Analysis of the MJO-wind speed relationship in the Indian Ocean using observations and models

The relationship between wind-speed and precipitation associated with the Madden-Julian Oscillation (MJO) over the Indian Ocean is examined using a combination of observational tools and cloud system resolving model (CSRM) simulations. Previous works showed a positive correlation between wind driven latent heat flux and precipitation associated with the MJO over the Pacific. The first goal of this work extends those previous works to the Indian Ocean. Wind-speed and other variables needed to compute latent heat flux are obtained from the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) buoy array. Though buoy data is sometimes intermittent, good data coverage occurs from 2008 – 2012 for the two equatorial based buoys at 80.5ºE and 90ºE. The COARE 3.0 flux algorithm is used to calculate surface fluxes. Buoy data is augmented with surface flux observations from the recent Dynamics of the MJO (DYNAMO) field campaign. Precipitation data from the buoys, the TRMM satellite, and the Global Precipitation Climatology Project (GPCP) are then related to surface fluxes. Comparisons between the three precipitation sources will be shown. Additionally, the relative magnitude of latent heat flux and precipitation anomalies will be shown in attempt to understand the relative importance of latent heat flux anomalies for destabilizing the MJO.

The second goal of this work examines the wind speed and precipitation relationship for CSRM simulated MJO events. The Regional Atmospheric Modeling System (RAMS) model is used to simulate the October and November 2011 DYNAMO observed MJO events. Preliminary results will show how well the model does at reproducing the DYNAMO MJO events and suggest ways forward for testing the role of wind induced surface fluxes in MJO initiation and maintenance.