Long-term climate variability at the Prince Edward Islands in the Southern Ocean

• Main Author: Shangheta, Anna Liisa Penelao Tulimevava
• Other Authors: Lamont, Tarron, Ansorge, Isabel, Rouault, Mathieu
• Format: Master Thesis
• Language: English
• Published: Faculty of Science 2021
• Subjects: Prince Edward Islands; sub-Antarctic Islands; Climatic changes; decadal variability; Antarctic; Southern Ocean; The Antarctic; Antarc*
• Online Access: http://hdl.handle.net/11427/36129; https://open.uct.ac.za/bitstream/11427/36129/1/thesis_sci_2021_shangheta%20anna%20liisa%20penelao%20tulimevava.pdf

A warming Southern Ocean (SO), due to climate change and global warming, has many implications on the sub-Antarctic Islands in the SO. Due to the distance away from continental land these islands experience an oceanic climate, making them the perfect sentinels to climate change in this sector of the Southern Ocean. Studies have proposed that climate changes reported at the Prince Edward Islands (PEIs) correspond in time to a southward shift of the Antarctic Circumpolar Current (ACC) particularly the Subantarctic Front (SAF). While other studies have shown distinctive trends in ocean and atmospheric parameters such as sea surface temperature (SST), air temperature, sunshine, rainfall, air sea level pressure and wind speed and direction from the 1950s to the early 2000s, the aim of this study is to update those studies to a more recent time with updated time series. Among the changes recorded is an increase in SST and air temperature, which is a strong indication of the changing local and global climate. Using linear regression, this study showed that the rates of increase from 1949 to 2018 of the SST (0.022°C/year), minimum (0.0072°C/year) and maximum air temperatures (0.016°C/year) are smaller than estimated in previous studies. The increasing trend in SST and air temperature reported by previous papers has actually stopped since the 2000s, which reduces the formerly reported trend (0.028°C/year). Although the in-situ measured SST data had gaps, a good correlation with in-situ SST and large scale satellite derived Reynolds SST help to corroborate the covariation between SST, in-situ SST and air temperature giving weight to the hypothesis of a reversal of the positive temperature trends reported by others. The change in decadal variability a decrease in air pressure of 4 hPa since the late 1990s to late 2000s, which coincided with a decrease in minimum and maximum air temperatures of 1°C over the same period; decrease in westerly wind and an increase in the northerly component of the wind, which would explain the ...