• Translation


Aérologie in a heated climate

Courtesy of the author (Vincent Chanderot), I warmly thank, I publish here a reflection on climate change, and its potential impact on our business.

Climate change promises many upheavals, as you would expect, also will impact the free flight. Doubts remain about the amplitudes and deadlines, depending on the involvement of everyone in the transition to a low-carbon living. COP 21 of Paris expressed the wish to limit to + 1.5 ° C warming at the end of century, but indicators rather promise the prospect of + 3 ° C if its provisions are complied with, or even more than 5 ° C in less optimistic scenarios.

five degrees, it is not much, yet it is the average global temperature between now and the last Ice Age, during which ran until the winter ice France. Beyond the weather phenomena out of control associated with a change of this magnitude is the question of adaptation to his brutality. For it is here question of a few years of transition, when this is thousands of years that agencies arranged to adapt to previous climate change. Will there be birds still wrap thermal or they will disappear in favor of locusts, mosquitoes tigers or parrots islands ? These rapid changes in the environment require adaptations, migrations (when there are other niches and corridors; in humans it seems more complicated) and often death. Faced with such challenges, an interest in flying conditions in the future may seem trivial, Yet we address the issue since many of us still will fly when the atmosphere has already taken 2 ° C. They will find here may be some reasons to enjoy what we have in making sure not to worsen the situation.

European climate in mid-century

Today it is difficult to predict the effectiveness of policy responses or citizens of tomorrow to save the climate. However, dynamics being launched, several studies estimate that the average global reach 2 ° C from the middle of the century, in a good twenty years. All climate models quickly promise major changes in average and extreme temperatures, precipitation and winds. The polar regions and those already vulnerable are likely to be most impacted, however much of Europe should undergo warming beyond the average[1]. The models, however, reveal large regional variability and it is certain that climate change will be very dependent effects Sites. In France, for example, warming in 30 years may be slightly lower than the European average despite stronger and more heat waves, with strong regional disparities with respect the multiplicity of hexagonal climates. The Mediterranean regions tend towards an Andalusian climate with very dry spells, which probably coexist with cévenols very intense rainfall events, as is often observed in recent years.

Will there beautiful tomorrow?

A climate warmed does not mean that time will be "better". It does not say that climate change is changing in favor or against the free flight. En effet, the surplus energy, although essentially absorbed by the oceans, most likely generate more intense atmospheric dynamics. Rain and wind, which are determining factors for paragliding will undergo changes. Local phenomena will add large-scale changes, such as (1) strengthening and northward shift of the Hadley cell that generates the Azores (2) The modification of the hall to storms (the Stormtrack) opened by the jet stream (3) The dominance of the NAO +, the positive phase of the North Atlantic Oscillation which reflects an important north-south pressure gradient. She could intensify again to generate, with a strong westerly flow, dry winters in the Mediterranean, but mild and rainy on the north side.

In the near time horizon (2020-2050), the models Aladin Météo France and WRF de l'IPSL[2], we can discover in detail on the portal Dria[3], converge for all scenarios to an overall increase of rainy days on the mountain regions. Of the Vosges whole year, and the Jura, which was, however, could benefit from a slight decrease in rainy days. More frequent rainfall are also provided on the Northern Alps, especially during the summer, to believe the model WRF. The Southern Alps, they could meet about a situation contrary, with a little less rain days, although the model of Météo France expects more wet summers in the transitional period from mid century. The models do not converge to the summers of the Pyrenean massif. his Falls, like those of Languedoc should be drier, while the spring would suffer the opposite fate, except in the Mediterranean part of the chain. Winters would generally tend to offer more days of rain, unfortunately without it being necessarily snowfall (whose stability on the slopes will also suffer from warming). Increasing the number of rainy days throughout the year could create another handicap : most regularly wet soils could be less favorable to regularly thermal conditions. The color of the sky could well not be more in favor of free flight, However, the French territory, high contrast, does not draw widespread. The years of transition to the harsher climate of the end of the century will suffer a significant interannual variability. The conditions encountered on the sites will probably enroll less in the tradition ...

More favorable winds

If there is concern about the power of storms, it seems that the speed of the wind can show daily is more favorable. A study by the CNRS[4] provides a strong regression of windy days and strong growth in low wind days, especially in the Mediterranean. The mistral could decrease, but Météo France can think up the frequency of the Autan wind, in response to increased endless South wind sequences of the Pyrenees, which generate an air call leeward chain. Reliance on models for complicated regions such as the Alps is limited, they envisage for the time significant changes down, but certainties. Throughout the area, the wind at 10m above sea level tend to decrease slightly over the summer but could experience a slight increase in winter in the Northwest of the country, for fans of soaring, aerate their wings between two rain, if erosion or stompers are staring down the sights by then.

Uncertainties on convection

Did they become exceptional thermal conditions standard ? The scorching summer of 2003, hottest to date (not to be confused with the warmest year was 2014 then 2015), offered anthology flights, whose first posed at the top of Mont Blanc. Ceilings exceeding 5000m presented themselves repeatedly to repeat this feat since and it could be that this is just the beginning, since these sweltering summers will soon have nothing exceptional. It is expected therefore to a higher surface warming and more powerful thermal, However, it is difficult to comment on all the favorable factors to usable heat. En effet, it is still many unknowns about the windshear, the layers of interest have not really investigated. The heat wave at ground level does not necessarily create good thermal, yet should he make it cooler in altitude. According to climatologist paraglider CNRS Etienne Terrenoire, the increase in sensible heat flux in the south and center of & rsquo; Europe should generate an increase in temperature gradients, but known that beyond -1 ° C per 100, they generate too strong updrafts, narrow and turbulent. The expected consequences of these powerful flows are higher inversions, higher ceilings. However, the likely expansion of the Hadley cell to the north could counteract this prognosis, due to a stronger subsidence. These high pressures, from 1020hPa, tend to slow down the heat and also make them very dry thermals, close to the ground conducive to closures.

Safety Issues

A more powerful anticyclone may remove thermal activity, forcing paragliders to take off in altitude, and when it will fall into place, it should arrive with more intensity. record conditions 2003 have apparently he showed the way : stronger and more agitated, they in return caused more injuries and deaths than ever. So will it be in future probably increase its driving level, eventually fall back on wisest wings and learn to choose with certainty the right conditions, because in convective systems most active, developments become less predictable for the observer and weather services.

Vincent Chanderot is environmental consultant

[1] The European climate under a 2°C global warming. Robert Vautard et al. Environemental Research Letters 2014

[2] Institut Pierre Simon Laplace : Institute of Environmental Science Research under the supervision of CNRS, CNES, THE, WRITE, ENS, Polytechnique, UPMC and 3 other universities.

[3] Meteo France/CNRS http://www.drias-climat.fr/decouverte/carte/experience?region=SAFRAN&generation=rcp

[4] Assessing climate change impacts on European wind energy from ENSEMBLES high-resolution climate projections Tobin et al. Climatic Change (2015)

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