Surface ocean response to Convectively Coupled Kelvin Waves in NEMO (#1051)
Despite the recent progress in understanding the dynamics of MJO evolution, the prediction of its propagation over the MC remains a challenge for models. It is hypothesized that the propagation of the MJO envelope over the MC is dependent on the ability of atmospheric equatorial convectively coupled Kelvin waves (CCKWs) to cross this barrier. CCKWs are strongly influenced by ocean-atmospheric interactions and thus, feedbacks between precipitation, salt-stratified oceanic barrier layers and the upper ocean diurnal cycle are likely to play important roles in the multi-scale interactions between modes of atmospheric convection. This work provides the first direct assessment of these processes and their likely impact on the atmospheric convection over the MC region. The variability of the development and evolution of the warm layer as CCKWs approaches the land is investigated initially using the NEMO ocean model . Using a Lagrangian database for CCKWs (Baranowski et al.2016), a climatology of the upper ocean warm layers in the MC region is constructed, considering a mean state and different convective conditions. The NEMO temperature composite fields present a distinctive signal before and after the passage of the CCKWs, showing a decrease in the ocean surface temperature after the CCKWs passage. This response from the ocean surface has been identified previously in case studies using in situ data and gives confidence in the use of this ocean model for further calculations. In the future Equatorial Line Observations (ELO) field campaign in 2019, high resolution temperature and salinity profiles sampled by ocean gliders during four months will provide an extensive dataset to further validate the model data and to investigate the impacts of the precipitation-induced barrier layers on the warm layer dynamics. These results will help elucidate how mainly locally driven processes can rectify onto the longer time scale of the MJO.