Tropical and global scale interactions among water vapor, atmospheric greenhouse effect, and surface temperature

We employ a multitude of global data sets to extend recent analyses of atmospheric greenhouse effect and its dependence on surface temperature, T(s), and vertical water vapor distribution. The new data encompasses a global domain including both the continents and the oceans, as well as both the ascending and descending branches of the Walker and Hadley cells and the extratropical storm track regions. We adopt the radiometric definition of the atmospheric greenhouse effect, G(a), which is the difference between the surface longwave emission and the outgoing longwave radiation. We derive the global average greenhouse effect over both oceans and land areas. The east to west variations of the normalized atmospheric greenhouse effect, g(a), and precipitable water (w) are just as strong as the north to south variations, thus illustrating the strong role of the dynamics in w and g(a). Between 60 deg N and 60 deg S the lowest values of g(a) (0.11-0.15) are found over the Saharan and other deserts, while the largest values (0.35-0.40) are found over the warm oceans with a deep convective atmosphere. (Author)