Model error estimation in ensemble data assimilation

A new methodology is proposed to estimate and account for systematic model error in linear filtering as well as in nonlinear ensemble based filtering. Our results extend the work of Dee and Todling (2000) on constant bias errors to time-varying model errors. In contrast to existing methodologies, the new filter can also deal with the case where no dynamical model for the systematic error is available. In the latter case, the applicability is limited by a matrix rank condition which has to be satisfied in order for the filter to exist. <br><br> The performance of the filter developed in this paper is limited by the availability and the accuracy of observations and by the variance of the stochastic model error component. The effect of these aspects on the estimation accuracy is investigated in several numerical experiments using the Lorenz (1996) model. Experimental results indicate that the availability of a dynamical model for the systematic error significantly reduces the variance of the model error estimates, but has only minor effect on the estimates of the system state. The filter is able to estimate additive model error of any type, provided that the rank condition is satisfied and that the stochastic errors and measurement errors are significantly smaller than the systematic errors. The results of this study are encouraging. However, it remains to be seen how the filter performs in more realistic applications

Editors’ Pick—Book Review: Global Sustainability and the Responsibilities of Universities

Weber, L.E., & Duderstadt, J. J. (Eds.). 2012. Global sustainability and the responsibilities of universities. Paris, France: Economica Ltd. 283 pp. ISBN 978-2-7178-6113-

Invited article: Bridging the gap – supporting the transition from high school to college

Idaho State University’s Bengal Bridge is a summer program designed to help students successfully transition from high school to their first year of college at Idaho State University. All Bridge students at ISU take two general education courses, plus an additional credit of supplemental instruction focused on academic strategies specific to the disciplines represented by those general education courses, as well as a First Year Transition (ACAD) course to facilitate engagement with and acculturation to the university community—a total of nine to 10 credits in just seven weeks. Bridge students are also supported by one-to-one academic coaching, supplemental tutoring, peer mentors, and additional study labs. What began as a summer “jumpstart” for a closely-monitored and tight-knit cohort of students in a specific demographic is now becoming the academic equivalent of “boot camp” for a larger, diverse population more representative of the typical fall semester student demographics in terms of the range of academic performance, financial resources, etc. Because this expanded Bengal Bridge is in an early stage of development and still evolving, we realized that we needed a more comprehensive understanding of the Bridge population if we are to accurately assess Bridge’s impact on FY student retention. To begin this process, we began collecting descriptive statistics and completing various surface level analyses. Ideally, the data will allow us to better serve future students, improve allocation of resources, and conclude whether participation in Bengal Bridge, in its present iteration, increases retention to the fall semester and beyond

Examining secondary school choice processes as a predictor of adjustment after the school transition

The secondary school transition is an important moment in adolescents' lives. Taking a prospective approach, the present study examined whether educational identity regarding a secondary school choice and own and parental expectations during the last year of primary school predicted post-transition school and psychological adjustment in Dutch adolescents (N = 314, Mage = 11.58). Additionally, the study qualitatively examined the reasons adolescents gave for their school choice, and linked these reasons to exploration behavior and post-transition adjustment. Identity processes and expectations predicted adjustment. Adolescents mostly reported multiple reasons for their school choice, with educational, practical, and social aspects of secondary schools appearing most important. The number of reasons mentioned was associated with pre-transition exploration behavior

Generating the future proportion of directed sardine catch taken west of Cape Agulhas in the absence of explicit spatial management

The relationship governing the proportion of directed sardine catch simulated to be taken west of Cape Agulhas during projections underlying the development of OMP-18 is updated. The relationship now differs for each draw from the posterior distribution

A comparison of the entanglement measures negativity and concurrence

In this paper we investigate two different entanglement measures in the case of mixed states of two qubits. We prove that the negativity of a state can never exceed its concurrence and is always larger then $\sqrt{(1-C)^2+C^2}-(1-C)$ where $C$ is the concurrence of the state. Furthermore we derive an explicit expression for the states for which the upper or lower bound is satisfied. Finally we show that similar results hold if the relative entropy of entanglement and the entanglement of formation are compared