Relationships between radiation, clouds, and convection during DYNAMO

Area of Science:

• Atmospheric Science
• Climate Dynamics
• Radiative Transfer

Background:

• The Madden-Julian Oscillation (MJO) significantly impacts tropical weather patterns.
• Understanding intraseasonal variations in radiation, clouds, and convection is crucial for MJO prediction.

Purpose of the Study:

• To investigate the intraseasonal relationships between radiative processes, cloud types, and convective activity during the MJO.
• To analyze radiative heating profiles and their influence on MJO dynamics.

Main Methods:

• Utilized data from the Dynamics of the Madden-Julian Oscillation (MJO) field campaign.
• Computed column-net and vertical profiles of radiative heating rates over Gan Island, Indian Ocean.
• Analyzed large-scale atmospheric fields for three MJO events (Oct-Dec 2011).

Main Results:

• Observed tilted radiative heating structures linked to shallow and deep convection phases.
• Found intraseasonal variations in cloud radiative forcing dominated by longwave effects (~0.4-0.6 K/d).
• Column-net radiative heating variations enhance the convective signal by ~20%.

Conclusions:

• Tilted radiative structures appear more influenced by water vapor than cloud fields alone.
• Cloud-radiative feedbacks play a role in maintaining the MJO as its convective envelope weakens and moves eastward.