Recent changes in the atmospheric circulation patterns during the dry-to-wet transition season in south tropical South America (1979-2020): Impacts on precipitation and fire season

Espinoza, Jhan Carlo; Arias, Paola A.; Moron, Vincent; Junquas, Clémentine; Segura, Hans; Sierra, Juan Pablo; Wongchuig, Sly; Condom, Thomas

doi:10.1175/jcli-d-21-0303.1

Cited by 19 publications

(63 citation statements)

References 101 publications

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“…Moreover, the increase in DDF over this region is related to a warming of the northern tropical Atlantic Ocean and a weakening of moisture transport from the tropical Atlantic Ocean 31 . This is consistent with previous findings demonstrating the increased dry season length 2 , 53 , 55 , 56 , also observed through the delayed WSO (Fig. 1 h).…”

Section: Resultssupporting

confidence: 94%

Increased climate pressure on the agricultural frontier in the Eastern Amazonia–Cerrado transition zone

Marengo

Jiménez

Espinoza

et al. 2022

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Several large-scale drivers of both anthropogenic and natural environmental changes are interacting nonlinearly in the transition zone between eastern Amazonia and the adjacent Cerrado, considered to be another Brazilian agricultural frontier. Land-use change for agrobusiness expansion together with climate change in the transition zone between eastern Amazonia and the adjacent Cerrado may have induced a worsening of severe drought conditions over the last decade. Here we show that the largest warming and drying trends over tropical South America during the last four decades are observed to be precisely in the eastern Amazonia–Cerrado transition region, where they induce delayed wet-season and worsen severe drought conditions over the last decade. Our results evidence an increase in temperature, vapor pressure deficit, subsidence, dry-day frequency, and a decrease in precipitation, humidity, and evaporation, plus a delay in the onset of the wet season, inducing a higher risk of fire during the dry-to-wet transition season. These findings provide observational evidence of the increasing climatic pressure in this area, which is sensitive for global food security, and the need to reconcile agricultural expansion and protection of natural tropical biomes.

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Section: Resultssupporting

confidence: 94%

Increased climate pressure on the agricultural frontier in the Eastern Amazonia–Cerrado transition zone

Marengo

Jiménez

Espinoza

et al. 2022

Sci Rep

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“…All the described above remarks the complexity and importance of studying the diverse climate processes over STSA to get a full picture of the past and future changes in a context of global warming. Thereby, the aim of the present work is to perform a process-based assessment of a set of CMIP6 historical GCMs in simulating the atmospheric circulation and its associated rainfall over STSA as a follow-on study from Espinoza et al (2021) using their weather-typing approach. Focus will be put on the spatio-temporal variability of CPs and, particularly, on the representation of the dry-to-wet (July-October) transition season.…”

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confidence: 99%

Circulation Patterns and Associated Rainfall Over South Tropical South America: GCMs Evaluation During the Dry‐To‐Wet Transition Season

et al. 2022

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South Tropical South America (STSA), extended approximately between 10°N-30°S and 90°W-30°W, is a wide region where diverse interactions among biomass, land surface processes and atmospheric convection take place. These interactions modulate the local and regional climate and directly impact on the socio-environmental activities (Fu et al., 2013;Reis et al., 2018;Zhang et al., 2015). STSA hosts the Amazonia -the world's largest rainforest and one of the major sources of evapotranspiration -playing a critical role in the global balances of energy, water, moisture and carbon (Gatti et al., 2021;Llopart et al., 2020). The region presents unique biodiversity and geographical patterns, mainly due to the interaction of the Amazonia and the Andes mountain range, which have deep implications in the atmospheric dynamics, moisture transport and river discharge not only throughout STSA but also in remote regions of the continent (Arias, Garreaud, et al., 2021;Espinoza et al., 2020;Sierra et al., 2021). Precipitation (PP) over STSA presents a marked spatio-temporal variability, strongly controlled by the South American Monsoon System (SAMS), with rainfall maxima during its active phase during the austral summer (Marengo et al., 2012;Vera et al., 2006). The monsoonal circulation -which develops in response to seasonal changes in thermal land-sea contrasts -is connected to different documented atmospheric features, including a NW-SE band of convergence and convective activity over the southeast of South America and the adjacent South Atlantic ocean known as the South Atlantic Convergence Zone (SACZ), an anticyclonic center located

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“…The Amazon contains vast reserves of C but can experience major changes in rainfall patterns, mainly because of the influence of large-scale phenomena (ENSO, SST anomalies, and moisture transport anomalies; e.g., Marengo and Espinoza [38], Espinoza et al [29], Towner et al [36], Funatsu et al [86]) which affect C dynamics [81]. Herein, the results obtained for the El Niño drought period, such as in 2009 when the annual absorption rate of C/pixel was 0.050 kg C m −2 year −1 , showed no significant differences with those obtained for the La Niña drought period (cold phase of ENSO).…”

Section: Discussionmentioning

confidence: 99%

“…Gutiérrez-Vélez et al [100] found that drought severity had the greatest influence on the occurrence of fires. Changes in the duration of the dry season, increase in dry days and delayed onset of the dry season were observed in the southern Amazon and Bolivia [29,86,101], all of which have the potential to intensify fires conditions. These areas are largely coincident with the "deforestation arc", wherein the largest land use conversions have occurred [21,87].…”

Section: Discussionmentioning

confidence: 99%

“…In the Amazon region, fires are ubiquitous at the end of the dry season (September-October; e.g., Espinoza et al [29]), but have often worsened in years of extreme drought (i.e., 2005, 2010, and 2015) [30][31][32][33]. Anomalously dry years are associated with tropical seas surface temperature anomalies [34][35][36]; high temperatures and low humidity provide favorable conditions for the rapid spread of fires [37,38].…”

Section: Introductionmentioning

confidence: 99%

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Fires Drive Long-Term Environmental Degradation in the Amazon Basin

et al. 2022

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The Amazon Basin is undergoing extensive environmental degradation as a result of deforestation and the rising occurrence of fires. The degradation caused by fires is exacerbated by the occurrence of anomalously dry periods in the Amazon Basin. The objectives of this study were: (i) to quantify the extent of areas that burned between 2001 and 2019 and relate them to extreme drought events in a 20-year time series; (ii) to identify the proportion of countries comprising the Amazon Basin in which environmental degradation was strongly observed, relating the spatial patterns of fires; and (iii) examine the Amazon Basin carbon balance following the occurrence of fires. To this end, the following variables were evaluated by remote sensing between 2001 and 2019: gross primary production, standardized precipitation index, burned areas, fire foci, and carbon emissions. During the examined period, fires affected 23.78% of the total Amazon Basin. Brazil had the largest affected area (220,087 fire foci, 773,360 km2 burned area, 54.7% of the total burned in the Amazon Basin), followed by Bolivia (102,499 fire foci, 571,250 km2 burned area, 40.4%). Overall, these fires have not only affected forests in agricultural frontier areas (76.91%), but also those in indigenous lands (17.16%) and conservation units (5.93%), which are recognized as biodiversity conservation areas. During the study period, the forest absorbed 1,092,037 Mg of C, but emitted 2908 Tg of C, which is 2.66-fold greater than the C absorbed, thereby compromising the role of the forest in acting as a C sink. Our findings show that environmental degradation caused by fires is related to the occurrence of dry periods in the Amazon Basin.

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Recent changes in the atmospheric circulation patterns during the dry-to-wet transition season in south tropical South America (1979-2020): Impacts on precipitation and fire season

Cited by 19 publications

References 101 publications

Increased climate pressure on the agricultural frontier in the Eastern Amazonia–Cerrado transition zone

Increased climate pressure on the agricultural frontier in the Eastern Amazonia–Cerrado transition zone

Circulation Patterns and Associated Rainfall Over South Tropical South America: GCMs Evaluation During the Dry‐To‐Wet Transition Season

Fires Drive Long-Term Environmental Degradation in the Amazon Basin

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