@InProceedings{MortariniDAOBGSTAMC:2021:InAtSt,
author = "Mortarini, Luca and Dias J{\'u}nior, Cl{\'e}o Quaresma and
Acevedo, Otavio and Oliveira, Pablo and Brondani, Daiane and
Giostra, Umberto and S{\"o}rgel, Matthias and Tsokankunku,
Anywhere and Ara{\'u}jo, Alessandro and Machado, Luiz Augusto
Toledo and Cava, Daniela",
affiliation = "{Institute of Atmospheric Sciences and Climate} and {Instituto
Nacional de Pesquisas da Amaz{\^o}nia (INPA)} and {Universidade
Federal de Santa Maria (UFSM)} and {Universidade Federal do Rio
Grande do Norte (UFRN)} and {Instituto Nacional de Pesquisas da
Amaz{\^o}nia (INPA)} and {Universita\̀ degli Studi di
Urbino “Carlo Bo”} and {Max Planck Institute for Chemistry} and
{Max Planck Institute for Chemistry} and {Empresa Brasileira de
Pesquisa Agropecu{\'a}ria (EMBRAPA)} and {Instituto Nacional de
Pesquisas Espaciais (INPE)} and {Institute of Atmospheric Sciences
and Climate}",
title = "Influence of Atmospheric Stability on the flow dynamics within and
above a dense Amazonian forest",
year = "2021",
organization = "EGU General Assembly",
publisher = "EGU",
abstract = "This study provides a detailed analysis of the influence of
atmospheric stratification on the flow dynamics above and within a
dense forest for a 19-days campaign at the Amazon Tall Tower
Observatory (ATTO) site. Observations taken at seven levels within
and above the forest along an 81-meter and a 325-meter towers
allow a unique investigation of the vertical evolution of the
turbulent field in the roughness sublayer and in the surface layer
above it. Five different stability classes were defined on the
basis of the behavior of turbulent heat, momentum and CO2 fluxes
and variance ratio as a function of h/L stability parameter (where
h is the canopy height and L is the Obukhov length). The novelty
is the identification of a super-stable (SS) regime (h/L>3)
characterized by extremely low wind speeds, the almost completely
suppression of turbulence and a clear dominance of submeso motions
both above and within the forest. The obtained data classification
was used to study the influence of atmospheric stratification on
the vertical profiles of turbulent statistics. The spectral
characteristics of coherent structures and of submeso motions
(that may influence the energy and mass exchange above the Amazon
forest) have been analyzed by wavelet analyses. The role of the
main structures in momentum, heat and CO2 transport at the
different levels inside and above the forest and in different
diabatic conditions was thoroughly investigated through
multiresolution and quadrant analyses. In unstable and neutral
stability, the flow above the canopy appears modulated by
ejections, whereas downward and intermittent sweeps dominate the
transport inside the canopy. In the roughness sublayer (z £ 2h)
the coherent structures dominating the transport within and above
the canopy have a characteristic temporal scale of about 100 sec,
whereas above this layer the transport is mainly driven by larger
scale convection (temporal scale of about 15 min). In stable
conditions the height of roughness sublayer progressively
decreases with increasing stability reaching the minimum value
(z<1.35h) in the SS regime. Above the canopy the flow is clearly
dominated by ejections but characterized by a higher intermittency
mainly in SS conditions. On the other hand, the rapid shear stress
absorption in the highest part of the vegetation produces a less
clear dominance of sweeps and a less defined role of odd and even
quadrants inside the canopy in the transport of momentum, heat and
CO2. In the weakly stable regime (0.15<h/L<1) transport is
dominated in the roughness sublayer by canopy coherent structures
with a characteristic temporal scale of about 60 sec. As stability
increases the influence of low-frequency (submeso) processes, with
a temporal scale of 20-30 min, on flow dynamics progressively
increases and becomes dominant in the SS regime where the buoyancy
strongly dampens or completely inhibits turbulent structures
whereas the large-scale oscillations propagate in the interior of
the canopy modulating the heat and CO2 transport.",
conference-location = "Online",
conference-year = "19-30 apr.",
doi = "10.5194/egusphere-egu21-12971",
url = "http://dx.doi.org/10.5194/egusphere-egu21-12971",
language = "en",
targetfile = "EGU21-12971-print.pdf",
urlaccessdate = "09 maio 2024"
}