Clouds and large-scale dynamics in tropical latitudes are unavoidably co-dependent. Clouds alter the large-scale environment through their collective vertical transport of energy in the atmosphere as well as radiative effects. On the other hand, the large-scale environment controls the evolution of the very clouds that alter the environment. The entwinement between the two means that research of cloud-scale processes and large-scale dynamics often work cooperatively. We are especially interested in tropical convection because clouds in the tropics are responsible for a majority of the precipitation that happens on Earth and are particularly important in governing large, global-scale atmospheric circulations.
One area of CaRS research in large-scale tropical dynamics is the Madden-Julian Oscillation (MJO). The MJO is the dominant mode of intraseasonal variability in precipitation, temperature, humidity, and zonal flow in the tropics. It is associated with positive anomalies of precipitation that develop over large regions over the Indian Ocean or Western Pacific and propagate eastward. In addition to its direct impact on precipitation in equatorial regions, the MJO has been documented to modulate tropical cyclone activity and other weather events throughout the globe. However, the mechanisms through which widespread convection in the MJO develops over the Indian Ocean and West Pacific remain largely unexplained, and global models of the atmosphere struggle to properly represent the MJO.
Our research explores how changes to the thermodynamic and dynamic properties of the atmosphere-- or changes to the ocean surface impact cloud growth on large spatial scales. For example, subtle changes in atmospheric temperature can have important implications on the growth of clouds. Our research has also elucidated some of the mechanisms through which clouds permit convection in large-scale phenomenon such as the MJO or other wave disturbances to develop, such as through moistening and/or destabilization of the troposphere. By studying how these different processes evolve with time, we may be able to gain better predict precipitation events, particularly in the tropics.
