by C. Schneider et al., April 2020 in FrontierEarthScience
The regional climate in Southernmost South America is heavily influenced by the proximity to the oceans. This generates rather weak seasonal cycles with cool to cold summers and moderate to cold winters, especially on the western Pacific side. Slightly more pronounced, continental seasonal cycles are observed in the East of the Andes. While annual mean air temperatures across the region are decreasing from North to South precipitation patterns show very pronounced east-west gradients. The distinctive gradients in precipitation are caused by the north-south striking mountain ranges of the Patagonian Andes, and the northwest-southeast stretching mountain chains of the Cordillera Darwin. Both mountain ranges enforce heavy precipitation on the west and southwest exposed flanks by uplift and dry foehn-like conditions on the leesides (e.g., Holmlund and Fuenzalida, 1995; Schneider et al., 2003; Rasmussen et al., 2007) which produces extremely high drying ratios (Escobar et al., 1992; Carrasco et al., 2002; Smith and Evans, 2007). At inter-annual to decadal time scales atmospheric teleconnections such as the El Niño Southern Oscillation (ENSO) (Schneider and Gies, 2004), Southern Annular Mode (SAM), and Pacific Decadal Oscillation (PDO) are influencing spatial and temporal patterns of both, precipitation and air temperature. For example, positive SAM modes (Garreaud, 2009; Weidemann, Sauter, Kilian et al.) and the PDO (Villalba et al., 2003) are associated with higher air temperatures. Langhamer et al. show that the source of precipitation in the Southern Andes also depends on these teleconnections.
An important aspect is that Patagonia and Tierra del Fuego, together with the sub-Antarctic islands are the only regions where direct proximity between Antarctica and land masses north of the Southern Ocean is given. Such linkages are for example explored with investigations by Hebel et al. on the biosphere and Oppedal et al. for the regional glacier history.
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by K. Richard, April 20, 2020 in NoTricksZone
Scientists now acknowledge cloud cover changes “control the Earth’s hydrological cycle”, “regulate the Earth’s climate”, and “dominate the melt signal” for the Greenland ice sheet via modulation of absorbed shortwave radiation. CO2 goes unmentioned as a contributing factor.
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by M. McCrae, April 21, 2020 in ClimateChangeDispatch
Our planet is constantly bathed in the winds coming off the blistering sphere at the center of our Solar System.
But even though the Sun itself is so ridiculously hot, once the solar winds reach Earth, they are hotter than they should be – and we might finally know why.
We know that particles making up the plasma of the Sun’s heliosphere cool as they spread out. The problem is that they seem to take their sweet time doing so, dropping in temperature far slower than models predict.
“People have been studying the solar wind since its discovery in 1959, but there are many important properties of this plasma which are still not well understood,” says physicist Stas Boldyrev from the University of Wisconsin–Madison.
“Initially, researchers thought the solar wind has to cool down very rapidly as it expands from the Sun, but satellite measurements show that as it reaches the Earth, its temperature is 10 times larger than expected.”
The research team used laboratory equipment to study moving plasma, and now think the answer to the problem lies in a trapped sea of electrons that just can’t seem to escape the Sun’s grip.
The expansion process itself has long been assumed to be subject to adiabatic laws, a term that simply means heat energy isn’t added or removed from a system.
This keeps the numbers nice and simple but assumes there aren’t places where energy slips in or out of the flow of particles.
Unfortunately, an electron’s journey is anything but simple, shoved around at the mercy of vast magnetic fields like a roller coaster from Hell. This chaos leaves plenty of opportunities for heat to be passed back and forth.
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La géologie, une science plus que passionnante … et diverse