Estimation of global annual river runoff based on atmospheric water balance

Abstract

It is very important to investigate the global water circulation and budget for the understanding and the prediction of the global changes. The distribution of precipitation minus evaporation over the globe is estimated by the atmospheric water balance, using the ECMWF global analysis data for the period 1985 to 1988. The calculated vapor flux convergence -∇H·Q shows good correspondence with former estimations of annual mean evaporation minus precipitation in the meridional profiles. The global annual runoff from land surface to ocean is estimated to be as much as 167 mm/year. -∇H·Q also shows good relationship with the annual runoff of large rivers, especially in the northern hemisphere.