Two field campaigns and associated modelling activities will take place in Indonesia during the Years of the Maritime Continent (YMC) programme, in the 2019-2020 period. Equatorial Line Observations (ELO) is a joint US-UK-Indonesian project, and will investigate the mechanisms behind convectively coupled equatorial Kelvin waves (CCKWs) and the Madden-Julian Oscillation (MJO). The ELO field campaign will take place during 2019 and will involve radiosonde, ocean gliders, a moored thermistor and other measurements along the equator to best capture the propagation of CCKWs and the MJO. TerraMaris is UK-Indonesian project to investigate scale interactions (particularly between the diurnal cycle and intraseasonal variability) within atmospheric convection over the Maritime Continent, their interactions with the ocean, and their effect on global climate. The TerraMaris field campaign will take place during 2019/2020, and will involve research aircraft (FAAM), land based observations (including Doppler radar, radiosondes, flux towers, lidar and radiometer), and oceanographic observations (subsurface ocean gliders and a surface autonomous vehicle). The observations will be mainly based along a section south from Java to Christmas Island to capture the onshore and offshore development of convection within the diurnal cycle, and its dependence on the large-scale environment controlled by intraseasonal variability such as the MJO.