Oceanic Variability during the CINDY/DYNAMO Field Campaign from Satellite Observations

During the CINDY/DYNAMO field campaign (fall/winter 2011), intensive measurements of the upper ocean, including an array of several surface moorings and ship observations for the area around 75E-80E, Equator-10S, are conducted. In this study, large-scale upper ocean variations surrounding the intensive array during the field campaign are described based on the analysis of the satellite-derived data.

Surface currents, sea surface height (SSH), surface winds and SST during the DYNAMO field campaign derived from satellite observations are analyzed. During the intensive observation period, three active episodes of large-scale convection associated with the MJO passed eastward across the tropical Indian Ocean. Surface westerly winds near the equator were particularly strong during the events in late November and late December, exceeding 10 m/s. These westerlies generate strong eastward jets (>1m/s) on the equator. Significant remote responses to these equatorial westerlies are observed in both northern and southern hemispheres in the tropical Indian Ocean. The strong eastward jets associated with the MJO generate large downwelling near the eastern boundary. The anomalous positive SSH then propagates along the coast of Sumatra and Java, which may impact the Indonesian Throughflow transport. Also, SSH in large areas of the Bay of Bengal increases due to the coastal Kelvin waves as well as reflected Rossby waves. The comparison of these upper ocean variations with model results (COAMPS, HYCOM) may also be discussed.