Purdue Climate Change Research Center

Modeling Coherent Structures in Convective Boundary Layers

Funded by the National Science Foundation

Coherent structures (CSs) are organized motions that spontaneously arise, are long-lived, trap much energy, and they occur in dynamical systems of all kinds, including in the Earth’s atmosphere and oceans. Turbulent convection in the atmosphere develops CSs called buoyant plumes, which under the effect of rotation, can turn into more dramatic events such as tornadoes and hurricanes. This project seeks to develop low-order models to capture the dynamics of CSs in convective boundary layers.

Describing turbulent flows with CSs is a formidable challenge. Turbulent flows with CSs are characterized by non-Gaussian statistics and are usually identified by values of skewness and kurtosis different from those for a Gaussian distribution (0 and 3, respectively). However, the accuracy of these measurements by conventional methods is low. The principal result of the team’s latest work is the development of subsampling techniques for computing reliable confidence intervals (CIs) for the skewness and kurtosis as a viable alternative to current practices (see Gluhovsky and Agee, 2009). This led to proposing subsampling techniques to construct simultaneous confidence bands (SCBs) for trends in meteorological and climatological variables (a pilot version was presented at the European Geosciences Union conference). SCBs quantify the associated uncertainty, similar to CIs in classical statistics. The grant supported the work of 3 students, Han Wu (PhD), Erin Jones (MS), and Emily Cornett (undergraduate).

Agee, E., and E. Jones, 2009: Proposed Conceptual Taxonomy for Proper Identification and Classification of Tornado Events. Wea. Forecasting, 24, 609-617.

Gluhovsky, A., and E. M. Agee, 2009: Estimating higher-order moments of nonlinear time series. J. Appl. Meteorol. Climatol. (accepted for publication).

Gluhovsky, A., 2009: Subsampling confidence bands for trends in atmospheric time series. European Geosciences Union General Assembly 2009, Vienna, Austria. Geophys. Res. Abstracts, 11.

Investigator(s)

Alexander Gluhovsky, EAS and Statistics

Ernest Agee, EAS

Contact Information

Purdue University
PCCRC
203 S. Martin Jischke Drive
MANN 105
West Lafayette, IN 47907