bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors Influencing Simulated Changes in Future Arctic Cloudiness
Authors: Vavrus Stephen J. , Bhatt Uma S. , Alexeev Vladimir A.
Published: May 2011

This study diagnoses the changes in Arctic clouds simulated by the Community Climate System Model version 3 (CCSM3) in a transient 2 × CO2 simulation. Four experiments—one fully coupled and three with prescribed SSTs and/or sea ice cover—are used to identify the mechanisms responsible for the projected cloud changes. The target simulation uses a T42 version of the CCSM3, in which the atmosphere is coupled to a dynamical ocean with mobile sea ice. This simulation is approximated by a T42 atmosphere-only integration using CCSM3’s atmospheric component [the Community Atmosphere Model version 3 (CAM3)] forced at its lower boundary with the changes in both SSTs and sea ice concentration from CCSM3’s 2 × CO2 run. The authors decompose the combined effect of the higher SSTs and reduced sea ice concentration on the Arctic cloud response in this experiment by running two additional CAM3 simulations: one forced with modern SSTs and the projected sea ice cover changes in CCSM3 and the other forced with modern sea ice coverage and the projected changes in SSTs in CCSM3.

The results suggest that future increases in Arctic cloudiness simulated by CCSM3 are mostly attributable to two separate processes. Low cloud gains are primarily initiated locally by enhanced evaporation within the Arctic due to reduced sea ice, whereas cloud increases at middle and high levels are mostly driven remotely via greater meridional moisture transport from lower latitudes in a more humid global atmosphere. The enhanced low cloudiness attributable to sea ice loss causes large increases in cloud radiative forcing during the coldest months and therefore promotes even greater surface warming. Because CCSM3’s Arctic cloud response to greenhouse forcing is similar to other GCMs, the driving mechanisms identified here may be applicable to other models and could help to advance our understanding of likely changes in the vertical structure of polar clouds.
Global Energy and Water Budgets in MERRA
Authors: Bosilovich Michael G. , Robertson Franklin R. , Chen Junye
Published: May 2011

Reanalyses, retrospectively analyzing observations over climatological time scales, represent a merger between satellite observations and models to provide globally continuous data and have improved over several generations. Balancing the earth’s global water and energy budgets has been a focus of research for more than two decades. Models tend to their own climate while remotely sensed observations have had varying degrees of uncertainty. This study evaluates the latest NASA reanalysis, the Modern Era Retrospective-Analysis for Research and Applications (MERRA), from a global water and energy cycles perspective, to place it in context of previous work and demonstrate the strengths and weaknesses.

MERRA was configured to provide complete budgets in its output diagnostics, including the incremental analysis update (IAU), the term that represents the observations influence on the analyzed states, alongside the physical flux terms. Precipitation in reanalyses is typically sensitive to the observational analysis. For MERRA, the global mean precipitation bias and spatial variability are more comparable to merged satellite observations [the Global Precipitation and Climatology Project (GPCP) and Climate Prediction Center Merged Analysis of Precipitation (CMAP)] than previous generations of reanalyses. MERRA ocean evaporation also has a much lower value, which is comparable to independently derived estimate datasets. The global energy budget shows that MERRA cloud effects may be generally weak, leading to excess shortwave radiation reaching the ocean surface.

Evaluating the MERRA time series of budget terms, a significant change occurs that does not appear to be represented in observations. In 1999, the global analysis increments of water vapor changes sign from negative to positive and primarily lead to more oceanic precipitation. This change is coincident with the beginning of Advanced Microwave Sounding Unit (AMSU) radiance assimilation. Previous and current reanalyses all exhibit some sensitivity to perturbations in the observation record, and this remains a significant research topic for reanalysis development. The effect of the changing observing system is evaluated for MERRA water and energy budget terms.
Observations of Internal Tides on the Oregon Continental Slope
Authors: Martini Kim I. , Alford Matthew H. , Kunze Eric , Kelly Samuel M. , Nash Jonathan D.
Published: May 2011

A complex superposition of locally forced and shoaling remotely generated semidiurnal internal tides occurs on the Oregon continental slope. Presented here are observations from a zonal line of five profiling moorings deployed across the continental slope from 500 to 3000 m, a 24-h expendable current profiler (XCP) survey, and five 15–48-h lowered ADCP (LADCP)/CTD stations. The 40-day moored deployment spans three spring and two neap tides, during which the proportions of the locally and remotely forced internal tides vary. Baroclinic signals are strong throughout spring and neap tides, with 4–5-day-long bursts of strong cross-slope baroclinic semidiurnal velocity and vertical displacement . Energy fluxes exhibit complex spatial and temporal patterns throughout both tidal periods. During spring tides, local barotropic forcing is strongest and energy flux over the slope is predominantly offshore (westward). During neap tides, shoaling remotely generated internal tides dominate and energy flux is predominantly onshore (eastward). Shoaling internal tides do not exhibit a strong spring–neap cycle and are also observed during the first spring tide, indicating that they originate from multiple sources. The bulk of the remotely generated internal tide is hypothesized to be generated from south of the array (e.g., Mendocino Escarpment), because energy fluxes at the deep mooring 100 km offshore are always directed northward. However, fluxes on the slope suggest that the northbound internal tide is turned onshore, most likely by reflection from large-scale bathymetry. This is verified with a simple three-dimensional model of mode-1 internal tides propagating obliquely onto a near-critical slope, whose output conforms fairly well to observations, in spite of its simplicity.
A Physical Method for the Calibration of the AVHRR/3 Thermal IR Channels. Part II: An In-Orbit Comparison of the AVHRR Longwave Thermal IR Channels on board MetOp-A with IASI
Authors: Mittaz Jonathan , Harris Andrew
Published: May 2011

Obtaining stable and accurate satellite radiances for climate change research requires extremely high standards for satellite calibration. Many satellite sensors do not currently meet the accuracy criteria, especially heritage sensors such as the Advanced Very High Resolution Radiometer (AVHRR), which shows scene temperature–dependent trends and biases of up to 0.5 K. Recently, however, a detailed study of the AVHRR/3 prelaunch data showed significant problems with both the calibration algorithm and the prelaunch data and indicated that the inherent accuracy of the AVHRR may actually be quite high. A new approach has been suggested that fixed many of the issues with the current (operational) calibration, but has not yet been applied to the in-orbit case. In this paper the behavior of the AVHRR in orbit is examined and compared to the operational AVHRR radiances from the Meteorological Operation (MetOp)-A with those based on the new calibration to radiances derived from the Infrared Atmosphere Sounding Instrument (IASI). It is shown that the current AVHRR calibration does indeed introduce large (0.5 K) biases, but these biases are remarkably stable. It is further shown that, with some modification related to differences between the prelaunch test environment and the in-orbit environment, a physically based AVHRR calibration can match IASI to better than ~0.05 K, which is an order of magnitude better than what is currently available. Finally, it is shown that, while the new calibration is capable of providing accurate and stable radiances for the nadir view, off-nadir biases of up to 1.5 K still exist at the largest zenith angles and at the coldest scene temperatures (~210 K). For surface temperature determination, however, the scan angle bias is very small (<0.02 K), implying that the new AVHRR calibration will provide a significant improvement to, for example, sea surface temperature measurements, one of the Global Climate Observing System (GCOS)-designated essential climate variables.
The Descending Stratified Flow and Internal Hydraulic Jump in the Lee of the Sierras
Authors: Armi Laurence , Mayr Georg J.
Published: May 2011

Cross-barrier density differences and westerly flow established a descending stratified flow across the Sierra Nevada (United States) on 9–10 April 2006. Downslope flow and an internal hydraulic jump occurred only when the potential temperature of the westerly descending flow was at least as cold as the existing upvalley-flowing valley air mass. The onset was observed in sequences of visible satellite images and with weather stations. The University of Wyoming King Air flew through the stratified flow and imaged the structure of the internal hydraulic jump with its cloud radar. Shear-layer instabilities, which first developed near the jump face, grew and paired downstream, mixing the internal hydraulic jump layer. A single wave response to the downslope flow and internal hydraulic jump was observed aloft, but only after the downslope flow had become established.
Vertical Variations of Mixing Lengths under Neutral and Stable Conditions during CASES-99
Authors: Sun Jielun
Published: May 2011

An investigation on vertical variations of the mixing lengths for momentum and heat under neutral and stable conditions was conducted using the data collected from the Cooperative Atmosphere–Surface Exchange Study in 1999 (CASES-99). By comparingκzwith the mixing lengths under neutral conditions calculated using the observations from CASES-99, the vertical layer where the Monin–Obukhov similarity theory (MOST) is valid was identified. Hereκis the von Kármán constant andzis the height above the ground. On average, MOST is approximately valid between 0.5 and 10 m. Above the layer, the observed mixing lengths under neutral conditions are smaller than the MOSTκzand can be approximately described by Blackadar’s mixing length,κz/[1 + (κz/l∞)], withl∞= 15 m for up toz~ 20 m for the mixing length for momentum and up to the highest observation height for the mixing length for heat. Above ~20 m, the mixing length for momentum approaches a constant. Both MOSTκzand Blackadar’s formula systematically overestimate the mixing length for momentum above ~20 m, leading to overestimates of turbulence.
Evolution and Distribution of Record-Breaking High and Low Monthly Mean Temperatures
Authors: Anderson Amalia , Kostinski Alexander
Published: May 2011

The ratio of record highs to record lows is examined with respect to extent of time series for monthly mean temperatures within the continental United States for 1900–2006. In counting the number of records that occur in a single year, the authors find a ratio greater than unity in 2006, increasing nearly monotonically as the time series increases in length via a variable first year over 1900–76. For example, in 2006, the ratio of record highs to record lows ≈ 13:1 with 1950 as the first year and ≈ 25:1 with 1900 as the first year; both ratios are an order of magnitude greater than 3σ for stationary simulations. This indicates a warming trend. It is also found that records are more sensitive to trends in time series of monthly averages than in time series of corresponding daily values. When the last year (1920–2006, starting in 1900) is varied, it is found that the ratio of record highs to record lows is strongly correlated with the ensemble mean temperature. Correlation coefficients are 0.76 and 0.82 for 1900–2006 and 1950–2006, respectively; 3σ = 0.3 for pairs of uncorrelated stationary time series. Similar values are found for globally distributed time series: 0.87 and 0.92 for 1900–2006 and 1950–2006, respectively. The ratios evolve differently, however: global ratios increase throughout (1920–2006) whereas continental U.S. ratios decrease from about 1940 to 1970. Last, the geographical and seasonal distributions of trends are considered by summing records over time rather than ensemble. In the continental United States, the greatest excess of record highs occurs in February (≈2:1) and the greatest excess of record lows occurs in October (≈2:3). In addition, ratios are pronounced in certain regions: in February in the Midwest the ratio ≈ 5:2, and in October in the Southeast the ratio ≈ 1:2.
Reducing the Biases in Simulated Radar Reflectivities from a Bulk Microphysics Scheme: Tropical Convective Systems
Authors: Lang Stephen E. , Tao Wei-Kuo , Zeng Xiping , Li Yaping
Published: May 2011

A well-known bias common to many bulk microphysics schemes currently being used in cloud-resolving models is the tendency to produce excessively large reflectivity values (e.g., 40 dBZ) in the middle and upper troposphere in simulated convective systems. The Rutledge and Hobbs–based bulk microphysics scheme in the Goddard Cumulus Ensemble model is modified to reduce this bias and improve realistic aspects. Modifications include lowering the efficiencies for snow/graupel riming and snow accreting cloud ice; converting less rimed snow to graupel; allowing snow/graupel sublimation; adding rime splintering, immersion freezing, and contact nucleation; replacing the Fletcher formulation for activated ice nuclei with that of Meyers et al.; allowing for ice supersaturation in the saturation adjustment; accounting for ambient RH in the growth of cloud ice to snow; and adding/accounting for cloud ice fall speeds. In addition, size-mapping schemes for snow/graupel were added as functions of temperature and mixing ratio, lowering particle sizes at colder temperatures but allowing larger particles near the melting level and at higher mixing ratios. The modifications were applied to a weakly organized continental case and an oceanic mesoscale convective system (MCS). Strong echoes in the middle and upper troposphere were reduced in both cases. Peak reflectivities agreed well with radar for the weaker land case but, despite improvement, remained too high for the MCS. Reflectivity distributions versus height were much improved versus radar for the less organized land case but not for the MCS despite fewer excessively strong echoes aloft due to a bias toward weaker echoes at storm top.
Missing Stratospheric Ozone Decrease at Southern Hemisphere Middle Latitudes after Mt. Pinatubo: A Dynamical Perspective
Authors: Poberaj C. Schnadt , Staehelin J. , Brunner D.
Published: May 2011

Although large total ozone decreases occurred in the Northern Hemisphere extratropics in the years after the volcanic eruption of Mt. Pinatubo that are generally attributed to the eruption, comparable decreases did not emerge in the Southern Hemisphere. To study this missing decrease, a multiple linear regression was applied to the Chemical and Dynamical Influences on Decadal Ozone Change (CANDIDOZ) Assimilated Three-Dimensional Ozone (CATO) dataset including the solar cycle, the quasi-biennial oscillation (QBO), the effect of volcanic eruptions, the lower stratospheric (LS) Eliassen–Palm (EP) flux to describe the Brewer–Dobson circulation, and stratospheric chlorine increase as explanatory variables. Volcanically induced chemical ozone depletion was overcompensated by the QBO and by a pronounced EP flux anomaly. Using NCEP–NCAR reanalysis data, it is found that the anomalous EP flux was caused by several significant stratospheric wave events (SWEs) from September–November 1991 through 1992 that, together with aerosol heating, led to a significantly enhanced Brewer–Dobson circulation and more ozone transport from the tropics to the extratropics. The onset of the volcanic ozone loss was shifted into 1992 and the strength of the signal was reduced. Most SWEs can be traced back to the troposphere and a significant fraction was associated with atmospheric blocking patterns preceding the SWEs. In 1991/92, the southern annular mode was in a negative phase and El Niño–Southern Oscillation in a warm phase. It is suggested that this constellation favored a flow preconditioning toward quasi-stationary features including blocking, which was significantly enhanced in 1991/92. During June–August 1992, blocking occurred preferably over the southeastern Pacific, pointing to a major ENSO influence on LS wave activity.
On Momentum Transport and Dissipative Heating during Hurricane Landfalls
Authors: Zhang Jun A. , Zhu Ping , Masters Forrest J. , Rogers Robert F. , Marks Frank D.
Published: May 2011

Momentum transport and dissipative heating are investigated using the high-resolution (10 Hz) wind data collected by Florida Coastal Monitoring Program portable weather stations in the surface layer of three landfalling hurricanes. The momentum flux is calculated using the eddy correlation method. The drag coefficient is determined from the momentum flux and surface wind speed. The values of the momentum flux and drag coefficient are found to be generally larger than those observed over the ocean at similar wind speeds up to near hurricane strength. The rate of dissipation is determined from the wind velocity spectra. The dissipative heating is estimated using two different methods: 1) integrating the rate of dissipation in the surface layer and 2) multiplying the drag coefficient by the cubic of the surface wind speed. It is found that the second method, which has been widely used in previous theoretical and numerical studies, significantly overestimates the magnitude of dissipative heating. This finding is consistent with a recent study on estimation of the dissipative heating over the ocean using in situ aircraft observations. This study is a first attempt at estimating the magnitude of dissipative heating in landfalling hurricanes using in situ observations. The results are believed to offer useful guidance in numerical weather prediction efforts aimed at improving the forecast of hurricane intensity.
El Niño–Southern Oscillation in Tropical and Midlatitude Column Ozone
Authors: Wang Jingqian , Pawson Steven , Tian Baijun , Liang Mao-Chang , Shia Run-Lie , Yung Yuk L. , Jiang Xun
Published: May 2011

The impacts of El Niño–Southern Oscillation (ENSO) on the tropical total column ozone, the tropical tropopause pressure, and the 3.5-yr ozone signal in the midlatitude total column ozone were examined using the Goddard Earth Observing System Chemistry–Climate Model (GEOS CCM). Observed monthly mean sea surface temperature and sea ice between 1951 and 2004 were used as boundary conditions for the model. Since the model includes no solar cycle, quasi-biennial oscillation, or volcanic forcing, the ENSO signal was found to dominate the tropical total column ozone variability. Principal component analysis was applied to the detrended, deseasonalized, and low-pass filtered model outputs. The first mode of model total column ozone captured 63.8% of the total variance. The spatial pattern of this mode was similar to that in Total Ozone Mapping Spectrometer (TOMS) observations. There was also a clear ENSO signal in the tropical tropopause pressure in the GEOS CCM, which is related to the ENSO signal in the total column ozone. The regression coefficient between the model total column ozone and the model tropopause pressure was 0.71 Dobson units (DU) hPa−1. The GEOS CCM was also used to investigate a possible mechanism for the 3.5-yr signal observed in the midlatitude total column ozone. The 3.5-yr signal in the GEOS CCM column ozone is similar to that in the observations, which suggests that a model with realistic ENSO can reproduce the 3.5-yr signal. Hence, it is likely that the 3.5-yr signal was caused by ENSO.
Rainfall Estimation with an Operational Polarimetric C-Band Radar in the United Kingdom: Comparison with a Gauge Network and Error Analysis
Authors: Bringi V. N. , Rico-Ramirez M. A. , Thurai M.
Published: May 2011

The estimate of rainfall using data from an operational dual-polarized C-band radar in convective storms in southeast United Kingdom is compared against a network of gauges. Four different rainfall estimators are considered: reflectivity–rain-rate (Z–R) relation, with and without correcting for rain attenuation; a composite estimator, based on (i) Z–R, (ii) R(Z, Zdr), and (iii) R(Kdp); and exclusively R(Kdp). The various radar rain-rate estimators are developed using Joss disdrometer data from Chilbolton, United Kingdom. Hourly accumulations over radar pixels centered on the gauge locations are compared, with approximately 2500 samples available for gauge hourly accumulations > 0.2 mm. Overall, the composite estimator performed the “best” based on robust statistical measures such as mean absolute error, the Nash–Sutcliffe coefficient, and mean bias, at all rainfall thresholds (>0.2, 1, 3, or 6 mm) with improving measures at the higher thresholds of >3 and >6 mm (higher rain rates). Error variance separation is carried out by estimating the gauge representativeness error using 4 yr of gauge data from the Hydrological Radar Experiment. The proportion of variance of the radar-to-gauge differences that could be explained by the gauge representativeness errors ranged from 20% to 55% (for the composite rain-rate estimator). The radar error is found to decrease from approximately 70% at the lower rain rates to 20% at the higher rain rates. The composite rain-rate estimator performed as well as can be expected from error variance analysis, at mean hourly rain rates of about 5 mm h−1 or larger with mean bias of ~10% (underestimate).
Diagnosing the Sensitivity of Local Land–Atmosphere Coupling via the Soil Moisture–Boundary Layer Interaction
Authors: Santanello Joseph A. , Peters-Lidard Christa D. , Kumar Sujay V.
Published: May 2011

The inherent coupled nature of earth’s energy and water cycles places significant importance on the proper representation and diagnosis of land–atmosphere (LA) interactions in hydrometeorological prediction models. However, the precise nature of the soil moisture–precipitation relationship at the local scale is largely determined by a series of nonlinear processes and feedbacks that are difficult to quantify. To quantify the strength of the local LA coupling (LoCo), this process chain must be considered both in full and as individual components through their relationships and sensitivities. To address this, recent modeling and diagnostic studies have been extended to 1) quantify the processes governing LoCo utilizing the thermodynamic properties of mixing diagrams, and 2) diagnose the sensitivity of coupled systems, including clouds and moist processes, to perturbations in soil moisture. This work employs NASA’s Land Information System (LIS) coupled to the Weather Research and Forecasting (WRF) mesoscale model and simulations performed over the U.S. Southern Great Plains. The behavior of different planetary boundary layers (PBL) and land surface scheme couplings in LIS–WRF are examined in the context of the evolution of thermodynamic quantities that link the surface soil moisture condition to the PBL regime, clouds, and precipitation. Specifically, the tendency toward saturation in the PBL is quantified by the lifting condensation level (LCL) deficit and addressed as a function of time and space. The sensitivity of the LCL deficit to the soil moisture condition is indicative of the strength of LoCo, where both positive and negative feedbacks can be identified. Overall, this methodology can be applied to any model or observations and is a crucial step toward improved evaluation and quantification of LoCo within models, particularly given the advent of next-generation satellite measurements of PBL and land surface properties along with advances in data assimilation schemes.
Low-Frequency Variability, Coherence Resonance, and Phase Selection in a Low-Order Model of the Wind-Driven Ocean Circulation
Authors: Pierini Stefano
Published: May 2011

In this paper, a low-order spectral quasigeostrophic (QG) model of the wind-driven ocean circulation is derived and used to analyze the low-order character of the intrinsic low-frequency variability of the midlatitude double-gyre ocean circulation and of the related coherence resonance and phase selection phenomena. The model includes an exponential in the basis functions that allows for westward intensification, retains only four modes in the Galerkin projection, is defined in a rectangular domain, and is forced by deterministic and stochastic winds, thus extending previous low-order QG ocean models. The solution under steady forcing is first obtained, and the results are also analyzed in terms of dynamical systems theory. A homoclinic bifurcation (with the wind amplitude chosen as the control parameter) leads to intrinsic decadal relaxation oscillations (ROs) similar in several respects to those obtained with primitive equation models. The system is then forced with an additional red noise wind, and, in a parameter range preceding the global bifurcation, a coherence resonance scenario very similar to the one found with a primitive equation model of the Kuroshio Extension is obtained: this suggests that such a phenomenon is of low-order character. To study the RO excitation mechanism, a method denoted as phase selection is proposed. The system is forced with additional fictitious periodic winds that produce an emergence of ROs yielding strong phase dependence with the periodic forcing. The subsequent analysis reveals the character of the wind forcing that is most likely to excite a RO. All the results are discussed within the general framework of climate dynamics.
Orogenic Convection in Subtropical South America as Seen by the TRMM Satellite
Authors: Rasmussen Kristen L. , Houze Robert A.
Published: May 2011

Extreme orogenic convective storms in southeastern South America are divided into three categories: storms with deep convective cores, storms with wide convective cores, and storms containing broad stratiform regions. Data from the Tropical Rainfall Measuring Mission satellite’s Precipitation Radar show that storms with wide convective cores are the most frequent, tending to originate near the Sierra de Cordoba range. Downslope flow at upper levels caps a nocturnally enhanced low-level jet, thus preventing convection from breaking out until the jet hits a steep slope of terrain, such as the Sierra de Cordoba Mountains or Andean foothills, so that the moist low-level air is lifted enough to release the instability and overcome the cap. This capping and triggering is similar to the way intense convection is released near the northwestern Himalayas. However, the intense storms with wide convective cores over southeastern South America are unlike their Himalayan counterparts in that they exhibit leading-line/trailing-stratiform organization and are influenced by baroclinic troughs more similar to storms east of the Rocky Mountains in the United States. Comparison of South American storms containing wide convective cores with storms in other parts of the world contributes to a global understanding of how major mountain ranges influence precipitating cloud systems.
Incorporating Condensational Heating into a Nonhydrostatic Atmospheric Model Based on a Hybrid Isentropic–Sigma Vertical Coordinate
Authors: Toy Michael D.
Published: May 2011

Using isentropic coordinates in atmospheric models has the advantage of eliminating the cross-coordinate vertical mass flux for adiabatic flow, and virtually eliminating the associated numerical error in the vertical transport. This is a significant benefit since much of the flow in the atmosphere is approximately adiabatic. Nonadiabatic processes, such as condensational heating, result in a nonzero vertical velocity [Formula: see text] in isentropic coordinates. A method for incorporating condensational heating into a nonhydrostatic atmospheric model based on a hybrid isentropic–sigma vertical coordinate is presented. The model is tested with various 2D moist simulations and the results are compared with those using a traditional terrain-following, height-based sigma coordinate. With the hybrid coordinate, there are improvements in the representation of the developing cloud field in a mountain wave experiment. In a simulation of deep convection, the adaptive hybrid coordinate successfully simulates the turbulent nature of the convection, while maintaining the quasi-Lagrangian nature of the isentropic coordinate in the surrounding dry air. The vertical cross-coordinate mass flux is almost zero in the environmental air, as well as in the stratosphere above the convective tower.
Exploring a Multiresolution Modeling Approach within the Shallow-Water Equations
Authors: Ringler Todd D. , Jacobsen Doug , Gunzburger Max , Ju Lili , Duda Michael , Skamarock William
Published: May 2011

The ability to solve the global shallow-water equations with a conforming, variable-resolution mesh is evaluated using standard shallow-water test cases. While the long-term motivation for this study is the creation of a global climate modeling framework capable of resolving different spatial and temporal scales in different regions, the process begins with an analysis of the shallow-water system in order to better understand the strengths and weaknesses of the approach developed herein. The multiresolution meshes are spherical centroidal Voronoi tessellations where a single, user-supplied density function determines the region(s) of fine- and coarse-mesh resolution. The shallow-water system is explored with a suite of meshes ranging from quasi-uniform resolution meshes, where the grid spacing is globally uniform, to highly variable resolution meshes, where the grid spacing varies by a factor of 16 between the fine and coarse regions. The potential vorticity is found to be conserved to within machine precision and the total available energy is conserved to within a time-truncation error. This result holds for the full suite of meshes, ranging from quasi-uniform resolution and highly variable resolution meshes. Based on shallow-water test cases 2 and 5, the primary conclusion of this study is that solution error is controlled primarily by the grid resolution in the coarsest part of the model domain. This conclusion is consistent with results obtained by others. When these variable-resolution meshes are used for the simulation of an unstable zonal jet, the core features of the growing instability are found to be largely unchanged as the variation in the mesh resolution increases. The main differences between the simulations occur outside the region of mesh refinement and these differences are attributed to the additional truncation error that accompanies increases in grid spacing. Overall, the results demonstrate support for this approach as a path toward multiresolution climate system modeling.
Diurnal Variations of Warm-Season Precipitation East of the Tibetan Plateau over China
Authors: Bao Xinghua , Zhang Fuqing , Sun Jianhua
Published: May 2011

This study explores the diurnal variations of the warm-season precipitation to the east of the Tibetan Plateau over China using the high-resolution NOAA/Climate Prediction Center morphing technique (CMORPH) precipitation data and the Global Forecast System (GFS) gridded analyses during mid-May to mid-August of 2003–09. Complementary to the past studies using satellite or surface observations, it is found that there are strong diurnal variations in the summertime precipitation over the focus domain to the east of the Tibetan Plateau. These diurnal precipitation cycles are strongly associated with several thermally driven regional mountain–plains solenoids due to the differential heating between the Tibetan Plateau, the highlands, the plains, and the ocean. The diurnal cycles differ substantially from region to region and during the three different month-long periods: the pre-mei-yu period (15 May–15 June), the mei-yu period (15 June–15 July), and the post-mei-yu period (15 July–15 August).

In particular, there is a substantial difference in the propagation speed and eastward extent of the peak phase of the dominant diurnal precipitation cycle that is originated from the Tibetan Plateau. This diurnal peak has a faster (slower) eastward propagation speed, the more (less) coherent propagation duration, and thus covers the longest (shortest) distance to the east during the pre-mei-yu (post-mei-yu) period than that during the mei-yu period. The differences in the mean midlatitude westerly flow and in the positioning and strength of the western Pacific subtropical high during different periods are the key factors in explaining the difference in the propagation speed and the eastward extent of this dominant diurnal precipitation cycle.
Podcasting and Political Life
Authors: MacDougall Robert C.
Published: May 2011

In this article, the author considers “podcasting” in relation to the work of McLuhan and other medium theorists. He then looks at the growing popularity of this new media form as another possible manifestation of Walter Ong’s secondary orality. In the tradition of the town crier, the beat poet, the DJ, and most recently, the blogger, podcasting recasts the personal experience (the “phenomenological feel”) as well as the actual perspectives and preferences accessible to people on the fly via digital storage and playback of audio content. Podcasting certainly seems to blur notions of “public” and “private” in unprecedented ways, and a recent concept dubbed “publicy” (privacy that occurs under the intense acceleration of instantaneous communications) accounts for this. Although the podcast may be the latest and perhaps purest form of publicy, is publicy itself really anything new, or is it just a new form of orality (i.e., secondary orality) that recasts all as witness-participants to the chants and decrees of the iconoclast, village elder, and cultural mystic? The author argues that podcast consumption, itself the product of complex cognitive and cultural processes, is consequential to its reconfigurations of everyday experiences and the personal and political significances bound up in them.
Comparative studies of the morphological and thermal properties of clay/polymer nanocomposites synthesized via melt blending and modified solution blending methods
Authors: Dlamini D.S. , Mishra S.B. , Mishra A.K. , Mamba B.B.
Published: May 2011

In this study, EVA/clay nanocomposites were prepared by two different methodologies i.e. melt blend technique and solution blend technique. Comparative analyzes of morphological and thermal properties of the nanocomposites fabricated by two different methods were done. The modified solution method was found to be an efficient method to obtain nanocomposite strips with uniform dispersion of the clay at organoclay loading of 8% and crystallinity by extrusion. The melt blending method produced nanocomposites with high porosity, intercalation, and thermal stability, whereas solution blending technique resulted in composites with more intercalated-exfoliated morphology, and less porosity and thermal stability.
Ultrasonic curing of one-part epoxy system
Authors: Sharma Suraj , Luzinov Igor
Published: May 2011

Ultrasonic curing of one-part epoxy system was studied using differential scanning calorimetry (DSC) analysis. During both isothermal oven curing and ultrasonic curing of this system, an induction period was observed. For the rapid progression of polymerization reaction in ultrasonic curing, a preheating temperature of 100°C was found to be sufficient. However, degree of curing due to the nonthermal effect of ultrasonic curing was found to be maximal at a preheating temperature of 80°C. It was noticed that the ultrasonic curing reduced the time of curing by a factor of four, and the curing level from pure thermal effects could be determined by incorporating the curing temperature history into the autocatalytic chemical model. The degree of curing from the experimental results of isothermal heating in DSC and the one predicted by the autocatalytic chemical model exhibited a good agreement.
Language Effects on Children’s Nonverbal Number Line Estimations
Authors: Helmreich Iris , Zuber Julia , Pixner Silvia , Kaufmann Liane , Nuerk Hans-Christoph , Moeller Korbinian
Published: May 2011

The mental number line of children is usually assumed to be language-independent; however, this independency has not yet been studied. In this cross-cultural study, we examined the influence of language properties on a nonverbal version of the number line task in Italian- and German-speaking first graders. The essential difference between the two languages concerns the inversion property of most German multi-digit numbers (e.g., 48 → “eight-and-forty”), whereas in Italian number-words no inversion is found. The analyses revealed two language-specific differences in the number line task: (a) Generally, the estimates of Italian children were more accurate than those of Austrian children, even when controlling for general cognitive abilities. (b) Italian children performed particularly better when inversion errors led to large estimation errors. In conclusion, these findings indicate that the organization of children’s mental number line is indeed influenced by language properties even in nonverbal settings.
Manufacturing techniques and electrical properties of conductive fabrics with recycled polypropylene nonwoven selvage
Authors: Ching Wen Lou  , Lin Chin-Mei , Hsing Wen-Hao , Chen An-Pang , Lin Jia-Horng
Published: May 2011

In this research, an original rotor twister machine, with a speed of 8000 rpm, spun complex ply yarns from recycled polypropylene nonwoven selvage (PPNS) and various metal wires. The core yarn was pieces of 30 g/m2 recycled PPNS and the wrap yarns were 80 μm stainless steel wires. Furthermore, 80 μm stainless steel wires and 80 μm copper wires, parallel to the core yarns, reinforced the complex ply yarns. Yarns were manufactured with wrap numbers of 0.5, 1.5, 2.5, 3.5, and 4.5 turns/cm. Complex fabrics were woven with the complex ply yarns as the weft yarns and PVC-coated PET filaments as the warp yarns. These fabrics were evaluated for surface resistivity and electromagnetic shielding effectiveness (EMSE). The presence of copper reinforcement wires was found to lower the surface resistivity of the fabrics. The lowest surface resistivity was recorded for a fabric woven from yarns with a wrap number of 4.5 turns/cm; that surface resistivity was 28.7 Ω/sq. EMSE measurements showed that fabrics with varied lamination angles provided good electromagnetic shielding. The optimum EMSE measured in this research was 56.1 dB on incident frequency as 2.36 GHz, for a fabric with 0°/90°/0°/90°/0°/90° lamination angles.
Happy People or Happy Places? A Multilevel Modeling Approach to the Analysis of Happiness and Well-Being
Authors: Ballas Dimitris , Tranmer Mark
Published: May 2011

This article aims to add a regional science perspective and a geographical dimension to our understanding of substantive questions regarding self-reported happiness and well-being through the specification and use of multilevel models. Multilevel models are used with data from the British Household Panel Survey and the Census of UK population to assess the nature and extent of variations in happiness and well-being to determine the relative importance of the area (district, region), household, and individual characteristics on these outcomes. Having taken into account the characteristics at these different levels, we are able to determine whether any areas are associated with especially positive or negative feelings of happiness and well-being. Whilst we find that most of the variation in happiness and well-being is attributable to the individual level, some variation in these measures is also found at the household and area levels, especially for the measure of well-being, before we control for the full set of individual, household, and area characteristics. However, once we control for these characteristics, the variation in happiness and well-being is not found to be statistically significant between areas.
Robotic‐Assisted Parathyroidectomy
Authors: Tolley Neil , Arora Asit , Palazzo Fausto , Garas George , Dhawan Ranju , Cox Jeremy , Darzi Ara
Published: May 2011

Objective

Targeted parathyroidectomy is the gold standard for localized parathyroid disease. A robotic‐assisted approach has not been investigated. The aim was to assess the feasibility of a robotic technique that avoids a neck scar.

Study Design

Feasibility study.

Setting

Tertiary referral center.

Subjects and Methods

Eleven patients with primary hyperparathyroidism were prospectively evaluated. Triple modality concordant localization was a prerequisite. All patients underwent robotic‐assisted parathyroidectomy (RAP). Outcome variables assessed were operative time, voice change, biochemical cure, and histopathological confirmation. Patient‐reported outcome measures (PROMs) included subjective assessment of pain and scar cosmesis, Voice Handicap Index 2, and EQ‐5D quality‐of‐life assessment. Mean follow‐up was 6 months (range, 3‐12 months).

Results

The parathyroid adenoma was successfully excised in all cases with negligible blood loss (<5 mL). There was 1 conversion. There was no voice change in any case. Robot docking time plateaued to 10 minutes after 8 cases. Mean exposure and console times (31 and 51 minutes, respectively) were affected by body habitus. The mean visual analog scale for scar cosmesis was 75% on the first postoperative day, improving to 92% at 6 months and 95% at 1 year. Pain scores decreased to 8% at 2 weeks. All 5 EQ‐5D quality‐of‐life parameters significantly improved following surgery.

Conclusion

The robotic approach is feasible for performing targeted parathyroidectomy that avoids a neck scar. The clinical efficacy and cost‐effectiveness of the robotic approach compared with conventional targeted parathyroidectomy warrant further evaluation to establish if this represents a viable alternative to the existing targeted techniques.
Feasibility study of a randomized controlled trial protocol to examine clinical effectiveness of shoulder strapping in acute stroke patients
Authors: Appel Caroline , Mayston Margaret , Perry Lin
Published: May 2011

Objective: The majority of stroke patients experience upper limb motor impairment and reduced ability to perform basic activities. Shoulder strapping has been reported as a beneficial adjunct to rehabilitation therapies but has not been rigorously trialled. This study tested the feasibility of recruitment, intervention and outcome assessment protocols for future trial of the clinical effectiveness of shoulder strapping.

Design and setting: Feasibility study using a randomized controlled trial in an East London stroke service.

Subjects: Fourteen acute stroke patients with mild to moderate upper limb hemiparesis were recruited between October 2004 and July 2005.

Intervention: Five strapping methods and criteria for use were identified from the literature. Shoulder strapping applied for one month in addition to routine rehabilitation was compared to routine rehabilitation only.

Main measures: The Motor Assessment Scale, Fugl Meyer Scale – Arm section and the Nine Hole Peg Test were measured at baseline and 1, 2, 3 and 5 weeks later. The Stroke-specific Quality of Life questionnaire was delivered at 6 and 12 weeks post stroke.

Results: Useful findings were demonstrated in relation to the feasibility of all elements of the protocol. Motor Assessment Scale findings showed a small-moderate (0.27) effect size for the strapping intervention used as an adjunct to routine rehabilitation compared to routine rehabilitation alone. Sample size calculation indicated 312 participants would be adequate to test a null hypothesis of nil benefit additional to routine rehabilitation.

Conclusion: Findings supported the value of pilot-testing, and enabled revision of the study protocol for future definitive trial.
Shangri-La
Authors: Llamas Rosa , Belk Russell
Published: May 2011

Lost Horizon (Hilton) is a captivating novel about a remote idyllic place called Shangri-La, located somewhere in the mountains of Tibet. This fabled place is a wonderland where man and nature coexist in harmony as do several ethnic groups. It is a land of eternally young inhabitants blessed with magnificent landscapes shrouded in mysticism. The fantasy of this mythical place has fueled a search that has yielded many Shangri-Las in the Himalayas, each attempting to fulfill Hilton’s vision. Nevertheless, only one of them, the county of Zhongdian in China’s Yunnan Province, has been granted the use of Shangri-La brand name by the People’s Republic of China (PRC) State Council. In the present study, the researchers find that the reshaping of Zhongdian into the enchanted land of Shangri-La relies upon processes of sacralization, ethnitization, and exoticization. This research explores the construction and marketization of this mythical creation and its cultural, economic, social, and environmental consequences. This analysis also distinguishes the contrasting aims of Han Chinese and Western tourists when traveling to this encapsulated paradise.
Association of Porcine Circovirus Type 2 With Vascular Lesions in Porcine Pneumonia
Authors: Szeredi L. , Dán Á. , Solymosi N. , Cságola A. , Tuboly T.
Published: May 2011

The aim of this study was to evaluate the vasculature in porcine circovirus type 2–infected (PCV2-infected) lungs and to identify the PCV2 subtypes involved in porcine pneumonia. Pulmonary samples from 140 pigs, 2 weeks to 7 months of age, from 36 Hungarian commercial herds with clinical signs of respiratory disease were examined for the presence of respiratory pathogens, with bacterial culture, pathologic evaluation, and immunohistochemistry for PCV2, porcine reproductive respiratory syndrome virus, and swine influenza virus. PCV2 was the most commonly identified pathogen (49 cases) among the 74 of 140 cases (53%) with respiratory pathogens. PCV2 was detected immunohistochemically in the wall of 13% to 100% of pulmonary vessels (mean, 89%) in 38 of 49 cases (78%). Detection of PCV2 antigen was positively correlated with the presence of vascular lesions ( P < .001, odds ratio [OR]: 159.54). Other pathogens capable of vascular injury in swine were found in 29 of 49 of the PCV2-positive cases (59%). The probability of detecting vascular lesions in PCV2-infected lung was higher than in infection with porcine reproductive respiratory syndrome virus ( P < .002, OR: 14.63), Pasteurella multocida infection ( P < .001, OR: 5.75), or Streptococcus spp. infection (not significant, OR: 1.45). Sequence analysis of open reading frame 2 amplicons was possible in 6 PCV2-positive cases, from which 5 cases proved to be PCV2b subtype and 1 case, PCV2a subtype. In conclusion, PCV2 antigen was commonly colocalized with pulmonary vascular lesions in pneumonia in Hungarian swine, and PCV2b was the dominant subtype.
Impact of Anticoagulation on the Short-Term Outcome in a Population of Neonates With Cerebral Sinovenous Thrombosis: A Retrospective Study
Authors: Pergami Paola , Abraham Lisa
Published: May 2011

To investigate the impact of anticoagulation on short-term outcome (1 month) in neonates with cerebral sinovenous thrombosis, the authors conducted a retrospective chart review of neonates admitted to 2 tertiary hospitals over a 5- and 8-year period, respectively. Neonates with confirmed radiographic evidence of cerebral sinovenous thrombosis were included. Eighteen total patients treated with hydration only were identified. Approximately 50% of these neonates showed clot extension or other complications on follow-up imaging that were obtained within 72 hours with either magnetic resonance imaging or computed topography. Five neonates were treated with anticoagulation, and none of these patients developed new infarcts or hemorrhages. The results of this retrospective study suggest that anticoagulation is safe in neonates with cerebral sinovenous thrombosis. Early follow-up scans can help treatment decision. Larger studies are needed to develop standardized guidelines for the evaluation and treatment of neonatal cerebral sinovenous thrombosis.