# title
Role of water vapor feedback on the amplitude of season cycle in the global mean surface air temperature

# abstract
<jats:p>We have analyzed the seasonal variations of global mean surface air temperature (<jats:italic>SAT</jats:italic>) and surface energy budgets of 17 AR4 models. Considerable differences in the amplitude of seasonal cycle (<jats:italic>A</jats:italic>) in the global mean <jats:italic>SAT</jats:italic> in the preindustrial control simulations among the models have been traced, to a large degree, to differences in their simulated clearsky downward longwave radiation (<jats:italic>LW</jats:italic><jats:sub></jats:sub>) and latent heat flux (<jats:italic>LH</jats:italic>). We suggest that water vapor feedback process influence the seasonal changes of <jats:italic>SAT</jats:italic> through its roles on the seasonal variations of <jats:italic>LW</jats:italic><jats:sub></jats:sub> and <jats:italic>LH</jats:italic>. This implies that the simulated seasonal change of global mean <jats:italic>SAT</jats:italic> might contain a clue about the sensitivity of water vapor feedback and the <jats:italic>A</jats:italic> of in <jats:italic>SAT</jats:italic> thus provides some constraint on climate sensitivity since both are subject to the same feedback process.</jats:p>