Um estudo do impacto de eventos ENOS na energética global

Abstract

The main purpose of this study was to quantify the impact of the El Niño - Southern Oscillation (ENSO) events over the global energetics using the data from NCEP/NCAR. The impacts were assessed by comparing the components of the Lorenz’s energy cycle for compounds of El Niño/La Niña events versus neutral and climatological fields. The energy analysis were divided into analysis of the Lorenz cycle trough energy diagrams, analysis of the temporal behaviour of the energy cycle components and a bi-dimensional energy analysis. In summary, we have observed that the zonal potential energy reservoir possesses the highest values in events El Niño type and that during events La Niña type the same reservoir is distinctly reduced. In contrast, values of Pe are smaller than climatology values during periods of El Niño and the reverse is observed during periods of La Niña. The results still suggest that El Niño events strengthen the zonal kinetic energy providing acceleration of zonal flow, and for La Niña compounds the opposite is observed, ie, the kinetic energy of the basic state is weakened. But no opposite relationship was found between the two types of ENSO events and the reservoir of kinetic energy of the disturbed state, wherein both were weakened, although periods of La Niña showing the lowest values. The analysis about temporal variations of the energy components of the Lorenz energy cycle show that ENSO events firstly change the potential energy at the beginning of the event, and then the effect on the zonal kinetic energy is seen from the middle to the end. During El Nino the zonal potential energy is used in much part to produce zonal kinetic energy than in the production of eddy potential energy, weakening the other baroclinic branch conversions and thereby reducing the production of kinetic energy of the disturbances. During La Niña the conversion between zonal forms of available potential energy and kinetic energy was weakened, but not enough to verify an intensification in other baroclinic conversion, also leading to a weakening of the kinetic energy of the disturbance in this fase of ENSO.