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.

Climate and the ocean circulation

Abstract: The ocean model used in a calculation of the earth's climate is described in detail. Compared with earlier numerical models used in ocean circulation studies, the present model includes several new features. Temperature and salinity are treated separately. Density is calculated with an accurate equation of state for sea water. The model also includes a method for calculating the growth and movement of sea ice. Due to the very slow adjustment of the deep water in the ocean model, a numerical integration extending over the equivalent of a century fails to reach a climatic equilibrium. At the termination of the run, the surface layers of the ocean show little change with respect to time, but the average heating rate for the ocean as a whole is 2° per century. The salinity patterns at the termination of the run are highly realistic compared to observations. A halocline forms in the Arctic Zone and a surface salinity maximum is present in the subtropics. A weak salinity minimum at a depth of 1 km indi...

Climatology of the SKYHI Troposphere–Stratosphere–Mesosphere General Circulation Model

Abstract: The long-term mean climatology obtained from integrations conducted with different resolutions of the GFDL “SKYHI” finite-difference general circulation model is examined. A number of improvements that have been made recently in the model are also described. The versions considered have 3° × 3.6°, 2° × 2.4°, and 1° × 1.2° latitude–longitude resolution, and in each case the model is run with 40 levels from the ground to 0.0096 mb. The integrations all employ a fixed climatological cycle of sea surface temperature. Over 25 years of integration with the 3° model and shorter integrations with the higher-resolution versions are analyzed. Attention is focused on the December–February and June–August periods. The model does a reasonable job of representing the atmospheric flow in the troposphere and lower stratosphere. The simulated tropospheric climatology has an interesting sensitivity to horizontal resolution. In common with several spectral GCMs that have been examined earlier, the surface zonal-mea...

Local and Global Baroclinic Instability of Zonally Varying Flow

Abstract: The baroclinic instability characteristics of zonally inhomogeneous basic states are examined with the intent of clarifying the factors governing the regional distribution of cyclogenesis The vertical shear of the basic state wind is allowed to vary gradually in the zonal direction, so as to permit the representation of zonally localized regions of high baroclinicity The resulting eigenvalue problem is solved directly by numerical means and also analytically via a WKB analysis It was established that flows with localized baroclinicity can support two distinct classes of unstable modes, which we call “local” and “global” The local modes have peak amplitude downstream of the point of maximum baroclinicity, decay to zero exponentially upstream and downstream of the peak and do not require zonally periodic boundary conditions for their existence The growth rate of a local mode is equal to the absolute growth rate (in the sense of Merkine) determined locally at the point of maximum shear The abs

The Climatology of Relative Humidity in the Atmosphere

Abstract: The present paper deals with the analysis of the time-average relative humidity fields in the atmosphere. Twice-daily estimates of relative humidity are used. After some theoretical considerations on the relations between relative humidity, other moisture parameters, and temperature, a critical analysis of the various sources of data is made considering their possible limitations. Various methods of computing relative humidity are formulated and discussed. The global distribution of relative humidity at various levels shows that it is not zonally uniform with centers of various intensities at all latitudes. The global maps show maxima in the equatorial zone and minima in the dry subtropical belts around 30°N and 30°S. The land–sea contrast and variations related to the orographic relief are also apparent. The general pattern of relative humidity is similar at all levels but its magnitude decreases with altitude. The seasonal analyses show a similar pattern as the annual analyses but are slightly ...

Algorithms for Density, Potential Temperature, Conservative Temperature, and the Freezing Temperature of Seawater

Abstract: Algorithms are presented for density, potential temperature, conservative temperature, and the freezing temperature of seawater. The algorithms for potential temperature and density (in terms of potential temperature) are updates to routines recently published by McDougall et al., while the algorithms involving conservative temperature and the freezing temperatures of seawater are new. The McDougall et al. algorithms were based on the thermodynamic potential of Feistel and Hagen; the algorithms in this study are all based on the “new extended Gibbs thermodynamic potential of seawater” of Feistel. The algorithm for the computation of density in terms of salinity, pressure, and conservative temperature produces errors in density and in the corresponding thermal expansion coefficient of the same order as errors for the density equation using potential temperature, both being twice as accurate as the International Equation of State when compared with Feistel’s new equation of state. An inverse function relating potential temperature to conservative temperature is also provided. The difference between practical salinity and absolute salinity is discussed, and it is shown that the present practice of essentially ignoring the difference between these two different salinities is unlikely to cause significant errors in ocean models.