Subsurface Evolution and Persistence of Marine Heatwaves in the
Northeast Pacific
Hillary A. Scannell
School of Oceanography, University of Washington, Seattle, WA, USA, School of Oceanography, University of Washington, Seattle, WA, USA
Corresponding Author:[email protected]
Author ProfileGregory C. Johnson
Pacific Marine Environmental Laboratory, NOAA, Seattle, WA, USA, Pacific Marine Environmental Laboratory, NOAA, Seattle, WA, USA
Author ProfileLuAnne Thompson
School of Oceanography, University of Washington, Seattle, WA, USA., School of Oceanography, University of Washington, Seattle, WA, USA.
Author ProfileJohn M. Lyman
Pacific Marine Environmental Laboratory, NOAA, Seattle, WA, USA., Pacific Marine Environmental Laboratory, NOAA, Seattle, WA, USA.
Author ProfileStephen C. Riser
School of Oceanography, University of Washington, Seattle, WA, USA., School of Oceanography, University of Washington, Seattle, WA, USA.
Author ProfileAbstract
The reappearance of a northeast Pacific marine heatwave (MHW) sounded
alarms in late summer 2019 for a warming event on par with the
2013–2016 MHW known as The Blob. Despite these two events having
similar magnitudes in surface warming, differences in seasonality and
salinity distinguish their evolutions. We compare and contrast the
ocean’s role in the evolution and persistence of the 2013–2016 and
2019–2020 MHWs using mapped temperature and salinity data from Argo
floats. An unusual near-surface freshwater anomaly in the Gulf of Alaska
during 2019 increased the stability of the water column, preventing the
MHW from penetrating as deeply as the 2013–2016 event. This freshwater
anomaly likely contributed to the intensification of the MHW by
increasing the near-surface buoyancy. The gradual buildup of subsurface
heat content throughout 2020 in the region suggests the potential for
persistent ecological impacts.
