A study of baroclinic wave packets in February 2003, Part II: dynamical analysis using energetics


Institute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, Iran


Using the global data of NOAA provided by the Iran Meteorological Organization, the energetics of the wave packets detected in part I of this paper are studied in detail. To this end, within the wave packets detected, six troughs with downstream development were selected and for each the eddy kinetic energy as well as the other important terms in the energy budget relation were computed for the life time of the troughs. The ageostrophic flux convergence, total convergence flux, baroclinic conversion, barotropic conversion, and the residual are the terms computed for the study.
The energetics results show that in nearly all the cases involving downstream development, baroclinic conversion plays a significant role as either a source in the mature state or a sink in the decaying state of the troughs. The initial perturbation is generated by baroclinic conversion and subsequently initiates the downstream development. The main cause of downstream development is the ageostrophic flux convergence by which energy is radiated from the upstream of the existing perturbation to its downstream. This process leads to the decay of the existing wave and generation of a new wave in its downstream.