Abstract
The spatiotemporal evolution of marine heatwaves (MHWs) is explored
using a tracking algorithm termed Ocetrac that provides objective
characterization of MHW spatiotemporal evolution. Candidate MHW grid
points are defined in detrended gridded sea temperature data using a
seasonally varying temperature threshold. Identified MHW points are
collected into spatially distinct objects using edge detection with weak
sensitivity to edge detection and size threshold criteria. These MHW
objects are followed in space and time while allowing objects to split
and merge. Ocetrac is applied to monthly satellite sea surface
temperature data from September 1981 through January 2021. The resulting
MHWs are characterized by their intensity, duration, and total area
covered. The global analysis shows that MHWs in the Gulf of Maine and
Mediterranean Sea evolve within a relatively small region, while major
MHWs in the Pacific and Indian Oceans are linked in space and time. The
largest and most long lasting MHW using this method lasts for 60 months
from November 2013 to October 2018, encompassing previously identified
MHW events including those in the Northeast Pacific (2014-2015), the
Tasman Sea (2015-2016, 2017-2018), and the Great Barrier Reef (2016).