Land Surface Energy Budget

The motion of the Earth’s atmosphere is driven by differential heating. The reservoir of the available potential energy, which describes the difference between the actual state of the atmosphere and a hypothetical atmosphere at rest, is estimated to be about 55 x 105 Jm−2 as a mean value around the globe. This reservoir feeds the reservoir of kinetic energy (15 x 105 Jm−2), from where the energy dissipates into heat with a rate of 2.3 Wm−2. As these reservoirs are fairly constant in a climatological sense, the production rate of available potential energy and the transformation rate into kinetic energy has also to be 2.3 Wm−2. In traditional weather forecast models it was not necessary to put much effort into a precise description of the differential heating, the main source of available potential energy, because the time to exhaust the reservoirs mentioned above is given in months.