نتایج جستجو برای: atmospheric circulation
تعداد نتایج: 162426 فیلتر نتایج به سال:
Large amplitude variations in atmospheric CO2 were associated with glacial terminations of the Late Pleistocene. Here we provide multiple lines of evidence suggesting that the ∼20 p.p.m.v. overshoot in CO2 at the end of Termination 2 (T2) ∼129 ka was associated with an abrupt (≤400 year) deepening of Atlantic Meridional Overturning Circulation (AMOC). In contrast to Termination 1 (T1), which wa...
Tropical Pacific sea surface temperature anomalies influence the atmospheric circulation, impacting climate far beyond the tropics. The predictability of the corresponding atmospheric signals is typically limited to less than 1 year lead time. Here we present observational and modelling evidence for multi-year predictability of coherent trans-basin climate variations that are characterized by a...
Global warming caused by an increase in the concentrations of greenhouse gases, is the direct result of greenhouse gas-induced radiative forcing. When a doubling of atmospheric carbon dioxide is considered, this forcing differed substantially among 15 atmospheric general circulation models. Although there are several potential causes, the largest contributor was the carbon dioxide radiation par...
Hyperdiffusion is used in atmospheric General Circulation Models to account for turbulent dissipation at subgrid scale and its intensity affects the efficiency of poleward heat transport by the atmospheric circulation. We perform sensitivity simulations with a dynamic-core GCM to investigate the effects of different intensities of hyperdiffusion and different model resolutions on the simulated ...
Atmospheric circulation leaves few direct traces in the geological record, making reconstructions of this crucial element of the climate system inherently difficult. We produced a regional Mediterranean synthesis of paleo-proxy data from the sea surface to alpine altitudes. This provides a detailed observational context for change in the three-dimensional structure of atmospheric circulation be...
In an analytical study the stability of the thermohaline circulation with respect to freshwater perturbations in high latitudes is investigated. The study is based on a coupled ocean and atmosphere box model in an idealized North Atlantic geometry. The box model provides a qualitative understanding of how the thermohaline circulation is a ected by feedback mechanisms associated with changes in ...
[1] The density structure across the Florida Straits is reconstructed for the last 8000 years from oxygen isotope measurements on foraminifera in sediment cores. The oxygen isotope measurements suggest that the density contrast across the Florida Current increased over this time period. The magnitude of this change corresponds to an increase in the geostrophic transport referenced to 800 m wate...
On account of the large thermal capacity of seawater and the slowly varying oceanic currents, the surface conditions of the world’s oceans typically fluctuate on timescales that are much longer than those of the atmosphere. Meteorologists have long regarded the surface properties of the oceans (in particular, sea surface temperature, or SST) as a prime candidate for inciting low-frequency atmos...
A fundamental difficulty in modeling global atmospheric circulation is the strong interaction among motions on a wide range of space and time scales. Explicit numerical representation of all the spatial scales that determine the global atmospheric circulation is impractical. An example of such difficulties is the effect of small-scale inertia-gravity waves on the circulation. Inertia-gravity wa...
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