Published: March 1, 2013

Estimating the hidden history of water in clouds and the subtropical atmosphere

David Noone


Cooperative Institute for Research in Environmental Sciences

Department of Atmospheric and Oceanic Sciences


Date and time: 

Friday, March 1, 2013 - 1:00pm


The humidity of the tropics and subtropics plays a disproportionate role in the radiative balance of the planet. Therefore understanding the processes that control the response of the tropical humidity to climate forcing is critical for determining climate sensitivity. A correct account of the complex set of processes involved requires consideration of large-scale transport, turbulence and cloud microphysical processes. While these are all included in climate models, many aspects associated with them are treated in a very simple parameterized form and are poorly observed. These limitations reduce the confidence one may place in the fidelity of simulated responses. Modern measurement capabilities, including in situ and satellite remote sensing, can help constrain some aspects of processes acting in and near clouds, but required more sophisticated estimation methods that better account for uncertainties and biases in both the models and observations. We discuss both the importance of these constraints and some of the limitations associated with using stable isotope tracers in assessing the balance the microphysical controls against influences of large-scale moisture transport.