Connections between Terrestrial Evaporation and Atmospheric Water Vapour (Invited)

Atmospheric water vapor is a strong greenhouse gas, and its radiative effects are typically considered as a feedback to external forcings like CO2-induced greenhouse warming. This is because the Earth's surface is not generally water limited, with roughly 70% of the planet covered by oceans. However, over land (particularly in interior continental regions), water availability is frequently a limiting factor to evapotranspiration. Here, we will explore how terrestrial processes modulate atmospheric water vapour on continental to global scales. Variations in continental evaporation modulate atmospheric water vapour not only by directly altering the water input to the base of the atmospheric column, but also by altering the temperature of the atmosphere - thus impacting the air's capacity to hold water. Changes in land temperatures can modulate continental water vapor through changes in water vapor transport. Moreover, idealized simulations demonstrate that the distribution of continental land masses can have a first-order control on the pattern of atmospheric water across the globe, with implications for both the water cycle and the global atmospheric energy budget.