Miss Yuwei Hu¹, Dr. Helen Beggs², Pro. Xiao Hua Wang¹, Dr.  Julio Salcedo-Castro^1,3

¹The Sino-Australian Research Consortium for Coastal Management, School of Science, UNSW Canberra, Canberra, Australia, ²Science & Innovation Group, Bureau of Meteorology, Melbourne, Australia, ³School of Earth and Atmospheric Sciences, Queensland University of Technology, Brisbane, Australia

Marine heat waves (MHWs) have recently been recognised as extreme climate events considering their devastating impacts on marine ecosystems. We analyse the main spatial and temporal features of historical MHW events on a pixel-wise scale over the Australian region by forming MHW metrics using CCI and C3S L4 SST from 1981 to 2020. Relatively short-term events (<10 days) account for over half of the identified MHWs over the domain, among which nearly 90% are classified as having moderate intensity. Even among the relatively longer events (≥10 days), more than 50% of the events in most coastal regions of Australia are classified as moderate. The spatial features of MHW parameters did not change when the short-term events were excluded.

Natural variability of the local climate system contributes to most of the short-term and less intense events, while the increasing trend of MHW areas over the entire domain is mainly driven by warming of the ocean surface. Manually excluding the short-term events would benefit the long-term studies (historical or predictive) of MHWs over a large domain, by highlighting the variations and impacts of the relatively longer and more intense events.

Three case study regions are selected according to historical MHWs: the northwest coastal region (Region 1, 17°S -25°S, 110°E -119°E), southwest coastal region (Region 2, 25°S-40°S, 110°E-120°E), and southeast coastal region (Region 3) containing Tasman Sea (33°S-45°S, 147°E-167°E, ) and southern Tasmania region (43°S-48°S, 142°E-152°E). Multiple SST (CCI, C3S L4 SST, IMOS AVHRR L3S, and Multi-sensor L3S SST), sea level anomaly (SLA, CMEMS) and wind stress (CMEMS) products are used to analyse MHWs in case study regions. SLA over the 90th percentile, as a complementary parameter, is recommended to identify MHWs in eddy-free regions, which could help improve the understanding and predictability of MHWs.

Biography:

Yuwei is an PhD candidature who has studied at UNSW Canberra since 2017. Her research is related to ocean surface properties such as Sea Surface Temperature (SST) based on remote sensing products. Her PhD project uses satellite observation products to study historical Marine Heat Wave events over the Australian region.