Abstract
According to TRMM and GPM satellite precipitation composites, a broad
maritime area over the far eastern Tropical Pacific and western Colombia
houses one of the rainiest spots on Earth. This study aims to present a
suite of mechanistic drivers that help create such a world-record
breaking rainy spot. Previous research has shown that this oceanic and
nearly-continental precipitation maximum has a strong early morning
precipitation peak and development of a high density of mesoscale
convective systems. We examined new and unique observational evidence
highlighting the role of both dynamical and thermodynamical drivers in
the activation and duration of organized convection. Results show the
existence of a rather large combination of mechanisms, including: (1)
dynamics of the Choco (ChocoJet) and Caribbean Low-Level Jets along
their confluence zone, including the Panama semi-permanent low; (2) land
breeze favors ChocoJet deceleration offshore, enhancing the nighttime
and early morning low-level convergence; (3) vertical wind shear and
tilting of vertical wind shear into vorticity lines that interact with
convective outflows; (4) action of mid-level gravity waves, which
support the strong diurnal variability; (5) mesoscale convective
vortices related to subsidence in the stratiform region in long lasting
MCSs reinforcing (3); and (6) the likely role of land surface-atmosphere
interactions and the rainforest over western Colombia. This study
emphasizes the multi-scale environmental processes associated with the
formation of one of the rainiest spots on Earth and showcases new
observations gathered during the Organization of Tropical East Pacific
Convection (OTREC; August-September, 2019) which support the outlined
mechanisms.