Marine Heatwaves in the Red Sea and their Relationship to Different Climate Modes: A Case Study of the 2010 Events in the Northern Red Sea
Abstract. In the context of climate change, the oceans are progressively warming, leading to an increase in the occurrence of marine heatwaves (MHWs). This warming trend is particularly striking in the Red Sea and has a significant impact on its ecosystem. The current study focuses on the characteristics of MHWs in the Red Sea in recent decades and examines their spatial patterns in the Red Sea sub-regions. In addition, the relationships between MHWs frequency and different climate modes are investigated. The extreme MHW events that occurred in the northern region in 2010 were analyzed. Through the analysis of satellite-derived sea surface temperatures (SST), a warming trend was observed that began in 1994 and has intensified significantly since 2016. This rise in temperature is accompanied by an increase in the frequency and total number of MHW days in the basin. In the last four decades (1982–2021), there have been 78 MHW events with a total of 1016 heat days. It is noteworthy that 46 % of the events and 58 % of the heat days occurred in the last decade. The spatial analysis of MHW characteristics in the Red Sea shows high variability, with longer and more intense MHWs occurring in the northern Red Sea (NRS), while they were more frequent in the southern Red Sea (SRS). The annual MHW frequency in the NRS peaked in 2010, 2018, 2019 and 2021, while it was highest in the SRS in 1998 and from 2017 to 2021. When comparing the annual mean values of atmospheric variables with the annual frequency of MHWs, a correlation was found. It was observed that years characterized by an increased frequency of MHWs coincided with anomalously high total heat fluxes and air temperatures, while exhibiting anomalously low wind speeds. This relationship was particularly pronounced in the NRS in 2010 and in the SRS in 1998. A link is then established between the SST anomaly, the MHW frequency and certain climate indices. The Atlantic Multidecadal Oscillation (AMO) and the Indian Ocean Dipole (IOD) showed a positive spatial correlation with the SSTA and the MHW frequency. In contrast, the East Atlantic/West Russian pattern (EATL/WRUS) showed a negative correlation with the SSTA and the MHW frequency, especially in the NRS. The MHWs of 2010 were further investigated as it was one of the warmest years in our study period, which had highly frequent MHWs with a different spatial distribution than the other warm years. It was also observed that the AMO and IOD were in a robust positive phase in 2010, while the EATL/WRUS and North Atlantic Oscillation (NAO) were in their most pronounced negative phase, which may have contributed to the increased occurrence of MHWs in that year. This study highlights the link between climate indices, atmospheric conditions and the occurrence of marine heatwaves in the Red Sea and provides valuable insights into this critical aspect of climate change.
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