Influence of cloud microphysics schemes on weather model predictions of heavy precipitation

Cloud microphysics is one of the major sources of uncertainty in numerical weather prediction models. In this work, the ability of a numerical weather prediction model to correctly predict high-impact weather events, i.e., hail and heavy rain, using different cloud microphysics schemes is evaluated statistically. Polarimetric C-band radar observations over 30 convection days are used as observation dataset. Simulations are made using the regional-scale Weather Research and Forecasting Model (WRF) with five microphysical schemes of varying complexity (double moment, spectral bin (SBM), and particle property prediction (P3)). Statistical characteristics of heavy rain and hail events of varying intensities are compared between simulations and observations. All simulations, regardless of the microphysical scheme, predict heavy rain events that cover larger average areas than those observed by radar. The frequency of these heavy rain events is similar to radar-measured heavy rain events, but still scatters by a factor of 2 around the observations, depending on the microphysical scheme. The model is generally unable to simulate extreme hail events with reflectivity thresholds of 55 dBZ and higher, although they have been observed by radar during the evaluation period. For slightly weaker hail/graupel events, only the P3 model is able to reproduce the observed statistics. Analysis of the raindrop size distribution in combination with the model mixing ratio shows that the P3, Thompson 2-mom, and Thompson aerosol-aware models produce large raindrops too frequently, and the SBM model misses large rain and graupel particles.</p

Einfluss unterschiedlicher Belastungsprotokolle und exogener Stressfaktoren auf ausgewählte kardio-vaskuläre, metabolische und hormonelle Belastungsmarker

Einleitung: Die Leistungsentwicklung deutscher Athleten/ -innen ist in den letzten Jahren, vor allem in Disziplinen, in denen ein hohes Niveau der Ausdauerleistungsfähigkeit vorhanden sein muss, im Vergleich zur Entwicklung derer in der Weltspitze als rückläufig einzustufen. In einer Untersuchung des konditionellen Leistungsstatus von Nachwuchskadersportlern konnte das Niveau der Leistungsfähigkeit als unzureichend eingestuft werden. Es zeigt sich, dass wichtige Zubringervariablen der kardiopulmonalen Leistungsfähigkeit (z.B. die maximale Sauerstoffaufnahme [VO2peak]) bereits im Nachwuchsbereich für ein zu geringes Leistungspotential aufweisen und es damit nahezu unmöglich ist im weiteren Karriereverlauf Leistungen auf dem Niveau der Weltspitze zu erreichen. Um Anschluss an die Weltspitze zu erlangen, bedarf es im Nachwuchsbereich neuer Konzepte im Bereich der Trainingsmaßnahmen. Als übergeordnete Reizdefinitoren einer genauen Beschreibung/ Quantifizierung von hoch intensivem Intervalltraining spielen vor allem die Variablen Reizquantität (Umfang) und Reizqualität (Intensität) eine essentielle Rolle. Das Ziel dieser Arbeit war es, durch die externe Modulation von Stimuli (u. a. pH-Wert, O2-Gehalt, etc.) Informationen über Wirkungsmechanismen verschiedener Trainingsregime zu generieren, um Hinweise für die Gestaltung und ggf. Verbesserung von Trainingsinhalten ableiten zu können. Methoden: Um zusätzlich ein besseres Verständnis von den Mechanismen von Ausdauertraining zu bekommen, wurden in mehreren Studien metabolische Stimuli moduliert. Zur Modulation des pH-Wertes in-vivo wurden zwei unterschiedliche Ansätze gewählt. Zum einen wurde durch eine orale Gabe von Natriumbikarbonat der pH-Wert akut vor einer hoch intensiven Intervalltrainingseinheit erhöht. Zum anderen wurde der pH-Wert über eine Trainingsperiode von zwei Wochen durch unterschiedliche Pausengestaltungen (aktive vs. passive Pause) moduliert. Weiterhin wurde die hormonelle Reaktion zu Beginn und am Ende einer zwei-wöchigen, hoch intensiven Trainingsperiode auf mögliche Anpassungserscheinungen untersucht. Ergebnisse: Es zeigte sich, dass die in-vivo Modulation des pH-Wertes durch eine orale Gabe von Bikarbonat während wiederholten, hoch intensiven Sprints eine Leistungssteigerung bewirkt, obwohl der Transport von Laktat und H+-Ionen in die Erythrozyten und damit weg vom Ort der Entstehung unbeeinflusst bleibt. Eine weitere in-vivo Modulation des pH-Wertes durch Modifikation der Pausengestaltung (aktive vs. passive Pause) innerhalb hoch intensiver Intervalle über einen längeren Zeitraum führte zu einer Verbesserung der Leistung im Zeitfahren und der Peak Power im Rampentest. Ausgehend von den hormonellen Reaktionen zu Beginn und am Ende eines zweiwöchigen Schockmikrozyklus mit ausschließlich hoch intensiven Trainingseinheiten, scheint der ausgelöste Reiz auch am Ende vergleichbar zu sein mit dem Reiz zu Beginn der Trainingsperiode. Zusammenfassung/ Diskussion: Die Ergebnisse der durchgeführten Studien liefern Informationen für die Gestaltung von hoch intensiven Trainingseinheiten und Trainingsperioden. Sie zeigen, dass während hoch intensivem Training nicht nur die Intervalle, sondern auch die Gestaltung der Pausen berücksichtigt werden muss. Ausgehend vom Leistungsabfall während einer hoch intensiven Intervalltrainingseinheit scheint es für die Leistung besser zu sein, eine aktive Pausengestaltung zu wählen. Demgegenüber stehen die Ergebnisse des zwei-wöchigen HIT-Schockmikrozyklus mit aktiver vs. passiver Pause. Um langfristig eine höhere Leistungssteigerung zu provozieren, scheint eine passive Pausengestaltung einen größeren Vorteil als eine aktive Pausengestaltung zu bringen. Die Ergebnisse der Hormonuntersuchungen im Laufe des HIT-Schockmikrozyklus zeigen, dass die Blockung hoch intensiver Inhalte aus endokrinologischer Sicht nicht sinnvoll erscheint, da sich keine Gewöhnungen in den präsentierten Daten gezeigt haben. Für Verbesserungen der Leistungsfähigkeit sind akute Reaktionen des hormonellen Systems wichtiger als eine lange Phase von gleichbleibend hohen Hormonspiegeln

SEMG MEASUREMENTS ON LAND AND IN WATER PRIOR TO AND AFTER 60- 90 MINUTES OF SUBMERSION (SWIMMING) ARE HIGHLY RELIABLE

The purpose of this study was to investigate the reliability of surface electromyography (sEMG) measurements after being submerged (swimming) for 60-90 minutes. Isometric maximal voluntary contractions (MVC) on land and in water were collected of eight muscles in three males and three females (mean age 22.5±4.5 years). A paired samples t-test showed no significant differences in the mean MVC signal between pre and post test after prolonged water submersion (

Evaluation of convective cloud microphysics in numerical weather prediction models with dual-wavelength polarimetric radar observations: methods and examples

The representation of cloud microphysical processes contributes substantially to the uncertainty of numerical weather simulations. In part, this is owed to some fundamental knowledge gaps in the underlying processes due to the difficulty of observing them directly. On the path to closing these gaps, we present a setup for the systematic characterization of differences between numerical weather model and radar observations for convective weather situations. Radar observations are introduced which provide targeted dual-wavelength and polarimetric measurements of convective clouds with the potential to provide more detailed information about hydrometeor shapes and sizes. A convection-permitting regional weather model setup is established using five different microphysics schemes (double-moment, spectral bin ("Fast Spectral Bin Microphysics", FSBM), and particle property prediction (P3)). Observations are compared to hindcasts which are created with a polarimetric radar forward simulator for all measurement days. A cell-tracking algorithm applied to radar and model data facilitates comparison on a cell object basis. Statistical comparisons of radar observations and numerical weather model runs are presented on a data set of 30 convection days. In general, simulations show too few weak and small-scale convective cells. Contoured frequency by altitude diagrams of radar signatures reveal deviations between the schemes and observations in ice and liquid phase. Apart from the P3 scheme, high reflectivities in the ice phase are simulated too frequently. Dual-wavelength signatures demonstrate issues of most schemes to correctly represent ice particle size distributions, producing too large or too dense graupel particles. Comparison of polarimetric radar signatures reveals issues of all schemes except the FSBM to correctly represent rain particle size distributions

Molecular phylogeny and taxonomic revision of the sportive lemurs (Lepilemur, Primates)

BACKGROUND: The number of species within the Malagasy genus Lepilemur and their phylogenetic relationships is disputed and controversial. In order to establish their evolutionary relationships, a comparative cytogenetic and molecular study was performed. We sequenced the complete mitochondrial cytochrome b gene (1140 bp) from 68 individuals representing all eight sportive lemur species and most major populations, and compared the results with those obtained from cytogenetic studies derived from 99 specimens. RESULTS: Interspecific genetic variation, diagnostic characters and significantly supported phylogenetic relationships were obtained from the mitochondrial sequence data and are in agreement with cytogenetic information. The results confirm the distinctiveness of Lepilemur ankaranensis, L. dorsalis, L. edwardsi, L. leucopus, L. microdon, L. mustelinus, L. ruficaudatus and L. septentrionalis on species level. Additionally, within L. ruficaudatus large genetic differences were observed among different geographic populations. L. dorsalis from Sahamalaza Peninsula and from the Ambanja/Nosy Be region are paraphyletic, with the latter forming a sister group to L. ankaranensis. CONCLUSION: Our results support the classification of the eight major sportive lemur taxa as independent species. Moreover, our data indicate further cryptic speciation events within L. ruficaudatus and L. dorsalis. Based on molecular data we propose to recognize the sportive lemur populations from north of the Tsiribihina River, south of the Betsiboka River, and from the Sahamalaza Peninsula, as distinct species

High-intensity interval training improves VO2peak, maximal lactate accumulation, time trial and competition performance in 9–11-year-old swimmers

Training volume in swimming is usually very high when compared to the relatively short competition time. High-intensity interval training (HIIT) has been demonstrated to improve performance in a relatively short training period. The main purpose of the present study was to examine the effects of a 5-week HIIT versus high-volume training (HVT) in 9–11-year-old swimmers on competition performance, 100 and 2,000 m time (T100 m and T2,000 m), VO2peak and rate of maximal lactate accumulation (Lacmax). In a 5-week crossover study, 26 competitive swimmers with a mean (SD) age of 11.5 ± 1.4 years performed a training period of HIIT and HVT. Competition (P < 0.01; effect size = 0.48) and T2,000 m (P = 0.04; effect size = 0.21) performance increased following HIIT. No changes were found in T100 m (P = 0.20). Lacmax increased following HIIT (P < 0.01; effect size = 0.43) and decreased after HVT (P < 0.01; effect size = 0.51). VO2peak increased following both interventions (P < 0.05; effect sizes = 0.46–0.57). The increases in competition performance, T2,000 m, Lacmax and VO2peak following HIIT were achieved in significantly less training time (~2 h/week)

Position statement and updated international guideline for safe and effective whole-body electromyostimulation training-the need for common sense in WB-EMS application

Whole-Body Electromyostimulation (WB-EMS) is a training technology that enables simultaneous stimulation of all the main muscle groups with a specific impulse intensity for each electrode. The corresponding time-efficiency and joint-friendliness of WB-EMS may be particularly attractive for people unable or unmotivated to conduct (intense) conventional training protocols. However, due to the enormous metabolic and musculoskeletal impact of WB-EMS, particular attention must be paid to the application of this technology. In the past, several scientific and newspaper articles reported severe adverse effects of WB-EMS. To increase the safety of commercial non-medical WB-EMS application, recommendations “for safe and effective whole-body electromyostimulation” were launched in 2016. However, new developments and trends require an update of these recommendations to incorporate more international expertise with demonstrated experience in the application of WB-EMS. The new version of these consensus-based recommendations has been structured into 1) “general aspects of WB-EMS”, 2) “preparation for training”, recommendations for the 3) “WB-EMS application” itself and 4) “safety aspects during and after training”. Key topics particularly addressed are 1) consistent and close supervision of WB-EMS application, 2) mandatory qualification of WB-EMS trainers, 3) anamnesis and corresponding consideration of contraindications prior to WB-EMS, 4) the participant’s proper preparation for the session, 5) careful preparation of the WB-EMS novice, 6) appropriate regeneration periods between WB-EMS sessions and 7) continuous interaction between trainer and participant at a close physical distance. In summary, we are convinced that the present guideline will contribute to greater safety and effectiveness in the area of non-medical commercial WB-EMS application

Commentaries on viewpoint : physiology and fast marathons

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