The Legality of Coercive Arms Control

On June 7, 1981 the Israeli air force bombed the Iraqi nuclear complex at Tuwaitha. The attack was strongly condemned by the U.N. Security Council as a clear violation of the Charter of the United Nations and the norms of international conduct. Nearly ten years after voting to condemn the Israeli raid, the United States struck at the same target. Unlike the Israeli raid, the American action was not denounced by a Security Council resolution

The generalized Ekman model for the tropical cyclone boundary layer revisited: Addendum

17 USC 105 interim-entered record; under review.The article of record as published may be found at http://dx.doi.org/10.1002/qj.4012Motivated by prior research examining the myth of inertial stability as a radial restoring force in the tropical cyclone boundary layer, we explore factors deter mining the vertical velocity at the top of the linear vortex boundary layer. Possible applications of these findings to mature tropical cyclone vortices are discussed briefly.NSFONRAGS-1313948 and IAA-1656075N0001417WX 00336,U.S. Naval Postgraduate Schoo

A unified view of tropical cyclogenesis and intensification

Quarterly Journal of the Royal Meteorological SocietyThe article of record as published may be found at http://dx.doi.org/10.1002/qj.2934Idealized high-resolution numerical simulations of tropical cyclogenesis are presented in a model that represents deep convection by a warm rain process only. Starting with an initially weak, cloud-free, axisymmetric warm-cored vortex (maximum wind speed 5 m s−1 at a radius of 100 km), rapid vortex intensification begins after a gestation period on the order of 2 days. From a three-dimensional perspective, the genesis process is similar to that in the rotating convection paradigm for vortex intensification starting with a much stronger initial vortex (Vmax = 15 m s−1). The patterns of deep convection and convectively amplified cyclonic relative vorticity are far from axisymmetric during the genesis period. Moreover, the organization of the cyclonic relative vorticity into a monopole structure occurs at relatively low wind speeds, before the maximum local wind speed has increased appreciably. Barotropic processes are shown to play an important role in helping to consolidate a single-signed vorticity monopole within a few hours near the intensification begin time. The rotating convection paradigm appears adequate to explain the basic genesis process within the weak initial vortex, providing strong support for a hypothesis of Montgomery and Smith that the genesis process is not fundamentally different from that of vortex intensification. In particular, genesis does not require a ‘trigger’ and does not depend on the prior existence of a mid-level vortex.Funded by Naval Postgraduate SchoolOffice of Naval Research GlobalNOAA HFIPNational Aeronautics and Space AdministrationDeutsche ForschungsgemeinschaftNational Science Foundatio

Putting to rest WISHE-ful misconceptions for tropical cyclone intensification

The purpose of this article is twofold. The first is to point out and correct several misconceptions about the putative WISHE mechanism of tropical cyclone intensification that currently are being taught to atmospheric science students, to tropical weather forecasters, and to laypeople who seek to understand how tropical cyclones intensify. The mechanism relates to the simplest problem of an initial cyclonic vortex in a quiescent environment. This first part is important because the credibility of tropical cyclone science depends inter alia on being able to articulate a clear and consistent picture of the hypothesized intensification process and its dependencies on key flow parameters. The credibility depends also on being able to test the hypothesized mechanisms using observations, numerical models, or theoretical analyses. The second purpose of the paper is to carry out new numerical experiments using a state-of-the-art numerical model to test a recent hypothesis invoking the WISHE feedback mechanism during the rapid intensification phase of a tropical cyclone. The results obtained herein, in conjunction with prior work, do not support this recent hypothesis and refute the view that the WISHE intensification mechanism is the essential mechanism of tropical cyclone intensification in the idealized problem that historically has been used to underpin the paradigm. This second objective is important because it presents a simple way of testing the hypothesized intensification mechanism and shows that the mechanism is neither essential nor the dominant mode of intensification for the prototype intensification problem. In view of the operational, societal, and scientific interest in the physics of tropical cyclone intensification, we believe this paper will be of broad interest to the atmospheric science community and the findings should be useful in both the classroom setting and frontier research

Why do tropical cyclones intensify more rapidly at low latitudes? [seminar announcement]

An announcement of a seminar hosted by NPS Department of Meteorology, presented by Professor Emeritus, Roger K. Smith, LMU, Munich, Germany, and hosted by Professor Michael T. Montgomery.We examine the problem of why model tropical cyclones intensify more rapidly at low latitudes. Our answer to this question touches on practically all facets of the dynamics and thermodynamics of tropical cyclones. The answer invokes the conventional spin up mechanism as articulated in classical and recent work together with a boundary layer feedback mechanism linking the strength of the boundary layer inflow to that of the diabatic forcing of the meridional overturning circulation. The specific role of the frictional boundary layer in regulating the dependence of the intensification rate on latitude is discussed. It is shown that, even if the tangential wind profile at the top of the boundary layer is held fixed, a simple, steady boundary layer model produces stronger low-level inflow and stronger and more confined ascent out of the boundary layer found in the time-dependent, three-dimensional numerical model as the latitude of the calculation is decreased. In an azimuthally-averaged view of the problem, the most prominent quantitative difference between the time-dependent simulations at 10oN and 30oN is the much larger diabatic heating rate and its radial gradient above the boundary layer at the lower latitude. This difference, in conjunction with the convectively-induced convergence of absolute angular momentum, greatly surpasses the effects of rotational stiffness (inertial stability) and evaporative-wind feedback that have been proposed in some prior explanations

An Observational Study of Tropical Cyclone Spinup in Supertyphoon Jangmi (2008) from 24 to 27 September

The article of record as published may be found at http://dx.doi.org/10.1175/MWR-D-12-00306.1An observational study of tropical cyclone intensification is performed using dropsondes, in situ flight-level data, satellite imagery, and Electra Doppler Radar (ELDORA) during the spinup of Tropical Storm Jangmi (2008) in the western North Pacific. This event was observed with research aircraft during the Tropical Cyclone Structure 2008 (TCS08) field experiment over the course of 3 days as Jangmi intensified rapidly from a tropical storm to a supertyphoon. The dropsonde analysis indicates that the peak azimuthally averaged storm-relative tangential wind speed occurs persistently within the boundary layer throughout the spinup period and suggests that significant supergradient winds are present near and just within the radius of maximum tangential winds. An examination of the ELDORA data in Tropical Storm Jangmi reveals multiple rotating updrafts near the developing eye beneath cold cloud top temperatures ≤ -65°C. In particular, there is a 12-km-wide, upright updraft with a peak velocity of 9m s¯¹ with collocated strong low-level (z < 2 km) convergence of 2 x 10¯³ s¯¹ and intense relative vorticity of 4 x 10¯³ s¯¹. The analysis of the corresponding infrared satellite imagery suggests that vortical updrafts are common before and during rapid intensification. The findings of this study support a recent paradigm of tropical cyclone intensification in which rotating convective clouds are important elements in the spinup process. In a system-scale view of this process, the maximum tangential wind is found within the boundary layer, where the tangential wind becomes supergradient before the air ascends into the eyewall updraft.Naval Postgraduate SchoolOffice of Naval Research (Grant N001408WR20129),National Science FoundationOffice of Naval Research (Grant N001408WR20129

Raising a Small Flock of Sheep in Ohio

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On the Applicability of Linear, Axisymmetric Dynamics in Intensifying and Mature Tropical Cyclones

The applicability of linearized axisymmetric dynamics to the intensification and structure change of tropical cyclones is investigated. The study is motivated by recent work that presented axisymmetric solutions to the linearized, non-hydrostatic, vortex-anelastic equations of motion (the so-called 3DVPAS model). The work called into question the importance of a recently proposed nonlinear, system-scale boundary-layer spinup mechanism both in intensifying storms and in mature storms undergoing secondary eyewall formation. The issue is examined using a three-dimensional mesoscale simulation of an intensifying tropical cyclone, alongside the linear 3DVPAS model. Solutions to the linear model, for imposed eddy forcing terms derived from the mesoscale simulation, are shown to be valid only for short times (t < 1 h) in the inner-core region of the vortex. At later times, the neglected nonlinear terms become significant and the linear results invalid. It follows that the linear results cannot be used to describe all aspects of the tropical cyclone dynamics at later times. In particular, they cannot be used (a) to dismiss the importance of the nonlinear boundary-layer spinup mechanism, nor (b) to isolate the separate effects of diabatic heating from those of friction, within the nonlinear boundary layer at least. Such separation depends on the linear superposition principle, which fails whenever nonlinearity is important. Similar caveats apply to the use of another linear model, the traditional Sawyer-Eliassen balance model. Its applicability is limited not only by linearity, but also by its assumption of strictly balanced motion. Both are incompatible with nonlinear spinup