Erosion of the nocturnal boundary layer in the central Amazon during the dry season

Carneiro, Rayonil Gomes; Fisch, Gilberto; Borges, Camilla Kassar; Henkes, Alice

doi:10.1590/1809-4392201804453

Cited by 5 publications

(12 citation statements)

References 29 publications

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“…In contrast, the year 2015 registered a significant reduction (approximately 30 %) of the total rainfall in relation to the previous year, with a total accumulation of 1764 mm, well below the normal climatological average. This reduction is associated with the occurrence of the El Niño-Southern Oscillation (ENSO) event of that year (ECMWF, 2017;Macedo and Fisch, 2018;Newman et al, 2018).…”

Section: Resultsmentioning

confidence: 99%

“…During IOP4, the total accumulated precipitation was well below the normal climatological value, as well as in comparison to the same period in 2014 (IOP2), with a total registered precipitation of 68 mm, a reduction of approximately 65 % compared to IOP2. This occurred due to the EN event being more intense during these months (ECMWF, 2017;Newman et al, 2018). The ENSO event (2015/2016) was considered one of the most intense in recent years, with an intensity similar to that which occurred during 1982/83 and 1997/98 (ECMWF, 2017).…”

Section: Resultsmentioning

confidence: 99%

“…The Vaisala ceilometers are a type of lidar remote sensing instrument that operate through a maximum vertical range of 7700 m and register the intensity of optical backscattering at the near-infrared wavelength between 900 and 1100 nm through the emission of a vertical pulse that is autonomously executed. These measurements are used to produce derived products that are recorded: the height of the cloud base, the retrieval of the particle backscatter coefficient and PBL height (Wiegner et al, 2014;Shukla et al, 2014;Morris, 2016;Geiß et al, 2017;Carneiro et al, 2020). Although the ceilometer measures the reflection of the aerosol layer (thus the mixing layer height), it was assumed to be the diurnal PBL height since the entrainment zone is very shallow.…”

Section: Ceilometermentioning

confidence: 99%

“…The PBL is a turbulent layer of the atmosphere near the surface that results from the interaction between the surface and the atmosphere. The knowledge of the properties of the PBL has important scientific and practical applications because through this understanding of the PBL operational models of weather and climate forecasting can be refined, pollutant dispersion processes can be adequately described, the eolic potential of a region can be objectively determined, patterns of ventilation in urban areas can be estimated and improvements in agricultural techniques can be made (Englberger and Dörnbrack, 2017). Furthermore, a more realistic representation of processes that occur in the PBL can benefit numeric models of weather forecasting with better parameterization of convection, clouds and rain (Holtslag et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Observational analysis of the daily cycle of the planetary boundary layer in the central Amazon during a non-El Niño year and El Niño year (GoAmazon project 2014/5)

Carneiro

Fisch²

2020

Atmos. Chem. Phys.

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Abstract. The Amazon biome contains more than half of the remaining tropical forests of the planet and has a strong impact on aspects of meteorology such as the planetary boundary layer (PBL). In this context, the objective of this study was to conduct observational evaluations of the daily cycle of the height of the PBL during its stable (night) and convective (day) phases from data that were measured and/or estimated using instruments such as a radiosonde, sodar, ceilometer, wind profiler, lidar and microwave radiometer installed in the central Amazon during 2014 (considered a typical year) and 2015 during which an intense El Niño–Southern Oscillation (ENSO) event predominated during the GoAmazon experiment. The results from the four intense observation periods (IOPs) show that during the day and night periods, independent of dry or rainy seasons, the ceilometer is the instrument that best describes the depth of the PBL when compared with in situ radiosonde measurements. Additionally, during the dry season in 2015, the ENSO substantially influenced the growth phase of the PBL, with a 15 % increase in the rate compared to the same period in 2014.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Ceilometermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Observational analysis of the daily cycle of the planetary boundary layer in the central Amazon during a non-El Niño year and El Niño year (GoAmazon project 2014/5)

Carneiro

Fisch²

2020

Atmos. Chem. Phys.

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“…With moisture freely available during the wet season, any conditional instability that favors cloud development such as surface heating or local instabilities can trigger 255 convection, thus lowering the PBL. Carneiro (2018) and Carneiro et al (2020), using observational data from ceilometer, LIDAR, and LES simulations shown that the erosion of the nocturnal boundary layer occurs 2 hours after the sunrise during the dry season and 3 hours after the sunrise during the wet season.…”

Section: Planetary Boundary Layer Analysis 240mentioning

confidence: 99%

What Drives Daily Precipitation Over Central Amazon? Differences Observed Between Wet and Dry Seasons

Biscaro¹,

Machado²,

Giangrande³

et al. 2020

Preprint

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Abstract. This study suggests a new approach on how diurnal precipitation is modulated by the nighttime events developed over Central Amazon using data from the Observations and Modelling of the Green Ocean Amazon (GoAmazon 2014/5) field campaign in the Central Amazon as well as radar and satellite data. Local observations of cloud occurrences, soil temperature, surface fluxes, and planetary boundary layer characteristics are coupled with satellite data to identify physical mechanisms that control the diurnal rainfall in Amazonas during the wet and dry season. This is accomplished by evaluating the atmospheric properties during the nocturnal periods from the days prior to rainfall and non-raining events. Comparisons between non-rainy and rainy transitions are presented for the wet (January to April) and dry (June to September) seasons. The results suggest that wet season diurnal precipitation is modulated mainly by night-time cloud coverage and local effects such as turbulence, while dry season rain events are mainly controlled by large-meso scale circulation.

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Nocturnal Boundary Layer Erosion Analysis in the Amazon Using Large-Eddy Simulation during GoAmazon Project 2014/5

et al. 2021

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This study investigated the erosion of the nocturnal boundary layer (NBL) over the central Amazon using a high-resolution model of large-eddy simulation (LES) named PArallel Les Model (PALM) and observational data from Green Ocean Amazon (GoAmazon) project 2014/5. This data set was collected during four intense observation periods (IOPs) in the dry and rainy seasons in the years 2014 (considered a typical year) and 2015, during which an El Niño–Southern Oscillation (ENSO) event predominated and provoked an intense dry season. The outputs from the PALM simulations represented reasonably well the NBL erosion, and the results showed that it has different characteristics between the seasons. During the rainy season, the IOPs exhibited slow surface heating and less intense convection, which resulted in a longer erosion period, typically about 3 h after sunrise (that occurs at 06:00 local time). In contrast, dry IOPs showed more intensive surface warming with stronger convection, resulting in faster NBL erosion, about 2 h after sunrise. A conceptual model was derived to investigate the complete erosion during sunrise hours when there is a very shallow mixed layer formed close to the surface and a stable layer above. The kinematic heat flux for heating this layer during the erosion period showed that for the rainy season, the energy emitted from the surface and the entrainment was not enough to fully heat the NBL layer and erode it. Approximately 30% of additional energy was used in the system, which could come from the release of energy from biomass. The dry period of 2014 showed stronger heating, but it was also not enough, requiring approximately 6% of additional energy. However, for the 2015 dry period, which was under the influence of the ENSO event, it was shown that the released surface fluxes were sufficient to fully heat the layer. The erosion time of the NBL probably influenced the development of the convective boundary layer (CBL), wherein greater vertical development was observed in the dry season IOPs (~1500 m), while the rainy season IOPs had a shallower layer (~1200 m).

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Erosion of the nocturnal boundary layer in the central Amazon during the dry season

Cited by 5 publications

References 29 publications

Observational analysis of the daily cycle of the planetary boundary layer in the central Amazon during a non-El Niño year and El Niño year (GoAmazon project 2014/5)

Observational analysis of the daily cycle of the planetary boundary layer in the central Amazon during a non-El Niño year and El Niño year (GoAmazon project 2014/5)

What Drives Daily Precipitation Over Central Amazon? Differences Observed Between Wet and Dry Seasons

Nocturnal Boundary Layer Erosion Analysis in the Amazon Using Large-Eddy Simulation during GoAmazon Project 2014/5

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