RESUMO
Globally, marine heatwaves (MHWs) are becoming more common, more intense, and longer-lasting. They could have a large ecological and societal impact when compounded by low oxygen concentrations or high acidity. Here, using a high-resolution satellite product and reanalysis datasets, we investigated the characteristics of the MHW at northern Yellow Sea (NYS) during mid-summer 2018 and the driving mechanisms of large-scale atmospheric circulations. Results showed that the MHW in mid-summer 2018 (lasting from 26 July to 18 August 2018) had been the most intense since 1982, reaching an anomaly peak of 5.15 °C. For the 2018 MHW, the onset rate was 0.49 °C/day, indicating that the reaction window was relatively short and hard to take mitigation measures, while the decline rate was 0.19 °C/day, meaning the coping window was long and easy to push an already stressed system. The synergy of the two large-scale dynamic systems, i.e., the northward-shifted western north Pacific subtropical high (WNPSH) and the northeastward-expanded South Asia high (SAH), was likely responsible for establishment and maintenance of the hot-weather conditions. These high-pressure systems could result in stronger descending motion, less cloud cover, more solar radiation, and smaller wind speeds which in combination aggravated the MHW. We further found that the unprecedented MHW was actually also impacted by terrestrial heatwave. From 14 July to 15 August 2018, Northeast China was affected by an exceptionally long and intense atmospheric heat wave (AHW). The AHW had impacted on the MHW through warm advection transportation and may significantly contribute to the record-breaking intensity of the MHW, in addition to the impact of abnormal atmospheric circulations. Finally, we showed that a mass mortality of sea cucumbers in the study region during mid-summer 2018 was highly likely caused by the MHW through severe heat stress.
