@PhDThesis{Lima:2024:ImFrSu,
author = "Lima, Luciana Shigihara",
title = "Impacts of freshwater supply on the coastal dynamics of the
Antarctic Peninsula",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2024",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2023-12-06",
keywords = "ice shelves, basal melting, oceanic numerical modeling, water
masses, ice-ocean-atmosphere interactions, plataformas de gelo,
derretimento basal, modelagem num{\'e}rica oce{\^a}nica, massas
de {\'a}gua, intera{\c{c}}{\~o}es gelo-oceano-atmosfera.",
abstract = "This work analyzes the impact of the introduction of freshwater
into the ocean resulting from the melting of ice shelves in the
Antarctic Peninsula. The reduction of ice shelves not only
contributes to sea level rise through increased freshwater inflow
into the ocean but also has the potential to alter ocean
circulation, sea ice production at the surface, and the consequent
stratification, along with changes in the characteristics of water
masses. In this study, we investigate the effects of basal melting
(melting at the base of the ice shelves) on circulation, water,
and sea ice mass production in the ocean surrounding the Antarctic
Peninsula (Bellingshausen and Weddell Seas). To do this, we used
the regional ocean model ROMS (Regional Ocean Model System) to
simulate the dynamic and thermodynamic mechanisms in this region.
Due to model limitations, the thickness and area of the ice
shelves remain unchanged throughout the simulation. Two
experiments were conducted: a control experiment (CTRL) and a
sensitivity experiment (SENST). The CTRL experiment (with the ice
shelf melting effect) was able to replicate the main oceanographic
features over the simulation period (2002-2020). In the
sensitivity test (SENST), the salt and heat fluxes representing
the freshwater flows from melting were set to zero. An increase in
sea ice production in the coastal region was observed in the CTRL
experiment compared to SENST, due to the extremely cold freshwater
plumes resulting from melting. There was also an increase in the
production of dense bottom waters originating from mixing
processes beneath the ice shelves, extremely cold ISW water from
melting, with modified deep circumpolar waters (mCDW) that enter
the ice shelf cavities, as well as super saline and dense waters
(HSSW) resulting from sea ice production. An increase in sea ice
concentration was also observed in the Weddell Gyre region in the
CTRL experiment, as well as an intensification of the gyre. The
increased sea ice concentration, affected by katabatic winds
(strong and constant winds from the interior of the continent) and
westerly winds, pushes the ice toward the center of the gyre.
Also, the current intensity is affected by changes in wind stress
on the ocean due to changes in sea ice thickness at the surface.
Over the Bellingshausen Sea, the intensification of westerly winds
increases the circulation of mCDW into the ice cavities,
contributing to changes in melting and platform instability.
Temporally, changes in wind patterns, sea ice formation and
extent, and basal melting patterns are observed after the year
2011. While no major differences in transport were found in the
studied sections between CTRL and SENST, an increase in the
production of dense bottom and surface water masses, as well as
the stratification process, was observed. RESUMO: Este trabalho
analisa o impacto da introdu{\c{c}}{\~a}o de {\'a}gua doce no
oceano decorrente do derretimento das plataformas de gelo na
Pen{\'{\i}}nsula Ant{\'a}rtica. A redu{\c{c}}{\~a}o das
plataformas de gelo n{\~a}o s{\'o} contribuem para o aumento do
n{\'{\i}}vel do mar atrav{\'e}s do aumento nos fluxos de
{\'a}gua doce para o oceano, como tamb{\'e}m tem potencial para
alterar a circula{\c{c}}{\~a}o oce{\^a}nica, a
produ{\c{c}}{\~a}o de gelo marinho na superf{\'{\i}}cie, e a
consequente estratifica{\c{c}}{\~a}o, al{\'e}m de
altera{\c{c}}{\~o}es nas caracter{\'{\i}}sticas
fisico-quimicas das massas de {\'a}gua. Aqui neste estudo
verificamos os efeitos do derretimento basal (processo de
derretimento na base das plataformas) na circula{\c{c}}{\~a}o,
na produ{\c{c}}{\~a}o de massas de {\'a}gua e de gelo marinho
sobre o oceano que circunda a Pen{\'{\i}}nsula Ant{\'a}rtica
(mares de Bellingshausen e de Weddell). Para isso, utilizou-se o
modelo regional oce{\^a}nico ROMS (Regional Ocean Model System)
para simular os mecanismos din{\^a}micos e termodin{\^a}micos
dessa regi{\~a}o. Devido a limita{\c{c}}{\~o}es do modelo, a
espessura e {\'a}rea das plataformas permanece inalterado durante
toda a simula{\c{c}}{\~a}o. Foram realizados dois experimentos:
um experimento controle (CTRL) e um experimento de sensibilidade
(SENST). O experimento CTRL (com o efeito do derretimento)
conseguiu reproduzir as principais fei{\c{c}}{\~o}es
oceanogr{\'a}ficas ao longo do per{\'{\i}}odo da
simula{\c{c}}{\~a}o (2002-2020). No teste de sensibilidade
(SENST), os fluxos de sal e calor que representam os fluxos de
{\'a}gua doce do derretimento, foram zerados. Foi observado o
aumento na produ{\c{c}}{\~a}o de gelo marinho na regi{\~a}o
costeira no experimento CTRL em rela{\c{c}}{\~a}o ao SENST,
devido {\`a}s plumas da {\'a}gua doce extremamente frias
resultante do derretimento sobre essas regi{\~o}es. Tamb{\'e}m
observou-se um aumento na produ{\c{c}}{\~a}o das {\'a}guas
densas de fundo que se originam dos processos de mistura sob as
plataformas, da {\'a}gua extremamente fria ISW, oriunda do
derretimento, com as {\'a}guas circumpolares profundas
modificadas (mCDW), que adentram as cavidades das plataformas,
assim como as {\'a}guas super salinas e densas (HSSW) resultantes
do processo de produ{\c{c}}{\~a}o de gelo marinho. Observou-se
tamb{\'e}m um aumento na concentra{\c{c}}{\~a}o de gelo marinho
no experimento CTRL, na regi{\~a}o do giro de Weddell, assim como
uma intensifica{\c{c}}{\~a}o do giro. O aumento na
concentra{\c{c}}{\~a}o de gelo marinho, afetados pelos ventos
catab{\'a}ticos (ventos fortes e constantes oriundos do interior
do continente) e de oeste, conduzem o gelo para o centro do giro,
a intensidade da corrente {\'e} afetado pela varia{\c{c}}{\~a}o
no estresse do vento sobre o oceano, devido as
altera{\c{c}}{\~o}es na espessura de gelo marinho na
superf{\'{\i}}cie. Sobre o mar de Bellingshausen, a
intensifica{\c{c}}{\~a}o dos ventos de oeste aumentam a
circula{\c{c}}{\~a}o da mCDW para dentro das cavidades de gelo,
contribuindo para as altera{\c{c}}{\~o}es no derretimento e
instabilidade das plataformas. Temporalmente, nota-se uma
mudan{\c{c}}a sobre os padr{\~o}es de vento, de
forma{\c{c}}{\~a}o e extens{\~a}o do gelo marinho e do
derretimento basal, ap{\'o}s o ano de 2011. N{\~a}o foram
encontrados grandes diferen{\c{c}}as no transporte nas
se{\c{c}}{\~o}es estudadas entre CTRL e SENST, por{\'e}m, foi
poss{\'{\i}}vel observar o aumento na produ{\c{c}}{\~a}o das
massas de {\'a}gua densas de fundo, e de superf{\'{\i}}cie,
assim como o processo de estratifica{\c{c}}{\~a}o.",
committee = "Lorenzzetti, Jo{\~a}o Antonio (presidente) and Pezzi, Luciano
Ponzi (orientador) and Mata, Mauricio Magalh{\~a}es (orientador)
and Klinck, John Michael and Schultz, Cristina",
englishtitle = "Impactos do aporte de {\'a}gua doce na din{\^a}mica costeira da
Pen{\'{\i}}nsula Ant{\'a}rtica",
language = "en",
pages = "148",
ibi = "8JMKD3MGP3W34T/4ABK752",
url = "http://urlib.net/ibi/8JMKD3MGP3W34T/4ABK752",
targetfile = "publicacao.pdf",
urlaccessdate = "07 maio 2024"
}