Rev. Dr. J. N. Cushing, Lecture on the Shans, edited by Michael Charney

Speech originally published in the Rangoon Gazette and Weekly Budget 26 October 1888, edited by Michael Charney for the SBBR

A study of the dynamics of the Intertropical Convergence Zone (ITCZ) in a symmetric atmosphere-ocean model

A numerical model of the circulation of a coupled axisymmetric atmosphere-ocean system was constructed to investigate the physical factors governing the location and intensity of the Intertropical Convergence Zone (ITCZ) over oceans and over land. The results of several numerical integrations are presented to illustrate the interaction of the individual atmospheric and oceanic circulations. It is shown that the ITCA cannot be located at the equator because the atmosphere-ocean system is unstable for lateral displacements of the ITCA from an equilibrium position at the equator

The generation of oceanic currents by wind

1. Introduction. In 1937 and 1938, C.-G. Rossby published results of investigations into the manner in which velocity and pressure adjust themselves in ocean currents. He showed that an initially unbalanced rectilinear current would execute transverse inertial oscillations in the process of creating the pressure field that is necessary to balance the Coriolis forces associated with its momentum...

Triple cascade behaviour in QG and drift turbulence and generation of zonal jets

We study quasigeostrophic (QG) and plasma drift turbulence within the Charney-Hasegawa-Mima (CHM) model. We focus on the zonostrophy, an extra invariant in the CHM model, and on its role in the formation of zonal jets. We use a generalized Fjørtoft argument for the energy, enstrophy, and zonostrophy and show that they cascade anisotropically into nonintersecting sectors in k space with the energy cascading towards large zonal scales. Using direct numerical simulations of the CHM equation, we show that zonostrophy is well conserved, and the three invariants cascade as predicted by the Fjørtoft argument

Mechanical Translation

Contains reports on two research projects.National Science Foundation (Grant G-24047

Disconnection clauses: an inevitable symptom of regionalism?

‘Disconnection clauses’ are legal provisions inserted into multilateral conventions to ensure that certain parties to the convention are not required to apply the rules of the convention because other relevant rules have already been agreed to among themselves. A disconnection clause can also be described more generally as a ‘conflict clause’ because it signals to all parties that parallel and potentially conflicting treaty obligations exist. This paper presents a discussion of the disconnection clause which argues that while these clauses make it possible for a limited group of parties to enhance the objectives of a treaty by taking measures that correspond to their special circumstance, this practice also creates a possibility that the inter se agreement will undermine the original treaty regime. The actual impact of a particular disconnection clause depends on how the clause is crafted, along with the changing nature of the regime that it refers to. The potential for a disconnection clause to undermine the object and purpose of the original treaty can therefore be removed during its design. Nevertheless, without full disclosure when negotiating the convention, any clause that seeks to replace treaty provisions with an alternative regime that would be applicable only between certain parties may, at worst, be creating different standards for different parties and, at best, be opaque and incoherent. This paper first describes the various types of disconnection clause, focusing on their purpose and development. It then assesses the main legal and political controversies surrounding these clauses before assessing whether these clauses could potentially create more legal problems than they are intended to solve or whether they are simply a practical response to deepening regionalism

Abelian subgroups of Garside groups

In this paper, we show that for every abelian subgroup $H$ of a Garside group, some conjugate $g^{-1}Hg$ consists of ultra summit elements and the centralizer of $H$ is a finite index subgroup of the normalizer of $H$. Combining with the results on translation numbers in Garside groups, we obtain an easy proof of the algebraic flat torus theorem for Garside groups and solve several algorithmic problems concerning abelian subgroups of Garside groups.Comment: This article replaces our earlier preprint "Stable super summit sets in Garside groups", arXiv:math.GT/060258

Climate sensitivity uncertainty : When is good news bad?

Climate change is real and dangerous. Exactly how bad it will get, however, is uncertain. Uncertainty is particularly relevant for estimates of one of the key parameters: equilibrium climate sensitivity—how eventual temperatures will react as atmospheric carbon dioxide concentrations double. Despite significant advances in climate science and increased confidence in the accuracy of the range itself, the “likely” range has been 1.5-4.5°C for over three decades. In 2007, the Intergovernmental Panel on Climate Change (IPCC) narrowed it to 2-4.5°C, only to reverse its decision in 2013, reinstating the prior range. In addition, the 2013 IPCC report removed prior mention of 3°C as the “best estimate.” We interpret the implications of the 2013 IPCC decision to lower the bottom of the range and excise a best estimate. Intuitively, it might seem that a lower bottom would be good news. Here we ask: When might apparently good news about climate sensitivity in fact be bad news in the sense that it lowers societal wellbeing? The lowered bottom value also implies higher uncertainty about the temperature increase, a definite bad. Under reasonable assumptions, both the lowering of the lower bound and the removal of the “best estimate” may well be bad news

The asymptotic quasi-stationary states of the two-dimensional magnetically confined plasma and of the planetary atmosphere

We derive the differential equation governing the asymptotic quasi-stationary states of the two dimensional plasma immersed in a strong confining magnetic field and of the planetary atmosphere. These two systems are related by the property that there is an intrinsic constant length: the Larmor radius and respectively the Rossby radius and a condensate of the vorticity field in the unperturbed state related to the cyclotronic gyration and respectively to the Coriolis frequency. Although the closest physical model is the Charney-Hasegawa-Mima (CHM) equation, our model is more general and is related to the system consisting of a discrete set of point-like vortices interacting in plane by a short range potential. A field-theoretical formalism is developed for describing the continuous version of this system. The action functional can be written in the Bogomolnyi form (emphasizing the role of Self-Duality of the asymptotic states) but the minimum energy is no more topological and the asymptotic structures appear to be non-stationary, which is a major difference with respect to traditional topological vortex solutions. Versions of this field theory are discussed and we find arguments in favor of a particular form of the equation. We comment upon the significant difference between the CHM fluid/plasma and the Euler fluid and respectively the Abelian-Higgs vortex models.Comment: Latex 126 pages, 7 eps figures included. Discussion on various forms of the equatio