CISL/CGD Joint Seminar: Understanding spatiotemporal characteristics of equatorial waves

Speaker

Nedjeljka Žagar, Meteorological Institute, Universität Hamburg, Germany

Bio

Nedjeljka Zagar is a professor at University of Hamburg, Germany. Her research interests include tropical dynamics and data assimilation, information content of observations in numerical weather prediction and atmospheric predictability. She maintains the MODES webpage. More about her research group and recent papers is available. 

Abstract

Large-scale equatorial waves are considered important ingredients of the tropical variability spectrum, and their excitation, filtering and interactions, as well as their numerical prediction, are the focus of intense research. In this seminar, I will discuss linear and nonlinear excitation of the most energetic equatorial waves, the Kelvin wave, the mixed Rossby-gravity wave and the n=1 Rossby wave, and their roles in shaping the observed red spectrum of tropical variability in wavenumber and frequency space. I will present numerical simulations using the TIGAR (Transient Inertia-Gravity And Rossby wave) model that is based on the Hough harmonics as basis functions. The feasibility of such a model was demonstrated by Akira Kasahara (1977 and 1978, JAS), but, despite obvious benefits and a few attempts in the past, Hough harmonics based models never gained popularity. The results of numerical simulations with TIGAR will be complemented by the equatorial wave analysis in reanalysis data based on wavenumber filtering using the linear wave theory in terrain-following coordinates, introduced by Akira Kasahara (1981, MWR, with K. Puri) and available in real time.

NCAR/UCAR/UCP employees may attend in-person at the Mesa Lab. External participants may join via the webcast (more information about that forthcoming). 

This talk is not being recorded.