STUDI INDIAN OCEAN DIPOLE (IOD) DI SAMUDRA HINDIA PADA SAAT ATLANTIC MERIDIONAL OVERTURNING CIRCULATION (AMOC) MELEMAH

• Main Author: Zahra Malik Hadibrata, Elviena
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/62599
• Institution: Institut Teknologi Bandung

Changes in the Atlantic Meridional Overturning Circulation (AMOC) are known to have a significant influence on global conveyor belt and the earth climate system. This study examines changes in climate variability in the Indian Ocean, called Indian Ocean Dipole (IOD) in connection with the experimental results of FN20, the 2Sv freshwater hosing experiment in the North Atlantic 50oLU – 70oLU by using the ocean - atmosphere interaction model Community Climate System Model Version 3 (CCSM3) assuming no change in global salinity (noncompensated salt). The analysis conducted on sea surface temperature (SST) data in the form of monthly average data for 30 years for the normal-AMOCscenario which refer to control conditions (CTRL). Then the AMOC scenario weakens with the assumption that global ocean salinity does not change, namely FN20 with time data for 90 years of model simulation divided into three times with 30- years intervals, to adjust the number of years in the CTRL scenario and Simple Ocean Data Assimilation (SODA) to describe the climate variability of the Indian Ocean at coordinates 15oLU – 15oLS and 40oBT – 120oBT. The average temporal pattern of SPL CTRL has a stronger variance than SODA with a Root Mean Square Error (RMSE) value of 0.4. CTRL has a regular pattern, while SODA has an increase in SPL. The average SPL CTRL has a higher temperature value reaching 28.09oC while the average FN20 has a lower temperature value than CTRL, which is lower than 27.9oC due to freshwater hosing in the North Atlantic Ocean. There was a decrease in SST in the Indian Ocean when there was a maximum freshwater hosing in the North Atlantic Ocean. By using the Empirical Orthogonal Function (EOF) known that the first and second modes in each FN20 simulation with intervals of 30 (60-90, 90-120, 120-150) exhibited negative IOD event with a total variance of 30.3% and 20.3% (FN20 (60-90)), a total variance of 35.5% and 14.8% (FN20 (90-120)), and a total of 33% and 20% (FN20 (120-150)). The weakening of AMOC causes changes in the frequency of the occurrence of negative IOD more often than positive IOD. Intensity of the positive IOD with DMI more than 1.5 was reduced in FN20. Then the negative IOD intensity of CTRL and FN20 is in the strong negative IOD classification, with DMI less than -1.5.