scholarly journals Spatio-temporal patterns of thermal anomalies and drought over tropical forests driven by recent extreme climatic anomalies

2018 ◽  
Vol 373 (1760) ◽  
pp. 20170300 ◽  
Author(s):  
Juan C. Jimenez ◽  
Jonathan Barichivich ◽  
Cristian Mattar ◽  
Ken Takahashi ◽  
Andrés Santamaría-Artigas ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Spatial Patterns ◽  
El Niño ◽  
El Nino ◽  
The Other ◽  
Extreme Drought ◽  
Drought Severity ◽  
Tropical Regions ◽  
Temperature Anomalies ◽  
The Impact

The recent 2015–2016 El Niño (EN) event was considered as strong as the EN in 1997–1998. Given such magnitude, it was expected to result in extreme warming and moisture anomalies in tropical areas. Here we characterize the spatial patterns of temperature anomalies and drought over tropical forests, including tropical South America (Amazonia), Africa and Asia/Indonesia during the 2015–2016 EN event. These spatial patterns of warming and drought are compared with those observed in previous strong EN events (1982–1983 and 1997–1998) and other moderate to strong EN events (e.g. 2004–2005 and 2009–2010). The link between the spatial patterns of drought and sea surface temperature anomalies in the central and eastern Pacific is also explored. We show that indeed the EN2015–2016 led to unprecedented warming compared to the other EN events over Amazonia, Africa and Indonesia, as a consequence of the background global warming trend. Anomalous accumulated extreme drought area over Amazonia was found during EN2015–2016, but this value may be closer to extreme drought area extents in the other two EN events in 1982–1983 and 1997–1998. Over Africa, datasets disagree, and it is difficult to conclude which EN event led to the highest accumulated extreme drought area. Our results show that the highest values of accumulated drought area over Africa were obtained in 2015–2016 and 1997–1998, with a long-term drying trend not observed over the other tropical regions. Over Indonesia, all datasets suggest that EN 1982–1983 and EN 1997–1998 (or even the drought of 2005) led to a higher extreme drought area than EN2015–2016. Uncertainties in precipitation datasets hinder consistent estimates of drought severity over tropical regions, and improved reanalysis products and station records are required.This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

scholarly journals An Analysis of the Energetics of Tropical and Extra-Tropical Regions for Warm ENSO Composite Episodes

2017 ◽  
Vol 32 (1) ◽  
pp. 39-51
Author(s):  
Zayra Christine Sátyro ◽  
José Veiga
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
El Niño ◽  
Energy Production ◽  
El Nino ◽  
Southern Oscillation ◽  
Stable Condition ◽  
The Other ◽  
Tropical Regions ◽  
Using Data

Abstract This study focuses on the quantification and evaluation of the effects of ENSO (El Niño Southern Oscillation) warm phases, using a composite of five intense El Niño episodes between 1979 – 2011 on the Energetic Lorenz Cycle for four distinct regions around the globe: 80° S – 5° N (region 1), 50° S – 5° N (region 2), 30° S – 5° N (region 3), and 30° S – 30° N (region 4), using Data from NCEP reanalysis-II. Briefly, the results showed that zonal terms of potential energy and kinetic energy were intensified, except for region 1, where zonal kinetic energy weakened. Through the analysis of the period in which higher energy production is observed, a strong communication between the available zonal potential and the zonal kinetic energy reservoirs can be identified. This communication weakened the modes linked to eddies of potential energy and kinetic energy, as well as in the other two baroclinic conversions terms. Furthermore, the results indicate that for all the regions, the system itself works to regain its stable condition.

scholarly journals Quantifying immediate carbon emissions from El Niño-mediated wildfires in humid tropical forests

2018 ◽  
Vol 373 (1760) ◽  
pp. 20170312 ◽  
Author(s):  
Kieran Withey ◽  
Erika Berenguer ◽  
Alessandro Ferraz Palmeira ◽  
Fernando D. B. Espírito-Santo ◽  
Gareth D. Lennox ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Carbon Emissions ◽  
El Niño ◽  
Secondary Forest ◽  
El Nino ◽  
Fire Intensity ◽  
Secondary Forests ◽  
Study Region ◽  
Fire Emissions ◽  
The Impact

Wildfires produce substantial CO 2 emissions in the humid tropics during El Niño-mediated extreme droughts, and these emissions are expected to increase in coming decades. Immediate carbon emissions from uncontrolled wildfires in human-modified tropical forests can be considerable owing to high necromass fuel loads. Yet, data on necromass combustion during wildfires are severely lacking. Here, we evaluated necromass carbon stocks before and after the 2015–2016 El Niño in Amazonian forests distributed along a gradient of prior human disturbance. We then used Landsat-derived burn scars to extrapolate regional immediate wildfire CO 2 emissions during the 2015–2016 El Niño. Before the El Niño, necromass stocks varied significantly with respect to prior disturbance and were largest in undisturbed primary forests (30.2 ± 2.1 Mg ha −1 , mean ± s.e.) and smallest in secondary forests (15.6 ± 3.0 Mg ha −1 ). However, neither prior disturbance nor our proxy of fire intensity (median char height) explained necromass losses due to wildfires. In our 6.5 million hectare (6.5 Mha) study region, almost 1 Mha of primary (disturbed and undisturbed) and 20 000 ha of secondary forest burned during the 2015–2016 El Niño. Covering less than 0.2% of Brazilian Amazonia, these wildfires resulted in expected immediate CO 2 emissions of approximately 30 Tg, three to four times greater than comparable estimates from global fire emissions databases. Uncontrolled understorey wildfires in humid tropical forests during extreme droughts are a large and poorly quantified source of CO 2 emissions. This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

scholarly journals Inter-comparison and assessment of gridded climate products over tropical forests during the 2015/2016 El Niño

2018 ◽  
Vol 373 (1760) ◽  
pp. 20170406 ◽  
Author(s):  
C. Burton ◽  
S. Rifai ◽  
Y. Malhi
Keyword(s):  
Southeast Asia ◽  
Tropical Forest ◽  
Tropical Forests ◽  
Air Temperature ◽  
El Niño ◽  
El Nino ◽  
Congo Basin ◽  
Wide Range ◽  
Spatio Temporal ◽  
The Impact

To understand the impacts of extreme climate events, it is first necessary to understand the spatio-temporal characteristics of the event. Gridded climate products are frequently used to describe climate patterns but have been shown to perform poorly over data-sparse regions such as tropical forests. Often, they are uncritically employed in a wide range of studies linking tropical forest processes to large-scale climate variability. Here, we conduct an inter-comparison and assessment of near-surface air temperature fields supplied by four state-of-the-art reanalysis products, along with precipitation estimates supplied by four merged satellite-gauge rainfall products. Firstly, spatio-temporal patterns of temperature and precipitation anomalies during the 2015–2016 El Niño are shown for each product to characterize the impact of the El Niño on the tropical forest biomes of Equatorial Africa, Southeast Asia and South America. Using meteorological station data, a two-stage assessment is then conducted to determine which products most reliably model tropical climates during the 2015–2016 El Niño, and which perform best over the longer-term satellite observation period (1980–2016). Results suggest that eastern Amazonia, parts of the Congo Basin and mainland Southeast Asia all experienced significant monthly mean temperature anomalies during the El Niño, while northeastern Amazonia, eastern Borneo and southern New Guinea experienced significant precipitation deficits. Our results suggest ERA-Interim and MERRA2 are the most reliable air temperature datasets, while TRMM 3B42 V7 and CHIRPS v2.0 are the best-performing rainfall datasets. This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

scholarly journals Tree growth and stem carbon accumulation in human-modified Amazonian forests following drought and fire

2018 ◽  
Vol 373 (1760) ◽  
pp. 20170308 ◽  
Author(s):  
Erika Berenguer ◽  
Yadvinder Malhi ◽  
Paulo Brando ◽  
Amanda Cardoso Nunes Cordeiro ◽  
Joice Ferreira ◽  
...  
Keyword(s):  
Wood Density ◽  
Tree Growth ◽  
El Niño ◽  
Human Disturbance ◽  
Amazon Basin ◽  
El Nino ◽  
Carbon Accumulation ◽  
Extreme Drought ◽  
The Difference ◽  
The Impact

Human-modified forests are an ever-increasing feature across the Amazon Basin, but little is known about how stem growth is influenced by extreme climatic events and the resulting wildfires. Here we assess for the first time the impacts of human-driven disturbance in combination with El Niño–mediated droughts and fires on tree growth and carbon accumulation. We found that after 2.5 years of continuous measurements, there was no difference in stem carbon accumulation between undisturbed and human-modified forests. Furthermore, the extreme drought caused by the El Niño did not affect carbon accumulation rates in surviving trees. In recently burned forests, trees grew significantly more than in unburned ones, regardless of their history of previous human disturbance. Wood density was the only significant factor that helped explain the difference in growth between trees in burned and unburned forests, with low wood–density trees growing significantly more in burned sites. Our results suggest stem carbon accumulation is resistant to human disturbance and one-off extreme drought events, and it is stimulated immediately after wildfires. However, these results should be seen with caution—without accounting for carbon losses, recruitment and longer-term changes in species composition, we cannot fully understand the impacts of drought and fire in the carbon balance of human-modified forests. This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Nino on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

scholarly journals ENSO effects on the transpiration of eastern Amazon trees

2018 ◽  
Vol 373 (1760) ◽  
pp. 20180085 ◽  
Author(s):  
Mauro Brum ◽  
Jose Gutiérrez López ◽  
Heidi Asbjornsen ◽  
Julian Licata ◽  
Thomas Pypker ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Use ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Critical Role ◽  
Extreme Drought ◽  
Flow Measurements ◽  
Tree Transpiration ◽  
The Impact

Tree transpiration is important in the recycling of precipitation in the Amazon and might be negatively affected by El Niño–Southern Oscillation (ENSO)–induced droughts. To investigate the relative importance of soil moisture deficits versus increasing atmospheric demand (VPD) and determine if these drivers exert different controls over tree transpiration during the wet season versus the dry season (DS), we conducted sap flow measurements in a primary lowland tropical forest in eastern Amazon during the most extreme ENSO-induced drought (2015/2016) recorded in the Amazon. We also assessed whether trees occupying different canopy strata contribute equally to the overall stand transpiration ( T stand ). Canopy trees were the primary source of T stand . However, subcanopy trees are still important as they transpired an amount similar to other biomes around the globe. Tree water use was higher during the DS, indicating that during extreme drought trees did not reduce transpiration in response to low soil moisture. Photosynthetically active radiation and VPD exerted an overriding effect on water use patterns relative to soil moisture during extreme drought, indicating that light and atmospheric constraints play a critical role in controlling ecosystem fluxes of water. Our study highlights the importance of canopy and subcanopy trees to the regional water balance and highlights the resilience to droughts that these trees show during an extreme ENSO event. This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

scholarly journals Analisis Dampak Fenomena El Nino (1997-1998) Terhadap Ketersediaan Air Tanah Pulau Ambon

Agrologia ◽  
2015 ◽  
Vol 4 (1) ◽  
Author(s):  
Rion Suaib Salman
Keyword(s):  
Water Balance ◽  
El Niño ◽  
Agricultural Sector ◽  
Hydrological Cycle ◽  
El Nino ◽  
The Other ◽  
Water Shortages ◽  
Profound Influence ◽  
The Government ◽  
The Impact

The availability of soil in water is needed to run an everyday life, especially for living beings. The availability of groundwater is highly dependent on the good hydrological patterns, whereby if rain occurs with sufficient criteria then groundwater will be available as much as we need, but if the hydrological cycle becomes disrupted as a result of meteorological phenomena such as el nino then it will decrease water content in the soil. El nino phenomenon that occurred in 1997-1998 had a profound influence on the availability of groundwater, especially on the island of Ambon. Based on the analysis of water balance on the island of Ambon in 1997-1998, water deficit (drought) was so significant in the mid to late 1997 and in 1998. This certainly greatly affected the agricultural sector which is very dependent on the availability of water ground. The dynamics of the atmosphere has changed significantly, Both the government and the other correspond institution must anticipate the impact of water shortages on agriculture.

The Impact of ENSO on Wave Breaking and Southern Annular Mode Events

2010 ◽  
Vol 67 (9) ◽  
pp. 2854-2870 ◽  
Author(s):  
Tingting Gong ◽  
Steven B. Feldstein ◽  
Dehai Luo
Keyword(s):  
El Niño ◽  
Wave Breaking ◽  
El Nino ◽  
Southern Annular Mode ◽  
La Niña ◽  
Background Flow ◽  
Austral Spring ◽  
Annular Mode ◽  
La Nina ◽  
The Impact

Abstract This study examines the relationship between intraseasonal southern annular mode (SAM) events and the El Niño–Southern Oscillation (ENSO) using daily 40-yr ECMWF Re-Analysis (ERA-40) data. The data coverage spans the years 1979–2002, for the austral spring and summer seasons. The focus of this study is on the question of why positive SAM events dominate during La Niña and negative SAM events during El Niño. A composite analysis is performed on the zonal-mean zonal wind, Eliassen–Palm fluxes, and two diagnostic variables: the meridional potential vorticity gradient, a zonal-mean quantity that is used to estimate the likelihood of wave breaking, and the wave breaking index (WBI), which is used to evaluate the strength of the wave breaking. The results of this investigation suggest that the background zonal-mean flow associated with La Niña (El Niño) is preconditioned for strong (weak) anticyclonic wave breaking on the equatorward side of the eddy-driven jet, the type of wave breaking that is found to drive positive (negative) SAM events. A probability density function analysis of the WBI, for both La Niña and El Niño, indicates that strong anticyclonic wave breaking takes place much more frequently during La Niña and weak anticyclonic wave breaking during El Niño. It is suggested that these wave breaking characteristics, and their dependency on the background flow, can explain the strong preference for SAM events of one phase during ENSO. The analysis also shows that austral spring SAM events that coincide with ENSO are preceded by strong stratospheric SAM anomalies and then are followed by a prolonged period of wave breaking that lasts for approximately 30 days. These findings suggest that the ENSO background flow also plays a role in the excitation of stratospheric SAM anomalies and that the presence of these stratospheric SAM anomalies in turn excites and then maintains the tropospheric SAM anomalies via a positive eddy feedback.

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