bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polar Stratospheric Cloud Observations in the 2006/07 Arctic Winter by Using an Improved Micropulse Lidar
Authors: Cordoba-Jabonero Carmen , Gil Manuel , Yela Margarita , Maturilli Marion , Neuber Roland 
Published: June 2009

Abstract
The potential of a new improved version of micropulse lidar (MPL-4) on polar stratospheric cloud (PSC) detection is evaluated in the Arctic over Ny-Ålesund (79°N, 12°E), Norway. The campaign took place from January to February 2007 in the frame of the International Polar Year (IPY) activities. Collocated Alfred Wegener Institute (AWI) Koldewey Aerosol Raman Lidar (KARL) devoted to long-term Arctic PSC monitoring is used for validation purposes. PSC detection is based on lidar retrievals of both backscattering ratio R and volume depolarization ratio δV. Two episodes were unequivocally attributed to PSCs: 21–22 January and 5–6 February 2007, showing a good correlation between MPL-4 and KARL backscattering ratio datasets (mean correlation coefficient = 0.92 ± 0.03). PSC layered structures were characterized for four observational periods coincident with KARL measurements. Also, PSC type classification was determined depending on the retrieved R and δV values as compared with those obtained by KARL long-term Arctic PSC measurements. Tropospheric cloud cover from lidar observations and both ECMWF potential vorticity and temperature at 475 K, in addition to temperature profiles from AWI daily radiosoundings, are also reported. Height-resolved and temporal evolution of both PSC episodes obtained from MPL-4 measurements clearly show that MPL-4 is a suitable instrument to provide long-term PSC statistic monitoring in polar regions. These results are the first reported on PSC detection in the Arctic by using a low-energy and highly pulsed lidar operating on autonomous and full-time continuous mode MPL-4.
Using Dual-Polarized Radar and Dual-Frequency Profiler for DSD Characterization: A Case Study from Darwin, Australia
Authors: Bringi V. N. , Williams C. R. , Thurai M. , May P. T. 
Published: June 2009

Abstract
Comparisons are made between the reflectivity Z, median volume diameter D0, and rain rate R from a dual-frequency profiler and the C-band polarimetric radar (C-POL), which are both located near Darwin, Australia. Examples from the premonsoon “buildup” regime and the monsoon (oceanic) regime are used to illustrate the excellent agreement between the dual-profiler retrievals and the polarimetric radar-based retrievals. This work builds on similar works that were limited in scope to shallow tropical showers and predominantly stratiform rain events. The dual-frequency profiler retrievals of D0 and R herein are based on ensemble statistics, whereas the polarimetric radar retrievals are based on algorithms derived by using one season of disdrometer data from Darwin along with scattering simulations. The latest drop shape versus D relation is used as well as the canting angle distribution results obtained from the 80-m fall bridge experiment in the scattering simulations. The scatterplot of D0 from dual-frequency profiler versus Zdr measurements from C-POL is shown to be consistent not only with the theoretical simulations and prior data but also within prior predicted error bars for both stratiform rain as well as convective rain.
Based on dual-frequency profiler–retrieved gamma drop size distribution parameters, a new smoothly varying “separator” indexing scheme has been developed that classifies between stratiform and convective rain types, including a continuous “transition” region between the two. This indexing technique has been applied on a number of low-elevation-angle plan position indicator (PPI) sweeps with the C-POL from the two regime examples, to construct “unconditioned” histograms of D0 in stratiform and convective rain (to within the sensitivity of the radar). With reference to the latter, it is demonstrated that the distribution of D0 is different in the buildup example than in the monsoon example, because of the differences in both the microphysical and kinematic features between the two regimes. In particular, (i) the mean D0 is significantly larger in the buildup example than in the monsoon example, irrespective of rain type; (ii) the histogram width (or standard deviation) is much larger for the buildup example than the monsoon example, irrespective of rain type; and (iii) the histogram skewness is negative for the monsoon regime example because of a lack of larger D0 values, whereas the buildup histogram is positively skewed irrespective of rain type.
Uncertainties of Estimates of Inertia–Gravity Energy in the Atmosphere. Part I: Intercomparison of Four Analysis Systems
Authors: Žagar N. , Tribbia J. , Anderson J. L. , Raeder K. 
Published: June 2009

Abstract
This paper presents the application of the normal-mode functions to diagnose the atmospheric energy spectra in terms of balanced and inertia–gravity (IG) contributions. A set of three-dimensional orthogonal normal modes is applied to four analysis datasets from July 2007. The datasets are the operational analysis systems of NCEP and ECMWF, the NCEP–NCAR reanalyses, and the Data Assimilation Research Testbed–Community Atmospheric Model (DART–CAM), an ensemble analysis system developed at NCAR. The differences between the datasets can be considered as a measure of uncertainty of the IG contribution to the global energetics.
The results show that the percentage of IG motion in the present NCEP, ECMWF, and DART–CAM analysis systems is between 1% and 2% of the total energy field. In the wave part of the flow (zonal wavenumber k ≠ 0), the IG energy contribution is between 9% and 15%. On the contrary, the NCEP–NCAR reanalyses contain more IG motion, especially in the Southern Hemisphere extratropics. Each analysis contains more energy in the eastward IG motion than in its westward counterpart. The difference is about 2%–3% of the total wave energy and it is associated with the motions projected onto the Kelvin wave in the tropics.
The selected truncation parameters of the expansion (zonal, meridional, and vertical truncation) ensure that the projection provides the optimal fit to the input data on model levels. This approach is different from previous applications of the normal modes and under the linearity assumption it allows the application of the inverse projection to obtain details of circulation associated with a selected type of motion. The bulk of the IG motion is confined to the tropics. For the successful reproduction of three-dimensional circulations by the normal modes it is important that the expansion includes a number of vertical modes.
Uncertainties of Estimates of Inertia–Gravity Energy in the Atmosphere. Part II: Large-Scale Equatorial Waves
Authors: Žagar N. , Tribbia J. , Anderson J. L. , Raeder K. 
Published: June 2009

Abstract
This paper analyzes the spectra and spatiotemporal features of the large-scale inertia-gravity (IG) circulations in four analysis systems in the tropics. Of special interest is the Kelvin wave (KW), which represents between 7% and 25% of the total IG wave (zonal wavenumber k ≠ 0) energy. The mixed Rossby–gravity (MRG) mode comprises between 4% and 15% of the IG wave energy. At the longest scales, the KW spectra are fitted by a law while the MRG energy spectrum appears flat. At shorter scales both modes follow a −3 law. Energy spectra of the total IG wave motion at long zonal scales (zonal wavenumber smaller than 7) have slopes close to −1.
The average circulation associated with KW is characterized by reverse flows in the upper and lower troposphere consistent with the ideas behind simple tropical models. The inverse projection is used to quantify the role of Kelvin and MRG waves in current analysis systems in the upper troposphere over the Indian Ocean. At these levels, easterlies between 10°S and 30°N are represented by the KW to a significant degree while the cross-equatorial flow toward the descending branch of the Hadley cell at 10°S is associated with the MRG waves.
The transient structure of equatorial waves is presented in the space of normal modes defined by the zonal wavenumbers, meridional Hough functions, and the vertical eigenfunctions. The difference in the depth of the model domain in DART–CAM and NCEP–NCAR on one hand and ECMWF and NCEP on the other appears to be one reason for different wave propagation properties. In the latter case the vertical energy propagation is diagnosed by filtering the propagating KW modes back to physical space. The results agree with the linear theory of vertically propagating equatorial waves.
The Amplitude Asymmetry between Synoptic Cyclones and Anticyclones: Implications for Filtering Methods in Feature Tracking
Authors: Donohoe Aaron , Battisti David S. 
Published: June 2009

Abstract
The “background” state is commonly removed from synoptic fields by use of either a spatial or temporal filter prior to the application of feature tracking. Commonly used spatial and temporal filters applied to sea level pressure data admit substantially different information to be included in the synoptic fields. The spatial filter retains a time-mean field that has comparable magnitude to a typical synoptic perturbation. In contrast, the temporal filter removes the entire time-mean field. The inclusion of the time-mean spatially filtered field biases the feature tracking statistics toward large cyclone (anticyclone) magnitudes in the regions of climatological lows (highs). The resulting cyclone/anticyclone magnitude asymmetries in each region are found to be inconsistent with the unfiltered data fields and merely result from the spurious inclusion of the time-mean fields in the spatially filtered data. The temporally filtered fields do not suffer from the same problem and produce modest cyclone/anticyclone magnitude asymmetries that are consistent with the unfiltered data. This analysis suggests that the weather forecaster’s assertion that cyclones have larger amplitudes than anticyclones is due to a composite of a small magnitude asymmetry in the synoptic waves and a large contribution from inhomogeneity in the background (stationary) field.
Leaf Area Index Specification for Use in Mesoscale Weather Prediction Systems
Authors: Knote Christoph , Bonafe Giovanni , Di Giuseppe Francesca 
Published: June 2009

Abstract
The energy budget at the surface is strongly influenced by the presence of vegetation, which alters the partitioning of thermal energy between sensible and latent heat fluxes. Despite its relevance, numerical weather prediction (NWP) systems often use only two parameters to describe the vegetation cover: the fractional area of vegetation occupying a given pixel and the leaf area index (LAI). In this study, the Consortium for Small-Scale Modelling (COSMO) limited-area forecast model is used to investigate the sensitivity of regional predictions to LAI assumptions over the Italian peninsula. Three different approaches are compared: a space- and time-invariant LAI dataset, a LAI specification based on Coordination of Information on the Environment (CORINE) land classes, and a Moderate Resolution Imaging Spectroradiometer (MODIS) satellite-retrieved dataset. The three approaches resolve increasingly higher moments both in time and space of LAI probability density functions. Forecast scores employing the three datasets can therefore be used to assess the required degree of accuracy needed for this parameter. The MODIS dataset is the only one able to capture the expected vegetative cycle that is typical of the Mediterranean ecosystem and noticeably improves the 850-hPa temperature and humidity forecast scores up to +72 h forecast time. This suggests that accounting for LAI temporal and spatial variability could potentially improve the prevision of lower-level variables. Nevertheless, model biases of 2-m screen temperatures are not substantially reduced by the more detailed LAI specification when comparisons to synoptic observing stations are performed. Using long-term measurements collected by the CarboEurope project, a detailed verification of sensible and latent heat flux predictions is also presented. It shows that the desirable positive impact arising from a better LAI specification is nullified by the large uncertainties in the initialization of the soil moisture, which remains a crucial parameter for the reduction of screen-level biases.
A Variational Multiple–Doppler Radar Three-Dimensional Wind Synthesis Method and Its Impacts on Thermodynamic Retrieval
Authors: Liou Yu-Chieng , Chang Ya-Ju 
Published: June 2009

Abstract
A multiple–Doppler radar synthesis method is developed to recover the three-dimensional wind field. In this method the solutions are obtained by variationally adjusting the winds to satisfy a series of constraints in weak formats. Among them, the primary ones are multiple-radar radial velocity observations, the anelastic continuity equation, the vertical vorticity equation, the background wind, and spatial smoothness terms. The retrieved wind products are at two time levels, and can be readily applied to deduce the information about the pressure and temperature through the use of the thermodynamic retrieval algorithm, in which the temporal derivatives of the wind fields are required.
Experiments using model-simulated data are conducted, from which two major findings are obtained. First, the wind field along and near the radar baseline can still be recovered. This is a major advantage over the traditional approach. Therefore, the proposed method is capable of providing uninterrupted observations of a weather system as it passes the baseline. This allows for more flexibility when designing the radar deployment in field experiments. Second, if the winds are applied to infer the thermodynamic fields using the traditional dynamic retrieval method, and an extra sounding (e.g., radiosonde or dropsonde) is combined in order to specify the horizontal average of the thermodynamic perturbations, the preferable place to release this sounding is within the region of weak, rather than strong, convection.
In additional to the aforementioned findings, with this method there is no need to prescribe the top or bottom boundary conditions for the vertical velocities in the traditional sense. Since the computation is performed without explicit vertical integration of the continuity equation, the problem of error accumulation due to inappropriate boundary conditions for the vertical velocities is prevented. These finding are consistent with some previous publications. Furthermore, the instability that occurs during traditional iterative dual-Doppler wind synthesis based on a Cartesian coordinate can also be avoided. Finally, data from any number of radars can be easily added to the computation.
This method is also tested using the radar datasets collected during the Southwest Monsoon Experiment/Terrain-Influenced Monsoon Rainfall Experiment (SoWMEX/TiMREX), which was conducted from May to June 2008 in Taiwan, and reasonable results are obtained.
Factors Affecting Surface Wind Speeds in Gravity Waves and Wake Lows
Authors: Coleman Timothy A. , Knupp Kevin R. 
Published: June 2009

Abstract
Ducted gravity waves and wake lows have been associated with numerous documented cases of “severe” winds (&gt;25 m s−1) and wind damage. These winds are associated with the pressure perturbations and transient mesoscale pressure gradients occurring in many gravity waves and wake lows. However, not all wake lows and gravity waves produce significant winds nor wind damage. In this paper, the factors that affect the surface winds produced by ducted gravity waves and wake lows are reviewed and examined. It is shown theoretically that the factors most conducive to high surface winds include a large-amplitude pressure disturbance, a slow intrinsic speed of propagation, and an ambient wind with the same sign as the pressure perturbation (i.e., a headwind for a pressure trough). Multiple case studies are presented, contrasting gravity waves and wake lows with varying amplitudes, intrinsic speeds, and background winds. In some cases high winds occurred, while in others they did not. In each case, the factor(s) responsible for significant winds, or the lack thereof, are discussed. It is hoped that operational forecasters will be able to, in some cases, compute these factors in real time, to ascertain in more detail the threat of damaging wind from an approaching ducted gravity wave or wake low.
Spatial Forecast Verification Methods Intercomparison Project: Application of the SAL Technique
Authors: Wernli Heini , Hofmann Christiane , Zimmer Matthias 
Published: June 2009

Abstract
In this study, a recently introduced feature-based quality measure called SAL, which provides information about the structure, amplitude, and location of a quantitative precipitation forecast (QPF) in a prespecified domain, is applied to different sets of synthetic and realistic QPFs in the United States. The focus is on a detailed discussion of selected cases and on the comparison of the verification results obtained with SAL and some classical gridpoint-based error measures. For simple geometric precipitation objects it is shown that SAL adequately captures errors in the size and location of the objects, however, not in their orientation. The artificially modified (so-called fake) cases illustrate that SAL has the potential to distinguish between forecasts where intense precipitation objects are either isolated or embedded in a larger-scale low-intensity precipitation area. The real cases highlight that a quality assessment with SAL can lead to contrasting results compared to the application of classical error measures and that, overall, SAL provides useful guidance for identifying the specific shortcomings of a particular QPF. It is also discussed that verification results with SAL and other error measures should be interpreted with care if considering large domains, which may contain meteorologically distinct precipitation systems.
Increasing access to health education in eastern Uganda: Rethinking the role and preparation of volunteers
Authors: Siu Godfrey E , Whyte Susan R 
Published: June 2009

Objective In many parts of Uganda, the demand for health education is greater than the conventional health sector can provide and community health education volunteers fill the gap. Using two case study non government organizations (NGOs) that heavily rely on volunteers as health educators, this article shows the problems of unsystematic preparation of volunteers for their roles in health education. Design An exploratory cross-sectional design using in-depth interviews and focus group discussions was used. Setting Two case study NGOs that heavily rely on volunteers as health educators were selected in a rural district in eastern Uganda. Method Focus group discussions and observation of health education sessions were conducted, as well as in-depth interviews with volunteers and staff of the selected NGOs. Results The NGOs were enthusiastic about the role of volunteers in health education and regarded them positively. However, the process of recruitment was informal. Orientation of the volunteers was insufficient and rather unsystematic. A minimal focus was placed on methods of conducting health education during the training of the volunteers, suggesting a failure to view health education as a professional field. This left the practice of health education at the mercy of the volunteers' own less reflective self-designed pedagogical approach. Conclusion While there is a high enthusiasm for the potential role of volunteers, by both the NGOs and the community, their preparation for health education so far does not measure up to the demands of the tasks they are to perform. The limited emphasis on skills in planning, organizing and methods of health education leaves the practice of health education haphazard and indicates failure to view the area as a professional field.
Perceptions of healthy eating: A qualitative study of school-going children in South India
Authors: Swaminathan S. , Thomas T. , Kurpad A.V. , Vaz M. 
Published: June 2009

Objective To document children's views on healthy eating, perceptions of healthy and unhealthy foods and health consequences of consuming unhealthy foods. Design Baseline data from a three-year longitudinal study. Setting A purposive sample of 307 school children aged 7 to 15 years were recruited from three schools representing various socio-economic status (SES). Method An interviewer-administered questionnaire was used to obtain information from children on their general dietary habits, perceptions on meaning of healthy eating, healthy and unhealthy foods and perceived health consequences of consuming unhealthy foods. Content analysis of the data was performed. Results Children's views on the meaning of healthy eating centred around seven concepts. In older children, those with mothers with higher educational levels and normal/underweight children, perception of meaning of healthy eating was largely based on diet composition. Listings of healthy foods varied based on age group, gender and mother's educational level, while that of unhealthy foods was related to age group and SES. This knowledge, however, did not translate into eating choices, with no differences in intake of fried foods/snacks, aerated drinks, fast foods, sweets and chocolates evident across age groups, gender, SES and mother's educational level. Children from families with a history of chronic disease had an increased awareness ( p < 0.001) of links between unhealthy eating and chronic disease, although intakes did not differ from those children without a family history of chronic disease. Conclusion A concerted effort is required to translate the knowledge of children into positive behaviour change towards healthy eating.
Helping teenagers stop smoking: Comparative observations across youth settings in Cardiff
Authors: Bowles Hannah , Maher Alison , Sage Robert 
Published: June 2009

Objective This paper presents comparative observations between schools/colleges, youth centres, and specialist youth provision, in relation to delivery of the 2tuff2puff six-week smoking cessation and awareness programme to young people in Cardiff. Design A six-week smoking cessation programme was delivered to 12—23 year olds in various youth venues, using weekly records of attendance and compulsory questionnaires delivered by the group facilitator at week one and week six. Setting Twenty-two groups were delivered in 14 youth settings across Cardiff. These settings were categorized into three types: schools/ colleges; youth centres; and specialist youth provisions. Method Data collected from 179 young people at week one and 84 young people at week six were used to measure changes in weekly smoking behaviour, weekly expenditure on cigarettes, knowledge about smoking and smoking cessation, attitudes toward smoking, motivation to quit/ cut down, and attrition. These were compared across the three different setting types. Youth Health Development Officers rated the three setting types on five factors (ease of access/communication with venue; suitability for sessions/acceptability to young people; supportiveness of environment for making a quit attempt; recruitment of young people; and data collection and evaluation) to reflect their practical experiences of delivering the six-week smoking cessation programme across the different youth settings. Results Schools/colleges and specialist youth provision had the highest levels of attendance, and positive change in attitude toward quitting was greatest in specialist youth settings (79 per cent of attendees were more determined to quit). Conclusion Overall, when both practical delivery issues and young peoples' outcome measures were considered, specialist youth provisions were the most effective settings for delivery of this programme. Delivery of smoking awareness as part of a wider health curriculum for groups of excluded young people is also recommended.