[A-CG33] Extratropical oceans and atmosphere

[ACG33-10] The North Pacific marine heatwave simulated in a high-resolution coupled general circulation model

*Tomonori Matsuura ¹, Ichiro Yasuda², Hiroaki Tatebe³ (1.The University of Tokyo , 2.The University of Tokyo, 3.Japan Agency for Marine-earth Science and Technology)

Keywords:The North Pacific marine heatwave, Coupled general circulation model, The Pacific decadal variability, The decadal ENSO

We are successful in simulating the recently notable ocean-atmosphere coupled phenomenon called the North Pacific Marine Heatwave (MHW) for the first time, using a coupled general circulation model with an eddy-permitting ocean model (MIROC6). During the analyzed 270 years of model integration, the anomalous climate events have appeared 16 times over the Gulf of Alaska (GOA) in the Eastern North Pacific. They are characterized by the warming of the sea surface temperature (SST) over standard deviations (~ 1.5°C) in the GOA, corresponding patterns of the Pacific decadal variability (PDV). The spatial transient patterns of the anomalous SST and SLP (Sea Level Pressure) show the 2014/2015 observed North Pacific MHW (Di Lorenzo and Mantua, 2016) called as “the Warm Blob”. This simulated MHW events link to NPGO (PDO second mode), PDO, and decadal ENSO (NINO 3.4). Timeseries analysis in mid-latitude ocean shows that eastward anomalous water (temperature, salinity, and potential vorticity) propagation (cf. Niinuma, 2022; MS thesis), which is mainly due to ocean dynamics, is crucial in generation the model MHW events.