An aerial netting study of insects migrating at high altitude over England

2004 ◽  
Vol 94 (2) ◽  
pp. 123-136 ◽  
Author(s):  
J.W. Chapman ◽  
D.R. Reynolds ◽  
A.D. Smith ◽  
E.T. Smith ◽  
I.P. Woiwod
Keyword(s):  
Global Warming ◽  
High Altitude ◽  
North Sea ◽  
Ground Level ◽  
Diel Periodicity ◽  
Tethered Balloon ◽  
Extensive Survey ◽  
Economic Significance ◽  
Large Populations ◽  
The Uk

AbstractDay and night sampling of windborne arthropods at a height of 200 m above ground was undertaken at Cardington, Bedfordshire, UK, during July 1999, 2000 and 2002, using a net supported by a tethered balloon. The results from this study are compared with those from the classic aerial sampling programmes carried out by Hardy, Freeman and colleagues over the UK and North Sea in the 1930s. In the present study, aerial netting was undertaken at night as well as daytime, and so the diel periodicity of migration could be investigated, and comparisons made with the results from Lewis and Taylor’s extensive survey of flight periodicity near ground level. In some taxa with day-time emigration, quite large populations could continue in high-altitude flight after dark, perhaps to a previously underrated extent, and this would greatly increase their potential migratory range. Any trend towards increases in night temperatures, associated with global warming, would facilitate movements of this type in the UK. Observations on the windborne migration of a variety of species, particularly those of economic significance or of radar-detectable size, are briefly discussed.

scholarly journals Adaptive strategies of high-flying migratory hoverflies in response to wind currents

2020 ◽  
Vol 287 (1928) ◽  
pp. 20200406 ◽  
Author(s):  
Boya Gao ◽  
Karl R. Wotton ◽  
Will L. S. Hawkes ◽  
Myles H. M. Menz ◽  
Don R. Reynolds ◽  
...  
Keyword(s):  
High Altitude ◽  
Ground Level ◽  
Adaptive Strategies ◽  
Sufficient Accuracy ◽  
Wind Drift ◽  
Complex Behaviour ◽  
Complex Orientation ◽  
Prevailing Direction ◽  
The Uk ◽  
Wind Currents

Large migrating insects, flying at high altitude, often exhibit complex behaviour. They frequently elect to fly on winds with directions quite different from the prevailing direction, and they show a degree of common orientation, both of which facilitate transport in seasonally beneficial directions. Much less is known about the migration behaviour of smaller (10–70 mg) insects. To address this issue, we used radar to examine the high-altitude flight of hoverflies (Diptera: Syrphidae), a group of day-active, medium-sized insects commonly migrating over the UK. We found that autumn migrants, which must move south, did indeed show migration timings and orientation responses that would take them in this direction, despite the unfavourability of the prevailing winds. Evidently, these hoverfly migrants must have a compass (probably a time-compensated solar mechanism), and a means of sensing the wind direction (which may be determined with sufficient accuracy at ground level, before take-off). By contrast, hoverflies arriving in the UK in spring showed weaker orientation tendencies, and did not correct for wind drift away from their seasonally adaptive direction (northwards). However, the spring migrants necessarily come from the south (on warm southerly winds), so we surmise that complex orientation behaviour may not be so crucial for the spring movements.

scholarly journals Simultaneous generalized and low-layer SCIDAR turbulence profiles at san pedro mártir observatory

2019 ◽  
Vol 490 (1) ◽  
pp. 1397-1405 ◽  
Author(s):  
R Avila ◽  
O Valdés-Hernández ◽  
L J Sánchez ◽  
I Cruz-González ◽  
J L Avilés ◽  
...  
Keyword(s):  
High Altitude ◽  
Wind Direction ◽  
Close Agreement ◽  
Baja California ◽  
Ground Level ◽  
Combined Effect ◽  
Moderate Altitude ◽  
San Pedro ◽  
Simultaneous Measurements

ABSTRACT We present optical turbulence profiles obtained with a Generalized SCIDAR (G-SCIDAR) and a low-layer SCIDAR (LOLAS) at the Observatorio Astronómico Nacional in San Pedro Mártir (OAN-SPM), Baja California, Mexico, during three observing campaigns in 2013, 2014, and 2015. The G-SCIDAR delivers profiles with moderate altitude-resolution (a few hundred metres) along the entire turbulent section of the atmosphere, while the LOLAS gives high altitude resolution (on the order of tens of metres) but only within the first few hundred metres. Simultaneous measurements were obtained on 2014 and allowed us to characterize in detail the combined effect of the local orography and wind direction on the turbulence distribution close to the ground. At the beginning of several nights, the LOLAS profiles show that turbulence peaks between 25 and 50 m above the ground, not at ground level as was expected. The G-SCIDAR profiles exhibit a peak within the first kilometre. In 55 per cent and 36 per cent of the nights stable layers are detected between 10 and 15 km and at 3 km, respectively. This distribution is consistent with the results obtained with a G-SCIDAR in 1997 and 2000 observing campaigns. Statistics computed with the 7891 profiles that have been measured at the OAN-SPM with a G-SCIDAR in 1997, 2000, 2014, and 2015 campaigns are presented. The seeing values calculated with each of those profiles have a median of 0.79, first and third quartiles of 0.51 and 1.08 arcsec, which are in close agreement with other long term seeing monitoring performed at the OAN-SPM.

scholarly journals Évolution des parois rocheuses gelées de haute montagne sous forçage climatique

2020 ◽  
pp. 034
Author(s):  
Ludovic Ravanel ◽  
Florence Magnin ◽  
Xavi Gallach ◽  
Philip Deline
Keyword(s):  
Global Warming ◽  
High Altitude ◽  
Recent Work ◽  
Time Scales ◽  
Heat Waves ◽  
High Mountain ◽  
Permafrost Degradation ◽  
Geomorphological Processes ◽  
Different Time Scales ◽  
Mont Blanc Massif

Avec le réchauffement du climat, la dégradation du permafrost est à l'origine d'une intensification des processus géomorphologiques sur les versants de haute montagne. Dans les parois rocheuses, les écroulements se multiplient et leur volume augmente, posant des problèmes de sécurité non seulement à haute altitude (infrastructures, alpinistes), mais également pour les fonds de vallée. Cet article présente les travaux récemment menés dans le massif du Mont-Blanc sur la relation entre climat et écroulements à différentes échelles de temps, les effets des épisodes caniculaires et la répartition et l'évolution du permafrost de paroi. Under global warming, permafrost degradation tends to intensify geomorphological processes on high mountain slopes. In the perennially frozen rock walls, the number and volume of rockfalls is increasing, causing safety problems not only at high altitude (infrastructure, mountaineers) but also for the valleys. This article summarizes recent work carried out in the Mont-Blanc massif on the climate-rockfall relationship at different time scales, the effects of heat waves, and the distribution/evolution of rock wall permafrost.

scholarly journals Efficient Bayesian inference of fully stochastic epidemiological models with applications to COVID-19

2021 ◽  
Vol 8 (8) ◽  
pp. 211065
Author(s):  
Yuting I. Li ◽  
Günther Turk ◽  
Paul B. Rohrbach ◽  
Patrick Pietzonka ◽  
Julian Kappler ◽  
...  
Keyword(s):  
Bayesian Inference ◽  
Information Matrix ◽  
Monte Carlo Sampling ◽  
Epidemiological Models ◽  
Large Populations ◽  
Model Evidence ◽  
Age Structured ◽  
The Uk ◽  
Functional Central Limit

Epidemiological forecasts are beset by uncertainties about the underlying epidemiological processes, and the surveillance process through which data are acquired. We present a Bayesian inference methodology that quantifies these uncertainties, for epidemics that are modelled by (possibly) non-stationary, continuous-time, Markov population processes. The efficiency of the method derives from a functional central limit theorem approximation of the likelihood, valid for large populations. We demonstrate the methodology by analysing the early stages of the COVID-19 pandemic in the UK, based on age-structured data for the number of deaths. This includes maximum a posteriori estimates, Markov chain Monte Carlo sampling of the posterior, computation of the model evidence, and the determination of parameter sensitivities via the Fisher information matrix. Our methodology is implemented in PyRoss, an open-source platform for analysis of epidemiological compartment models.

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