The Orinoco Low-Level Jet: An Investigation of its Mechanisms of Formation Using the WRF Model

Jiménez-Sánchez, Giovanni; Markowski, Paul; Young, George S.; Stensrud, David J.

doi:10.1002/essoar.10503152.1

Cited by 4 publications

(18 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, the diurnal cycle of convection in the Orinoco basin (north of

\sim

3°N) is probably related to the combined effect of surface heating and the dynamics of the Orinoco Low Level Jet (OLLJ), a feature first identified by Montoya et al . (2001), and recently investigated through numerical simulations by Jiménez‐Sánchez et al . (2019, 2020). These simulations indicate that the OLLJ has maximum wind speeds during the morning and lowest in the afternoon, likely associated with convection development.…”

Section: Resultsmentioning

confidence: 99%

Features of atmospheric deep convection in northwestern South America obtained from infrared satellite data

Hernández-Deckers

2021

Quart J Royal Meteoro Soc

View full text Add to dashboard Cite

Atmospheric deep convection in equatorial continental regions is not homogeneously distributed in space or time, primarily due to surface inhomogeneities such as elevated topography and coastlines. This is the case in northwestern South America, which has particularly complex topography which, together with its geographical location, is responsible for some of the most prominent precipitation features around the globe. Although some of these features have been previously investigated in detail, others have not yet been studied, and some not even documented in the literature. The diverse atmospheric convective activity that takes place in this region constitutes a natural laboratory that can provide important insights into fundamental questions relevant for global climate. We use seven years of infrared brightness temperature data in 30 min intervals from the GOES‐13 geostationary satellite to estimate the spatial, seasonal and diurnal distributions of deep convective events in this region. By doing so, we bring forward several relevant features, providing a starting point for future investigations. For example, we find that deep convective events have a bimodal seasonal distribution throughout most of the Colombian Orinoco and Amazon basins, where precipitation is known to have a unimodal distribution. Furthermore, deep convective events in this region tend to be comparable in size to those offshore the Colombian Pacific coast or over the Magdalena river valley, but with significantly shorter lifetimes. On the other hand, nocturnal convection dominates at several continental locations; one of these, the middle‐lower Magdalena river valley, has been previously identified as one of the most active lightning hotspots on Earth, but its convective mechanisms have not yet been fully investigated. Another such location worth investigating is the middle Magdalena river valley, which may have strong similarities with the Maracaibo Lake area.

show abstract

“…On the other hand, the diurnal cycle of convection in the Orinoco basin (north of

\sim

Section: Resultsmentioning

confidence: 99%

Features of atmospheric deep convection in northwestern South America obtained from infrared satellite data

Hernández-Deckers

2021

Quart J Royal Meteoro Soc

View full text Add to dashboard Cite

show abstract

“…During this season, southward cross‐equatorial flow is enhanced (e.g., Wang & Fu, 2002), the Orinoco basin is in its dry season (e.g., Arias et al., 2020), and the northwestern Amazon is in the transition toward its rainfall maximum in February‐March (e.g., Vera, Higgins, et al., 2006; Espinoza, Ronchail, Frappart, et al., 2013; Marengo et al., 2012; Espinoza et al., 2020; Arias et al., 2020, 2021). During this season, some extreme wet (dry) events, producing floods (droughts) have been associated with La Niña (El Niño) events, such as in 1999, 2011, 2012 (1992, 1998, 2010; e.g., Espinoza et al., 2011, 2012; 2013a; Arias et al., 2015; Jiménez‐Sánchez et al., 2020). Details of the OLLJ are examined from area averages over a region in the lower Orinoco basin, hereafter Region 1, in the domain 64°W‐70°W, 7°N‐10°N.…”

Section: Methodsmentioning

confidence: 99%

“…We also used the eddy‐diffusivity/mass‐flux option of this scheme, which makes it in this case a non‐local scheme. The MYNN is a state‐of‐the‐art scheme used in the High‐Resolution Rapid Refresh system in the United States (Olson et al., 2019) and that has been previously used for studying the OLLJ (Jiménez‐Sánchez et al., 2019, 2020). Each PBL scheme is used with its corresponding surface layer scheme, which has a direct effect on the simulation of surface fluxes.…”

Section: Methodsmentioning

confidence: 99%

“…Low‐level jets (LLJs) are important structures that contribute to the transport of water vapor in the atmosphere, helping to the creation and support of precipitation (Gimeno et al., 2016; Stensrud, 1996). An important fraction of the cross‐equatorial transport of atmospheric moisture toward the Amazon is related to the nocturnal Orinoco Low‐level Jet (OLLJ), also known as the Los Llanos Jet (Jiménez‐Sánchez et al., 2019, 2020; Montoya et al., 2001; Poveda & Mesa, 1999; Torrealba & Amador, 2010; Vernekar et al., 2003). Using observations from radiosondes and estimates from the NCEP/NCAR reanalysis, Torrealba and Amador (2010) found that the OLLJ varies over the Orinoco basin, with zonal easterly winds over central Venezuela and a southward component downwind (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

“…In a follow‐up paper, Jiménez‐Sánchez et al. (2020) found that several factors contribute to the formation and structure of the OLLJ, including sea‐breezes (from the Caribbean toward northern South America), katabatic flows (from the northern Andes), and acceleration due to topographic features (including parts of the eastern tropical Andes and the Guyana Highlands over Venezuela).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Orinoco Low‐Level Jet and the Cross‐Equatorial Moisture Transport Over Tropical South America: Lessons From Seasonal WRF Simulations

et al. 2022

View full text Add to dashboard Cite

A study of the simulation of the Orinoco Low‐Level Jet (OLLJ) and the cross‐equatorial moisture transport over tropical South America using the Weather Research and Forecasting (WRF) model is presented. The focus is on the diurnal cycle and monthly means during one December‐January‐February (DJF) season (2003–2004). The sensitivity of the OLLJ and cross‐equatorial moisture transport to the representation of surface fluxes and turbulence is explored by using two different Land Surface Models (LSM) and three Planetary Boundary Layer (PBL) schemes. Different LSMs produce large differences in the sensible heat flux over the Orinoco basin, but no substantial differences in the flow at the entrance of the OLLJ. However, these changes in surface fluxes were associated with a change in the low‐level pressure gradient between the Orinoco and Amazon basins, and with up to 10% change in the simulated cross‐equatorial moisture transport. The largest effects from different PBL schemes were found in the low‐level flow near the Andes cordillera, and on the low‐level southward cross‐equatorial flow during the daytime. One of the PBL schemes exhibited a reduced moisture transport on the eastern flank of the Andes but enhanced southward transport around the core of the cross‐equatorial moisture flux. Another PBL scheme produced a stronger net cross‐equatorial moisture transport, with enhanced precipitation over the Andes‐Amazon region by up to 30% during the afternoon and up to 13% in the daily mean. Improved observations over the region are needed to evaluate which combination best represents the flow.

show abstract

The Orinoco low‐level jet during El Niño–Southern Oscillation

Builes‐Jaramillo

Yepes

Salas

2022

Intl Journal of Climatology

View full text Add to dashboard Cite

This study shows the influence of El Niño-Southern Oscillation (ENSO) over the seasonal and diurnal variability of the Orinoco low-level jet (OLLJ) during the December-January-February (DJF) season. Results show changes in the occurrence and intensity of the OLLJ winds during the phases of ENSO (El Niño and La Niña) in relation to Neutral conditions. During El Niño (La Niña), the OLLJ days decrease (increase) over the mid and exit of the OLLJ corridor. Furthermore, the mean wind vertical profiles (and the intensity of the diurnal cycle) decrease (increase) with values ranging from 5 to 9 mÁs −1 . We highlight that the OLLJ days decrease (increase) in January (February) during El Niño (La Niña) up to 24% (15%). These changes are modulated by the pressure gradient between the Atlantic subtropical high and the nearequatorial trough regions that decreases (increases) during El Niño (La Niña) and thus induces a decrease (increase) of the OLLJ winds. Moreover, the water vapour flux and precipitation reduce during both phases of ENSO along the OLLJ corridor. This work shows new insights on the OLLJ features during ENSO, which contributes to improving our understanding of the processes that influence the hydro-climatology of northern South America.

show abstract

The Orinoco Low-Level Jet: An Investigation of its Mechanisms of Formation Using the WRF Model

Cited by 4 publications

References 9 publications

Features of atmospheric deep convection in northwestern South America obtained from infrared satellite data

Features of atmospheric deep convection in northwestern South America obtained from infrared satellite data

The Orinoco Low‐Level Jet and the Cross‐Equatorial Moisture Transport Over Tropical South America: Lessons From Seasonal WRF Simulations

The Orinoco low‐level jet during El Niño–Southern Oscillation

Contact Info

Product

Resources

About