Understanding Cloud Radiative Feedbacks Within the Madden-Julian Oscillation

Abstract:

The Madden-Julian Oscillation (MJO) as profound effects on weather and climate such as the midlatitude storm track, frequency of extreme rainfall events, and tropical cyclone activity. However, it has been proven challenging to accurately represent the MJO in General Circulation Models (GCMs), which can lead to unreliable forecasts. An important feature of the MJO is its transition from suppressed to enhanced convection. This transition is characterized by clouds developing more frequently, deeper, and stratiform anvil clouds becoming more pronounced, all of which lead to changes in radiative properties over the lifetime of the MJO. The current GCMs struggle to accurately capture these cloud-radiative interactions, which can lead to an inaccurate representation of the MJO. Therefore, improving our understanding of cloud radiative feedbacks and diabatic processes is crucial to advancing MJO forecasts. Recent studies have also shown that cold pools during the transitional phase of the MJO can aid in initiating, strengthening, and organizing convection, which can affect the strength of radiative feedbacks. To study cloud-radiative interactions within the MJO, we investigate cloud populations and how their associated radiative feedbacks evolve with the MJO. We then explore why the strength of cloud radiative feedbacks depend on wavenumber by analyzing cloud properties through satellite, reanalysis, and radar data during DYNAMO. Furthermore, we investigate other wave modes such as Kelvin and Westward Inertial Gravity waves and compare them with the MJO. By doing so, we can observe how the relationships between cloud organization, cold pools, and radiative feedbacks depend on wave types. This study will lead to an improved understanding of cloud evolution and their radiative feedbacks within the MJO and other wave modes.