A new aircraft-mounted probe for collecting samples of cloud water has been designed, fabricated, and extensively tested. Following previous designs, the probe uses inertial separation to remove ...cloud droplets from the airstream, which are subsequently collected and stored for offline analysis. We report details of the design, operation, and modelled and measured probe performance. Computational fluid dynamics (CFD) was used to understand the flow patterns around the complex interior geometrical features that were optimized to ensure efficient droplet capture. CFD simulations coupled with particle tracking and multiphase surface transport modelling provide detailed estimates of the probe performance across the entire range of flight operating conditions and sampling scenarios. Physical operation of the probe was tested on a Lockheed C-130 Hercules (fuselage mounted) and de Havilland Twin Otter (wing pylon mounted) during three airborne field campaigns. During C-130 flights on the final field campaign, the probe reflected the most developed version of the design and a median cloud water collection rate of 4.5 mL min
was achieved. This allowed samples to be collected over 1-2 min under optimal cloud conditions. Flights on the Twin Otter featured an inter-comparison of the new probe with a slotted-rod collector, which has an extensive airborne campaign legacy. Comparison of trace species concentrations showed good agreement between collection techniques, with absolute concentrations of most major ions agreeing within 30 %, over a range of several orders of magnitude.
A hydrostatic global weather prediction model based on an icosahedral horizontal grid and a hybrid terrain-following/isentropic vertical coordinate is described. The model is an extension to three ...spatial dimensions of a previously developed, icosahedral, shallow-water model featuring user-selectable horizontal resolution and employing indirect addressing techniques. The vertical grid is adaptive to maximize the portion of the atmosphere mapped into the isentropic coordinate subdomain. The model, best described as a stacked shallow-water model, is being tested extensively on real-time medium-range forecasts to ready it for possible inclusion in operational multimodel ensembles for medium-range to seasonal prediction.
IntroductionWide variation in the management of key paediatric surgical conditions in the UK has likely resulted in outcomes for some children being worse than they could be. Consequently, it is ...important to reduce unwarranted variation. However, major barriers to this are the inability to detect differences between observed and expected hospital outcomes based on the casemix of the children they have treated, and the inability to detect variation in significant outcomes between hospitals. A stated-preference study has been designed to estimate the value key stakeholders place on different elements of the outcomes for a child with a surgical condition. This study proposes to develop a summary metric to determine what represents successful treatment of children with surgical conditions.Methods and analysisPreferences from parents, individuals treated for surgical conditions as infants/children, healthcare professionals and members of the public will be elicited using paired comparisons and kaizen tasks. A descriptive framework consisting of seven attributes representing types of operations, infections treated in hospital, quality of life and survival was identified. An experimental design has been completed using a D-efficient design with overlap in three attributes and excluding implausible combinations. All participants will be presented with an additional choice task including a palliative scenario that will be used as an anchor. The survey will be administered online. Primary analysis will estimate a mixed multinomial logit model. A traffic light system to determine what combination of attributes and levels represent successful treatment will be created.Ethics and disseminationEthics approval to conduct this study has been obtained from the Medical Sciences Inter-Divisional Research Ethics Committee (IDREC) at the University of Oxford (R59631/RE001-05). We will disseminate all of our results in peer-review publications and scientific presentations. Findings will be additionally disseminated through relevant charities and support groups and professional organisations.
This study uses airborne cloud water composition measurements to characterize the vertical structure of air‐equivalent mass concentrations of water‐soluble species in marine stratocumulus clouds off ...the California coast. A total of 385 cloud water samples were collected in the months of July and August between 2011 and 2016 and analyzed for water‐soluble ionic and elemental composition. Three characteristic profiles emerge: (i) a reduction of concentration with in‐cloud altitude for particulate species directly emitted from sources below cloud without in‐cloud sources (e.g., Cl− and Na+), (ii) an increase of concentration with in‐cloud altitude (e.g., NO2− and formate), and (iii) species exhibiting a peak in concentration in the middle of cloud (e.g., non–sea‐salt SO42−, NO3−, and organic acids). Vertical profiles of rainout parameters such as loss frequency, lifetime, and change in concentration with respect to time show that the scavenging efficiency throughout the cloud depth depends strongly on the thickness of the cloud. Thin clouds exhibit a greater scavenging loss frequency at cloud top, while thick clouds have a greater scavenging loss frequency at cloud base. The implications of these results for treatment of wet scavenging in models are discussed.
Key Points
Three characteristic in‐cloud vertical concentration profiles are identified: those that peak at the base, middle, and top of cloud
Nonreactive surface‐derived species present the in‐cloud vertical concentration profiles that are most influenced by rainout
Rainout loss frequency is greatest at cloud base for moderate‐drizzling thick clouds, and at cloud top for light‐drizzling thin clouds
This paper uses cognitive mapping techniques to understand how brand associations, an important aspect of political brand equity are formed, differ, and change, from the perspective of citizens, ...across the four largest Irish political parties between 2013 and 2016. The paper focuses in particular upon the strength, favourability and uniqueness of these brand associations. The results constitute a first attempt to longitudinally explore changing political brand associations through cognitive mapping techniques, using data generated with the participation of hundreds of citizens. Our findings suggest that this approach can contribute to our understanding of how and why political brand associations change over time.
A general method for modeling on irregular grids MacDonald, Alexander E.; Middlecoff, Jacques; Henderson, Tom ...
The international journal of high performance computing applications,
11/2011, Letnik:
25, Številka:
4
Journal Article
Recenzirano
For simulation on a spherical surface, such as global numerical weather prediction, icosahedral grids are superior to their competitors in uniformity of grid mesh distance across the entire globe and ...lack of neighboring grid cells that share only a single vertex. Use of such a grid presents unique programming challenges related to iteration across grid cells and location of neighboring cells. Here we describe an icosahedral grid with a one-dimensional vector loop structure, table specified memory order, and an indirect addressing scheme that yields very compact code despite the complexities of this grid. This approach allows the same model code to be used for many grid structures. Indirect addressing also allows grid cells to be stored in any order, selectable at run time. This permits easy implementation of different memory layouts for cache blocking, distributed-memory parallelism, and static load balancing. Since indirect addressing can adversely affect execution time we organize arrays to place a directly addressable index innermost. We also describe experiments designed to measure any performance penalties accrued from use of indirect addressing.
This article is one in a series describing the functionality of the Flow-Following, Finite-Volume Icosahedral Model (FIM) developed at NOAA's Earth System Research Laboratory. Emphasis in this ...article is on the design of the vertical coordinate-the 'flow following' aspect of FIM. The coordinate is terrain-following near the ground and isentropic in the free atmosphere. The spatial transition between the two coordinates is adaptive and is based on the arbitrary Lagrangian-Eulerian (ALE) paradigm. The impact of vertical resolution trade-offs between the present hybrid approach and traditional terrain-following coordinates is demonstrated in a three-part case study.
Low 25-OH serum vitamin D (VitD) is pervasive in older adults and linked to functional decline and progression of frailty. We have previously shown that chronic VitD insufficiency in "middle-aged" ...mice results in impaired anaerobic exercise capacity, decreased lean mass, and increased adiposity. Here, we examine if VitD insufficiency results in similar deficits and greater frailty progression in old-aged (24 to 28 months of age) mice. Similar to what we report in younger mice, older mice exhibit a rapid and sustained response in serum 25-OH VitD levels to differential supplementation, including insufficient (125 IU/kg chow), sufficient (1000 IU/kg chow), and hypersufficient (8000 IU/kg chow) groups. During the 4-month time course, mice were assessed for body composition (DEXA), physical performance, and frailty using a Fried physical phenotype-based assessment tool. The 125 IU mice exhibited worse grip strength (
= 0.002) and inverted grip hang time (
= 0.003) at endpoint and the 8000 IU mice transiently displayed greater rotarod performance after 3 months (
= 0.012), yet other aspects including treadmill performance and gait speed were unaffected. However, 125 and 1000 IU mice exhibited greater frailty compared to baseline (
= 0.001 and
= 0.038, respectively), whereas 8000 IU mice did not (
= 0.341). These data indicate targeting higher serum 25-OH vitamin D levels may attenuate frailty progression during aging.
A multistep flux-corrected transport scheme Lee, Jin-Luen; Bleck, Rainer; MacDonald, Alexander E.
Journal of computational physics,
12/2010, Letnik:
229, Številka:
24
Journal Article
Recenzirano
A multistep flux-corrected transport (MFCT) scheme is developed to achieve conservative and monotonic tracer transports for multistep dynamical cores. MFCT extends Zalesak two-time level scheme to ...any multistep time-differencing schemes by including multiple high-order fluxes in the antidiffusive flux, while computing the two-time level low-order monotone solution. The multistep time-differencing scheme used in this study is the third-order Adams–Bashforth (AB3) scheme implemented in a finite-volume icosahedral shallow-water model. The accuracy of AB3 MFCT is quantified by the shape-preserving advection experiments in non-divergent flow, as well as a cosine bell whose shape changes during advection in shear flow. AB3 MFCT has been shown to be insensitive to time step size. This make AB3 MFCT an attractive transport scheme for explicit high resolution model applications with small time step. MFCT is tested in shallow-water model simulations to demonstrate that the use of MFCT maintains positive-definite tracer transport, while at the same time conserving both fluid mass and tracer mass within round-off errors in the AB3 dynamic core.
This study reports on airborne measurements of stratocumulus cloud properties under varying degrees of influence from biomass burning (BB) plumes off the California coast. Data are reported from five ...total airborne campaigns based in Marina, California, with two of them including influence from wildfires in different areas along the coast of the western United States. The results indicate that subcloud cloud condensation nuclei number concentration and mass concentrations of important aerosol species (organics, sulfate, nitrate) were better correlated with cloud droplet number concentration (Nd) as compared to respective above‐cloud aerosol data. Given that the majority of BB particles resided above cloud tops, this is an important consideration for future work in the region as the data indicate that the subcloud BB particles likely were entrained from the free troposphere. Lower cloud condensation nuclei activation fractions were observed for BB‐impacted clouds as compared to non‐BB clouds due, at least partly, to less hygroscopic aerosols. Relationships between Nd and either droplet effective radius or drizzle rate are preserved regardless of BB influence, indicative of how parameterizations can exhibit consistent skill for varying degrees of BB influence as long as Nd is known. Lastly, the composition of both droplet residual particles and cloud water changed significantly when clouds were impacted by BB plumes, with differences observed for different fire sources stemming largely from effects of plume aging time and dust influence.
Key Points
Primary activation of sub‐cloud CCN was the key driver of cloud droplet concentration (Nd) in biomass burning (BB) and non‐BB conditions
Relationships between Nd and either droplet effective radius (re) or rain rate (R) are similar regardless of the level of BB influence
Cloud water and droplet residual particle composition differed between BB and non‐BB conditions
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