
Realistic modeling and analysis of synchronization dynamics in powergrid networks
08 May 2015  Presentations  Contributor(s): Mary Lou Zeeman
An imperative condition for the functioning of a powergrid 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...

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...

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...

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.

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...

Toward a hybrid particleensemble 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 32615Abstract:We discuss a recently proposed hybrid particleensemble Kalman filter for assimilating Lagrangian data, and apply it to a highdimensional quasigeostrophic ocean model. Effectively the hybrid filter applies a particle filter to the highly nonlinear,...

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...

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 NavierStokes equations. The inherent uncertainties in coastal ocean models are a...

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...

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 11132014.

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 10302014.

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....

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 3DVAR and 4DVAR. This talk was given on 10214.

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 wellposedness, error analysis/perturbation theory, and describe codes we have developed. We then discuss application of...

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 2182015 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...