The atmospheric energy budgets over North America, the North Atlantic and Europe based on ECMWF analyses and forecasts

Abstract

The kinetic energy, sensible heat and latent heat budgets and the total energy balance of the earth-atmosphere system are studied over North America, the North Atlantic and Europe. The data consist of 1 year (December 1979–November 1980) of ECMWF initialized objective grid point σ-coordinate analyses and the ensemble of forecasts for day 3. The results quantit atively confirm the thermally direct meridional circulation over North America with generation of kinetic energy and adiabatic heating in the troposphere; kinetic energy and sensible heat are exported out of the region. The opposite holds for the North Atlantic area. The residuals of the energy budgets give a realistic approximation of the unresolved sub-grid scale processes (friction, diabatic heating, moisture sources/sinks) in the analysed data. Budgets from the forecast data reproduce the main features present in the analysed data, but also indicate some defects in the parameterization of the sub-grid scale processes in the ECMWF model. The analysed data, taking 4 analyses per day separately, exhibit diurnal variations, the magnitude of which is consistent with observed small diurnal wind variations. The total energy balance obtained for the 3 areas is reasonable and points to a considerable heat convergence in the North Atlantic ocean.