Towards a Mechanistic Understanding of Precipitation Over the Far Eastern Tropical Pacific and Western Colombia,One of the Rainiest Spots on Earth

摘要

According to Tropical Rainfall Measuring Mission (TRMM) and Global Precipitation Measurement (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 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 showed 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) ChocoJet deceleration offshore is favored by land breeze, enhancing the nighttime and early morning low-level convergence; (3) a wind sheared environment that conforms to the long-lived squall line theory;(4) action of mid-level gravity waves, which further support the strong diurnal variability; and (5) mesoscale convective vortices related to subsidence in the stratiform region and top-heavy mass flux profiles. This study emphasizes the multiscale circulation and thermodynamics mechanisms 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 field campaign (OTREC; August-September, 2019) that support the outlined mechanisms.