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  1. Introduction to the Mathematics of Climate at UMN - Lecture 18

    12 May 2015 | Presentations

    This is lecture 18 in the series "Introduction to the Mathematics of Climate" offered at the University of Minnesota in 2014 with the support of MCRN and The Institute for Mathematics and its Applications.

  2. Introduction to the Mathematics of Climate at UMN - Lecture 14

    12 May 2015 | Presentations

    This is lecture 14 in the series "Introduction to the Mathematics of Climate" offered at the University of Minnesota in 2014 with the support of MCRN and The Institute for Mathematics and its Applications.  

  3. Realistic modeling and analysis of synchronization dynamics in power-grid networks

    08 May 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    An imperative condition for the functioning of a power-grid network is that its power generators remain synchronized. Disturbances can prompt desynchronization, which is a process that has been involved in large power outages. In this talk I will first give a comparative review of three leading...

  4. Introduction to the Mathematics of Climate

    07 May 2015 | Series

    This course will investigate the following questions from a mathematical perspective. What determines the Earth's surface temperature? Why does the carbon dioxide in the atmosphere affect the climate? How do changes in the Earth's orbital parameters change the climate? Why has the Earth...

  5. Synchronization in power grid networks

    07 May 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    This survey discusses Master Stability Function (MSF) analysis for determining stability of synchronization of coupled oscillators on network. In addition, we briefly discuss the derivation of the Swing equation that determine the dynamics of a node in power grid network, and...

  6. Complex Energy Systems

    07 May 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    This is the opening guest lecture for the Electric Grid Focus Group.  Dr. Michael Chertkov of Los Alamos National Lab describes the statistical and mathematical problems arising in complex energy systems, including the electric grid and gas networks.  Systems with high penetration of...

  7. A Survey of Grid Control and Optimization

    07 May 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    This is an introductory survey of how control problems arise on different time scales in electric grid transmission problems.  The set up and general form of such problems are considered, along with operational considerations.

  8. Particle filters for geophysical applications

    30 Apr 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    Avoiding degeneracy is a crucial challenge for particle filters. Results have shown that the number of particles scales exponentially with respect to the number of independent observations. In this talk I will review attempts to counteract this phenomenon by exploiting proposal densities. I will...

  9. Toward a hybrid particle-ensemble Kalman filter for assimilating data from Lagrangian instruments into high dimensional models

    30 Apr 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    Presented by Elaine Spiller on 3-26-15Abstract:We discuss a recently proposed hybrid particle-ensemble Kalman filter for assimilating Lagrangian data, and apply it to a high-dimensional quasi-geostrophic ocean model. Effectively the hybrid filter applies a particle filter to the highly nonlinear,...

  10. Emulators in climate science. Uncertainty, sensitivity, calibration and more

    30 Apr 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    An emulator or a surrogate is a statistical approximation of a complex numerical model. Emulators are fast to run and include a measure of their own uncertainty. This makes them suitable for a number of applications in climate science. Emulators were originally devised for uncertainty...

  11. Statistical Data Assimilation For Parameter Estimation In Costal Ocean Hydrodynamics Modeling

    30 Apr 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    Coastal ocean models are used for a variety of applications, including modeling tides and hurricane storm surge. These models numerically solve the shallow water equations, which are derived by depth integrating the Navier-Stokes equations. The inherent uncertainties in coastal ocean models are a...

  12. Correlated Observation Errors in Data Assimilation

    30 Apr 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    Remote sensing observations often have correlated errors, but the correlations are typically ignored in data assimilation for numerical weather prediction. The assumption of zero correlations is often used with data thinning methods, resulting in a loss of information, and reduction in analysis...

  13. An Introduction to Lagrangian Data Assimilation - Part II

    23 Mar 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    Lauara Slivinski at Woods Hole Oceanographic Institution gives an introduction to Lagrangian Data Assimilation on 11-13-2014.

  14. An Introduction to Lagrangian Data Assimilation - Part I

    23 Mar 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    Laura Slivinski at Woods Hole Oceanographic Institute gives an introduction to Lagrangian Data Assimlation on 10-30-2014.

  15. Andy Reagan: Masters Thesis

    23 Mar 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    Andy Reagan at UVM gives a talk about his masters work on uncertainty quantification and data assimilation to improve the numerical prediction of fluids in the thermosyphon. This talk will involve several data assimilation methods, including variational techniques, but will focus on LETKF....

  16. An Introduction to Variational Data Assimilation

    23 Mar 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    Naratip Santitissadeekorn gives an introductory survey of variational techniques in data assimilation including 3D-VAR and 4D-VAR.  This talk was given on 10-2-14.

  17. Computational Techniques for Lyapunov Exponents and Vectors

    23 Mar 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    In this talk we present computational techniques for Lyapunov exponents and vectors based upon continuous matrix factorizations (QR and SVD). We outline the techniques, their well-posedness, error analysis/perturbation theory, and describe codes we have developed. We then discuss application of...

  18. Extending the square root method to account for model noise in the ensemble Kalman filter

    25 Feb 2015 | Presentations | Contributor(s): Mary Lou Zeeman

    Presented by Patrick Raanes on 2-18-2015 Abstract:A novel approach to account for model noise in the forecast step of the Ensemble Kalman filter (EnKF) is proposed.  The core method is based on the approach of the analysis step of ensemble square root filters (ETKF), and...