@PhDThesis{Rudorff:2013:OcCoVa,
author = "Rudorff, Nat{\'a}lia de Moraes",
title = "Ocean Colour Variability across the Southern Atlantic and
Southeast Pacific",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2013",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2013-08-19",
keywords = "bio-optical variability, uncertainties, ocean colour radiances,
Southern Atlantic, Soueastern Pacific, variabilidade bio-optica,
incertezas, radi{\^a}ncias da cor do oceano, Atl{\^a}ntico Sul
Subtropical, Pac{\'{\i}}fico Sudeste.",
abstract = "Ocean colour radiometry (OCR) provides essential information for
studies of primary productivity, heat fluxes, and biogeochemical
cycles in the upper ocean. Generalized OCR models relating
satellite radiometric data to biogeochemical variables are
developed using global in situ data sets. However, when applied to
specific regions these models commonly give results with
significant deviation from in situ measurements, mainly due to
field and satellite measurement uncertainties and model
underrepresentation of ocean colour variability. Hence to improve
OCR products further understanding of the sources of measurement
uncertainty and bio-optical variability across different oceanic
regions is needed. This work was focused on the Southern Atlantic
and Southeast Pacific Oceans encompassing important biogeochemical
provinces with highly distinct optical waters. In situ data was
collected during a summer campaign on board the research vessel
Melville (MV1102 cruise). The first part of the investigation was
an uncertainty analysis of the radiometric and bio-optical data
with three main objectives: (i) test different radiometric
techniques with above and in-water approaches (ii) apply closure
analyses with forward modeling of remote sensing reflectance
(Rrs); and (iii) analyze the impacts of the uncertainties on
operational OCR models. The uncertainty analysis revealed moderate
to high levels associated with the various techniques, with 12 to
26\% relative differences (RD) for the ocean-colour bands (412-
555 nm) and 3-12\% for the reflectance ratios (412-510/555). The
use of a merged Rrs (Instruments, INS) reduced uncertainties since
each individual technique was subject to different instrumental
and environmental biases. Complete closure was not obtained,
especially for the stations with more adverse environmental
conditions (with winds, waves and clouds), with 18-34\% RD
compared to modeled Rrs bands. Nonetheless, the impact of INS
uncertainties on retrieved OCR products for empirical and
semi-analytical (SA) models was still generally smaller than the
intrinsic errors of the inversion schemes. Hence, the approaches
applied to obtain more accurate measurements were effective in
reducing the main sources of uncertainties. Significant sources of
deviations of the OCR models were related to the optical
variability of the study region and intrinsic model errors. The
second part of the investigation analyzed the sources of
bio-optical variability and their relations to biogeochemical
variables across distinct provinces. The bulk inherent optical
properties (IOPs) were in first order associated with the
chlorophyll a concentration (Chla) gradient. Second order
variations were explained by specific IOPs linked to the
phytoplankton community structure, composition and size
distribution of the particle assemblage and variability of the
coloured dissolved and particulate organic matter (CDM). To
synthetize the first and second order optical variations across
the study region, a Regional Specific Optical Water Type (R-SOWT)
classification was proposed by defining 5 classes that integrate
the specific IOPs and bio-optical indices, i.e., a phytoplankton
Size Index, CDM index, the specific backscattering coefficient
(bbp/Chla) and spectral slope (\$\eta\$). The R-SOWT
significantly improved the performance of SA models by using
class-specific parameterizations, especially for the bbp retrieved
by the GSM (Garver-Siegel-Maritorena) model, reducing from 35 to
9\% RP, and the CDM absorption coefficient of the QAA
(Quasi-Analytical Algorithm) model, reducing from 30 to 23\% RD.
For more optically complex waters the improvements of the
retrievals were much more significant. Further analysis of
spatiotemporal variations of the optical relations and
applicability of the R-SOWT for different seasons (and regions)
are recommended for future studies. This approach has potential to
improve OCR satellite products and be used as a new product that
integrates relevant information for biogeochemical studies.
RESUMO: A radiometria da cor do oceano oferece
informa{\c{c}}{\~o}es essenciais para estudos de produtividade
prim{\'a}ria, fluxos de calor e ciclos biogeoqu{\'{\i}}micos na
superf{\'{\i}}cie dos oceanos. Modelos generalizados de cor do
oceano que relacionam dados radiom{\'e}tricos de sat{\'e}lite
com vari{\'a}veis biogeoqu{\'{\i}}micos s{\~a}o desenvolvidos
com bases de dados globais in situ. No entanto, quando aplicados a
regi{\~o}es espec{\'{\i}}ficas estes modelos apresentam desvios
significativos que est{\~a}o relacionados a incertezas nas
medidas in situ e satelitais, e sub-representa{\c{c}}{\~o}es da
variabilidade da cor do oceano. Portanto, para a melhoria de
produtos de cor do oceano {\'e} preciso conhecer melhor as fontes
incertezas das medidas e a variabilidade bio-{\'o}ptica em
diferentes regi{\~o}es oce{\^a}nicas. O presente trabalho teve
como foco os Oceanos Atl{\^a}ntico Sul Sub-tropical e
Pac{\'{\i}}fico Sudeste abrangendo importantes
prov{\'{\i}}ncias biogeogr{\'a}ficas com {\'a}guas opticamente
distintas. Dados in situ foram coletados durante uma campanha de
ver{\~a}o a bordo do navio de pesquisa R/V Melville (MV1102). A
primeira parte do trabalho compreendeu an{\'a}lises de incertezas
dos dados radiom{\'e}tricos e bio-{\'o}pticos com tr{\^e}s
objetivos principais: a) a compara{\c{c}}{\~a}o de diferentes
t{\'e}cnicas de amostragem com instrumentos emersos e submersos;
b) compara{\c{c}}{\~o}es com a reflect{\^a}ncia de
sensoriamento remoto (Rsr) modelada; e c) an{\'a}lises dos
impactos das incertezas em modelos operacionais de cor do oceano.
As an{\'a}lises de incertezas revelaram n{\'{\i}}veis de altos
a moderados associados {\`a}s diferentes t{\'e}cnicas, com
diferen{\c{c}}as relativas (DR) de 12 a 26\% para as bandas de
cor do oceano (412-555 nm) e 3 a 12% para as raz{\~o}es de bandas
(412-510/555). O uso de uma medida de Rsr integrada (Instrumentos,
INS) reduziu as incertezas j{\'a} que cada t{\'e}cnica
individual estava sujeita a diferentes erros instrumentais e
ambientais. O ajuste perfeito com a Rsr modelada n{\~a}o foi
obtido, principalmente para as esta{\c{c}}{\~o}es com
condi{\c{c}}{\~o}es ambientais mais adversidades (de vento,
ondas e nuvens), com 18-34\% DR para as bandas espectrais. Ainda
assim, o impacto das incertezas do INS foi de modo geral, menor
que os erros intr{\'{\i}}nsecos aos modelos emp{\'{\i}}ricos e
semi-anal{\'{\i}}ticos (SA) de cor do oceano. Dessa forma, os
m{\'e}todos empregados para obter medidas mais acuradas foram
razoavelmente eficazes em reduzir as incertezas. Desvios
significativos dos modelos de cor do oceano foram relacionados
{\`a} variabilidade {\'o}ptica da regi{\~a}o de estudo e erros
intr{\'{\i}}nsecos aos modelos. A segunda parte da
investiga{\c{c}}{\~a}o compreendeu an{\'a}lises das fontes de
variabilidade bio-{\'o}ptica e suas rela{\c{c}}{\~o}es com as
vari{\'a}veis biogeoqu{\'{\i}}micas nas diferentes
prov{\'{\i}}ncias. A distribui{\c{c}}{\~a}o dominante das
propriedades {\'o}pticas inerentes (POIs) esteve associada ao
gradiente de concentra{\c{c}}{\~a}o de clorofila a (Cla).
Varia{\c{c}}{\~o}es de segunda ordem foram relacionadas a POIs
espec{\'{\i}}ficas associadas {\`a} estrutura da comunidade
fitoplanct{\^o}nica, a composi{\c{c}}{\~a}o e
distribui{\c{c}}{\~a}o do tamanho das part{\'{\i}}culas e
{\`a} variabilidade da mat{\'e}ria org{\^a}nica dissolvida e
particulada (MODP). Para sintetizar as varia{\c{c}}{\~o}es de
primeira e segunda ordem na regi{\~a}o de estudo, uma
classifica{\c{c}}{\~a}o Regional de Tipos Espec{\'{\i}}ficas
de {\'A}guas {\'O}pticas (R-TEAO) foi proposta para definir 5
classes, integrando as POIs espec{\'{\i}}ficas e
{\'{\i}}ndices bio-{\'o}pticos, i.e., o {\'{\I}}ndice de
tamanho do fitopl{\^a}ncton, {\'{\i}}ndice de CDM, o
coeficiente especifico de retroespalhamento das
part{\'{\i}}culas (bbp/Cla) e o par{\^a}metro de
varia{\c{c}}{\~a}o espectral (\$\eta\$). O R-TEAO melhorou
significativamente o desempenho de modelos SA com
parametriza{\c{c}}{\~o}es especificas para cada classe,
reduzindo a DR do bbp do modelo GSM01 (Garver-Siegel-Maritorena)
de 35 a 9\% e o coeficiente de absor{\c{c}}{\~a}o do MODP de 30
a 23\% para o modelo QAAv5 (Quase Analytical Algorithm). Para
{\'a}guas mais opticamente complexas a melhoria dos modelos foi
ainda mais significativa. An{\'a}lises das varia{\c{c}}{\~o}es
espa{\c{c}}o-temporais das rela{\c{c}}{\~o}es {\'o}pticas e a
aplicabilidade do R-TEAO para esta{\c{c}}{\~o}es sazonais
diferentes e outras regi{\~o}es oce{\^a}nicas, s{\~a}o
recomendadas para pesquisas futuras. O m{\'e}todo tem potencial
de ser aplicado para a melhoria de produtos de cor do oceano por
sat{\'e}lite e ser usado como um novo produto integrando
informa{\c{c}}{\~o}es importantes para estudos
biogeoqu{\'{\i}}mica.",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)}",
committee = "Lorenzzetti, Jo{\~a}o Antonio (Presidente) and Kampel, Milton
(Orientador) and Frouin, Robert (Orientador) and Novo, Evlyn
M{\'a}rcia Le{\~a}o de Moraes and Ciotti, Aurea Maria and Lutz,
Vivian",
englishtitle = "Variabilidade da cor do oceano no Alt{\^a}ntico Sul Subtropical e
Pac{\'{\i}}fico Sudeste",
language = "en",
pages = "321",
ibi = "8JMKD3MGP7W/3ERLCSE",
url = "http://urlib.net/ibi/8JMKD3MGP7W/3ERLCSE",
targetfile = "publicacao.pdf",
urlaccessdate = "03 maio 2024"
}