Impacts of 2009 typhoons on seawater properties in the Western North Pacific Ocean

• Main Author: Dayang Siti Maryam Mohd Hanan
• Format: Thesis
• Language: English; English
• Published: 2013
• Subjects: HC94-1085 By region or country
• Online Access: https://eprints.ums.edu.my/id/eprint/38216/1/24%20PAGES.pdf; https://eprints.ums.edu.my/id/eprint/38216/2/FULLTEXT.pdf; https://eprints.ums.edu.my/id/eprint/38216/
• Institution: Universiti Malaysia Sabah

This study focuses on the effects of typhoons on the amount of heat removed and seawater properties, mainly its temperature and salinity. A total of 15 typhoons occurred in the Western North Pacific in 2009, and ARGO floats data before and after the passage of each typhoon were obtained and analyzed to evaluate the changes on the affected areas. It was found out that sea surface temperature (SST) decreased after passage of each typhoon, with cooling ranging from 0.10 °C to 2.97 °C. Sea surface salinity (SSS) increased from 0.01 pss to 0.44 pss after passage of the typhoons. Amount of heat removed after individual typhoon's passing were also estimated, and it was observed that typhoon Lupit removed the most heat (841 MJ m-2) while typhoon Chan Hom removed the least heat (30 MJ m- 2). It was also evident from this study that the ocean's structure (thermocline and halocline) changed after a typhoon had passed over the area. The depth of thermocline and halocline of the affected area deepened by 30.5 m and 29.4 m respectively after the passage of typhoon Lupit, mainly due to the increase of mixed layer depth of the ocean. A formulation for the relationship between the change of SST and SSS was also done in this study, and results showed that SSS changes based on the formulation are smaller in a consistent manner when compared to the actual SSS changes (from ARGO floats data). When typhoon's strength ( expressed by its wind speed) and 6SST, amount of heat removed, llSSS, change of thermocline as well as change of halocline were individually considered, all showed positive correlation with different coefficients: when typhoon's strength increases, higher changes on each are also observed. Although the life span of a typhoon over an area is relatively short, it has shown to bring positive impacts: as it is a natural heat removal mechanism, transferring of heat from the tropical waters to mid latitude waters will therefore maintain a moderate and suitable temperature for life; as well as increasing the rate of primary production in the ocean from turbulent mixing and upwelling caused by passing of the typhoons.