Physical Sciences and Mathematics Commons^™

Predictability And Dynamics Of Warm-Core Mesoscale Vortex Formation With The 8 May 2009 "Super Derecho" Event, Caleb Todd Grunzke

Theses and Dissertations

The predictability and dynamics of the warm-core mesovortex associated with the northern-flank of the 8 May 2009 “Super Derecho” event are examined by coupling the Advanced Research Weather Forecasting Model with the Data Assimilation Research Testbed facility. A 50-member convection-allowing EnKF ensemble was produced with 6 hourly-cycled analysis and assimilated observations. Cycled analysis started five days prior to 1200 UTC 7 May 2009, at which time the 36 h ensemble forecasts were launched.

The ensemble forecasts all attempted to produce a mesoscale convective system (MCS) but only fourteen percent produced a warm-core mesovortex-like feature similar to the intensity of the …

The Influence Of Assimilated Targeted Observations Upon Ensemble Forecasts Of Convection Initiation, Alexandra Marie Keclik

Theses and Dissertations

The influence of assimilating targeted meso-α- to synoptic-scale observations collected in the upstream, pre-convective environment upon subsequent short-range ensemble forecasts of convection initiation (CI) across the central United States for the fifteen aircraft missions conducted by the Mesoscale Predictability Experiment (MPEX) in May and June 2013 is evaluated in this study. Utilizing the ensemble Kalman filter implementation within the Data Assimilation Research Testbed software package as coupled to version 3.4.1 of the Advanced Research version of the Weather Research and Forecasting model, two nearly-identical thirty- member ensembles of short-range forecasts are conducted for each mission. Initial conditions for one ensemble …

Predictability Of Sea Ice Near Bifurcations, Dawn Marie Kopacz

Theses and Dissertations

There is evidence in Earth’s history of relatively stable climate regimes abruptly transitioning to alternative states. It has been argued that the greatest potential for such abrupt transitions in Earth’s system in the near future is located in the Arctic. Here we analyze the Arctic sea ice evolution of two current generation climate models that exhibit critical transitions. We demonstrate the detectability of two early warning signals: increased variance and increased autocorrelation. We introduce another metric that forewarns of abrupt changes in sea ice; a decrease in predictability before the threshold points. Observations of Arctic sea ice extent are searched …