Global Energy and Water Balances

Abstract

AbstractThe earth's energy and water balances are summarised with the most recent observational and computational results. A special reference is given to the earth's surface. After a brief discussion of the limits of the observational accuracy, the author explains the mean state of the energy balance starting with the sun, through the atmosphere and to the earth's surface. The main contents are the Total Solar Irradiance (earlier called solar constant) and its variability, the climatic effect of the earth's orbital change, extinction processes of solar radiation in the atmosphere, the distributions of solar radiation on the earth's surface, reflection and albedo, terrestrial radiation from the atmosphere and the earth's surface, net radiation, sensible and latent heat fluxes, subsurface heat flux, and latent heat of melt. The distributions of the individual components are presented in maps. The important points of geographical distributions and energy fluxes are explained in the text. The energy balance climatology in the present article differs from earlier works mainly on three topics: 1) larger atmospheric absorption of solar radiation; 2) smaller solar radiation on the earth's surface; and 3) larger terrestrial counter radiation. These new situations are the results of the recent advances in spectrometry, observational technology both on the earth's surface and in the space, and also in computational skill. Therefore, the historical development of the understanding of the earth's energy balance is added. The article ends with a brief description of the mean hydrological cycle, allowing unsteady conditions due to the melt of glaciers during the twentieth century.