leads to an increase in the evaporation rate of the falling rain, resulting in less precipitation reaching the ground. Analysis of the moisture distributions from both the National Centers for Environmental Prediction numerical weather prediction model reanalysis data and the National Aeronautics and Space Administration Water Vapor Project global moisture dataset reveals that the lower troposphere in this region of Africa is relatively dry, which suggests that cloud bases are high.
Nitric Acid–Sea Salt Reactions: Implications for Nitrogen Deposition to Water Surfaces
Authors: Pryor S. C. , Sørensen L. L.
Published: August 2010

Many previous studies have indicated the importance of nitric acid (HNO3) reactions on sea salt particles for flux divergence of HNO3 in the marine surface layer. The potential importance of this reaction in determining the spatial and temporal patterns of nitrogen dry deposition to marine ecosystems is investigated using models of sea spray generation and particle- and gas-phase dry deposition. Under horizontally homogeneous conditions with near-neutral stability and for wind speeds between 3.5 and 10 m s−1, transfer of HNO3 to the particle phase to form sodium nitrate may decrease the deposition velocity of nitrogen by over 50%, leading to greater horizontal transport prior to deposition to the sea surface. Conversely, for wind speeds above 10 m s−1, transfer of nitrogen to the particle phase would increase the deposition rate and hence decrease horizontal transport prior to surface removal.
A Guide for Health Care Practitioners in the Assessment of Young People’s Capacity to Consent to Treatment
Authors: Geist Rose , Opler Susan E.
Published: August 2010

The Health Care Consent Act, 1996, states that every person in Ontario, regardless of age, is presumed to be capable of consenting to or refusing medical treatment unless he or she is found incapable with respect to a specific treatment or plan of treatment. Health care practitioners may find it especially challenging to apply the legal test of capacity to young people. As an aid to assessment, a guide incorporating both legal and medical perspectives has been developed. This article describes the background and context of the development of the guide and explains how it helps practitioners to conduct a simpler, more focused evaluation of capacity in youth. The guide, along with an introduction and comments for parents, is included in an appendix.
Cardiovascular Safety of Stimulant Medications for Pediatric Attention-Deficit Hyperactivity Disorder
Authors: Silva Raul R. , Skimming Jeffrey W. , Muniz Rafael
Published: August 2010

Attention-deficit hyperactivity disorder (ADHD) is a common neurobehavioral disorder that is often treated with stimulants such as methylphenidate and mixed amphetamine salts. Despite their efficacy and long history of use, there is concern about their potential for adverse cardiovascular effects in children and adolescents. Data from placebo-controlled and open-label extension trials published after 2000 were reviewed, and cardiovascular adverse event data were compared. Both placebo-controlled and open-label extension trials have repeatedly shown stimulant-induced increases in mean blood pressure, heart rate, and QT interval in children, adolescents, and adults. Although these increases seem relatively minor, their existence raises questions regarding whether stimulants could influence the likelihood of sudden death or other serious cardiovascular consequences, especially in patients with underlying heart problems. Moreover, questions have been raised regarding the necessity of screening patients for occult or unrecognized heart problems that are felt to be adversely affected by stimulant use. Obtaining a baseline electrocardiogram for any patient starting stimulant treatment is reasonable if access to such screening is readily available and not too costly.
Positive Behavior Support Through Family–School Collaboration for Young Children With Autism
Authors: Blair Kwang-Sun Cho , Lee In-Suk , Cho Su-Je , Dunlap Glen
Published: August 2010

In this study, a multiple baseline design across three young children with autism was used to assess the impact of individualized behavior support, implemented through family—school collaboration, on the children’s appropriate and problem behaviors and adult—child interactions. A positive behavior support process was used to promote family—school collaboration and to design the individualized intervention. Data indicated that the children’s target behaviors improved with the intervention during circle time at school and play time at home, and their behaviors generalized to nontargeted center time at school and play at the community playground. Teacher and mother positive interactions with the children increased while negative interactions decreased. Social validity indicated that the interventions provided through family—school collaboration were acceptable and effective.
Differential activation of the middle-temporal complex to visual stimulation in migraineurs
Authors: Antal Andrea , Polania Rafael , Saller Katharina , Morawetz Carmen , Schmidt-Samoa Carsten , Baudewig Jürgen , Paulus Walter , Dechent Peter
Published: August 2010

Objective: Differences between people with and without migraine on various measures of visual perception have been attributed to abnormal cortical processing due to the disease. The aim of the present study was to explore the dynamics of the basic interictal state with regard to the extrastriate, motion-responsive middle temporal area (MT-complex) with functional magnetic resonance imaging (fMRI) at 3 tesla using coherent/incoherent moving dot stimuli.

Method: Twenty-four migraine patients (12 with aura [MwA], 12 without aura [MwoA]) and 12 healthy subjects participated in the study. The individual cortical folding pattern was accounted for by using a cortical matching approach.

Results: In the inferior-posterior portion of the MT-complex, most likely representing MT, control subjects showed stronger bilateral activation compared to MwA and MwoA patients. Compared with healthy controls MwoA and MwA patients showed significantly stronger activation mainly at the left side in response to visual stimulation in the superior-anterior portion of the MT-complex, representing the medial-superior temporal area (MST).

Conclusion: Our findings strengthen the hypothesis that hyperresponsiveness of the visual cortex in migraine goes beyond early visual areas, even in the interictal period.
Cardiovascular risk factors associated with migraine among the elderly with a low income: The São Paulo Ageing & Health Study (SPAH)
Authors: Benseñor Isabela M , Goulart Alessandra C , Lotufo Paulo A , Menezes Paulo R , Scazufca Márcia
Published: August 2010

Background: To investigate the association between cardiovascular risk-factor profile and migraine in the elderly, we evaluated a population sample of ageing men and women (65 years or more) living in a low-income area in the city of São Paulo, Brazil.

Patients and Methods: We investigated migraine status and cardiovascular profile from a baseline of 1450 participants (65–102 years of age) of the São Paulo Ageing & Health Study (SPAH), a longitudinal population-based study with low-income elderly in Brazil. The following age and sex-adjusted cardiovascular risk factors were analyzed: blood pressure, pulse pressure, serum total and high-density lipoprotein cholesterol, body mass index, smoking, history of hypertension, diabetes and the 10-year risk of myocardial infarction or coronary heart disease death based on the Framingham Risk Score.

Results: The overall prevalence of migraine was 11.4%, and it was 3 times more frequent among women than men (15.3% vs 5.4%; P < 0.0001). Migraineurs were younger than non-migraineurs (mean age 70.6 years vs 72.1 years; P = 0.001, respectively). There was no statistically significant difference regarding the cardiovascular risk-factor profile after adjustment for age and sex among migraineurs and non-migraineurs. Only a decrease in the risk of hypertension among women (OR 0.58; 95% CI 0.38–0.90; P = 0.01) was also observed even after adjustment for age.

Conclusions: Overall, we did not find a worse cardiovascular risk profile among elderly migraineurs. An inverse association between hypertension and migraine in women warrants further investigation.
The Prospective Relationship Between Binge Drinking and Physician Visits Among Older Adults
Authors: Jenkins Kristi Rahrig , Zucker Robert A.
Published: August 2010

Objectives: The objectives are to (a) determine if binge drinking is related to physician visits and (b) estimate the degree to which the relationship between binge drinking and physician visits can be explained by other health characteristics. Method: Data on a sample of 4,960 older adults (70+ years of age in 2002) from the Health and Retirement Study (HRS) were used. Three linear regression models estimated the impact of binge drinking on physician visits. Results: In the fully adjusted models, binge drinking did have an effect on the number of physician visits by older adults, with more frequent binge drinkers having fewer physician visits. This negative relationship exists even when demographic as well as other current health characteristics are controlled. Discussion: The implications of these results are discussed in terms of more broadly communicating the risks associated with binge drinking and more effectively targeting interventions to older binge drinkers.
A Network Perspective on State-Society Synergy to Increase Community-Level Social Capital
Authors: Varda Danielle M.
Published: August 2010

“Can state–society synergy be created in the short run, or does it require historically deep institutional and normative foundations?” In other words, what role can an outside party—such as a government or state actor—play in constructing social capital when it is not a permanent fixture of the existing interrelationships within a community? Taking a network perspective, this exploratory research examines community-level social capital outcomes of a government-led intervention. Operationalized as social networks, social capital is measured as an increase to the strength of weak ties and reduction in redundancy among exchange relationships. Findings suggest that state–society synergy has the potential to increase bridging social capital in communities. In addition, communities with higher levels of cohesion and connectivity pre-intervention results in greater increases to social capital, and although trust plays a crucial role in development of social capital, the influence organizations are perceived to have does not.
Lifibrol as a Model Compound for a Novel Lipid-Lowering Mechanism of Action
Authors: Berthold Heiner K. , Sudhop Thomas , von Bergmann Klaus , Gouni-Berthold Ioanna
Published: August 2010

Lifibrol is a potent lipid-lowering drug with an unknown mechanism of action. We investigated its effects on lipoprotein and sterol metabolism in normocholesterolemic male participants. Seven participants were treated for 4 weeks with 600 mg/d lifibrol and 9 with 40 mg/d pravastatin in a double-blind randomized parallel-group trial. Kinetic studies were performed at baseline and under acute and chronic treatment. Turnover of apolipoprotein B-100 was investigated with endogenous stable-isotope labeling, and kinetic parameters were derived by multicompartmental modeling. Lathosterol and cholesterol metabolism were investigated using mass isotopomer distribution analysis (MIDA) after [1-13C]acetate labeling. Carbon metabolism was investigated by calculating the total isotope incorporation into newly formed sterols and measuring the disposal of acetate by 13CO2 breath analysis. Total- and low-density lipoprotein (LDL) cholesterol decreased by 18% and 27% under lifibrol and by 17% and 28% under pravastatin, respectively, whereas very-low-density lipoprotein (VLDL) cholesterol, triglycerides, and high-density lipoprotein (HDL) cholesterol did not change. Very-low-density lipoprotein apoB fractional synthesis and production increased under lifibrol but remained unchanged under pravastatin. Low-density lipoprotein apoB fractional synthesis and production increased under pravastatin but remained unchanged under lifibrol. Mass isotopomer distribution analysis indicated that both drugs decrease endogenous sterol synthesis after acute administration, but pravastatin had more powerful effects. Carbon-13 appearance in breath was higher during pravastatin than during lifibrol treatment. Mass isotopomer distribution analysis and carbon metabolism analysis indicated compartmentalization at the site of sterol synthesis, thus suggesting differential effects of the 2 drugs. Although having comparable lipid-lowering properties, lifibrol seems to have a mechanism of action distinct from that of statins. Lifibrol could serve as a model compound for the development of new lipid-lowering agents.
Both Mitochondrial KATP Channel Opening and Sarcolemmal KATP Channel Blockage Confer Protection Against Ischemia/Reperfusion-Induced Arrhythmia in Anesthetized Male Rats
Authors: Gonca Ersöz , Bozdoğan Ömer
Published: August 2010

Aim: This study was performed to assess the effect of selective sarcolemmal adenosine triphosphate (ATP)-sensitive K+channel (KATP) inhibition and the mitochondrial KATPchannel activation on ischemia and reperfusion (I/R)-induced arrhythmias in different gender of rats. We compared the effect of a selective sarcolemmal KATPchannel blocker HMR 1098, a selective mitochondrial KATPchannel opener diazoxide, a nonselective KATPchannel opener pinacidil, and the combination of pinacidil with HMR 1098 on the incidence and duration of ventricular arrhythmias in 2 groups: anesthetized males (n = 31) and females (n = 31). Main Methods: Ischemia and reperfusion was produced by occluding the left main coronary artery of Sprague-Dowley rats for 6 minutes followed by re-opening of the artery for 6 minutes. Key Findings: The arrhythmia score and the duration of arrhythmias were significantly reduced by HMR 1098, diazoxide, and pinacidil in male rats. The combination of the pinacidil with HMR 1098 did not change the antiarrhythmic effect of pinacidil. The duration of arrhythmas was shorter in females than that in the corresponding males. Drug treatments were not effective in decreasing arrhythmias in female groups to the same extent as in the male group. However, the mitochondrial KATPchannel activation that is provided by the combination of pinacidil with HMR 1098 significantly decreased the total length of arrhythmias in females. Significance: Results of the current study indicate that both mitochondrial KATPchannel activation and sarcolemmal KATPchannel inhibition exert antiarrhythmic action in male rats. The antiarrhythmic effect of pinacidil is not depend on the sarcolemmal KATPchannel opening. These results also indicate that KATPchannel modulators show no discernable effect in female rats due to the already low incidence of arrhythmias in females.