@PhDThesis{Ferreira:2023:CoNuEv,
author = "Ferreira, Willian Jos{\'e}",
title = "Contribui{\c{c}}{\~a}o das nuvens para eventos de
amplifica{\c{c}}{\~a}o da irradi{\^a}ncia solar ultravioleta
medida em superf{\'{\i}}cie",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2023",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2023-08-25",
keywords = "radia{\c{c}}{\~a}o ultravioleta, nuvens, {\'o}ptica
instrumental, sensoriamento remoto da atmosfera, ultraviolet
radiation, clouds, instrumental optics, remote sensing of the
atmosphere.",
abstract = "A radia{\c{c}}{\~a}o ultravioleta (RUV, 100-400 nm) impulsiona
numerosos processos fotoqu{\'{\i}}micos e fotobiol{\'o}gicos na
superf{\'{\i}}cie terrestre, cabendo {\`a}s nuvens o papel de
seu principal modulador atmosf{\'e}rico, em raz{\~a}o das
varia{\c{c}}{\~o}es de curto per{\'{\i}}odo que promovem na
irradi{\^a}ncia medida em superf{\'{\i}}cie. No entanto,
in{\'u}meras vezes ao dia, Eventos de Amplifica{\c{c}}{\~a}o da
Radia{\c{c}}{\~a}o Solar (EARS) fazem com que a irradi{\^a}ncia
ultravioleta (UV) supere a irradi{\^a}ncia medida em
condi{\c{c}}{\~a}o de c{\'e}u n{\~a}o encoberto por nuvens.
Neste trabalho, quantificou-se a contribui{\c{c}}{\~a}o das
nuvens para EARS, em S{\~a}o Jos{\'e} dos Campos (23,20º S,
45,86º W, 621 m), a partir de irradi{\^a}ncias espectrais UV em
seis comprimentos de onda (305 nm, 313 nm, 320 nm, 340 nm, 380 nm,
395 nm) e banda PAR (Radia{\c{c}}{\~a}o Fotossint{\'e}tica
Ativa, 400- 700 nm) obtidas em superf{\'{\i}}cie e imagens do
c{\'e}u. Os eventos foram detectados quando o fator de
modifica{\c{c}}{\~a}o das nuvens apresentou diferen{\c{c}}as
maiores que dois erros-padr{\~a}o entre a irradi{\^a}ncia
espectral medida em condi{\c{c}}{\~o}es de c{\'e}us com nuvens
e a irradi{\^a}ncia de refer{\^e}ncia. A an{\'a}lise da
ocorr{\^e}ncia de EARS em v{\'a}rias bandas de RUV e PAR revelou
um aumento no n{\'u}mero de eventos {\`a} medida que o
comprimento de onda aumenta, onde, de 1.735 EARS observados, a
radia{\c{c}}{\~a}o UV-B (305nm) representa 6,0% do total,
enquanto a UV-A (340 nm) e banda PAR representam 17,5% e 30,5%,
respectivamente. Verificou-se que h{\'a} 99,6% de chances dos
EARS serem observados com dura{\c{c}}{\~a}o de at{\'e} 5
minutos, ocorrendo aumentos mais acentuados na primavera e no
ver{\~a}o, e mais proeminentes na regi{\~a}o do UV-A e PAR do
que no UV-B. Identificou-se que EARS em {\^a}ngulo solar de
z{\^e}nite (ASZ) de 30º a 35º ocorrem, principalmente, devido a
nuvens Cumulus e Stratus, mas tamb{\'e}m por nuvens de m{\'e}dia
altitude, do tipo Altocumulus e Altostratus. Para ASZ de 45º a
55º, as amplifica{\c{c}}{\~o}es, em sua maioria, s{\~a}o
associadas a Altostratus e Cirrus. Por{\'e}m, no ver{\~a}o,
quando associadas a Cumulus e Stratocumulus, essas nuvens s{\~a}o
capazes de gerar aumentos de curta dura{\c{c}}{\~a}o que podem
chegar a 70% no caso do UV-B (305 nm). Tamb{\'e}m foi
quantificado o n{\'u}mero de pixels brilhantes das nuvens por
meio da utiliza{\c{c}}{\~a}o do par{\^a}metro de brilho do
espa{\c{c}}o de cores HSV, modelo que expressa as cores em termos
do matiz, satura{\c{c}}{\~a}o e valor. Apesar da aus{\^e}ncia
de correla{\c{c}}{\~a}o entre irradi{\^a}ncia e
varia{\c{c}}{\~a}o de brilho de nuvens durante os EARS nas
diferentes faixas de comprimento de onda medidas em
superf{\'{\i}}cie, {\'e} crucial desenvolver algoritmos
preditores para estudos futuros. Considerando os impactos dos EARS
na dose di{\'a}ria de radia{\c{c}}{\~a}o, em geral, a
radia{\c{c}}{\~a}o adicional em eventos prolongados equivale a
cerca de 5% do total. Embora a contribui{\c{c}}{\~a}o dos
eventos possa parecer insignificante, considerou-se que o aumento
repentino do {\'{\I}}ndice Ultravioleta (IUV) ao longo do tempo
tem o potencial de afetar o meio ambiente e agravar os indicadores
de sa{\'u}de em diversas regi{\~o}es. ABSTRACT: Ultraviolet
radiation (RUV, 100-400 nm) drives numerous photochemical and
photobiological processes at the Earth's surface, with clouds
playing the role of the main atmospheric modulator due to the
short-term variations in surface irradiance they induce. However,
many times a day, radiation enhancement events (REE) cause
ultraviolet (UV) irradiance to exceed that measured under
clear-sky conditions. This study quantified the cloud contribution
to REE at S{\~a}o Jos{\'e} dos Campos (23.20º S, 45.86º W, 621
m) using UV spectral irradiances at six wavelengths (305 nm, 313
nm, 320 nm, 340 nm, 380 nm, 395 nm) and the PAR band
(Photosynthetically Active Radiation, 400-700 nm) obtained at the
surface, as well as sky images. Events were detected when the
cloud modification factor showed differences greater than two
standard errors between the spectral irradiance measured under
cloudy conditions and the reference irradiance. Evaluation of the
occurrence of REE in different RUV and PAR bands showed an
increase in the number of events with longer wavelengths, with
UV-B radiation (305 nm) making up 6.0% of the 1,735 REE observed,
while UV-A (340 nm) and PAR bands accounted for 17.5% and 30.5%,
respectively. It was found that there is a 99.6% chance of
observing REE up to 5 minutes in duration, with more pronounced
increases in spring and summer, and more pronounced increases in
the UV-A and PAR regions than in the UV-B region. REE with a solar
zenith angle (SZA) of 30º to 35º are mainly caused by cumulus and
stratus clouds, but also by mid-level clouds such as altocumulus
and altostratus. For SZA of 45º to 55º, most enhancements are
associated with altostratus and cirrus clouds. However, in summer,
when associated with cumulus and stratocumulus clouds, these
clouds can produce short term enhancements that can reach up to
70% in the case of UV-B (305 nm). The number of bright cloud
pixels was also quantified using the brightness parameter in the
HSV color space model, which expresses colors in terms of hue,
saturation, and value. Although no statistical correlation was
found between surface spectral irradiance and cloud brightness
variation during REE for any of the wavelengths evaluated, it was
considered critical to develop predictive algorithms for spectral
irradiance and reference brightness under cloudy sky conditions
for future research. The effect of the extended REE on the daily
radiation dose is about 5% of the total. Despite the apparent
insignificance, a sustained increase in the UV index could have an
impact on the environment and worsen health indicators in
different regions.",
committee = "Alves, Maria Virginia (presidente) and Alval{\'a},
Pl{\'{\i}}nio Carlos (orientador) and Silva, Abel Ant{\^o}nio
da (orientador) and Echer, Ezequiel and Gobbi, Delano and
Pinheiro, Damaris Kirsch and Martins, Fernando Ramos",
englishtitle = "Contribution of cloudiness to solar ultraviolet irradiance
enhancement events measured at the surface",
language = "pt",
pages = "134",
ibi = "8JMKD3MGP3W34T/49P9NS5",
url = "http://urlib.net/ibi/8JMKD3MGP3W34T/49P9NS5",
targetfile = "publicacao.pdf",
urlaccessdate = "16 jun. 2024"
}