Designing Water Markets to Manage Coupled Externalities: An Application to Irrigation-Induced Salinity in Australia

In this paper, the design of water markets for the management of irrigation-induced salinity in Australia is addressed. Indeed, this setting exhibits complex interactions between the different features of the resource water. Quality, quantity of surface and ground-water interact in ways that produce coupled environmental externalities. It is then difficult to design efficient policy instruments to tackle all the issues at stake. This paper provides a preliminary analysis of three types of water market mechanisms, involving diversion rights and recharge rights.water markets, irrigation induced salinity, Australia, externalities, policy instruments, Resource /Energy Economics and Policy, Q25, Q53,

Evidence for a k^{-5/3} spectrum from the EOLE Lagrangian balloons in the low stratosphere

The EOLE Experiment is revisited to study turbulent processes in the lower stratosphere circulation from a Lagrangian viewpoint and resolve a discrepancy on the slope of the atmospheric energy spectrum between the work of Morel and Larcheveque (1974) and recent studies using aircraft data. Relative dispersion of balloon pairs is studied by calculating the Finite Scale Lyapunov Exponent, an exit time-based technique which is particularly efficient in cases where processes with different spatial scales are interfering. Our main result is to reconciliate the EOLE dataset with recent studies supporting a k^{-5/3} energy spectrum in the range 100-1000 km. Our results also show exponential separation at smaller scale, with characteristic time of order 1 day, and agree with the standard diffusion of about 10^7 m^2/s at large scales. A still open question is the origin of a k^{-5/3} spectrum in the mesoscale range, between 100 and 1000 km.Comment: 19 pages, 1 table + 5 (pdf) figure

The Theory of Turbulence in Two Dimensions

The methods of conformal field theory are used to obtain the series of exact solutions of the fundamental equations of the theory of turbulence. The basic conjecture, proved to be self-consistent ,is the conformal invariance of the inertial range. The resulting physical picture is different from the standard one , since the enstrophy transfer is catalyzed by the large scale motions. The theory gives some unambiguous predictions for the correlations in the inertial range.Comment: 18 pages (Plain LateX), PUPT - 136

A Path to Graduation: An Evaluation of Degree Planning Resources at Western Oregon University

Evidence suggests that additional registration tools may improve graduation and retention rates in higher education institutions like Western Oregon University (WOU). The tools that WOU currently employs to support students and advisors could be enhanced to benefit students, advisors, departments, and consequently, the university as a whole. With the guidance of the Student Success and Advising Office and the Office of the Registrar, I conducted research in order to better understand the degree pathway planning needs of students and advisors. Using formal software implementation techniques to elicit software requirements, I evaluated the potential benefits and challenges of available degree pathway planning tools to students, advisors, and administrators. I hope that information generated from this project may be of use to the Office of the Registrar in the process of implementing new systems throughout the continuous improvement of the registration process at WOU. Furthermore, I hope that the recommendations from this research will be a valuable contribution to the university’s mission and its strategic planning initiative, Forward Together. I hope that this project will inspire and inform a successful software implementation and be an asset to the university in its plan to promote student success

Mixing processes and exchanges in the tropical and the subtropical UT/LS

International audienceBoth in situ measurements and satellite observations indicate evidence of mixing in the upper troposphere (UT) and the lower-stratosphere (LS). In this study, the measurements performed during the Pre-AVE and Costa-Rica AVE campaigns are analysed with diffusive back-trajectories to assess mixing properties in the tropical and the subtropical UT/LS. A description of cross-tropopause pathways and mixing time scales is provided. In the subtropics, Troposphere-Stratosphere mixing processes are found to differ in the vicinity of the tropopause and at higher altitudes. Below 350 K, the mixing line observed during Pre-AVE is shown to result from fast and local cross-tropopause irreversible exchange, involving two initially distant air masses with distinct chemical compositions. For measurements located above 350 K, mixing of the tropospheric air in the subtropical stratosphere occurs over a period of a month, the origins of the tropospheric source being localised in the tropical UT and the tropical boundary layer. In the tropics, quantitative reconstructions of CO and O3 profiles above 360 K are obtained for one month back-trajectories calculations, pointing out that long term mixing is essential to determine the chemical composition in the tropical ascent. In particular, the existence of two-way meridional irreversible exchanges between 360 and 450 K is found to export tropical air in the subtropical stratosphere and to entrain old stratospheric air in the tropical ascent. Calculations of the Lagrangian mean age of air is shown to be in qualitative agreement with the CO2 observations and diabatic calculations

Turbulent vertical diffusivity in the sub-tropical stratosphere

Vertical (cross-isentropic) mixing is produced by small-scale turbulent processes which are still poorly understood and paramaterized in numerical models. In this work we provide estimates of local equivalent diffusion in the lower stratosphere by comparing balloon borne high-resolution measurements of chemical tracers with reconstructed mixing ratio from large ensembles of random Lagrangian backward trajectories using European Centre for Medium-range Weather Forecasts analysed winds and a chemistry-transport model (REPROBUS). We focus on a case study in subtropical latitudes using data from HIBISCUS campaign. An upper bound on the vertical diffusivity is found in this case study to be of the order of 0.5 m<sup>2</sup> s<sup>−1</sup> in the subtropical region, which is larger than the estimates at higher latitudes. The relation between diffusion and dispersion is studied by estimating Lyapunov exponents and studying their variation according to the presence of active dynamical structures

A Lagrangian view of convective sources for transport of air across the Tropical Tropopause Layer: distribution, times and the radiative influence of clouds

International audienceThe tropical tropopause layer (TTL) is a key region controlling transport between the troposphere and the stratosphere. The efficiency of transport across the TTL depends on the continuous interaction between the large-scale advection and the small-scale intermittent convection that reaches the Level of Zero radiative Heating (LZH). The wide range of scales involved presents a significant challenge to determine the sources of convection and quantify transport across the TTL. Here, we use a simple Lagrangian model, termed TTL detrainment model, that combines a large ensemble of 200-day back trajectory calculations with high-resolution fields of brightness temperatures (provided by the CLAUS dataset) in order to determine the ensemble of trajectories that are detrained from convective sources. The trajectories are calculated using the ECMWF ERA-Interim winds and radiative heating rates, and in order to establish the radiative influence of clouds, the latter rates are derived both under all-sky and clear-sky conditions. We show that most trajectories are detrained near the mean LZH with the horizontal distributions of convective sources being highly-localized, even within the space defined by deep convection. As well as modifying the degree of source localization, the radiative heating from clouds facilitates the rapid upwelling of air across the TTL. However, large-scale motion near the fluctuating LZH can lead a significant proportion of trajectories to alternating clear-sky and cloudy regions, thus generating a large dispersion in the vertical transport times. The distributions of vertical transport times are wide and skewed and are largely insensitive to a bias of about +/- 1 km (-/+ 5 K) in the altitude of cloud top heights (the main sensitivity appearing in the times to escape the immediate neighbourhood of the LZH) while some seasonal and regional transport characteristics are apparent for times up to 60 days. The strong horizontal mixing that characterizes the TTL ensures that most air of convective origin is well-mixed within the tropical and eventually within the extra-tropical lower-stratosphere

Covariant hydrodynamic Lyapunov modes and strong stochasticity threshold in Hamiltonian lattices

We scrutinize the reliability of covariant and Gram-Schmidt Lyapunov vectors for capturing hydrodynamic Lyapunov modes (HLMs) in one-dimensional Hamiltonian lattices. We show that,in contrast with previous claims, HLMs do exist for any energy density, so that strong chaos is not essential for the appearance of genuine (covariant) HLMs. In contrast, Gram-Schmidt Lyapunov vectors lead to misleading results concerning the existence of HLMs in the case of weak chaos.Comment: 4 pages, 4 figures. Accepted for publication in Physical Review