173 research outputs found
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Evaluation of the Met Office global forecast model using Geostationary Earth Radiation Budget (GERB) data
Simulations of the top-of-atmosphere radiative-energy budget from the Met Office global numerical weather-prediction model are evaluated using new data from the Geostationary Earth Radiation Budget (GERB) instrument on board the Meteosat-8 satellite. Systematic discrepancies between the model simulations and GERB measurements greater than 20 Wm-2 in outgoing long-wave radiation (OLR) and greater than 60 Wm-2 in reflected short-wave radiation (RSR) are identified over the period April-September 2006 using 12 UTC data. Convective cloud over equatorial Africa is spatially less organized and less reflective than in the GERB data. This bias depends strongly on convective-cloud cover, which is highly sensitive to changes in the model convective parametrization. Underestimates in model OLR over the Gulf of Guinea coincide with unrealistic southerly cloud outflow from convective centres to the north. Large overestimates in model RSR over the subtropical ocean, greater than 50 Wm-2 at 12 UTC, are explained by unrealistic radiative properties of low-level cloud relating to overestimation of cloud liquid water compared with independent satellite measurements. The results of this analysis contribute to the development and improvement of parametrizations in the global forecast model
An evaluation of modeled evaporation regimes in Europe using observed dry spell land surface temperature
Soil moisture availability exerts control over the land surface energy partition in parts of Europe. However, determining the strength and variability of this control is impeded by the lack of reliable evaporation observations at the continental scale. This makes it difficult to refine the broad range of soil moistureāevaporation behaviours across global climate models (GCMs). Previous studies show that satellite observations of land surface temperature (LST) during rain-free dry spells can be used to diagnose evaporation regimes at the GCM grid box scale. This Relative Warming Rate (RWR) diagnostic quantifies the increase in dry spell LST relative to air temperature, and is used here to evaluate a land surface model (JULES) both offline and coupled to a GCM (HadGEM3-A). It is shown that RWR can be calculated using outputs from an atmospheric GCM provided the satellite clear-sky sampling bias is incorporated. Both offline JULES and HadGEM3-A reproduce the observed seasonal and regional RWR variations, but with weak springtime RWRs in central Europe. This coincides with sustained bare soil evaporation (Ebs) during dry spells, reflecting previous site-level JULES studies in Europe. To assess whether RWR can discriminate between surface descriptions, the bare soil surface conductance and the vegetation root profile are revised to limit Ebs. This increases RWR by increasing the occurrence of soil moisture limited dry spells, yielding more realistic springtime RWRs as a function of antecedent precipitation but poorer relationships in summer. This study demonstrates the potential for using satellite LST to assess evaporation regimes in climate models
Beam Test of the First Prototype of SiPM-on-Tile Calorimeter Insert for the Electron-Ion Collider Using 4 GeV Positrons at Jefferson Laboratory
We recently proposed a high-granularity calorimeter insert for the
Electron-Ion Collider (EIC) that uses plastic scintillator tiles read out by
SiPMs. Among its innovative features are an ASIC-away-of-SiPM strategy for
reducing cooling requirements and minimizing space use, along with employing
3D-printed frames to reduce optical crosstalk and dead areas. To evaluate these
features, we built a 40-channel prototype and tested it using a 4 GeV positron
beam at Jefferson Laboratory. The measured energy spectra and 3D shower shapes
are well described by simulations, confirming the effectiveness of the design,
construction techniques, and calibration strategy. This constitutes the first
use of SiPM-on-tile technology in EIC detector designs
Gene expression studies for the analysis of domoic acid production in the marine diatom Pseudo-nitzschia multiseries
Background:
Pseudo-nitzschia multiseries Hasle (Hasle) (Ps-n) is distinctive among the ecologically important marine diatoms because it produces the neurotoxin domoic acid. Although the biology of Ps-n has been investigated intensely, the characterization of the genes and biochemical pathways leading to domoic acid biosynthesis has been limited. To identify transcripts whose levels correlate with domoic acid production, we analyzed Ps-n under conditions of high and low domoic acid production by cDNA microarray technology and reverse-transcription quantitative PCR (RT-qPCR) methods. Our goals included identifying and validating robust reference genes for Ps-n RNA expression analysis under these conditions.
Results:
Through microarray analysis of exponential- and stationary-phase cultures with low and high domoic acid production, respectively, we identified candidate reference genes whose transcripts did not vary across conditions. We tested eleven potential reference genes for stability using RT-qPCR and GeNorm analyses. Our results indicated that transcripts encoding JmjC, dynein, and histone H3 proteins were the most suitable for normalization of expression data under conditions of silicon-limitation, in late-exponential through stationary phase. The microarray studies identified a number of genes that were up- and down-regulated under toxin-producing conditions. RT-qPCR analysis, using the validated controls, confirmed the up-regulation of transcripts predicted to encode a cycloisomerase, an SLC6 transporter, phosphoenolpyruvate carboxykinase, glutamate dehydrogenase, a small heat shock protein, and an aldo-keto reductase, as well as the down-regulation of a transcript encoding a fucoxanthin-chlorophyll a-c binding protein, under these conditions.
Conclusion:
Our results provide a strong basis for further studies of RNA expression levels in Ps-n, which will contribute to our understanding of genes involved in the production and release of domoic acid, an important neurotoxin that affects human health as well as ecosystem function.Plymouth State University Graduate Programs OfficeWoods Hole Oceanographic Institution Academic Programs OfficeNew Hampshire IDeA Network of Biological Research Excellence (NH-INBRE)National Center for Research Resources (U.S.) (Grant 5P20RR030360-03)National Institute of General Medical Sciences (U.S.) (Grant 8P20GM103506-03
Comparing critical speed modelling approaches and exploring relationships with match-play variables in elite male youth soccer players
Background: A novel bi-exponential method has emerged to estimate critical speed (CS) and D-prime (Dā²) from a 3-min all- out test (3MT).
Objectives: To compare CS analysis methods to determine whether parameter estimations were interchangeable. Reference values and relationships with key soccer match- play variables were explored.
Methods: Thirteen elite male youth (14-15 years old) players completed a 30 m shuttle run 3MT to estimate CS, Dā², rate of speed decline time constant, maximal speed (Smax), time to Smax (tmax), and fatigue index (FI), using the traditional method and bi-exponential model on average (Bi-ExpAverage) and max speed settings (Bi-ExpMax-Speed). High-speed running (HSR) and sprinting distances and counts, and the number of accelerations were collected from two matches. Magnitude- based inferences (p < 0.05) with smallest worthwhile change of 0.2 effect sizes were used to analyse differences. Pearsonās and Spearmanās correlation coefficients were used to measure associations between CS model variables and match-play parameters.
Results: There were significant differences between the traditional method and both bi-exponential models for CS and Dā², as well as between the bi-exponential models for all variables except tmax. Using the Bi-ExpAverage model, strong correlations (r = 0.70-0.73; p < 0.05) were observed for Dā² and FI with the number of standardised and individualised HSRs, respectively. With the Bi-ExpMax-Speed model, there were strong correlations (r/Ļ = 0.64-0.68; p < 0.05) between Dā² and the number of standardised HSRs and sprints, and the number of individualised sprints.
Conclusion: There is a lack of interchangeability between analysis methods. It appears that Dā² and FI from the bi- exponential models could be associated with high-intensity actions in soccer match-play
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Meteorological training for the digital age: A Blueprint for a new curriculum
Almost all professional meteorologists take part in meteorological training during their undergraduate or graduate study or professional job training in the public or private sector. Increased benefits can be accrued by employers and employees, if this training is based on the same underpinning skills and attributes, aimed to equip people entering meteorology for the wide range of future roles they might undertake.
While there is a great deal of excellent, innovative practice in our community, the time is now right to look again at the nature of the meteorological curriculum. Meteorology faces significant challenges in the 21st century to deal with the twin challenges of increases in the number and severity of extreme weather events and the increased complexity of forecasts demanded by end-users.
Here, a blueprint which describes a number of key principles which should be used to design, evaluate and enhance curricula for students entering our field in the next 10 years is proposed. The blueprint does not discuss in detail the core mathematical and physical principles which underlie any high quality training in meteorology but rather focuses on the key skills and attributes needed to make the next-generation of meteorologists innovative and effective which include:
ā¢ Meteorological competencies,
ā¢ Personal and inter-personal attributes,
ā¢ Core skills as a scientist and
ā¢ Ethical and professional interaction with broader society.
The blueprint is intended to encourage debate about how we equip new meteorologists for the digital age. We plan to use these principles to review and enhance our own curricula in the near future
The impact of equilibrating hemispheric albedos on tropical performance in the HadGEM2-ES coupled climate model
AcceptedArticle in PressĀ©2015. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Ā©2015. The Authors. The Earth's hemispheric reflectances are equivalent to withinĀ±0.2Wm-2, even though the Northern Hemisphere contains a greater proportion of higher reflectance land areas, because of greater cloud cover in the Southern Hemisphere. This equivalence is unlikely to be by chance, but the reasons are open to debate. Here we show that equilibrating hemispheric albedos in the Hadley Centre Global Environment Model version 2-Earth System coupled climate model significantly improves what have been considered longstanding and apparently intractable model biases. Monsoon precipitation biases over all continental land areas, the penetration of monsoon rainfall across the Sahel, the West African monsoon "jump", and indicators of hurricane frequency are all significantly improved. Mechanistically, equilibrating hemispheric albedos improves the atmospheric cross-equatorial energy transport and increases the supply of tropical atmospheric moisture to the Hadley cell. We conclude that an accurate representation of the cross-equatorial energy transport appears to be critical if tropical performance is to be improved
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Forecasting the monsoon on daily to seasonal timeāscales in support of a field campaign
The successful planning and execution of a major field campaign relies on the availability and reliability of weather forecasts on a range of timeāscales. Here, we describe the wide range of forecast products generated in support of a field campaign that took place in India in 2016 as part of the Interaction of Convective Organization with Monsoon Precipitation, Atmosphere, Surface and Sea (INCOMPASS) project. We show examples of the suite of plots generated every day from the forecasts and supplied to the mission scientists, and describe how these were used to plan the flights. We highlight the benefits of having access to forecasts from a range of model resolutions and configurations; these allowed judgements to be made about uncertainty, particularly in the amount and location of deep convective rainfall, which is an important consideration for flight planning. Finally, we discuss the legacy of the forecasting activity, which has not only advanced our understanding of monsoon forecasting but also created a large database of targeted model forecast products for the whole of the 2016 monsoon season. These can be used by researchers for comparisons with in situ observations as well as future modelling studies
The impact of equilibrating hemispheric albedos on tropical performance in the HadGEM2-ES coupled climate model
The Earth's hemispheric reflectances are equivalent to within Ā± 0.2 Wm-2, even though the Northern Hemisphere contains a greater proportion of higher reflectance land areas, because of greater cloud cover in the Southern Hemisphere. This equivalence is unlikely to be by chance, but the reasons are open to debate. Here we show that equilibrating hemispheric albedos in the Hadley Centre Global Environment Model version 2-Earth System coupled climate model significantly improves what have been considered longstanding and apparently intractable model biases. Monsoon precipitation biases over all continental land areas, the penetration of monsoon rainfall across the Sahel, the West African monsoon 'jump', and indicators of hurricane frequency are all significantly improved. Mechanistically, equilibrating hemispheric albedos improves the atmospheric cross-equatorial energy transport and increases the supply of tropical atmospheric moisture to the Hadley cell. We conclude that an accurate representation of the cross-equatorial energy transport appears to be critical if tropical performance is to be improved
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