Terrestrial Circulation Research Articles

Quasinormal scale elimination theory of the anisotropic energy spectra of atmospheric and oceanic turbulence

Quasinormal scale elimination theory of rotating turbulence offers a new explanation of physics governing atmospheric and oceanic spectra including the well-known Nastrom and Gage spectra observed in the upper troposphere and lower stratosphere. The terrestrial circulations may be characterized as flows with ``compactified dimensionality'' (spatial dimension between 2 and 3). Such flows may have both inverse and direct cascades in the same inertial range (dual cascade) and their spectral amplitudes may be determined not by energy/enstrophy fluxes, but by the magnitude of the Coriolis parameter.

Evolutionary Exobiology II: investigating biological potential of synchronously-rotating worlds

AbstractPlanets that orbit M-class dwarf stars in their habitable zones are expected to become tidally-locked in the first billion years of their history. Simulations of potentially habitable planets orbiting K and G-class stars also suggest that many will become tidally-locked or become pseudo-synchronous rotators in a similar time frame where certain criteria are fulfilled. Simple models suggest that such planets will experience climatic regions organized in broadly concentric bands around the sub-stellar point, where irradiation is maximal. Here, we develop some of the quantitative, as well as the qualitative impacts of such climate on the evolutionary potential of life on such worlds, incorporating the effects of topography and ocean currents on potential biological diversity. By comparing atmospheric circulation models with terrestrial circulation and biological diversity, we are able to construct viable thought models of biological potential. While we await the generation of atmospheric circulation models that incorporate topography and varying subaerial landscape, these models can be used as a starting point to determine the overall evolutionary potential of such worlds. The planets in these thought-models have significant differences in their distribution of habitability that may not be apparent from simple climate modelling.

Zonostrophic turbulence

Geostrophic turbulence is a flow regime attained by turbulent, rotating, stably stratified fluids in near-geostrophic balance. When a small-scale forcing is present, flows in this regime may develop an inverse energy cascade. Geostrophic turbulence has been used in geophysical fluid dynamics as a relatively simple model of the large-scale planetary and terrestrial circulations. When the meridional variation of the Coriolis parameter (or a β-effect) is taken into account, the horizontal flow symmetry breaks down giving rise to the emergence of jet flows. In a certain parameter range, a new flow regime comes to life. Its main characteristics include strongly anisotropic kinetic energy spectrum and slowly evolving systems of alternating zonal jets. This regime is a subset of geostrophic turbulence and has been coined zonostrophic turbulence; it can develop both on a β-plane and on the surface of a rotating sphere. This regime was first discovered in computer simulations but later revealed in the laboratory experiments, in the deep terrestrial oceans, and on solar giant planets where it is believed to be the primary physical mechanism responsible for the generation and maintenance of the stable systems of alternating zonal jets. The hallmarks of zonostrophic turbulence are the anisotropic inverse energy cascade and complicated interaction between turbulence and Rossby–Haurwitz waves. Addressing the goals of the conference ‘Turbulent Mixing and Beyond’ that took place in August 2007 in Trieste, Italy, this paper exposes the regime of zonostrophic turbulence to a wide scientific community, provides a survey of this regime, elaborates its main characteristics, offers novel approaches to describe and understand this phenomenon, and discusses its applicability as a model of the large-scale planetary and terrestrial circulations.

Anisotropic turbulence and zonal jets in rotating flows with a β-effect

Abstract. Numerical studies of small-scale forced, two-dimensional turbulent flows on the surface of a rotating sphere have revealed strong large-scale anisotropization that culminates in the emergence of quasi-steady sets of alternating zonal jets, or zonation. The kinetic energy spectrum of such flows also becomes strongly anisotropic. For the zonal modes, a steep spectral distribution, E(n)=CZ (Ω/R)2 n-5, is established, where CZ=O(1) is a non-dimensional coefficient, Ω is the angular velocity, and R is the radius of the sphere, respectively. For other, non-zonal modes, the classical, Kolmogorov-Batchelor-Kraichnan, spectral law is preserved. This flow regime, referred to as a zonostrophic regime, appears to have wide applicability to large-scale planetary and terrestrial circulations as long as those are characterized by strong rotation, vertically stable stratification and small Burger numbers. The well-known manifestations of this regime are the banded disks of the outer planets of our Solar System. Relatively less known examples are systems of narrow, subsurface, alternating zonal jets throughout all major oceans discovered in state-of-the-art, eddy-permitting simulations of the general oceanic circulation. Furthermore, laboratory experiments recently conducted using the Coriolis turntable have basically confirmed that the lateral gradient of ''planetary vorticity'' (emulated via the topographic β-effect) is the primary cause of the zonation and that the latter is entwined with the development of the strongly anisotropic kinetic energy spectrum that tends to attain the same zonal and non-zonal distributions, −5 and , respectively, in both the slope and the magnitude, as the corresponding spectra in other environmental conditions. The non-dimensional coefficient CZ in the −5 spectral law appears to be invariant, , in a variety of simulated and natural flows. This paper provides a brief review of the zonostrophic regime. The review includes the discussion of the physical nature, basic mechanisms, scaling laws and universality of this regime. A parameter range conducive to its establishment is identified, and collation of laboratory and naturally occurring flows is presented through which the zonostrophic regime manifests itself in the real world.

Planetary Circulations: 3. The Terrestrial Quasi-Geostrophic Regime

Abstract The characteristics of the two-level quasi-geostrophic model are evaluated for a wide range of parameters in the terrestrial domain. Flow form is determined primarily by β (the Coriolis gradient) and by τD, (the time scale of the surface drag), acting through the influence of Rhines' transitional wave-number kβ = (β/2U)1/2 where U2 is the barotropic energy level. Two extreme types of circulation occur: jets when kβ is large, and gyres when wave propagation and drag are negligible. The present terrestrial circulation, in its quasi-geostrophic representation, is extremely efficient: the system can cope with increased heating rates without a significant rise in the pole-to-equator temperature differential. Although each hemisphere is, on occasion, near to transforming into a double-jet state, multi-jet circulations–corresponding to those in the Jovian regime–occur more readily at higher rotation rates. For the existing circulation to switch to a gyre form requires a large, unrealizable drop in surfa...

Planetary Circulations: 1. Barotropic Representation of Jovian and Terrestrial Turbulence

Abstract We seek the formative processes of the planetary circulations of Jupiter and Saturn. The study concentrates on examining whether processes known to control the terrestrial circulation, namely, two-dimensional turbulence and baroclinic instability, can produce Jovian circulations under Jovian conditions. The first numerical model involves a spherical barotropic vorticity equation subjected to a stochastic representation of baroclinic processes. The resulting solutions suggest that a strong affinity exists between the Jovian and terrestrial circulations. This leads to a reevaluation of terrestrial circulation theory from the broader perspective of parameter space. The solutions in the Jovian regime support the hypothesis that a variation of the Rhines effect—an interaction of the two-dimensional turbulence cascade and Rossby wave propagation—creates the pseudoaxisymmetry and scale Lβ=π(2U/β)½ of the bands (U is the rms zonal velocity, and β the northward gradient of the Coriolis force). The anisotr...

Climatic pulsations in inner Asia and correlations between sunspots and weather

Based on the author's experience with physics, it is suggested that scientiets in general can gain from reviewing earlier writings in a search for unduly ignored insights. The writings of Ellsworth Huntington have been unjustly condemned by geographers, many of whom, as a result, do not even believe in climatic change during history. Huntington's work in demonstrating the reality of historic climatic change in Inner Asia is reviewed, and contrasted with the inadequacy of the arguments of his critics. Certain criticisms of his similar views on Southwest Asia also are shown to be inadequate. Then a discussion of Huntington's ideas on sunspots as a major cause of climatic changes suggests ways in which climatic change specialists might achieve a more adequate theory correlating solar disturbances with terrestrial weather. Huntington has already achieved a clear success in correlating sunspot activity with planetary positions. His “solar-cyclonic” hypothesis correlates high sunspots with intensified terrestrial circulation and cyclonic storm activity. Although data from 1870 to the 1920's convinced him and others of his time that the sunspot-temperative correlation was negative, Huntington's heterochronic view of climatic cycles allows adaptation of the solar-cyclonic view to a positive sunspot-temperature correlation. A further possibility is a two-stage response of the atmosphere to solar disturbances. Thus, both initially increased storminess and ultimately increased temperature can result from increased sunspot activity. Beyond some rather high number, it has been found, additional sunspots may lower the value of the solar constant, and accordingly reverse the effect on storms and temperature.

SOME ASPECTS OF THE METEOROLOGY OF MARS

Abstract After a description of the important observational facts for Mars, a discussion is given of the probable vertical structure of the Martian atmosphere based upon the ideas of radiative equilibrium in the stratosphere and near convective equilibrium in the troposphere. The proposed tropopause temperature is low enough to cause condensation of CO2 and thus may explain the blue clouds of Mars. Radiometric observations of temperatures on Mars are used to delineate the surface temperature field, and this is combined with cloud drift observations to define the circulation pattern. Considerable resemblance to terrestrial circulation is found, but differences exist and are discussed.