On the general circulation of the atmosphere around Colombia

Sánchez, Óscar José Mesa; Rojo‐Hernández, Julián David

doi:10.18257/raccefyn.899

Cited by 14 publications

(9 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Llanos comprises four subregions (piedmont, high plains-flat and dissected, alluvial overflow plains, and aeolian plains), each having different landforms, soil, savanna formations and vegetation patterns. The Llanos westerly wind patterns are synoptically controlled by a Walker-type circulation (Mesa-Sánchez and Rojo-Hernández, 2020), and its climate is highly influenced by the position of the Inter-Tropical Convergence Zone. The precipitation regime is primarily unimodal in most of the region, except for the piedmont, where the regime is bimodal due to the Andes influence (Pulwarty et al, 1998;Pacheco and León-Aristizábal, 2001).…”

Section: Site Descriptionmentioning

confidence: 99%

Carbon Exchange and Accumulation in an Orinoco High Plains Native Savanna Ecosystem as Measured by Eddy Covariance

Morales-Rincon

Hernandez

Rodriguez-Hernandez

et al. 2021

Front. Environ. Sci.

View full text Add to dashboard Cite

Savanna ecosystems cover ∼20% of the total land surface and account for ∼30% of the terrestrial global net primary production. They are also highly sensitive to climate change, since their carbon (C) sink capacity may decline under rising temperatures and irregular rainfall. These responses, which will define the future climate role of the savanna ecosystems, are currently not well understood. The Colombian Orinoco River basin (“Llanos”) natural savannas are being rapidly converted to agriculture. The impact of this transformation on C fluxes and accumulation is not clear. It is thus urgent to understand the Llanos natural savanna ecosystem services, including their C cycle and underlying mechanisms. Here we report and analyze 2 years of measurements of carbon dioxide fluxes from a naturally-restored (secondary) Llanos High Plains savanna ecosystem, using eddy covariance. Meteorological conditions, particularly rainfall, were quite variable during the measurement period. During the first year of measurements, the savanna was a weak carbon source (35 gC m−2), while during the second year, the system was a comparatively strong carbon sink (−273 gC m−2), despite receiving less rainfall than during the first year. As expected, the savanna net ecosystem exchange (NEE) was highly dependent on global solar radiation, soil water content, and ecosystem respiration. We found that after ∼10 days of nominal drought, i.e., with less than ∼5 mm/day of precipitation, the NEE became highly dependent on drought duration. The ecosystem reached a critical condition of low photosynthetic activity after ∼60 days of nominal drought. Based on these findings, we developed and applied a simple standard meteorology-based model that properly reproduced the observations. Our results indicate that a shift to a climate with similar total precipitation but split into extreme dry and wet seasons might eventually suppress the savanna C uptake capacity.

show abstract

Section: Site Descriptionmentioning

confidence: 99%

Carbon Exchange and Accumulation in an Orinoco High Plains Native Savanna Ecosystem as Measured by Eddy Covariance

Morales-Rincon

Hernandez

Rodriguez-Hernandez

et al. 2021

Front. Environ. Sci.

View full text Add to dashboard Cite

show abstract

“…In 2018, 26,987 mm of rainfall was recorded in the Yurumanguí village, 120 km south of our study area (Mesa & Rojo, 2020). The high regional precipitation is associated with the low‐level jet stream (tropopause air current) centred around 5°N, known as the Chocó Jet (Mesa & Rojo, 2020). Furthermore, the high floristic richness and endemism make the Chocó region one of the most biodiverse hotspots on Earth (Myers et al, 2000; Pérez‐Escobar et al, 2019).…”

Section: Methodsmentioning

confidence: 97%

“…We carried out this study at the lower Calima River basin (LCRB) (3°57′12.54″N, 76°59′27.96″W), within the Chocó Biogeographic Region in northwestern South America, near Colombia's Pacific coast (Figure 1), which is the rainiest region in the Americas. In some places, the mean annual rainfall is higher than 12,000 mm (Mesa & Rojo, 2020; Poveda & Mesa, 2000). In 2018, 26,987 mm of rainfall was recorded in the Yurumanguí village, 120 km south of our study area (Mesa & Rojo, 2020).…”

Section: Methodsmentioning

confidence: 99%

“…In some places, the mean annual rainfall is higher than 12,000 mm (Mesa & Rojo, 2020; Poveda & Mesa, 2000). In 2018, 26,987 mm of rainfall was recorded in the Yurumanguí village, 120 km south of our study area (Mesa & Rojo, 2020). The high regional precipitation is associated with the low‐level jet stream (tropopause air current) centred around 5°N, known as the Chocó Jet (Mesa & Rojo, 2020).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Tree growth periodicity in the ever‐wet tropical forest of the Americas

et al. 2023

View full text Add to dashboard Cite

The occurrence of annual growth rings in tropical trees—the result of the seasonal activity of vascular cambium—has been explained by seasonal water deficit or flooding periods. However, little is known about the drivers of annual tree‐ring formation under tropical hyper‐humid conditions without clear seasonal dry periods or flooding (ever‐wet conditions). Shelford's law states that the deficit or the excess of environmental resources limits plant growth. Accordingly, we hypothesize that excess soil moisture, a slight seasonal reduction of precipitation and a reduction in light availability determine rhythmic growth in ever‐wet tropical forests. We first assessed the occurrence of rhythmic growth in 14 tree species from the Biogeographic Chocó Region (annual rainfall 7200 mm) using three methods: Radiocarbon (14C) dating (all studied species), tree‐ring synchronization (4 species that have replicates) and automatic dendrometers (two species). Then, we assessed the effect of environmental drivers (rainfall, short‐wave radiation, temperature and soil moisture) on tree growth based on tree ring and dendrometer observations. We present evidence of annual tree‐ring formation in all 14 studied tree species. Depending on the tree species, we observed positive and negative correlations between growth, water availability and light availability. These relationships suggest that both excess or deficit of environmental resources may explain the seasonal pattern of tree growth. Although we cannot differentiate between excess soil water and low light availability by high cloudiness, we suggest that cloudiness frequency could affect tree growth in these forests. Synthesis. We reveal the annual formation of growth rings in the unexplored wetter‐end tropical forests, where seasonal growth depends on either high soil moisture and hypoxia or light limitations by cloudiness and photosynthesis constraints.

show abstract

“…On intraseasonal and shorter time scales, exogenous transient phenomena such as the Madden–Julian Oscillation (MJO; Madden and Julian, 1971; Barlow and Salstein, 2006; Barrett and Esquivel‐Longoria, 2013; Poleo et al ., 2014), easterly waves (Serra et al ., 2010), tropical cyclones (Amador et al ., 2010), upper‐tropospheric troughs in westerlies (Fernández et al ., 1996; Allen and Mapes, 2017), and cold surge intrusions from mid‐latitudes (Henry, 1979; Schultz, 1998; Zárate‐Hernández, 2013; Luna‐Niño and Cavazos, 2017) are also important factors shaping the regional precipitation climatology. The forcing exerted by endogenous convection on the atmospheric circulation (Gill, 1980) over CA‐SM has been reported for the cases of robust convection over the Pacific slopes of Colombia affecting the circulation in southern Central America and the Panamá Bight (Mesa‐Sánchez and Rojo‐Hernández, 2020; Mejía et al ., 2021), and of summer deep convection over Central America and surrounding oceans producing anomalous lower‐tropospheric (upper‐tropospheric) cyclonic (anti cyclonic) circulations over northern Central America, Mexico, and southwestern United States (Siu and Bowman, 2019; Chang et al ., 2021).…”

Section: Introductionmentioning

confidence: 98%

Atmospheric circulation types controlling rainfall in the Central American Isthmus

Hidalgo

Muñoz

et al. 2022

Intl Journal of Climatology

View full text Add to dashboard Cite

Rainfall mechanisms in the Central American Isthmus are controlled by complex physical interactions across spatial and temporal scales, which are reflected on the dynamics of atmospheric circulation patterns affecting the region. However, physical mechanisms and their relationships with thermodynamic distributions connected to overturning circulations remain elusive. Here, a set of six recurrent daily atmospheric patterns, or weather types (WT), is defined using a k-means++ clustering algorithm on standardized fields of Convective Available Potential Energy (CAPE) and winds at 925, 850, and 200 hPa. The relationships between these weather types, their temporal characteristics, and anomalous distributions of moisture flux divergence, equivalent potential temperature (saturated and unsaturated), and observed rainfall areu s e dt od e s c r i b ep h y s i c a lp r o c e s s e s controlling the latter, for all seasons. Regional observed rainfall is analysed from a set of 174 automatic stations from all countries from Mexico to Panama. By modulating vertically integrated moisture fluxes, these weather types, and the different climate drivers linked to them, control the temporal and spatial rainfall characteristics in the region, especially over the Pacific side of the isthmus. During some stages of the regional rainy season, described by two weather types, thermal anomalies in convective quasiequilibrium characteristic of the upward branch of the Hadley cell force westerly flow over Central America, enhancing rainfall. While during other stages, the enhancement of the trades and the displacement of convection to the ITCZ area over the eastern tropical Pacific, characteristic of the midsummer drought, diminishes rainfall. This study sets the stage for a better understanding of the mechanistic relationship between these weather types and rainfall characteristics in general, like onset, demise, and duration of rainy seasons. Hence, these results can inform process-based model diagnostics aiming at bias-correcting climate predictions at multiple timescales.

show abstract

On the general circulation of the atmosphere around Colombia

Cited by 14 publications

References 33 publications

Carbon Exchange and Accumulation in an Orinoco High Plains Native Savanna Ecosystem as Measured by Eddy Covariance

Carbon Exchange and Accumulation in an Orinoco High Plains Native Savanna Ecosystem as Measured by Eddy Covariance

Tree growth periodicity in the ever‐wet tropical forest of the Americas

Atmospheric circulation types controlling rainfall in the Central American Isthmus

Contact Info

Product

Resources

About