CHOCO-JEX: A Research Experiment Focused on the Chocó Low-Level Jet over the Far Eastern Pacific and Western Colombia

Yepes, Johanna; Poveda, Germán; Mejía, John F.; Moreno, Leonardo; Rueda, Carolina

doi:10.1175/bams-d-18-0045.1

Cited by 65 publications

(91 citation statements)

References 53 publications

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“…2a), easterly winds exceeding 8 m s −1 are observed over a large area in the western tropical Atlantic between [5N-17.5N; 100W-40W]; this is the region where the Caribbean low-level jet (CLLJ) is active. 26,27 At the core of the trade winds extending over the Caribbean, Central America, and eastern Pacific, wind speeds exceed 10 m s −1 . The trade winds in the Caribbean split into another branch which, influenced by the presence of the continent and the mountain barrier, flows southwestward to Venezuela, Colombia, and northern Peru reaching speeds higher than 10 m s −1 over a narrow extent known as Llanos.…”

Section: Resultsmentioning

confidence: 99%

“…The trade winds in the Caribbean split into another branch which, influenced by the presence of the continent and the mountain barrier, flows southwestward to Venezuela, Colombia, and northern Peru reaching speeds higher than 10 m s −1 over a narrow extent known as Llanos. 26 This jet is referred here as the northern branch of the SALLJ. During other seasons, when the SALLJ northern branch is active, the extent and intensity of the CLLJ is more pronounced than during SALLJ occurrences limited to the central Andes.…”

Section: Resultsmentioning

confidence: 99%

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Recent changes in the South America low-level jet

Jones

2019

npj Clim Atmos Sci

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level Jet (SALLJ) is a climatological feature with a critical role in the spatiotemporal distribution of precipitation in South America. While previous studies have focused on the mechanisms and variability of the SALLJ in the central Andes (i.e., southeast Peru, Bolivia, and Paraguay), the occurrence of the low-level jet in the eastern slopes of the northern Andes (i.e., northeast Peru, Colombia, and Venezuela) and its linkages to the central region have not been previously explored. This study shows that the SALLJ in the northern branch exceeds 10 m s −1 during September-February and the frequency can be as high as in the central region. Moreover, the SALLJ can occur simultaneously or separately in both regions. When the SALLJ is active only in the northern branch, wind speeds are very low from Bolivia towards southeast South America (SESA) and precipitation is significantly reduced (1-4 mm day −1) from climatology. In contrast, precipitation increases over eastern Bolivia by 2-4 mm day −1. Composites suggest that the SALLJ northern branch is forced by a large-scale circulation pattern with the enhancement of the North Atlantic Subtropical High driving northeasterly winds over the northern Andes. Further analysis shows that the frequency and intensity of the SALLJ in the northern Andes has substantially increased in the last 39 years.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Recent changes in the South America low-level jet

Jones

2019

npj Clim Atmos Sci

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“…In particular, diurnal cycles associated to local circulation features in the tropical Andes have been poorly studied (e.g., diurnal thermally driven circulations related to the topography and propagation of off coast convective rainfall). One of the rainiest spots in the World (in Colombia) has been recently center of a field experiment performed to study diverse aspects of the Choco Jet and its effect in convection (Mejia and Poveda, 2005;Yepes et al, 2019). This unique observational data will help to characterize the variability of the diurnal cycle of precipitation and wind circulations in the mesoscale, and the dominant mechanisms of westerly propagation of convection offshore (Yepes et al, submitted).…”

Section: Summary and Open Research Questionsmentioning

confidence: 99%

Hydroclimate of the Andes Part I: Main Climatic Features

et al. 2020

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The Andes is the longest cordillera in the world and extends from northern South America to the southern extreme of the continent (from 11 • N to 53 • S). The Andes runs through seven countries and is characterized by a wide variety of ecosystems strongly related to the contrasting climate over its eastern and western sides, as well as along its latitudinal extension. This region faces very high potential impacts of climate change, which could affect food and water security for about 90 million people. In addition, climate change represents an important threat on biodiversity, particularly in the tropical Andes, which is the most biodiverse region on Earth. From a scientific and societal view, the Andes exhibits specific challenges because of its unique landscape and the fragile equilibrium between the growing population and its environment. In this manuscript, we provide an updated review of the most relevant scientific literature regarding the hydroclimate of the Andes with an integrated view of the entire Andes range. This review paper is presented in two parts. Part I is dedicated to summarize the scientific knowledge about the main climatic features of the Andes, with emphasis on mean large-scale atmospheric circulation, the Andes-Amazon hydroclimate interconnections and the most distinctive diurnal and annual cycles of precipitation. Part II, which is also included in the research topic "Connecting Mountain Hydroclimate Through the American Cordilleras," focuses on the hydroclimate variability of the Andes at the sub-continental scale, including the effects of El Niño-Southern Oscillation.

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“…A bimodal annual cycle of rainfall is mostly confined to the Andean region (Poveda et al, 2005) with two distinct wet seasons (March to May, M-A-M, and September to November, S-O-N), and two drier (less rainy) seasons (December to February, D-J-F, and June to August, J-J-A). Furthermore, the activity of the CHOCO lowlevel jet explains the world-record breaking precipitation area over the western Pacific coast of Colombia (Poveda and Mesa, 2000;Mapes et al, 2003a;Warner et al, 2003;Rueda and Poveda, 2006;Sakamoto et al, 2011;Poveda et al, 2014;Sierra et al, 2015;Hoyos et al, 2017;Yepes et al, 2019). The CHOCO jet originates and develops over the far eastern Pacific, and it can be traced back as 30 • S, off the Chilean coast (Sakamoto et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Seasonal Shift of the Diurnal Cycle of Rainfall Over Medellin's Valley, Central Andes of Colombia (1998–2005)

et al. 2019

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The spatiotemporal variability of precipitation in regions of complex mountainous terrains constitutes one of the most challenging research topics of geosciences. This paper explores hourly precipitation data from a set of 25 stations spanning the period 1998 to 2005 within northwestern Colombia, in the Aburrá Valley and the neighboring San Nicolás plateau (75.16 • W−6 • N and 75.66 • W−6.6 • N) which accounts for a land area of ∼4,000 km 2. Our aim is to identify the main features of the diurnal cycle of precipitation over this complex terrain. We found that the average diurnal cycle of rainfall in the study region is bimodal at regional scale although it results from the superposition of two unimodal diurnal cycles shifting its phase throughout the seasons of the year. From October to April, average diurnal rainfall peaks in the afternoon hours (13:00-16:00 LST) but from May to September, the phase of the diurnal cycle changes to midnight hours (22:00-02:00 LST). Three low-level jets (LLJs), namely Caribbean, CHOCO, and the so-called Corriente de los Andes Orientales (CAO), are relevant to explain the seasonal shift of the diurnal cycle given their modulation of the seasonal variation of moisture sources and transport over this region. During June-July-August, moisture from afternoon evaporation processes at the bottom of the inter-Andean Magdalena Valley, located at the east of the study region, is transported by anabatic and easterly trade winds and contribute to explain the midnight and early morning peak. The life cycle of convective processes influences the orographic nature of rainfall distribution and timing in the region since deep convective cores are related with the afternoon peak, whereas wide convective cores with the early morning peak.

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CHOCO-JEX: A Research Experiment Focused on the Chocó Low-Level Jet over the Far Eastern Pacific and Western Colombia

Cited by 65 publications

References 53 publications

Recent changes in the South America low-level jet

Recent changes in the South America low-level jet

Hydroclimate of the Andes Part I: Main Climatic Features

Seasonal Shift of the Diurnal Cycle of Rainfall Over Medellin's Valley, Central Andes of Colombia (1998–2005)

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