Abstract
Abstract Satellite data enabled the Intergovernmental Panel on Climate Change (IPCC), through Report V, to indicate that the regional distribution of sea ice has been reducing in the Northern hemisphere high latitudes. This study assimilated that reduction into a general circulation model of intermediate complexity to simulate the tropical rainfall response. The Northern hemisphere tropospheric wind field simulations presented a clear similarity to the Northern Annular Mode negative phase. In particular, the meridional wind anomalies of the Northern hemisphere Ferrel cell suggest that the energy upsurge due to the boreal sea ice decrease results in an increase in the amplitude of the Rossby waves, thus connecting the polar zone to the tropics. The 500 hPa vertical motion and the rainfall distribution in the tropical belt simulations show a southward displacement of the Atlantic Intertropical Convergence Zone and also the South Atlantic Convergence Zone. Although several studies indicate the Intertropical Convergence Zone is shifted towards the hemisphere most heated by climatic variations, the apparent disagreement with our results can be understood by considering that some continental sectors in the Northern Hemisphere mid-latitudes have shown cooling in recent years, probably in response to the boreal sea ice decrease.
Highlights
Otto Corrêa Rotunno Filho Programa de Engenharia Civil, COPPE, Universidade Federal do Rio de Janeiro, Av
The atmospheric model SPEEDY was fed with boundary condition files, derived from ERA Interim, the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis, in order to determine the fluxes of momentum, heat and moisture at the surface, and the flux of incoming solar radiation at the top of the atmosphere
The modelled behaviour of the meridional wind component at 850 and 200 hPa was analysed, as shown in Figures 2 and 3, for the so-called Intergovernmental Panel on Climate Change (IPCC) and Radical simulations implemented in the SPEEDY model
Summary
Otto Corrêa Rotunno Filho Programa de Engenharia Civil, COPPE, Universidade Federal do Rio de Janeiro, Av. The connection between polar energy balance variations and tropical atmospheric behaviour occurs through teleconnections, which denote significant temporal correlations between meteorological parameter fluctuations at distant points These correlations allow establishment of relationships between apparently unrelated climatic anomalies at great distances. Journal of Water and Climate Change | 11.1 | 2020 hemisphere mid-latitude continental regions It is clear the sea ice coverage reduction in the polar regions increases the heat flow from the ocean to the atmosphere, but several studies show that recent atmospheric circulation anomalies resemble the Northern Annular Mode (NAM) negative phase and the North Atlantic Oscillation (NAO) negative phase, along with warming in more Northern latitudes (Takaya & Nakamura ; Vihma ; Nakamura et al ; Ruggieri et al , among other studies). Nakamura et al ( ) have found evidence that the recent decline in Arctic sea ice results in cold winters in mid-latitude continental regions, associated with an abnormal circulation pattern similar to both NAM and NAO negative phases, and the frequency of these teleconnection negative patterns has increased
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