Influence of Ocean–Atmosphere Interaction on the Arctic Oscillation in Two General Circulation Models
نویسنده
چکیده
The influence of ocean–atmosphere interaction on the wintertime Arctic oscillation (AO) is investigated using a hierarchy of experiments made with two general circulation models (GCMs), ranging from climatologically forced atmospheric to fully coupled ocean–atmosphere GCMs with increasing greenhouse gas concentrations. Both GCMs reproduce well the AO spatial pattern, defined by the leading hemispheric mode of monthly sea level pressure or daily 700-hPa geopotential height, although the North Pacific pole is more pronounced as compared with observations. Coupling is not found to influence this spatial pattern. Power spectra are examined for evidence of ocean–atmosphere interaction in the form of spectral reddening or significant spectral peaks. No measurable influence is found. On interannual timescales, all the model AO spectra are approximately ‘‘white,’’ with no clear evidence of any statistically significant spectral peaks in the coupled experiments. Greenhouse gas–induced changes in sea level pressure are found to project onto the AO in one of the GCMs but not the other. On subseasonal timescales, the spectra are ‘‘red’’ in all the model configurations, but ocean–atmosphere interaction is not found to amplify the redness. Significant spectral peaks are found in the 15–25-day period range, consistent with observed spectra. Daily histograms of the simulated AO indices are found to be negatively skewed. A Gaussian mixture model is used to estimate the probability density function of daily hemispheric height maps, and yields three circulation regimes in both the simulations and observed data. The uncoupled atmospheric GCM simulations exhibit AOlike regimes that acquire stronger wavelike characteristics in the coupled runs.
منابع مشابه
Evaluating the performance of Atmosphere-Ocean Global Circulation Models (AOGCM) in simulating temperature variable in Ahwaz and Abadan stations
Climate changes caused by global warming has presented challenges to human society. Studying the Changes of climate variables in the future decades by using output data’s of Atmosphere-Ocean Global Circulation Models (AOGCM) is a way of perusing climate fluctuation in a region. In this study, the focus is on the AOGCM proceeds in simulating of variable temperature in Ahwaz and Abadan stations. ...
متن کاملImplications of the recent trend in the Arctic/North Atlantic Oscillation for the North Atlantic thermohaline circulation
Most projections of greenhouse gas-induced climate change indicate a weakening of the thermohaline circulation (THC) in the North Atlantic in response to increased freshening and warming in the subpolar region. These changes reduce high latitude upper ocean density, and therefore weaken the THC. Using ensembles of numerical experiments with a coupled ocean-atmosphere model, it is found that thi...
متن کاملLETTERS Implications of the Recent Trend in the Arctic/North Atlantic Oscillation for the North Atlantic Thermohaline Circulation
Most projections of greenhouse gas–induced climate change indicate a weakening of the thermohaline circulation (THC) in the North Atlantic in response to increased freshening and warming in the subpolar region. These changes reduce high-latitude upper-ocean density and therefore weaken the THC. Using ensembles of numerical experiments with a coupled ocean–atmosphere model, it is found that this...
متن کاملInfluence of atmospheric circulation patterns on dust transport during Harmattan Period in West Africa
This study has used TOMS AI as well as the reanalysis dataset of thirty-four years (1979-2012) to investigate the influence of atmospheric circulation on dust transport during the Harmattan period in West Africa, using Aerosol Index (AI) data, obtained from various satellite sensors. Changes in Inter-Tropical Discontinuity (ITD), Sea Surface Temperature (SST) over the Gulf of Guinea, and North ...
متن کاملTropical ocean‐atmosphere controls on inter‐annual climate variability in the Cretaceous Arctic
[1] The first annually resolved sedimentary record from the Cretaceous is used to develop time series of inter‐annual and decadal scale climate variability from the Arctic Ocean. Analysis of records spanning 1000 years reveals strong periodicities in the quasi‐biennial oscillation and El Niño ‐ Southern Oscillation (ENSO) band as well as a 14 year period, which all closely match periodicities t...
متن کامل