Energetics Examination of Winter Blocking Simulations in the Northern Hemisphere

Abstract

Four numerical simulations of the global atmosphere for January 1979 are analyzed to study the formation of blocking in terms of Northern Hemisphere energetics. The Goddard Laboratory for Atmospheres (GLA) 4° ? 5° latitude-longitude grid general circulation model (GCM) and 2° ? 2.5° grid GCM are employed with the GLA and Geophysical Fluid Dynamics Laboratory (GFDL) initial datasets. The difficulty in simulating a realistic blocking due to inadequate wave?wave interaction can be attributed in part to inadequate grid resolution. Among four simulations, the simulations by the high resolution GCM produce realistically strong blockings with compatible spectral energetics as in the observed blocking episodes. The latitude?height cross sections of the energy variables of wavenumber 1 is presented to describe the dipole structure of blockings. Blocking development is also examined in time series of barotropic and baroclinic components of energy and associated conversions.