SCIENTIA GEOGRAPHICA SINICA ›› 2023, Vol. 43 ›› Issue (4): 719-725.doi: 10.13249/j.cnki.sgs.2023.04.015

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Multi-scale variations of marine heatwaves and its mechanisms

Liang Kunming1,2(), Qiu Yun2(), Zhou Xiwu2, Teng Hui2, Lin Xinyu2, He Yijun1   

  1. 1. School of Marine Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, Jiangsu, China
    2. Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, Fujian, China
  • Received:2022-02-13 Revised:2022-07-12 Online:2023-04-30 Published:2023-04-20
  • Contact: Qiu Yun E-mail:20201209008@nuist.edu.cn;qiuyun@tio.org.cn
  • Supported by:
    National Natural Science Foundation of China(42130406);Scientific Research Foundation of Third Institute of Oceanography, MNR(2022027);Scientific Research Foundation of Third Institute of Oceanography, MNR(2023018);Cooperation Funding Program of Asia(99950410);Ministry of Natural Resources Program on Global Change and Air-Sea Interactions(GASI-04-WLHY-01);Ministry of Natural Resources Program on Global Change and Air-Sea Interactions(GASI-04-WLHY-03)

Abstract:

Marine heatwaves are extremely warm sea surface temperature (SST) events that can last for several days to years and extend up to thousands of kilometers. Under the influence of various external forcings such as weather systems, air-sea coupling modes, and human activities, marine heatwaves have multi-time-scale variation characteristics. Reviewing the domestic and international main literatures, this paper reviews the main research progress on the seasonal, interannual and decadal variability and long-term trends of marine heatwave and its mechanisms. Existing studies have shown that: 1) Due to the shallow depth of the mixed layer in summer, the SST is more sensitive to the surface heating process, which leads to the most intense marine heatwave in summer and the opposite in winter. the complex local oceanic and atmospheric forcing also makes the seasonal variability of marine heatwaves have significant regional characteristics. 2) The interannual variability of marine heatwaves is mainly affected by interannual-scale coupled air-sea modes such as El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). Among them, ENSO has the most significant impact on marine heatwaves, and its impact covers most of the world's oceans, including tropical Pacific Ocean, tropical Indian Ocean, the west coast of Australia, the Northeast Pacific Ocean and some parts of the Southern Ocean, through oceanic and atmospheric local or remote forcing. The influence of IOD is mainly concentrated in the tropical Indian Ocean and the tropical Pacific Ocean. Negative (Positive) IOD events cause the thermocline to become deeper (shallower) in the tropical southeastern Indian Ocean, weaken (enhance) the upwelling of coastal cold water, and then promote (inhibit) the occurrence of marine heatwaves. The main influenced areas of the North Atlantic Oscillation (NAO) and Atlantic Niño (ANINO) are located in the North Atlantic Ocean and the offshore west Africa, respectively. The negative phase of NAO causes large-scale warming of SST in the North Atlantic, which promotes the enhancement of marine heatwaves in the North Atlantic, while the positive phase of ANINO causes polar warm advection in the coastal waters off the west coast of Africa, leading to an increase in the number of marine heatwaves in this area. 3) Low-frequency climate fluctuations such as the Interdecadal Pacific Oscillation and the Pacific Decadal Oscillation play an important role in the interdecadal occurrence and variation of marine heatwave in the Pacific Ocean, tropical Atlantic Ocean and southeast Indian Ocean which greatly affect the occurrence and variation of global marine heatwaves by influencing changes in SST or the frequency and intensity of El Niño. 4) In addition to natural climate variability, the long-term trend of marine heatwaves is mainly affected by human activities. The results of the global climate model show that under the RCP8.5 scenario, the intensity of the marine heatwave is twice that of the RCP4.5 by 2100, and most of the world's oceans are trapped in a "permanent" marine heatwave state. At the same time, human-caused climate change also has dramatically increased the probability of some recent large and severe marine heatwave events. Finally, some important scientific issues in marine heatwaves research are discussed, and the possible development trend in future are prospected.

Key words: marine heatwave, El Niño, Indian Ocean Dipole (IOD), extreme climate

CLC Number: 

  • P732