Moisture Sources and Life Cycle of Convective Systems over Western Colombia

Abstract

This paper describes life cycle and moisture sources of mesoscale convective systems (MCSs) observed over western Colombia. Results show that, in general, MCS are more frequent during boreal summer and autumn, and particularly, systems observed in summer season present longer life and larger extension. On the continent, MCS genesis is strongly affected by sea breeze and diurnal heating and presents a peak from 15 to 18 LST. For oceanic systems, the main genesis period is later, from 00 to 03 LST. Continental and oceanic systems present a tendency of westward displacement. Analysis using a Lagrangian approach implemented to estimate air parcel trajectories suggests that, during boreal winter, the main moisture sources are from the Caribbean Sea and tropical north Atlantic, possibly resulting from the moisture-laden trade winds and the land-ocean temperature contrast over northern South America. In summer, it is clear the influence of ITCZ positioning with moisture particles traveling from the tropical Atlantic over Amazonian river basin. In Autumn, Chilean-Peruvian Pacific is the main moisture source, confirming the importance of Chocó low level jet to MCS genesis.

Seasonal precipitation patterns along pathways of South American low-level jets and aerial rivers

“…The lowlands along the Pacific coast of western Colombia are among the rainiest places on Earth, with average annual precipitation exceeding 12,500 mm [ López , ; Arnett and Steadman , ; Snow , ; Nieuwolt , ; Eslava , ; Poveda and Mesa , ; Mapes et al ., ; Sakamoto et al ., ; Álvarez‐Villa et al ., ; Durán‐Quesada et al ., ]. Such copious rainfall intensities are explained by the interaction of a low‐level westerly (CHOCO) jet, with topography and evapotranspiration from the tropical rainforests of western Colombia [ Poveda and Mesa , ; Poveda et al ., ].…”

“…The study of Sakamoto et al . [] evidenced that the transport of moisture by the CHOCO jet can be traced back as far south as 30°S, off the Chilean coast.…”

“…During the boreal winter, the northeast trades blow across the Isthmus, and three distinct wind jets form off the major gaps of the Central American mountain range, in the Gulfs of Tehuantepec, Papagayo, and Panama [ Chelton et al ., ; Xie et al ., ; Serra et al ., ]. The branch across Panama veers to the south‐southeast and merges with the CHOCO jet [ Poveda and Mesa , ; Chelton et al ., ; Xie et al ., ; Sakamoto et al ., ].…”

Sea surface temperature‐related response of precipitation in northern South America according to a WRF multi‐decadal simulation

“…In fact, WRF shows an abrupt change in the correlation patterns with the Pacific from December to January; such an abrupt change is not seen with the GPCC data (Figures a,e). In general, regarding the variability of dry season DJ precipitation over the Andes region, Figure shows the dominant role of SSTs in the Pacific compared to the Atlantic, which is remarkable given that most of the mean atmospheric moisture that arrives at northwestern South America comes from the Atlantic (see mean VIMF in Figures and ; see also Sakamoto et al ., ; Arias et al, ; Hoyos et al, ). There is also an interesting positive correlation pattern that appears over the Gulf of Mexico during January, which is not present in WRF.…”

Sistema convectivo de mesoescala atuantes na região semiárida do nordeste do Brasil

“…A maior probabilidade de convecção ocorre quando os ventos formam o maior ângulo possível com as isolinhas de convecção, o que ocasiona um transporte mais rápido de umidade e calor, favorecendo as instabilidades. Em latitudes tropicais, os CCM possuem praticamente o mesmo comportamento das latitudes médias, com exceção da influência dos JBN, e com seu ciclo de vida tendo início mais tardio, e a preferência para sua formação é na região boliviana e colombiana, praticamente durante o ano todo (Velasco e Fritsch 1987;Machado e Laurente 2004;Sakamoto 2009;Sakamoto et al 2011).…”