The moisture convergence process, especially prior to the onset of deep convection, is a difficult-to-observe process early in the active phase of a Madden-Julian Oscillation (MJO) event. Nonetheless, moisture convergence in the atmospheric planetary boundary layer is thought to play a key role in energy transfers that drive MJO evolution with implications for MJO propagation mechanisms and processes of convective organization. Conversely, downdrafts associated with subsidence characterize the transition to stratiform processes occurring at the end of the active phase of the MJO life-cycle. We examine the feasibility of detecting moisture convergence and subsidence signals associated with a single MJO event, Dec 2007 - Jan 2008, in the tropical Indian and western Pacific oceans. Correlations and covariances of water isotope concentrations and surface vector winds (SVWs) are analyzed given SVW retrievals from the NASA QuikSCAT mission and water-isotope:water vapor ratio (i.e., delta-D) retrievals from the Tropospheric Emission Spectrometer (TES) aboard the NASA Aura mission. Implications for spaceborne observing systems focused on tropical processes are discussed.