Spectral Characteristics and Meridional Variations of Energy Transformations during the First and Second Special Observation Periods of FGGE

Abstract

Global features and meridional variations of spectral energy transformations are investigated for the first and second special observation periods (SOP-1 and SOP-2) of FGGE. The latitudinal distribution of the kinetic energy balance is also examined. The diagnosis presented is based on the GFDL data set. The spectral distributions of the global transformations, R(n) between the zonal mean and eddy components of the available potential energy, M(n) between the zonal mean and eddy components of the kinetic energy and C(n) between the available potential energy and the kinetic energy, all show specific seasonal characteristics for SOP-1 and SOP-2. The characteristic latitudinal distribution of cell conversion C(0) and eddy conversion C(n) at various wavenumbers are presented with their vertical totals and latitude-height profiles. The equatorial maximum of C(0) is associated with the upward motion of the Hadley cells. During SOP-1 the middle latitude maximum of eddy conversion C(n) in the Northern Hemisphere is identified with the very active long waves n=1, 2 and 3. During SOP-2 the pronounced C(1) and C(2) in the Northern Hemisphere are associated with the summer monsoon system, and the Southern Hemispheric conversion is intense in the Antarctic region at n=0 and 1. There is maximum production of the kinetic energy ?V.?? at subtropical latitudes, with a secondary maximum at higher middle latitudes. Between these two regions of maximum production, there is a region of adiabatic destruction of kinetic energy above the lower troposphere. The convergence of the kinetic energy ??.Vk is an important additional source of kinetic energy in middle latitudes. Dissipation D is at its maximum in middle latitudes. The seasonal contrast of the energy transformation is much more pronounced in the Northern Hemisphere than in the Southern Hemisphere, leading to more intense global energy processes during SOP-1 than SOP-2.