@Article{SampaioRoVoSiArRo:2021:SeHeFl,
author = "Sampaio, Rafael Jo{\~a}o and Rodriguez, Daniel Andres and Von
Randow, Celso and Silva, Fabr{\'{\i}}cio Polifke da and
Ara{\'u}jo, Afonso Augusto Magalh{\~a}es de and Rotunno Filho,
Otto Correa",
affiliation = "{Universidade Federal do Rio de Janeiro (UFRJ)} and {Universidade
Federal do Rio de Janeiro (UFRJ)} and {Instituto Nacional de
Pesquisas Espaciais (INPE)} and {Universidade Federal do Rio de
Janeiro (UFRJ)} and {Universidade Federal do Rio de Janeiro
(UFRJ)} and {Universidade Federal do Rio de Janeiro (UFRJ)}",
title = "Sensible heat flux assessment in a complex coastal-mountain urban
area in the metropolitan area of Rio de Janeiro, Brazil",
journal = "Meteorology and Atmospheric Physics",
year = "2021",
volume = "133",
pages = "973--987",
abstract = "Obtaining accurate estimates of surface-atmosphere energy
exchanges and improved comprehension of the mechanisms generating
turbulent fluxes over non-uniform landscapes are both challenging
goals and essential for validating numerical weather forecasting
modeling. In this work, a large-aperture scintillometer (LAS) was
deployed to evaluate the effect of mesoscale sea and valley
breezes with respect to diurnal sensible heat flux (H) variability
over an urban area close to a coastal bay near the metropolitan
area of Rio de Janeiro (MARJ) during the austral summer of
2017-2018 time span. The region is characterized by a densely
urbanized environment, surrounded by mountainous relief and
bounded by a large ocean bay. The transmitter and the receiver of
the LAS system were installed 1955 m apart. Diurnal cycle was
divided into four periods according to the local time: dawn (00
a.m. to 6 a.m.), morning (6 a.m. to 12 a.m.), afternoon (12 a.m.
to 6 p.m.), and night (6 p.m. to 00 a.m.). The results
demonstrated the sensitivity of the LAS to record variations in H
over the course of the day, taking into account the corresponding
sea and valley breezes and the relative humidity variability.
During the morning, when valley breezes are predominant, footprint
area shrinks to its smallest size, encompassing an area of
approximately 2 km(2). On the other side, during afternoon and
night time periods, during afternoon and night time periods, the
presence of sea breeze jointly with a densely urbanized
continental area contribute to promote significant changes in the
footprint area ranging from 2.05 to 5.38 km(2). The effects of
topography are also well captured in the diurnal H cycle once
sunset and corresponding shading in the late afternoon abruptly
reduces heat-sensible flux. Diurnal variations in footprint shape
and area lead to modifications in terms of the mode each type of
urban surface will contribute to H, increasing the influence of
anthropogenic elements in afternoon and early evening.
Complementarily, it is noteworthy to mention that a sensitivity
test was performed to assess uncertainties in H estimates for the
free convection method, which requires the estimation of an
empirical constant b. Variations in this constant introduce larger
dispersion in H estimates than potential errors in LAS effective
height (Z(eff)) estimations or temperature measurements. These
last results highlight the importance of conducting further
evaluations as the one pursued in this study to more rigorously
validate the outputs of numerical mesoscale and local
hydrometeorological models and remotely sensed products.",
doi = "10.1007/s00703-021-00812-2",
url = "http://dx.doi.org/10.1007/s00703-021-00812-2",
issn = "0177-7971",
language = "en",
targetfile = "sampaio_sensible_2021.pdf",
urlaccessdate = "23 maio 2024"
}