Teleconnection between Antarctic sea ice variability and Indian summer monsoon / Siti Syairah Atiqah Azhar
Teleconnection between the Antarctic sea ice and the tropical climate has become an important issue in recent years, particularly among scientists and researchers. Further investigating the subject, this study examines the teleconnection between the Antarctic sea ice extent in the Indian Ocean se...
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| Format: | Thesis |
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2023
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| Online Access: | http://studentsrepo.um.edu.my/15696/1/Siti_Syairah.pdf http://studentsrepo.um.edu.my/15696/2/Siti_Syairah_Atiqah_Azhar.pdf http://studentsrepo.um.edu.my/15696/ |
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| Summary: | Teleconnection between the Antarctic sea ice and the tropical climate has become
an important issue in recent years, particularly among scientists and researchers. Further
investigating the subject, this study examines the teleconnection between the Antarctic
sea ice extent in the Indian Ocean sector and the Indian summer monsoon rainfall. It
utilises reanalysis, satellite and in-situ observation data, and model output from the
coupled model Intercomparison project phase 5 (CMIP5) from 1979 to 2013. The study
is divided into three main parts. Firstly, examining the climatology of the sea ice extent
in the Indian Ocean sector and Indian summer monsoon rainfall, both seasonal and
monthly. Secondly, examines the relationship between the sea ice extent in the Indian
Ocean sector and Indian summer monsoon rainfall variability under the influence of the
Mascarene High. Thirdly, offers the mechanism connecting the sea ice extent in the
Indian Ocean sector and Indian summer monsoon rainfall regarding atmospheric
circulation features and compares it with several CMIP5 models. The long term monthly
average of the sea ice extent in the Indian Ocean sector for 35 years shows that the
maximum amount of sea ice extent produced is in October while the minimum amount is
in February. The highest seasonal month of the sea ice extent during September-October-
November (SON), and the lowest was in December-January-February (DJF).
Furthermore, the northeastern region of India receives the highest mean annual rainfall
during the summer monsoon season, whereas the northwestern region of India receives
the lowest mean annual rainfall. The correlation analysis revealed that the April-May-
June (AMJ) sea ice extent in the Indian Ocean sector significantly positively correlated
with the Indian summer monsoon rainfall, particularly over the Peninsular India region from 1979 to 2013 (r = 0.44, p < 0.05). This connection is indicated by the correspondence
of the high ice phase (HIP) and low ice phase (LIP) years to the strengthening and
weakening of the Mascarene High, resulting in the increase and decrease of Indian
summer monsoon rainfall. The empirical orthogonal function (EOF) and correlation
analysis show that the first and third modes of principal component (PC1 and PC3) of
AMJ sea ice extent in the Indian Ocean sector during are significantly correlated with the
second mode of principal component (PC2) of Indian summer monsoon rainfall. The
reanalysis data revealed that the changes in the sea ice extent excite meridional wave train
responses along the Indian Ocean for both principal component modes. Positive
(negative) sea ice extent anomalies based on first and third EOFs (EOF1 and EOF3),
contribute to the strengthening (weakening) of the Polar, Ferrel, and Hadley cells,
inducing stronger (weaker) convective activity over the Indian latitudes. The stronger
(weaker) convective activity over the Indian region leads to more (less) rainfall over the
region during high (low) ice phase years. Furthermore, a stronger (weaker) polar jet
during the high (low) ice phase is also noted. The AMJ sea ice extent simulated by the
NorESM1-M model was significantly positively correlated with Indian summer monsoon
rainfall, whereas the IPSL-CM54-LR model showed a negative correlation. Both models
were able to captured certain atmospheric teleconnection features found in the reanalysis.
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