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Morning boundary layer conditions for shallow to deep convective cloud evolution during the dry season in the central Amazon

Henkes, Alice ; Fisch, Gilberto ; Machado, Luiz A. T ; Chaboureau, Jean-Pierre

Atmospheric chemistry and physics, 2021-09, Vol.21 (17), p.13207-13225 [Periódico revisado por pares]

Katlenburg-Lindau: Copernicus GmbH

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Título:
Morning boundary layer conditions for shallow to deep convective cloud evolution during the dry season in the central Amazon
Autor: Henkes, Alice ; Fisch, Gilberto ; Machado, Luiz A. T ; Chaboureau, Jean-Pierre
Assuntos: Aerosols ; Analysis ; Atmospheric boundary layer ; Atmospheric models ; Boundary layers ; Case studies ; Cloud formation ; Clouds ; Convection ; Convective clouds ; Cumulus clouds ; Dry season ; Enthalpy ; ENVIRONMENTAL SCIENCES ; Evolution ; Ground-based observation ; Heat flux ; Heat transfer ; High humidity ; Humidity ; Mixed layer ; Night ; Night-time ; Nighttime ; Ocean models ; Precipitation ; Radiative cooling ; Rain ; Sciences of the Universe ; Seasons ; Sensible heat ; Sensible heat flux ; Sensible heat transfer ; Statistical analysis ; Statistical methods ; Statistics ; Turbulent fluxes ; Turbulent mixing ; Vertical wind shear ; Wind shear
É parte de: Atmospheric chemistry and physics, 2021-09, Vol.21 (17), p.13207-13225
Notas: FAPESP
AC05-76RL01830; 2009/15235-8
USDOE Office of Science (SC), Biological and Environmental Research (BER)
Descrição: Observations of the boundary layer (BL) processes are analyzed statistically for dry seasons of 2 years and in detail, as case studies, for 4 shallow convective days (ShCu) and 4 shallow-to-deep convective days (ShDeep) using a suite of ground-based measurements from the Observation and Modeling of the Green Ocean Amazon (GoAmazon 2014/5) Experiment. The BL stages in ShDeep days, from the nighttime to the cloudy mixing layer stage, are then described in comparison with ShCu days. Atmospheric thermodynamics and dynamics, environmental profiles, and surface turbulent fluxes were employed to compare these two distinct situations for each stage of the BL evolution. Particular attention is given to the morning transition stage, in which the BL changes from stable to unstable conditions in the early morning hours. Results show that the decrease in time duration of the morning transition on ShDeep days is associated with high humidity and well-established vertical wind shear patterns. Higher humidity since nighttime not only contributes to lowering the cloud base during the rapid growth of the BL but also contributes to the balance between radiative cooling and turbulent mixing during nighttime, resulting in higher sensible heat flux in the early morning. The sensible heat flux promotes rapid growth of the well-mixed layer, thus favoring the deeper BL starting from around 08:00 LST (UTC-4 h). Under these conditions, the time duration of morning transition is used to promote convection, having an important effect on the convective BL strength and leading to the formation of shallow cumulus clouds and their subsequent evolution into deep convective clouds. Statistical analysis was used to validate the conceptual model obtained from the case studies. Despite the case-to-case variability, the statistical analyses of the processes in the BL show that the described processes are very representative of cloud evolution during the dry season.
Editor: Katlenburg-Lindau: Copernicus GmbH
Idioma: Inglês

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Morning boundary layer conditions for shallow to deep convective cloud evolution during the dry season in the central Amazon

Henkes, Alice ; Fisch, Gilberto ; Machado, Luiz A. T ; Chaboureau, Jean-Pierre

Katlenburg-Lindau: Copernicus GmbH

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