Ozone transport and thermodynamics during the passage of squall line in Central Amazon

Melo, Adayana Maria Queiroz de; Dias-Júnior, Cléo Q.; Cohen, Julia; Sá, Leonardo Deane de Abreu; Cattânio, José Henrique; Kuhn, Paulo Afonso Fischer

doi:10.1016/j.atmosenv.2019.02.018

Cited by 15 publications

(11 citation statements)

References 45 publications

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“…According to Dias-Júnior et al [21], once this denser air reaches the atmospheric layers near the surface it diverges and propagates horizontally in the form of density current causing increases in the U values. These results are consistent with those of Melo et al [43] through results of numerical simulations. Figure 5 shows temporal variations of the vertical profiles of σ w now for the region within and immediately above the forest canopy at T0k site.…”

Section: Case Study Of a Squall Linesupporting

confidence: 93%

“…Several studies have already shown that, during the occurrence of downdrafts, it is possible to observe an increase in the superficial levels of O 3 in the Amazonian forest [15,17,18,21,[42][43][44]. According to Betts et al [17], this increase is probably due to the action of an air parcel, rich in O 3 , from the middle and upper troposphere, moving via the downdraft towards the ground.…”

Section: Case Study Of a Squall Linementioning

confidence: 97%

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Near-Surface Atmospheric Turbulence in the Presence of a Squall Line above a Forested and Deforested Region in the Central Amazon

et al. 2021

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Squall lines (SLs) are convective systems that cause heavy precipitation and consequently modify the atmospheric thermodynamic structure near the surface. SLs generated along the northern coast of Brazil and their effect upon atmospheric structure during their westward displacement into the Amazon are studied. Satellite imagery was employed to identify an SL above two experimental sites in the central Amazon and to characterize differences in the near-surface turbulent and ozone exchange during the passage of the SLs. The two sites, which are separated by about 100 km, feature contrasting vegetation. One site is tall canopy rainforest and the other is deforested. From our case study, it is noted that: equivalent potential temperature significantly drops, principally in the forested region; the average near-surface wind speed increases 5 fold; the skewness of vertical wind velocity becomes considerably negative; significant increases in turbulence intensity are observed. These changes suggest the presence of strong downdrafts generated by the SL. Shear production and dissipation rate of turbulent kinetic energy are considerably larger during the SL when compared to periods with absence of SL. In this study, we show that SLs are capable of modifying the vertical organization of the turbulence over forested and deforested areas, leading to changes in certain chemical processes that occur near the surface. To the best of our knowledge, this study represents a first in demonstrating that near-surface turbulent flow in the Amazon region is modified by the presence of SLs.

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Section: Case Study Of a Squall Linesupporting

confidence: 93%

Section: Case Study Of a Squall Linementioning

confidence: 97%

Near-Surface Atmospheric Turbulence in the Presence of a Squall Line above a Forested and Deforested Region in the Central Amazon

et al. 2021

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“…Before the arrival of Friagem at ATTO site region, between July 6 th and 8 th , it is observed that the values of O 3 (black line) were close to the monthly average (orange line), with minimum values occurring around 10 UTC (06 LT) and maximum around 17 UTC (Fig 10b). This result is consistent with those observed in other studies conducted in the Amazon (Betts et al, 2002;Gerken et al, 2016;Dias-Júnior et al, 2017;Melo et al, 2019). However, during the occurrence of Friagem, between…”

Section: Atto Site Wind Directionsupporting

confidence: 93%

“…This convection propagated in the West direction, arriving in the ATTO site region at 13 UTC (Fig 5c). Since this convective system is not associated to the squall lines that form along the coast (Cohen et al, 1995;Alcântara et al, 2011;Melo et al, 2019) it is possible to state that this convection has its formation associated with the convergence of these two air masses with different properties (Fig 4). It is noteworthy that during the propagation of this convection on July 11 th , it intensified and caused the highest rainfall (starting at 12:30 UTC) registered at the ATTO site during the month of July 2014, with a record rainfall of 21 mm.…”

Section: Environmental Characteristics In the Amazon Basin Scalementioning

confidence: 99%

Friagem Event in Central Amazon and its Influence on Micrometeorological Variables and Atmospheric Chemistry

Camarinha-Neto¹,

Cohen²,

Dias-Júnior³

et al. 2020

Preprint

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Abstract. In the period between July 9th and 11th, 2014 a Friagem event reached the central Amazon region causing significant changes in microclimate and atmospheric chemistry. On July 11th, the southwest flow related to the Friagem converged with the easterly winds in the central Amazon region. The interaction between these two distinct air masses formed a convection band, which intensified over the Manaus region and the Amazon Tall Tower Observatory (ATTO) site. The satellite images show the evolution of convective activity on July 11th, which lead to 21 mm of precipitation in the ATTO site. Moreover, the arrival of the Friagem caused a sudden drop in temperature and a predominance of southerly winds, which could be seen in Porto Velho between July 7th and 8th and in Manaus and ATTO site from July 9th to 11th. The results of ERA reanalysis and Brazilian developments on the Regional Atmospheric Modeling System (BRAMS) simulations show that this Friagem event coming from the southwest, carries a mass of air with higher O3 and NO2 mixing ratios and lower CO mixing ratio compared to the air masses present at the central Amazon. At lake Balbina the Friagem intensifies the local circulations, such as the breeze phenomena. At the Manaus region and ATTO site, the main effects of the Friagem event are: a decrease in the incoming solar radiation (due to intense cloud formation), a large temperature drop and a distinct change in surface O3 and CO2 mixing ratios. As the cold air of the Friagem was just in the lower 500 m the most probable cause of this change is that a cold pool above the forest prevented vertical mixing causing accumulation of CO2 from respiration and very low O3 mixing ratio due to photochemistry reduction and limited mixing within the boundary layer.

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“…BRAMS represents a Brazilian version of the Regional Atmospheric Modeling System (RAMS) (Cotton et al, 2003) adapted to tropical conditions. This version of BRAMS contains the coupling of the JULES (Joint UK Land Environment Simulator) (Best et al, 2011;Clark et al, 2011) and CCATT (Coupled Chemistry-Aerosol-Tracer Transport) models (Longo et al, 2010;Freitas et al, 2009), making BRAMS a new and fully coupled numerical system of atmosphere-biosphere-chemical modeling, called JULES-CCATT-BRAMS (Moreira et al, 2013).…”

Section: Experimental Designmentioning

confidence: 99%

The friagem event in the central Amazon and its influence on micrometeorological variables and atmospheric chemistry

et al. 2021

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Abstract. In the period between 9 and 11 July 2014, a friagem event reached the Amazon region. On 11 July, the southwest flow related to the friagem converged with the easterly winds in the central Amazon. The interaction between these two distinct air masses formed a convection band, which intensified over the Manaus region and the Amazon Tall Tower Observatory (ATTO) site. The satellite images show the evolution of convective activity on 11 July, which led to 21 mm of precipitation at the ATTO site. Moreover, the arrival of the friagem caused a sudden drop in temperature and a predominance of southerly winds, which could be seen in Porto Velho between 7 and 8 July and in Manaus and the ATTO site from 9 to 11 July. The results of ERA-Interim reanalysis and Brazilian developments on the Regional Atmospheric Modeling System (BRAMS) simulations show that this friagem event coming from the southwest, carries a mass of air with higher O3 and NO2 mixing ratios and lower CO mixing ratio compared to the air masses present in the central Amazon. At Lake Balbina, the friagem intensifies the local circulations, such as the breeze phenomena. In the Manaus region and at the ATTO site, the main effects of the friagem event are a decrease in the incoming solar radiation (due to intense cloud formation), a large temperature drop and a distinct change in surface O3 and CO2 mixing ratios. As the cold air of the friagem was just in the lower 500 m the most probable cause of this change is that a cold pool above the forest prevented vertical mixing causing accumulation of CO2 from respiration and very low O3 mixing ratio due to photochemistry reduction and limited mixing within the boundary layer.

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Ozone transport and thermodynamics during the passage of squall line in Central Amazon

Cited by 15 publications

References 45 publications

Near-Surface Atmospheric Turbulence in the Presence of a Squall Line above a Forested and Deforested Region in the Central Amazon

Near-Surface Atmospheric Turbulence in the Presence of a Squall Line above a Forested and Deforested Region in the Central Amazon

Friagem Event in Central Amazon and its Influence on Micrometeorological Variables and Atmospheric Chemistry

The friagem event in the central Amazon and its influence on micrometeorological variables and atmospheric chemistry

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