Geophysical Fluid Dynamics Laboratory

About: Geophysical Fluid Dynamics Laboratory is a facility organization based out in Princeton, New Jersey, United States. It is known for research contribution in the topics: Climate model & Climate change. The organization has 525 authors who have published 2432 publications receiving 264545 citations. The organization is also known as: GFDL.

Mechanisms of Forced Tropical Meridional Energy Flux Change

Abstract: Anthropogenically forced changes to the mean and spatial pattern of sea surface temperatures (SSTs) alter tropical atmospheric meridional energy transport throughout the seasonal cycle—in total, its partitioning between the Hadley cells and eddies and, for the Hadley cells, the relative roles of the mass flux and the gross moist stability (GMS). The authors investigate this behavior using an atmospheric general circulation model forced with SST anomalies caused by either historical greenhouse gas or aerosol forcing, dividing the SST anomalies into two components: the tropical mean SST anomaly applied uniformly and the full SST anomalies minus the tropical mean.For greenhouse gases, the polar-amplified SST spatial pattern partially negates enhanced eddy poleward energy transport driven by mean warming. Both SST components weaken winter Hadley cell circulation and alter GMS. The Northern Hemisphere–focused aerosol cooling induces northward energy flux anomalies in the deep tropics, which manifest pa...

Cloud-radiative effects on implied oceanic energy transports as simulated by Atmospheric General Circulation Models

Abstract: This paper summarizes the ocean surface net energy flux simulated by fifteen atmospheric general circulation models constrained by realistically-varying sea surface temperatures and sea ice as part of the Atmospheric Model Intercomparison Project. In general, the simulated energy fluxes are within the very large observational uncertainties. However, the annual mean oceanic meridional heat transport that would be required to balance the simulated surface fluxes is shown to be critically sensitive to the radiative effects of clouds, to the extent that even the sign of the Southern Hemisphere ocean heat transport can be affected by the errors in simulated cloud-radiation interactions. It is suggested that improved treatment of cloud radiative effects should help in the development of coupled atmosphere-ocean general circulation models.

East‐west asymmetry in nonlinear internal waves from Luzon Strait

Abstract: The nonhydrostatic Regional Ocean Modeling System is applied to study the effects of thermocline shoaling/deepening, bathymetry, and asymmetric modulated tides on the soliton growth to the west and east of Luzon Strait in the South China Sea and western Pacific Ocean. Luzon Strait comprises a shallow east ridge and a deep west ridge, and its interaction with barotropic tidal currents yields strong westward internal tides that disperse into solitons. Satellite imagery indicates that the westward solitons are more numerous and better defined than the eastward solitons. The model results show that the eastward solitons are 45%, 39%, 28%, and 23% smaller than the westward solitons due to asymmetric modulated barotropic tides at the east ridge, a deeper Pacific Ocean, westward thermocline shoaling related to the Kuroshio current, and internal tide resonance in a double ridge configuration, respectively. Due to the westward location of the Kuroshio, little thermocline deepening occurs east of the east ridge. Hence, the influence of thermocline deepening on counteracting eastward soliton growth is small. The Kuroshio mainly enhances westward soliton growth. The dispersion of internal tides into solitons is governed by the balance between the nonlinearity parameter on the one hand and the nonhydrostatic and Coriolis dispersions on the other. It is shown that this balance favors soliton growth for thermocline shoaling, while it counters it for a deeper ocean. A series of double ridge experiments is performed, in which the distance between the ridges and the height of the west ridge are varied. For a semidiurnal tidal forcing and two Gaussian ridges separated by 100 km, barotropic to baroclinic energy conversion is enhanced at both ridges, causing larger westward internal tides and solitons. The combination of Coriolis forcing, thermocline shoaling, and a double ridge configuration enhances the distinctiveness of the so-called type a and b solitons when a modulated tide occurs.

GCM Response of Northern Winter Stationary Waves and Storm Tracks to Increasing Amounts of Carbon Dioxide

Abstract: The response of the Geophysical Fluid Dynamics Laboratory (GFDL) coupled ocean-atmosphere R15, 9-level GCM to gradually increasing C02 amounts is analyzed with emphasis on the changes in the stationary waves and storm tracks in the Northern Hemisphere wintertime troposphere. A large part of the change is described by an equivalent-barotropic stationary wave with a high over eastern Canada and a low over southern Alaska. Consistent with this, the Atlantic jet weakens near the North American coast. Perpetual winter runs of an R15, nine-level atmospheric GCM with sea surface temperature, sea ice thickness, and soil moisture values prescribed from the coupled GCM results are able to reproduce the coupled model's response qualitatively. Consistent with the weakened baroclinicity associated with the stationary wave change, the Atlantic storm track weakens with increasing C02 concentrations while the Pacific storm track does not change in strength substantially. An R15, nine-level atmospheric model line...

Importance of initial conditions in seasonal predictions of Arctic sea ice extent

Abstract: We present seasonal predictions of Arctic sea ice extent (SIE) over the 1982–2013 period using two suites of retrospective forecasts initialized from a fully coupled ocean-atmosphere-sea ice assimilation system. High skill scores are found in predicting year-to-year fluctuations of Arctic SIE, with significant correlations up to 7 month ahead for September detrended anomalies. Predictions over the recent era, which coincides with an improved observational coverage, outperform the earlier period for most target months. We find, however, a degradation of skill in September during the last decade, a period of sea ice thinning in observations. The two prediction models, Climate Model version 2.1 (CM2.1) and Forecast-oriented Low Ocean Resolution (FLOR), share very similar ocean and ice component and initialization but differ by their atmospheric component. FLOR has improved climatological atmospheric circulation and sea ice mean state, but its skill is overall similar to CM2.1 for most seasons, which suggests a key role for initial conditions in predicting seasonal SIE fluctuations.