Abstract
A series of symmetric, aquachannel simulations obtained with the WRF model are used to study the propagation of tropical Cloud Clusters (CCs) in association with eastwardmoving Super Cloud Clusters (SCCs). The analysis is carried out using the precipitation field in time-longitude coordinates. Two independent but complementary methods are used: the first, from a local approach, involves a CC-tracking algorithm, while the second uses Lagrangian Trajectories in a non-local framework. It is found that the background flow in low-to-mid-levels advects the CCs either eastward or westward depending on model climatology, proximity to the SCC axis, and latitude. Moreover, for most analyzed cases, sequences of CCs oscillate describing qualitatively sinusoidal-like paths, although with sharp transitions from westward to eastward motion, due to Westerly Wind Bursts associated with the SCCs. The patterns defined by the CCs on x-t diagrams have been defined as “S-shapes”. The S-shape signal on frequency-wavenumber space is masked by the dominant SCC (Kelvin) mode, although it can be still detected, while it has no correspondence with any other observed mode in the tropics. TRMM precipitation data and wind fields from MERRA2 reanalysis are used to find evidence of the S-shapes for the 1998 year. Conceptual models of the SCC-CC interaction are also presented.