bluuebunny/crossref_metadata_2025_split huggingface dataset:
Swimming and asthma: factors underlying respiratory symptoms in competitive swimmers
Authors: Päivinen Marja Kristiina , Keskinen Kari Lasse , Tikkanen Heikki Olavi 
Published: July 2009

AbstractBackground:  Swimming is recommended for asthmatics. However, many competitive swimmers report asthmatic symptoms. While some studies identify the swimming environment as a trigger for allergy and asthmatic symptoms, even more studies suggest swimming to be suitable for people with allergies and asthma. The factors behind the symptoms were studied first by determining the prevalence of asthma, allergy and self‐reported asthmatic symptoms in experienced Finnish swimmers and then by examining the relationships between the reported symptoms and the main triggering factors: medical history, environment and exercise intensity.Materials and Methods:  Top swimmers (n = 332) of the Finnish Swimming Association registry (N = 4578) were asked to complete a structured questionnaire on their medical history, swimming background, swimming environment and symptoms in different swimming intensities. Two hundred experienced swimmers, 107 females and 93 males, with an average age of 18.5 [standard deviation (SD) = 3.0] years and a swimming training history of 9 (SD = 3.8) years completed the questionnaire.Results:  Physician‐diagnosed asthma was reported by 32 swimmers (16%), including 24 (12%) with exercise‐induced asthma. Physician‐diagnosed allergy was reported by 81 (41%) swimmers. Asthmatic symptoms during swimming were described by 84 subjects (42%). Most symptoms occurred when swimming exceeded speeds corresponding to the lactic/anaerobic threshold. Family history of asthma was significant and the most important risk factor for asthmatic symptoms.Conclusions:  The prevalence of asthma in swimmers was higher than in the general population but not different from that in other endurance athletes. Family history of asthma and increased swimming intensity had the strongest associations with the reported asthmatic symptoms.Please cite this paper as: Päivinen MK, Keskinen KL and Tikkanen HO. Swimming and asthma: factors underlying respiratory symptoms in competitive swimmers. The Clinical Respiratory Journal 2010; 4: 97–103.
Tissue‐direct PCR, a rapid and extraction‐free method for barcoding of ferns
Authors: LI F‐W. , KUO L‐Y. , HUANG Y‐M. , CHIOU W‐L. , WANG C‐N. 
Published: July 2009

AbstractFern gametophytes and young sporophytes often provide too little material for DNA extraction and are particularly difficult to identify to genus. Here we developed an efficient procedure called ‘Tissue‐direct PCR’, in which a slice of fern tissue is mixed with PCR reagents and primers, allowing certain genomic regions to be amplified directly in the thermal cycler. For these diminutive and featureless stages of ferns, Tissue‐direct PCR combined with amplifying plant barcodes promises to make the identification of immature ferns easy and rapid. Tissue‐direct PCR would also be very helpful for large‐scale ecological studies surveying distribution and population structure.
Energy–Vorticity Theory of Ideal Fluid Mechanics
Authors: Névir Peter , Sommer Matthias 
Published: July 2009

Abstract
Nambu field theory, originated by Névir and Blender for incompressible flows, is generalized to establish a unified energy–vorticity theory of ideal fluid mechanics. Using this approach, the degeneracy of the corresponding noncanonical Poisson bracket—a characteristic property of Hamiltonian fluid mechanics—can be replaced by a nondegenerate bracket. An energy–vorticity representation of the quasigeostrophic theory and of multilayer shallow-water models is given, highlighting the fact that potential enstrophy is just as important as energy. The energy–vorticity representation of the hydrostatic adiabatic system on isentropic surfaces can be written in complete analogy to the shallow-water equations using vorticity, divergence, and pseudodensity as prognostic variables. Furthermore, it is shown that the Eulerian equation of motion, the continuity equation, and the first law of thermodynamics, which describe the nonlinear evolution of a 3D compressible, adiabatic, and nonhydrostatic fluid, can be written in Nambu representation. Here, trilinear energy–helicity, energy–mass, and energy–entropy brackets are introduced. In this model the global conservation of Ertel’s potential enstrophy can be interpreted as a super-Casimir functional in phase space. In conclusion, it is argued that on the basis of the energy–vorticity theory of ideal fluid mechanics, new numerical schemes can be constructed, which might be of importance for modeling coherent structures in long-term integrations and climate simulations.
Atlantic Tropical Cyclogenetic Processes during SOP-3 NAMMA in the GEOS-5 Global Data Assimilation and Forecast System
Authors: Reale Oreste , Lau William K. , Kim Kyu-Myong , Brin Eugenia 
Published: July 2009

Abstract
This article investigates the role of the Saharan air layer (SAL) in tropical cyclogenetic processes associated with a nondeveloping and a developing African easterly wave observed during the Special Observation Period (SOP-3) phase of the 2006 NASA African Monsoon Multidisciplinary Analyses (NAMMA). The two waves are chosen because they both interact heavily with Saharan air. A global data assimilation and forecast system, the NASA Goddard Earth Observing System, version 5 (GEOS-5), is being run to produce a set of high-quality global analyses, inclusive of all observations used operationally but with additional satellite information. In particular, following previous works by the same authors, the quality-controlled data from the Atmospheric Infrared Sounder (AIRS) used to produce these analyses have a better coverage than the one adopted by operational centers. From these improved analyses, two sets of 31 five-day high-resolution forecasts, at horizontal resolutions of both half and quarter degrees, are produced. Results indicate that very steep moisture gradients are associated with the SAL in forecasts and analyses, even at great distances from their source over the Sahara. In addition, a thermal dipole in the vertical (warm above, cool below) is present in the nondeveloping case. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra and Aqua satellites shows that aerosol optical thickness, indicative of more dust as opposed to other factors, is higher in the nondeveloping case. Altogether, results suggest that the radiative effect of dust may play some role in producing a thermal structure less favorable to cyclogenesis. Results also indicate that only global horizontal resolutions on the order of 20–30 km can capture the large-scale transport and the fine thermal structure of the SAL, inclusive of the sharp moisture gradients, reproducing the effect of tropical cyclone suppression that has been hypothesized by previous authors from observational and regional modeling perspectives. These effects cannot be fully represented at lower resolutions, therefore global resolution of a quarter of a degree is a minimum critical threshold necessary to investigate Atlantic tropical cyclogenesis from a global modeling perspective.
Dynamics of the Cumulus Cloud Margin: An Observational Study
Authors: Wang Yonggang , Geerts Bart , French Jeffrey 
Published: July 2009

Abstract
Aircraft observations of shallow to moderately deep cumulus clouds are analyzed with the purpose of describing the typical horizontal structure of thermodynamic and kinematic parameters near the cumulus margin from the cloud center into the ambient clear air. The cumuli were sampled in a broad range of environments in three regions: the tropical Atlantic Ocean in winter, the Sonoran Desert during the monsoon, and the arid high plains of Wyoming in summer. The composite analysis of 1624 cumulus penetrations shows that the vertical mass flux, temperature, buoyancy, the buoyancy flux, and the turbulent kinetic energy all tend to reach a minimum near the cloud edge. Most of these variables, and also the liquid water content, the droplet concentration, and the mean droplet size, generally decrease in value from within the cumulus toward the cloud edge, slowly at first and rapidly close to the cloud edge. These findings corroborate recent observational and modeling studies and provide further evidence for significant evaporative cooling in laterally entraining and detraining eddies in the cloud margin, a transition zone within ∼200 m (or ∼10% of the cloud diameter) of the cloud edge. This cooling explains the tendency for downward accelerating, buoyantly driven subsidence in the cloud margin.
Impact of Freshwater Release in the North Atlantic under Different Climate Conditions in an OAGCM
Authors: Swingedouw Didier , Mignot Juliette , Braconnot Pascale , Mosquet Eloi , Kageyama Masa , Alkama Ramdane 
Published: July 2009

Abstract
The response of climate to freshwater input in the North Atlantic (NA) has raised a lot of concern about the issue of climate stability since the discovery of abrupt coolings during the last glacial period. Such coolings have usually been related to a weakening of the Atlantic meridional overturning circulation (AMOC), probably associated with massive iceberg surges or meltwater pulses. Additionally, the recent increase in greenhouse gases in the atmosphere has also raised the possibility of a melting of the Greenland ice sheet, which may impact the future AMOC, and thereby the climate. In this study, the extent to which the mean climate influences the freshwater release linked to ice sheet melting in the NA and the associated climatic response is explored. For this purpose the simulations of several climatic states [last interglacial, Last Glacial Maximum, mid-Holocene, preindustrial, and future (2 × CO2)] are considered, and the climatic response to a freshwater input computed interactively according to a surface heat flux budget over the ice sheets is analyzed. It is shown that the AMOC response is not linear with the freshwater input and depends on the mean climate state. The climatic responses to these different AMOC changes share qualitative similarities for the general picture, notably a cooling in the Northern Hemisphere and a southward shift of the intertropical convergence zone (ITCZ) in the Atlantic and across the Panama Isthmus. The cooling in the Northern Hemisphere is related to the sea ice cover response, which strongly depends on the responses of the atmospheric circulation, the local oceanic heat transport, and the density threshold of the oceanic convection sites. These feedbacks and the magnitude of temperature and precipitation changes outside the North Atlantic depend on the mean climate.
Application of MJO Simulation Diagnostics to Climate Models
Authors: Kim D. , Sperber K. , Stern W. , Waliser D. , Kang I.-S. , Maloney E. , Wang W. , Weickmann K. , Benedict J. , Khairoutdinov M. , Lee M.-I. , Neale R. , Suarez M. , Thayer-Calder K. , Zhang G. 
Published: July 2009

Abstract
The ability of eight climate models to simulate the Madden–Julian oscillation (MJO) is examined using diagnostics developed by the U.S. Climate Variability and Predictability (CLIVAR) MJO Working Group. Although the MJO signal has been extracted throughout the annual cycle, this study focuses on the boreal winter (November–April) behavior. Initially, maps of the mean state and variance and equatorial space–time spectra of 850-hPa zonal wind and precipitation are compared with observations. Models best represent the intraseasonal space–time spectral peak in the zonal wind compared to that of precipitation. Using the phase–space representation of the multivariate principal components (PCs), the life cycle properties of the simulated MJOs are extracted, including the ability to represent how the MJO evolves from a given subphase and the associated decay time scales. On average, the MJO decay (e-folding) time scale for all models is shorter (∼20–29 days) than observations (∼31 days). All models are able to produce a leading pair of multivariate principal components that represents eastward propagation of intraseasonal wind and precipitation anomalies, although the fraction of the variance is smaller than observed for all models. In some cases, the dominant time scale of these PCs is outside of the 30–80-day band.
Several key variables associated with the model’s MJO are investigated, including the surface latent heat flux, boundary layer (925 hPa) moisture convergence, and the vertical structure of moisture. Low-level moisture convergence ahead (east) of convection is associated with eastward propagation in most of the models. A few models are also able to simulate the gradual moistening of the lower troposphere that precedes observed MJO convection, as well as the observed geographical difference in the vertical structure of moisture associated with the MJO. The dependence of rainfall on lower tropospheric relative humidity and the fraction of rainfall that is stratiform are also discussed, including implications these diagnostics have for MJO simulation. Based on having the most realistic intraseasonal multivariate empirical orthogonal functions, principal component power spectra, equatorial eastward propagating outgoing longwave radiation (OLR), latent heat flux, low-level moisture convergence signals, and vertical structure of moisture over the Eastern Hemisphere, the superparameterized Community Atmosphere Model (SPCAM) and the ECHAM4/Ocean Isopycnal Model (OPYC) show the best skill at representing the MJO.
Retrieving Properties of Thin Clouds from Solar Aureole Measurements
Authors: DeVore J. G. , Stair A. T. , LePage A. , Rall D. , Atkinson J. , Villanucci D. , Rappaport S. A. , Joss P. C. , McClatchey R. A. 
Published: July 2009

Abstract
This paper describes a newly designed Sun and Aureole Measurement (SAM) aureolegraph and the first results obtained with this instrument. SAM measurements of solar aureoles produced by cirrus and cumulus clouds were taken at the Atmospheric Radiation Measurement Program (ARM) Central Facility in Oklahoma during field experiments conducted in June 2007 and compared with simultaneous measurements from a variety of other ground-based instruments. A theoretical relationship between the slope of the aureole profile and the size distribution of spherical cloud particles is based on approximating scattering as due solely to diffraction, which in turn is approximated using a rectangle function. When the particle size distribution is expressed as a power-law function of radius, the aureole radiance as a function of angle from the center of the solar disk also follows a power law, with the sum of the two powers being −5. This result also holds if diffraction is modeled with an Airy function. The diffraction approximation is applied to SAM measurements with optical depths ≲2 to derive the effective radii of cloud particles and particle size distributions between ∼2.5 and ∼25 μm. The SAM results yielded information on cloud properties complementary to that obtained with ARM Central Facility instrumentation. A network of automated SAM units [similar to the Aerosol Robotic Network (AERONET) system] would provide a practical means to gain fundamental new information on the global statistical properties of thin (optical depth ≲ 10) clouds, thereby providing unique information on the effects of such clouds upon the earth’s energy budget.
Evaluating Polarimetric X-Band Radar Rainfall Estimators during HMT
Authors: Matrosov Sergey Y. 
Published: July 2009

Abstract
Different relations between rainfall rate R and polarimetric X-band radar measurables were evaluated using the radar, disdrometer, and rain gauge measurements conducted during the 4-month-long field experiment. The specific differential phase shift KDP–based estimators generally show less scatter resulting from variability in raindrop size distributions than with the power-based relations. These estimators depend on model assumptions about the drop aspect ratios and are not applicable for lighter rainfalls. The polynomial approximation for the mean drop aspect ratio provides R–KDP relations that result overall in good agreement between the radar retrievals of rainfall accumulations and estimates from surface rain gauges. The accumulation data obtained from power estimators that use reflectivity Zeh and differential reflectivity ZDR measurements generally exhibit greater standard deviations with respect to the gauge measurements. Unlike the phase-based estimators, the power-based estimators have an advantage of being “point” measurements, thus providing continuous quantitative precipitation estimation (QPE) for the whole area of radar coverage. The uncertainty in the drop shape model can result in errors in the attenuation and differential attenuation correction procedures. These errors might provide biases of radar-derived QPE for the estimators that use power measurements. Overall, for all considered estimators, the radar-based total rainfall accumulations showed biases less than 10% (relative to gauges). The standard deviations of radar retrievals were about 23% for the mean Zeh–R relation, 17%–22% for the KDP-based estimators (depending on the drop shape model), and about 20%–32% for different Zeh–ZDR-based estimators. Comparing ZDR-based retrievals of mean mass raindrop size Dm (for Dm &gt; 1 mm) with disdrometer-derived values reveals an about 20%–25% relative standard deviation between these two types of estimates.
Data Assimilation of Tropopause Height Using Dry Intrusion Observations
Authors: Michel Yann 
Published: July 2009

Abstract
This article investigates the problem of initializing upper-level potential vorticity by using the detection of dry intrusions that can be seen in water vapor images. First, a satellite image processing technique has been developed for the identification and tracking of dry intrusions on geostationary satellite images. This technique can also be applied to images derived from model fields through a radiative transfer model. A linking algorithm automatically compares the trajectories of the dry intrusions in the model and in the satellite images. Differences of brightness temperatures are then converted to differences of tropopause height through a simple linear model, which is based on the correlation found in the background. As the scheme is likely to provide observations of the tropopause height, it also suggests that a space-alignment representation of the errors be used. A simple one-dimensional study provides a depiction of the background error covariance in alignment space, which is compared to the traditional approach of background error covariance in amplitude space. An approximate form of the Ertel potential vorticity operator is then used to incorporate pseudo-observations inside a global four-dimensional variational assimilation scheme. A case study of cyclogenesis highlights the difference between the amplitude–space assimilation of potential vorticity values and the alignment space assimilation of the height of the tropopause.
A Numerical Investigation of the Effects of Dry Air Aloft on Deep Convection
Authors: James Richard P. , Markowski Paul M. 
Published: July 2009

AbstractA three-dimensional cloud model was used to investigate the sensitivity of deep convective storms to dry air above the cloud base. In simulations of both quasi-linear convective systems and supercells, dry air aloft was found to reduce the intensity of the convection, as measured by updraft mass flux and total condensation and rainfall. In high-CAPE line-type simulations, the downdraft mass flux and cold pool strength were enhanced at the rear of the trailing stratiform region in a drier environment. However, the downdraft and cold pool strengths were unchanged in the convective region, and were also unchanged or reduced in simulations of supercells and of line-type systems at lower CAPE. This result contrasts with previous interpretations of the role of dry air aloft in the development of severe low-level outflow winds.The buoyancy-sorting framework is used to interpret the influence of environmental humidity on the updraft entrainment process and the observed strong dependence on the environmental CAPE. The reduction in convective vigor caused by dry air is relatively inconsequential at very high CAPE, but low-CAPE convection requires a humid environment in order to grow by entrainment.The simulated responses of the downdraft and cold pool intensities to dry air aloft reflected the changes in diabatic cooling rates within the downdraft formation regions. When dry air was present, the decline in hydrometeor mass exerted a negative tendency on the diabatic cooling rates and acted to offset the favorable effects of dry air for cooling by evaporation. Thus, with the exception of the rearward portions of the high-CAPE line-type simulations, dry air was unable to strengthen the downdrafts and cold pool.A review of the literature demonstrates that observational evidence does not unambiguously support the concept that dry air aloft favors downdraft and outflow strength. It is also shown that the use of warm rain microphysics in previous modeling studies may have reinforced the tendency to overemphasize the role of dry air aloft.
Impacts of Satellite-Observed Winds and Total Precipitable Water on WRF Short-Range Forecasts over the Indian Region during the 2006 Summer Monsoon
Authors: Rakesh V. , Singh Randhir , Pal P. K. , Joshi P. C. 
Published: July 2009

Abstract
Assimilation experiments have been performed with the Weather Research and Forecasting (WRF) model’s three-dimensional variational data assimilation (3DVAR) scheme to assess the impacts of NASA’s Quick Scatterometer (QuikSCAT) near-surface winds, and Special Sensor Microwave Imager (SSM/I) wind speed and total precipitable water (TPW) on the analysis and on short-range forecasts over the Indian region. The control (without satellite data) as well as WRF 3DVAR sensitivity runs (which assimilated satellite data) were made for 48 h starting daily at 0000 UTC during July 2006. The impacts of assimilating the different satellite dataset were measured in comparison to the control run, which does not assimilate any satellite data. The spatial distribution of the forecast impacts (FIs) for wind, temperature, and humidity from 1-month assimilation experiments for July 2006 demonstrated that on an average, for 24- and 48-h forecasts, the satellite data provided useful information. Among the experiments, WRF wind speed prediction was improved by QuikSCAT surface wind and SSM/I TPW assimilation, while temperature and humidity prediction was improved due to the assimilation of SSM/I TPW. The rainfall prediction has also been improved significantly due to the assimilation of SSM/I TPW, with the largest improvement seen over the west coast of India. Through an improvement of the surface wind field, the QuikSCAT data also yielded a positive impact on the precipitation, particularly for day 1 forecasts. In contrast, the assimilation of SSM/I wind speed degraded the humidity and rainfall predictions.