Hydrological cycle and ocean stratification in a coupled climate system: a theoretical study

Abstract

As a logical progression of a deductive climate theory, this paper addresses three interconnected climatic features: the humidity profile, the atmospheric water transport and the ocean stratification—taking as given the thermal field previously determined. The theory invokes the maximization of the entropy production, which propels the tropospheric temperature and specific humidity to their updraft values, yielding moist-adiabatic lapse rate and bi-modal relative humidity in the vertical.With the humidity profile known, the atmospheric water transport at mid-latitudes can be linked to the thermal field, which then determines the ocean salinity range. The deduced density ratio across the thermocline however is quite larger than unity, suggesting considerable static stability.

The model deductions, while crude, are consistent with observations, which underscore the internal control of the hydrological cycle and ocean stratification by energy balances, with significant implications on climate changes. Doubling the atmospheric CO2, for example, only slightly perturbs the energy balance and with it the global precipitation and the high relative humidity near the surface. The warming would however more strongly enhance the atmospheric water transport to accentuate the zonal-mean E-P pattern and ocean salinity contrast.