Diurnal, Synoptic, and Intraseasonal Rain Statistics from Ground and Space-Borne Radar over the Maritime Continent

While much work has been done analyzing the multi-scale variability of convection across the Maritime Continent, we still lack details about processes at each of the scales and how they interact. For example, it has been regularly noted that the diurnal cycle over land weakens during active MJO events across the Maritime Continent and some have postulated that this may play a role in whether an MJO successfully traverses the region, but there are a number of possible physical mechanisms at play (variations in surface fluxes, heating profiles, cloud radiative forcing, etc.) so it is difficult to prove causality.

We plan to flesh out the observational side of these kind of questions in two ways. The first is to composite the long-term (1998-2017) TRMM and GPM radar time series at high resolution over the Maritime Continent diurnally, synoptically (i.e., by equatorial wave mode), and intraseasonally to discern patterns that emerge concerning convective organization; in particular, convective and stratiform rain contributions and their attendant heating profiles in various combinations of the above scales. This analysis will add to the primarily IR- and passive MW-based satellite work done to date, which are less direct measures of rainfall than from radar and are at times imperfect over the complex topography of the islands of the Maritime Continent. We will also perform a similar analysis using a multi-month time series from an Indonesian BMKG operational C-band radar located on the mountainous central west coast of West Sumatra in Padang and compare the higher spatial and temporal resolution ground radar statistics to those derived from the space-borne radars. This initial multi-month analysis from one Indonesian radar will be expanded to a year-long (early 2018 to early 2019) analysis of dozens of BMKG radars as part of the Years of Maritime Continent.