bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Volcanic Eruptions on the Vertical Temperature Profile in Radiosonde Data and Climate Models
Authors: Free Melissa , Lanzante John
Published: January 2009

Both observed and modeled upper-air temperature profiles show the tropospheric cooling and tropical stratospheric warming effects from the three major volcanic eruptions since 1960. Detailed comparisons of vertical profiles of Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC) and Hadley Centre Atmospheric Temperatures, version 2 (HadAT2), radiosonde temperatures with output from six coupled GCMs show good overall agreement on the responses to the 1991 Mount Pinatubo and 1982 El Chichón eruptions in the troposphere and stratosphere, with a tendency of the models to underestimate the upper-tropospheric cooling and overestimate the stratospheric warming relative to observations. The cooling effect at the surface in the tropics is amplified with altitude in the troposphere in both observations and models, but this amplification is greater for the observations than for the models. Models and observations show a large disagreement around 100 mb for Mount Pinatubo in the tropics, where observations show essentially no change, while models show significant warming of ∼0.7 to ∼2.6 K. This difference occurs even in models that accurately simulate stratospheric warming at 50 mb. Overall, the Parallel Climate Model is an outlier in that it simulates more volcanic-induced stratospheric warming than both the other models and the observations in most cases.

From 1979 to 1999 in the tropics, RATPAC shows a trend of less than 0.1 K decade−1 at and above 300 mb before volcanic effects are removed, while the mean of the models used here has a trend of more than 0.3 K decade−1, giving a difference of ∼0.2 K decade−1. At 300 mb, from 0.02 to 0.10 K decade−1 of this difference may be due to the influence of volcanic eruptions, with the smaller estimate appearing more likely than the larger. No more than ∼0.03 K of the ∼0.1-K difference in trends between the surface and troposphere at 700 mb or below in the radiosonde data appears to be due to volcanic effects.
Examination of Relationships between Clear-Sky Longwave Radiation and Aspects of the Atmospheric Hydrological Cycle in Climate Models, Reanalyses, and Observations
Authors: Allan Richard P.
Published: January 2009

Relationships between clear-sky longwave radiation and aspects of the atmospheric hydrological cycle are quantified in models, reanalyses, and observations over the period 1980–2000. The robust sensitivity of clear-sky surface net longwave radiation (SNLc) to column-integrated water vapor (CWV) of 1–1.5 W m−2 mm−1 combined with the positive relationship between CWV and surface temperature (Ts) explains substantial increases in clear-sky longwave radiative cooling of the atmosphere (QLWc) to the surface over the period. Clear-sky outgoing longwave radiation (OLRc) is highly sensitive to changes in aerosol and greenhouse gas concentrations in addition to temperature and humidity. Over tropical ocean regions of mean descent, QLWc increases with Ts at ∼3.5–5.5 W m−2 K−1 for reanalyses, estimates derived from satellite data, and models without volcanic forcing included. Increased QLWc with warming across the tropical oceans helps to explain model ensemble mean increases in precipitation of 0.1–0.15 mm day−1 K−1, which are primarily determined by ascent regions where precipitation increases at the rate expected from the Clausius–Clapeyron equation. The implications for future projections in the atmospheric hydrological cycle are discussed.
Analysis of Spurious Surface Temperature at the Atmosphere–Land Interface and a New Method to Solve the Surface Energy Balance Equation
Authors: Tomita Hirofumi
Published: January 2009

Solving the surface energy balance equation is the most important task when combining an atmospheric model and a land surface model. However, while the surface energy balance equation determines the interface temperature between the models, this temperature is often oscillatory and without physical significance. This paper discusses the spurious mode of surface temperature. The energy balance equation is solved by the linearization around the surface temperature in most models. When this conventional scheme is used, oscillation of surface temperature occurs, caused by the exclusion or poor consideration of the surface temperature dependence of the turbulent transfer coefficient at the surface. By more strictly solving the surface energy balance equation, no spurious mode appears. However, it is often difficult to obtain such a solution because the equation is highly nonlinear. Indeed, the Newton–Raphson method at times cannot find the convergence solution. To overcome this difficulty, a new method based on a modified Newton–Raphson method is proposed to solve the surface energy balance equation. As confirmed by conducting a long-term climate simulation, the new method can robustly obtain the true solution with reasonable computational efficiency.
On the Mechanisms of Episodic Salinity Outflow Events in the Strait of Hormuz
Authors: Thoppil Prasad G. , Hogan Patrick J.
Published: January 2009

Observations in the Strait of Hormuz (26.26°N, 56.08°E) during 1997–98 showed substantial velocity fluctuations, accompanied by episodic changes in the salinity outflow events with amplitude varying between 1 and 2 psu on time scales of several days to a few weeks. These events are characterized by a rapid increase in salinity followed by an abrupt decline. The mechanisms behind these strong pulses of salinity events are investigated with a high-resolution (∼1 km) Hybrid Coordinate Ocean Model (HYCOM) with particular reference to the year 2005. In accordance with the observations, the simulated salinity events are characterized by strong coherence between the enhanced flows in zonal and meridional directions. It is inferred that most of the simulated and observed outflow variability is associated with the continuous formation of strong mesoscale cyclonic eddies, whose origin can be traced upstream to around 26°N, 55.5°E. These cyclonic eddies have a diameter of about 63 km and have a remnant of Persian Gulf water (PGW) in their cores, which is eroded by lateral mixing as the eddies propagate downstream at a translation speed of 4.1 cm s−1. The primary process that acts to generate mesoscale cyclones results from the barotropic instability of the exchange circulation through the Strait of Hormuz induced by fluctuations in the wind stress forcing. The lack of salinity events and cyclogenesis in a model experiment with no wind stress forcing further confirms the essential ingredients required for the development of strong cyclones and the associated outflow variability.
Coastal Wind-Driven Circulation in the Vicinity of a Bank. Part I: Modeling Flow over Idealized Symmetric Banks
Authors: Whitney Michael M. , Allen J. S.
Published: January 2009

This study examines how coastal banks influence wind-driven circulation along stratified continental shelves. Numerical experiments are conducted for idealized symmetric banks; the standard bank (200 km long and 50 km wide) has dimensions similar to the Heceta Bank complex along the Oregon shelf. Model runs are forced with 10 days of steady winds (0.1 Pa); upwelling and downwelling cases are compared. The bank introduces significant alongshelf variability in the currents and density fields. Upwelling-favorable winds create an upwelling front and a baroclinic jet (flowing opposite coastal-trapped wave propagation) that bend around the standard bank, approximately centered on the 90-m isobath. The upwelling jet is strongest over the upstream bank half, where it advects a tongue of dense water over the bank. There is a current reversal shoreward of the main jet at the bank center. Upwelling is most intense over the upstream part of the bank, while there is reduced upwelling and even downwelling over other bank sections. Downwelling-favorable winds create a near-bottom density front and a baroclinic jet (flowing in the direction of coastal-trapped wave propagation) that bend around the standard bank; the jet core moves from the 150-m isobath to the 100-m isobath and back over the bank. The downwelling jet is slowest and widest over the bank; there are no current reversals. Results over the bank are more similar to 2D results (that preclude alongshelf variability) than in the upwelling case. Downwelling is weakened over the bank. The density field evolution over the bank is fundamentally different from the upwelling case. Most model results for banks with different dimensions are qualitatively similar to the standard run. The exceptions are banks having a radius of curvature smaller than the inertial radius; the main jet remains detached from the coast far downstream from these banks. The lowest-order across-stream momentum balance indicates that the depth-averaged flow is geostrophic. Advection, ageostrophic pressure gradients, wind stress, and bottom stress are all important in the depth-averaged alongstream momentum balance over the bank. There is considerable variability in alongstream momentum balances over different bank sections. Across-shelf and alongshelf advection both change the density field over the bank. Barotropic potential vorticity is not conserved, but the tendency for relative vorticity changes and depth changes to partially counter each other results in differences between the upwelling and downwelling jet paths over the bank. Only certain areas of the bank have significant vertical velocities. In these areas of active upwelling and downwelling, vertical velocities at the top of the bottom boundary layer are due to either the jet crossing isobaths or bottom Ekman pumping.
Laboratory Experiments on the Interaction of a Buoyant Coastal Current with a Canyon: Application to the East Greenland Current
Authors: Sutherland David A. , Cenedese Claudia
Published: January 2009

This paper presents a set of laboratory experiments focused on how a buoyant coastal current flowing over a sloping bottom interacts with a canyon and what controls the separation, if any, of the current from the upstream canyon bend. The results show that the separation of a buoyant coastal current depends on the current width W relative to the radius of curvature of the bathymetry ρc. The flow moved across the mouth of the canyon (i.e., separated) for W/ρc > 1, in agreement with previous results. The present study extends previous work by examining both slope-controlled and surface-trapped currents, and using a geometry specific to investigating buoyant current–canyon interaction. The authors find that, although bottom friction is important in setting the position of the buoyant front, the separation process driven by the inertia of the flow could overcome even the strongest bathymetric influence. Application of the laboratory results to the East Greenland Current (EGC), an Arctic-origin buoyant current that is observed to flow in two branches south of Denmark Strait, suggests that the path of the EGC is influenced by the large canyons cutting across the shelf, as the range of W/ρc in the ocean spans those observed in the laboratory. What causes the formation of a two-branched EGC structure downstream of the Kangerdlugssuaq Canyon (∼68°N, 32°W) is still unclear, but potential mechanisms are discussed.
Why Were Sea Surface Temperatures so Different in the Eastern Equatorial Atlantic in June 2005 and 2006?
Authors: Marin Frédéric , Caniaux Guy , Giordani Hervé , Bourlès Bernard , Gouriou Yves , Key Erica
Published: January 2009

A comparison of June 2005 and June 2006 sea surface temperatures in the eastern equatorial Atlantic exhibits large variability in the properties of the equatorial cold tongue, with far colder temperatures in 2005 than in 2006. This difference is found to result mainly from a time shift in the development of the cold tongue between the two years. Easterlies were observed to be stronger in the western tropical Atlantic in April–May 2005 than in April–May 2006, and these winds favorably preconditioned oceanic subsurface conditions in the eastern Atlantic. However, it is also shown that a stronger than usual intraseasonal intensification of the southeastern trades was responsible for the rapid and early intense cooling of the sea surface temperatures in mid-May 2005 over a broad region extending from 20°W to the African coast and from 6°S to the equator. This particular event underscores the ability of local intraseasonal wind stress variability in the Gulf of Guinea to initiate the cold tongue season and thus to dramatically impact the SST in the eastern equatorial Atlantic. Such intraseasonal wind intensifications are of potential importance for year-to-year variability in the onset of the African monsoon.
Observations of Turbulence in the Ocean Surface Boundary Layer: Energetics and Transport
Authors: Gerbi Gregory P. , Trowbridge John H. , Terray Eugene A. , Plueddemann Albert J. , Kukulka Tobias
Published: January 2009

Observations of turbulent kinetic energy (TKE) dynamics in the ocean surface boundary layer are presented here and compared with results from previous observational, numerical, and analytic studies. As in previous studies, the dissipation rate of TKE is found to be higher in the wavy ocean surface boundary layer than it would be in a flow past a rigid boundary with similar stress and buoyancy forcing. Estimates of the terms in the turbulent kinetic energy equation indicate that, unlike in a flow past a rigid boundary, the dissipation rates cannot be balanced by local production terms, suggesting that the transport of TKE is important in the ocean surface boundary layer. A simple analytic model containing parameterizations of production, dissipation, and transport reproduces key features of the vertical profile of TKE, including enhancement near the surface. The effective turbulent diffusion coefficient for heat is larger than would be expected in a rigid-boundary boundary layer. This diffusion coefficient is predicted reasonably well by a model that contains the effects of shear production, buoyancy forcing, and transport of TKE (thought to be related to wave breaking). Neglect of buoyancy forcing or wave breaking in the parameterization results in poor predictions of turbulent diffusivity. Langmuir turbulence was detected concurrently with a fraction of the turbulence quantities reported here, but these times did not stand out as having significant differences from observations when Langmuir turbulence was not detected.
Modeling the Pathways and Mean Dynamics of River Plume Dispersal in the New York Bight
Authors: Zhang Weifeng G. , Wilkin John L. , Chant Robert J.
Published: January 2009

This study investigates the dispersal of the Hudson River outflow across the New York Bight and the adjacent inner- through midshelf region. Regional Ocean Modeling System (ROMS) simulations were used to examine the mean momentum dynamics; the freshwater dispersal pathways relevant to local biogeochemical processes; and the contribution from wind, remotely forced along-shelf current, tides, and the topographic control of the Hudson River shelf valley. The modeled surface currents showed many similarities to the surface currents measured by high-frequency radar [the Coastal Ocean Dynamics Applications Radar (CODAR)]. Analysis shows that geostrophic balance and Ekman transport dominate the mean surface momentum balance, with most of the geostrophic flow resulting from the large-scale shelf circulation and the rest being locally generated. Subsurface circulation is driven principally by the remotely forced along-shelf current, with the exception of a riverward water intrusion in the Hudson River shelf valley. The following three pathways by which freshwater is dispersed across the shelf were identified: (i) along the New Jersey coast, (ii) along the Long Island coast, and (iii) by a midshelf offshore pathway. Time series of the depth-integrated freshwater transport show strong seasonality in dispersal patterns: the New Jersey pathway dominates the winter–spring seasons when winds are downwelling favorable, while the midshelf pathway dominates summer months when winds are upwelling favorable. A series of reduced physics simulations identifies that wind is the major force for the spreading of freshwater to the mid- and outer shelf, that remotely forced along-shelf currents significantly influence the ultimate fate of the freshwater, and that the Hudson River shelf valley has a modest dynamic effect on the freshwater spreading.
A Combined Wind Profiler and Polarimetric Weather Radar Method for the Investigation of Precipitation and Vertical Velocities
Authors: Teshiba Michihiro S. , Chilson Phillip B. , Ryzhkov Alexander V. , Schuur Terry J. , Palmer Robert D.
Published: January 2009

A method is presented by which combined S-band polarimetric weather radar and UHF wind profiler observations of precipitation can be used to extract the properties of liquid phase hydrometeors and the vertical velocity of the air through which they are falling. Doppler spectra, which contain the air motion and/or fall speed of hydrometeors, are estimated using the vertically pointing wind profiler. Complementary to these observations, spectra of rain drop size distribution (DSD) are simulated by several parameters as related to the DSD, which are estimated through the two polarimetric parameters of radar reflectivity (ZH) and differential reflectivity (ZDR) from the scanning weather radar. These DSDs are then mapped into equivalent Doppler spectra (fall speeds) using an assumed relationship between the equivolume drop diameter and the drop’s terminal velocity. The method is applied to a set of observations collected on 11 March 2007 in central Oklahoma. In areas of stratiform precipitation, where the vertical wind motion is expected to be small, it was found that the fall speeds obtained from the spectra of the rain DSD agree well with those of the Doppler velocity estimated with the profiler. For those cases when the shapes of the Doppler spectra are found to be similar in shape but shifted in velocity, the velocity offset is attributed to vertical air motion. In convective rainfall, the Doppler spectra of the rain DSD and the Doppler velocity can exhibit significant differences owing to vertical air motions together with atmospheric turbulence. Overall, it was found that the height dependencies of Doppler spectra measured by the profiler combined with vertical profiles of Z, ZDR, and the cross correlation (ρHV) as well as the estimated spectra of raindrop physical terminal fall speeds from the polarimetric radar provide unique insight into the microphysics of precipitation. Vertical air motions (updrafts/downdrafts) can be estimated using such combined measurements.
The Retrieval of Profiles of Particulate Extinction from Cloud-Aerosol Lidar Infrared Pathfinder Satellite Observations (CALIPSO) Data: Algorithm Description
Authors: Young Stuart A. , Vaughan Mark A.
Published: January 2009

This work describes the algorithms used for the fully automated retrieval of profiles of particulate extinction coefficients from the attenuated backscatter data acquired by the lidar on board the Cloud-Aerosol Lidar Infrared Pathfinder Satellite Observations (CALIPSO) spacecraft. The close interaction of the Hybrid Extinction Retrieval Algorithms (HERA) with the preceding processes that detect and classify atmospheric features (i.e., cloud and aerosol layers) is described within the context of the analysis of measurements from scenes of varying complexity. Two main components compose HERA: a top-level algorithm that selects the analysis pathway, the order of processing, and the analysis parameters, depending on the nature and spatial extent of the atmospheric features to be processed; and a profile solver or “extinction engine,” whose task it is to retrieve profiles of particulate extinction and backscatter coefficients from specified sections of an atmospheric scene defined by the top-level algorithm. The operation of these components is described using synthetic data derived from Lidar In Space Technology Experiment (LITE) measurements. The performance of the algorithms is illustrated using CALIPSO measurements acquired during the mission on 1 January 2007.
Validation of Two-Dimensional Variational Ambiguity Removal on SeaWinds Scatterometer Data
Authors: Vogelzang Jur , Stoffelen Ad , Verhoef Anton , de Vries John , Bonekamp Hans
Published: January 2009

A two-dimensional variational ambiguity removal technique (2DVAR) is presented. It first makes an analysis based on the ambiguous scatterometer wind vector solutions and a model forecast, and next selects the ambiguity closest to the analysis as solution. 2DVAR is applied on SeaWinds scatterometer data and its merits for nowcasting applications are shown in a general statistical comparison with model forecasts and buoy observations, and in a number of case studies. The sensitivity of 2DVAR to changes in the parameters of its underlying error model is studied. It is shown that observational noise in the nadir swath of SeaWinds is effectively suppressed by application of 2DVAR in combination with the multisolution scheme (MSS). MSS retains the local wind vector probability density function after inversion, rather than only a limited number of ambiguous solutions. As a consequence, the influence of the background increases, but this can be mitigated by switching off variational quality control. A case study on an extratropical cyclone of hurricane force intensity observed with SeaWinds at 25-km resolution shows that reliable wind estimates can be obtained for wind speeds up to 40 m s−1 and more. At 25 km, the results of 2DVAR with MSS compare better with buoy measurements than with the ECMWF model. At 100-km resolution this is reversed, proving that 2DVAR retrieves small-scale features absent in the ECMWF model.
Observational Analysis of Heavy Rainfall Mechanisms Associated with Severe Tropical Storm Bilis (2006) after Its Landfall
Authors: Gao Shuanzhu , Meng Zhiyong , Zhang Fuqing , Bosart Lance F.
Published: January 2009

This observational study attempts to determine factors responsible for the distribution of precipitation over large areas of southern China induced by Bilis, a western North Pacific Ocean severe tropical storm that made landfall on the southeastern coast of mainland China on 14 July 2006 with a remnant circulation that persisted over land until after 17 July 2006. The heavy rainfalls associated with Bilis during and after its landfall can be divided into three stages. The first stage of the rainfall, which occurred in Fujian and Zhejiang Provinces, could be directly induced by the inner-core storm circulation during its landfall. The third stage of rainfall, which occurred along the coastal areas of Guangdong and Fujian Provinces, likely resulted from the interaction between Bilis and the South China Sea monsoon enhanced by topographical lifting along the coast. The second stage of the rainfall, which appeared inland around the border regions between Jiangxi, Hunan, and Guangdong Provinces, caused the most catastrophic flooding and is the primary focus of the current study. It is found that during the second stage of the rainfall all three ingredients of deep moist convection (moisture, instability, and lifting) are in place. Several mechanisms, including vertical wind shear, warm-air advection, frontogenesis, and topography, may have contributed simultaneously to the lifting necessary for the generation of the heavy rainfall at this stage.
A New Way to Improve Seasonal Prediction by Diagnosing and Correcting the Intermodel Systematic Errors
Authors: Ke Zongjian , Zhang Peiqun , Dong Wenjie , Li Laurent
Published: January 2009

Seasonal climate prediction, in general, can achieve excellent results with a multimodel system. A relevant calibration of individual models and an optimal combination of individual models are the key elements leading to this success. However, this commonly used approach appears to be insufficient to remove the intermodel systematic errors (IMSE), which represent similar error properties in individual models after their calibration. A new postprocessing method is proposed to correct the IMSE and to increase the prediction skill. The first step consists of carrying out a diagnosis on the calibrated errors before constructing the multimodel ensemble. In contrast to previous studies, the calibrated errors here are treated directly as the investigation target, and temporal correlation coefficients between the calibrated errors and other meteorological variables are calculated. In the second stage, mathematical and statistical tools are applied in an effort to forecast the IMSE in individual models. Then, the IMSE are removed from the calibrated results and the new corrected data are used to construct the multimodel ensemble. The hindcast of the European Union–funded Development of a European Multimodel Ensemble System for Seasonal-to-Interannual Prediction (DEMETER) multimodel system is used to test the method. The simulated Southern Oscillation index is used to diagnose and to correct the calibrated errors of the simulated precipitation. The prediction qualities of the corrected data are assessed and compared with those of the uncorrected dataset. The results show that it is feasible to improve seasonal precipitation prediction by forecasting and correcting the IMSE. This improvement is visible not only for the individual models, but also for the multimodel ensemble.
Statistical Downscaling of Precipitation in Korea Using Multimodel Output Variables as Predictors
Authors: Kang Hongwen , Park Chung-Kyu , Hameed Saji N. , Ashok Karumuri
Published: January 2009

A pattern projection downscaling method is applied to predict summer precipitation at 60 stations over Korea. The predictors are multiple variables from the output of six operational dynamical models. The hindcast datasets span a period of 21 yr from 1983 to 2003. A downscaled prediction was made for each model separately within a leave-one-out cross-validation framework. The pattern projection method uses a moving window, which scans globally, in order to seek the most optimal predictor for each station. The final forecast is the average of six model downscaled precipitation forecasts using the best predictors and will be referred to as “DMME.” It is found that DMME significantly improves the prediction skill by correcting the erroneous signs of the rainfall anomalies in coarse-resolution predictions of general circulation models. Although Korea’s precipitation is strongly influenced by local mountainous terrain, DMME performs well at 59 stations with correlation skill significant at the 95% confidence level. The improvement of the prediction skill is attributed to three steps: coupled pattern selection, optimal predictor selection, and the multimodel downscaled precipitation ensemble. This study indicates that the large-scale circulation variables, which are predicted by the current operational dynamical models, if selected, can be used to make skillful predictions of the local precipitation by using appropriate statistical downscaling methods.
Climatology of Severe Hail in Finland: 1930–2006
Authors: Tuovinen Jari-Petteri , Punkka Ari-Juhani , Rauhala Jenni , Hohti Harri , Schultz David M.
Published: January 2009

A climatology of severe hail (2 cm in diameter or larger) in Finland was constructed by collecting newspaper, storm-spotter, and eyewitness reports. The climatology covered the warm season (1 May–14 September) during the 77-yr period of 1930–2006. Altogether, 240 severe-hail cases were found. The maximum reported severe-hail size was mainly 4 cm in diameter or less (65% of the cases), with the number of cases decreasing as hail size increased. In a few extreme cases, 7–8-cm (baseball sized) hailstones have been reported in Finland. Most of the severe-hail cases (84%) occurred from late June through early August, with July being the peak month (almost 66% of the cases). Most severe hail fell during the afternoon and early evening hours 1400–2000 local time (LT). Larger hailstones (4 cm or larger) tended to occur a little later (1600–2000 LT) than smaller (2–3.9 cm) hailstones (1400–1800 LT). Most severe-hail cases occurred in southern and western Finland, generally decreasing to the north, with the majority of the cases near population centers. The proportion of severe hail less than 4 cm in diameter is greatest over the agricultural area in southwestern Finland where crop damage caused by severe hail is more likely to be reported. The underreporting of hail is a particular problem across much of Finland because of the vast forest and lake areas, low population density, and relatively small hail swaths. Since the 1990s, a greater interest in severe weather among the general public and media, a storm-spotter network, improved communications technology, and an official Web site for reporting hail have increased the number of reported hail cases. According to the most recent 10 yr (1997–2006), Finland experiences an annual average of 10 severe-hail cases during 5 severe-hail days.
Convection-Permitting Simulations of the Environment Supporting Widespread Turbulence within the Upper-Level Outflow of a Mesoscale Convective System
Authors: Trier Stanley B. , Sharman Robert D.
Published: January 2009

Widespread moderate turbulence was recorded on three specially equipped commercial airline flights over northern Kansas near the northern edge of the extensive cirrus anvil of a nocturnal mesoscale convective system (MCS) on 17 June 2005. A noteworthy aspect of the turbulence was its location several hundred kilometers from the active deep convection (i.e., large reflectivity) regions of the MCS. Herein, the MCS life cycle and the turbulence environment in its upper-level outflow are studied using Rapid Update Cycle (RUC) analyses and cloud-permitting simulations with the Weather Research and Forecast Model (WRF). It is demonstrated that strong vertical shear beneath the MCS outflow jet is critical to providing an environment that could support dynamic (e.g., shearing type) instabilities conducive to turbulence. Comparison of a control simulation to one in which the temperature tendency due to latent heating was eliminated indicates that strong vertical shear and corresponding reductions in the local Richardson number (Ri) to ∼0.25 at the northern edge of the anvil were almost entirely a consequence of the MCS-induced westerly outflow jet. The large vertical shear is found to decrease Ri both directly, and by contributing to reductions in static stability near the northern anvil edge through differential advection of (equivalent) potential temperature gradients, which are in turn influenced by adiabatic cooling associated with the mesoscale updraft located upstream within the anvil. On the south side of the MCS, the vertical shear associated with easterly outflow was significantly offset by environmental westerly shear, which resulted in larger Ri and less widespread model turbulent kinetic energy (TKE) than at the northern anvil edge.
Correcting for Surface Pressure Background Bias in Ensemble-Based Analyses
Authors: Baek Seung-Jong , Szunyogh Istvan , Hunt Brian R. , Ott Edward
Published: January 2009

Model error is the component of the forecast error that is due to the difference between the dynamics of the atmosphere and the dynamics of the numerical prediction model. The systematic, slowly varying part of the model error is called model bias. This paper evaluates three different ensemble-based strategies to account for the surface pressure model bias in the analysis scheme. These strategies are based on modifying the observation operator for the surface pressure observations by the addition of a bias-correction term. One estimates the correction term adaptively, while another uses the hydrostatic balance equation to obtain the correction term. The third strategy combines an adaptively estimated correction term and the hydrostatic-balance-based correction term. Numerical experiments are carried out in an idealized setting, where the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) model is integrated at resolution T62L28 to simulate the evolution of the atmosphere and the T30L7 resolution Simplified Parameterization Primitive Equation Dynamics (SPEEDY) model is used for data assimilation. The results suggest that the adaptive bias-correction term is effective in correcting the bias in the data-rich regions, while the hydrostatic-balance-based approach is effective in data-sparse regions. The adaptive bias-correction approach also has the benefit that it leads to a significant improvement of the temperature and wind analysis at the higher model levels. The best results are obtained when the two bias-correction approaches are combined.
Improved Simulation of the East Asian Summer Monsoon Rainfall with Satellite-Derived Snow Water Equivalent Data*
Authors: Souma Kazuyoshi , Wang Yuqing
Published: January 2009

The effect of Eurasian spring snow amount on the summer monsoon rainfall over East Asia has been studied both observationally and numerically. The results indicate that the Eurasian spring snow amount could be important for seasonal prediction of East Asian summer monsoon (EASM) rainfall. Therefore, accurately initializing snow could be critical to improving seasonal prediction of EASM rainfall by numerical models. An attempt has been made in this study to initialize snow in a regional climate model using snow water equivalent (SWE) data derived from a microwave imager. Results from an ensemble seasonal prediction experiment for the 2005 EASM show that the satellite-derived SWE data can be effectively used to initialize a dynamical seasonal prediction model, which leads to improved seasonal prediction of EASM rainfall. Possible effects of snow anomalies over the Tibetan Plateau on EASM rainfall were also studied through a comparative ensemble simulation in which snow was initialized by spinning up the same model from the previous winter. It is found that the anomalous snow amount over the Tibetan Plateau could lead to cooling of the surface and lower troposphere not only over the Tibetan Plateau but also in the surrounding areas because of the reduced net surface shortwave radiation associated with the high snow albedo. This would result in positive anomalies in geopotential height and weaken the cyclonic monsoon circulation in the lower troposphere in East Asia, causing a rainfall increase in South China but a reduction in the Yangtze River Valley in early summer (May–June). The difference in rainfall in midsummer (July–August) was not significant when compared with that in early summer. The surface heat budget indicates that the reduced net surface shortwave radiation is largely balanced by the reduced surface sensible heat flux.
Weather Regimes and Forecast Errors in the Pacific Northwest
Authors: McMurdie Lynn A. , Casola Joseph H.
Published: January 2009

Despite overall improvements in numerical weather prediction and data assimilation, large short-term forecast errors of sea level pressure and 2-m temperature still occur. This is especially true for the west coast of North America where short-term numerical weather forecasts of surface low pressure systems can have large position and central pressure errors. In this study, forecast errors of sea level pressure and temperature in the Pacific Northwest are related to the shape of the large-scale flow aloft. Applying a hierarchical limited-contour clustering algorithm to historical 500-hPa geopotential height data produces four distinct weather regimes. The Rockies ridge regime, which exhibits a ridge near the axis of the Rocky Mountains and nearly zonal flow across the Pacific, experiences the highest magnitude and frequency of large sea level pressure errors. On the other hand, the coastal ridge regime, which exhibits a ridge aligned with the North American west coast, experiences the highest magnitude and frequency of large 2-m minimum temperature errors.
Voice Range Profiles of Middle School and High School Choral Directors
Authors: Schwartz Sandra M.
Published: January 2009

Vocal demands of teaching are significant, and this challenge is compounded for choral directors who depend on the voice for communicating information or demonstrating music concepts. The purpose of this study is to examine the frequency and intensity of middle and high school choral directors' voices and to compare choral directors' voices with vocally trained and untrained singers and trained healthy and dysphonic voices using a voice range profile. Results indicated that (a) choral directors' vocal intensity range was significantly smaller than both healthy and dysphonic trained voices, (b) choral directors' minimum intensity was significantly higher than healthy and dysphonic trained voices, and (c) vocal frequency ranges of choral directors were reduced as compared with trained and untrained singers and healthy trained voices. The results of this study provide evidence that choral directors are at risk for developing vocal problems. Preservice vocal health training is recommended to reduce voice problems among choral directors.
It's Not How Much; It's How
Authors: Duke Robert A. , Simmons Amy L. , Cash Carla Davis
Published: January 2009

We observed 17 graduate and advanced-undergraduate piano majors practicing a difficult, three-measure keyboard passage from a Shostakovich concerto. Participants' instructions were to practice until they were confident they could play the passage accurately at a prescribed tempo in a retention test session the following day. We analyzed the practice behaviors of each pianist in terms of numeric and nonnumeric descriptors and ranked the pianists according to the overall performance quality of their retention tests. Results indicated no significant relationship between the rankings of pianists' retention test performances and any of the following variables: practice time, number of total practice trials, and number of complete practice trials. There were significant relationships between retention test rankings and the percentage of all performance trials that were performed correctly, r = —.51, the percentage of complete performance trials that were performed correctly, r = —.71, and the number of trials performed incorrectly during practice, r = .48. The results showed that the strategies employed during practice were more determinative of performance quality at retention than was how much or how long the pianists practiced, a finding consistent with the results of related research.
Internal Consistency of Performance Evaluations as a Function of Music Expertise and Excerpt Familiarity
Authors: Kinney Daryl W.
Published: January 2009

The purpose of this study was to examine the effects of music experience and excerpt familiarity on the internal consistency of performance evaluations. Participants included nonmusic majors who had not participated in high school music ensembles, nonmusic majors who had participated in high school music ensembles, music majors, and experts (graduate music majors and music faculty). Participants listened to 45 piano performances of two familiar stimuli and one unfamiliar stimulus and rated each for accuracy and musical expression. Fifteen excerpts were repeated within the presentation of stimuli so that internal consistency could be calculated. Results indicated that both expertise and familiarity significantly affected internal consistency and that these two factors interacted significantly. Internal consistency means reflected linear trends, with more experienced groups demonstrating greater internal consistency for both accuracy and expression evaluations. Greater internal consistency was also evidenced for familiar excerpts, although the effect size associated with this variable was modest. Findings suggest that expertise is a salient influence on the consistency of performance evaluations.
A University—School Music Partnership for Music Education Majors in a Culturally Distinctive Community
Authors: Soto Amanda Christina , Lum Chee-Hoo , Campbell Patricia Shehan
Published: January 2009

University—community collaborations are a fairly recent phenomenon, which has often been manifested through the establishment of university partnerships with schools. This research sought to document the process and outcomes of a university—school collaboration called Music Alive! in the Valley (MAV), a yearlong partnership between 33 university music education students and faculty with an elementary school within a rural location of a western state. MAV was intended to serve a Mexican American migrant community whose children frequently spoke only Spanish at home and to provide occasions for university students of music education to engage in positive social contact via music performances, participation, and training experiences. An ethnographic method was employed by which observations, interviews, and examination of material culture were assembled over the course of the school year, and an assessment was offered of the benefits and challenges in the creation of a music education partnership in distinctive (and remote) cultural communities.
Music Listening Preferences in Early Life
Authors: Ilari Beatriz , Sundara Megha
Published: January 2009

This study investigated infant listening preferences for two versions of an unfamiliar Chinese children's song: unaccompanied (i.e., voice only) and accompanied (i.e., voice and instrumental accompaniment). Three groups of 5-, 8- and 11-month-old infants were tested using the Headturn Preference Procedure. A general linear model analysis of variance was carried out with gender and age as the between-subjects variables and listening time to the two renditions (unaccompanied, accompanied) as the within-subjects variable. Results indicated a clear preference for the unaccompanied version of the song in all age groups.
The Influence of Beginning Instructional Grade on String Student Enrollment, Retention, and Music Performance
Authors: Hartley Linda A. , Porter Ann M.
Published: January 2009

The purpose of this study was to investigate three primary variables concerning the starting grade level of beginning string instruction in public schools: (a) initial enrollment, (b) retention data for both the end of the first year and at the seventh-grade year of instruction, and (c) music performance level in the seventh grade. Secondary variables including schedule of instruction, decision makers, grade-level organization, and private lessons also were examined. Research objectives were developed to provide string teachers with information for use when they consider the grade level of beginning instruction in their school districts. Later starting grades yielded the highest retention rates, when retention data for both the end of the initial year of instruction and the beginning of seventh grade were compared with starting grade level. The starting grade level of instruction did not, however, affect initial enrollment figures or music performance of string ensembles.
The Embeddedness of Academic Online Groups in Offline Social Networks
Authors: Matzat Uwe
Published: January 2009

This article examines the conditions under which members of academic Internet discussion groups (IDGs) are motivated to provide help and answers to colleagues during group discussions on the Internet. It presents a simple microeconomic model that specifies mechanisms by which the embeddedness of IDGs in academic social networks provides incentives for active participation of members during group discussions. According to the reputation model, the sending of public email messages is a means for the researcher to gain reputation in the academic community. Hypotheses of the models are tested with the help of data on the observed communication behaviour of researchers in 49 academic IDGs. The results provide some support for the hypotheses of the model. Most important, they show that the embeddedness of academic IDGs in social networks stimulates the active participation in online discussions. The findings contribute to filling an important gap. They help understand how offline networks influence online communication by showing which characteristics of offline networks have what impact. Conclusions are drawn for the social design of online groups.
The Transnational Social Question
Authors: Faist Thomas
Published: January 2009

In the 19th century, the `social question' was the central subject of extremely volatile political conflicts between the ruling classes and the working-class movements in Europe, North America and Australia. Are we now on the verge of a new social conflict, this time on a transnational scale? This analysis seeks to clarify main concepts and thus set the stage for future empirical research. The main argument is that various factors discourage one from expecting the establishment of sanctionable global social norms in the form of transnational social rights and social citizenship but that such a conclusion could be altered as a result of the mobilizing force of a politics of rights and obligations. The following five issues are thereby examined. First, what are the origins of the debate on transnational social rights? Second, what theoretical concepts are meaningful for an analysis of the transnational social question? Third, how advanced or fragmentary are social rights and citizenship in the different partial worlds? Fourth, how are existing transnational social standards regulated? Finally, what are the implications for an empirical analysis of the politics of social rights and social standards?
`Fundamental Causes' of Health Disparities
Authors: Willson Andrea E.
Published: January 2009

This article examines the relative impact of socioeconomic status as a `fundamental cause' of health disparities in Canada and the US. Fundamental cause theory suggests that persons of higher socioeconomic status have available a broad range of resources to benefit their health and therefore hold an advantage in warding off whatever particular threats to health exist at a given time. This leads to two predictions: (1) SES is more strongly associated with diseases that are more highly preventable than with less preventable diseases; and (2) SES has a stronger relationship to health in the US, where higher economic inequality and a lack of universal health insurance leads to a greater vying for resources. Findings indicate lower levels of SES increase the odds of experiencing a highly preventable disease relative to a less preventable disease in the US, but not in Canada, suggesting that social policies and level of economic inequality may buffer the relationship between socioeconomic resources and the incidence of preventable disease.
Political-Economic Integration, Industrial Pollution and Human Health
Authors: Jorgenson Andrew K.
Published: January 2009

Bridging multiple areas of sociology, the author tests hypotheses derived from foreign investment dependence theory, ecologically unequal exchange theory and world society theory in analyses of industrial organic water pollution in less-developed countries, 1980—2000. Using panel data from a variety of sources, the author proposes three hypotheses: (1) industrial organic water pollution intensity is positively associated with foreign investment in manufacturing; (2) industrial organic water pollution intensity is positively associated with overall export intensity; and (3) industrial organic water pollution intensity is negatively associated with the presence of environmental international non-governmental organizations. Further analyses investigate the impact of organic water pollution on infant mortality rates in less-developed countries. In general, findings for Prais—Winsten regression analyses with panel-corrected standard errors and generalized least squares panel regression analyses of less-developed countries confirm the tested hypotheses, and indicate that industrial organic water pollution intensity does indeed contribute to infant mortality, net of the effects of economic development, fertility rates, health expenditures and other relevant factors.