As the Arctic warms faster than the mid-latitudes, the temperature difference between these regions is narrowing. Scientists hypothesized that under these so-called arctic amplification conditions, the jet stream would lose intensity and its meanders would migrate more slowly to the east, resulting in more consistent, even more extreme weather conditions. The persistence (persistence (statistics) persistence (computer science) in painting: The persistence of memory (1931) in medicine: the persistence of the ductus arteriosus persistence …) of weather conditions which can vary significantly during a season (the season) is a period of the year in which a relative constancy of the climate and temperature is observed. It lasts about three months (see table solstice and equinox …) and from one season to another. The assessment of long-term changes and thus this assumption is not easy.
Daily values of the phase velocity of waves (A wave is the propagation of a fault which, when passing through it, creates a reversible variation in local physical properties. It transports energy without transporting matter.) From Rossby in the mid-latitudes of the northern hemisphere (the north is a Cardinal point towards the south) in the last few decades. This quantity measures the persistence of weather conditions: high values are associated with fast-moving storms and low values are associated with stationary lows and highs. The seasonal averages (blue dots for winter, red for summer) show quite a large variability between the years, but no significant trend (blue and red lines).
To solve this problem, researchers from the Meteorological Laboratory (the subject of meteorology is the study of atmospheric phenomena such as clouds, precipitation or wind in the …) dynamics (the word dynamics is often used to denote or qualify this is relative to movement. It can be used as 🙂 I have developed a “tachometer (we distinguish 🙂 meteorological” based on spectral analysis (spectral analysis is a method used in physics to determine the properties of (an observed phenomenon. The intensity of the phenomenon as a function of time represents a signal, and this signal …) This counter enabled them to quantify the movements of the meanders of the jet stream (a jet stream, also commonly known by the English name jet stream, is a fast and limited airflow that is in the atmosphere up to …) over the middle latitudes of the northern hemi sphere in the last 40 years (between March 1979 and November 2018) and thus determine whether every day (The day or the day is the interval between sunset; it is the period between two nights when the sun’s rays light up the sky. Its beginning (compared to midnight time) and its duration …), meanders that spread out on average (the mean is a statistical measure that characterizes the elements of a set of quantities: it expresses the size that each member of the Crowd to the east would have …), stagnated or even retreated to the west (L ‘West is a cardinal point opposite east. This is the direction in which the sun sets (or ponant) at the equinox.).
The researchers confirm that periods of low jet velocity are related to the extreme temperatures over the northern mid-latitudes. However, they estimate that the spread of the meanders has not decreased overall in spite of the significant reduction in the southern temperature difference (temperature is a physical quantity that was measured with a thermometer and examined in thermometry .. In everyday life it has …) Observed for decades. Amplification (We’re talking about a booster for a whole range of systems that amplify the effort: mechanical, hydraulic, pneumatic, electrical.) Arctic (The Arctic is the region that surrounds the North Pole of the Earth, inside and on the edge of the Arctic Circle. It located opposite Antarctica. The Arctic encompasses part of Canada, …) would therefore not have played a decisive role in modulating the waves of the current -jet in the past few decades. These results suggest the need for a better understanding of the factors that make this Determine persistence of meteorological conditions and recall with caution that recent extreme weather conditions must be attributed to increased stagnation of the jet stream meanders.
1 – LMD / IPSL, CNRS (The National Center for Scientific Research, better known by the acronym CNRS, is the largest public public scientific research organization in France …) / École Polytechnique / Sorbonne (The Sorbonne is a monumental complex in the Latin Quarter of Paris. It takes its name from the 13th century theologian Robert de Sorbon, founder of the College of Sorbonne, college …) University (A university is a university whose aim is the production of knowledge (research), its preservation and transmission (studies etc.) / ENS Paris (Paris is a French city, the capital of France and the capital of the Île-de-France region. This city is built on a loop of the Seine in the center of the Paris basin between the confluences the Marne and the Seine in …) / École des Ponts ParisTech (ParisTech or Institut des Sciences et Technologies de Paris) is an institution that brings twelve together gt major engineering and business schools in paris ennes. The goal, initiated in 1991, is …)
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About the link between the Rossby wave phase (the word phase can have several meanings, it is used in different fields and mainly in physics 🙂 speed, atmospheric blockage and arctic reinforcement, Jacopo Riboldi, François Lott, Fabio D’Andrea, Gwendal Rivière (In hydrography, a river is a watercourse that flows under the influence of gravity and flows into another river or …), Geophysical Research Letters, Volume (The volume, in the natural sciences or in mathematics is a quantity which measures the extent of an object or part of the room.) 47, edition 19. https://doi.org/10.1029/2020GL087796
Jacopo Riboldi – LMD / IPSL – jacopo.riboldi at lmd.ens.fr
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