Spatial variability of marine heatwaves in the Chesapeake Bay

Rachel Wegener , Jacob O. Wenegrat, Veronica Lance, Skylar Lama

The Chesapeake Bay is the largest and one of the most productive estuaries in
the United States. Like many estuaries, rising global temperatures have impacted
this ecologically important zone. Marine heatwaves, extreme temperature events,
are increasingly common in the Chesapeake Bay. Although marine heatwaves
evolve across space and time, a complete spatial picture of marine heatwaves in
the Bay is missing. Here we use satellite sea surface temperature data to characterize
marine heatwaves in the Chesapeake Bay. We consider two products:
NASA MUR and NOAA Geo-Polar, and validate their effectiveness for studying
marine heatwaves in an estuary using in situ data from the Chesapeake Bay
Program. A north-south (along estuary) gradient is identified as a common pattern
of spatial variability, seen in both marine heatwave duration and number
of events. Our satellite-based approach enables us to analyze marine heatwaves
in Chesapeake Bay tributaries for the first time, and finds marine heatwaves in these regions to display different characteristics from the main stem of the Bay.
For example, marine heatwave maximum intensity is higher in tributary waters.
Long term trends in marine heatwave characteristics are also analyzed, although
confidence in long term trends is tempered by changes in satellite error over time,
pointing to the criticality of periodic reanalyses of satellite data to identify and
correct for systematic error. MHW analysis with a detrended baseline suggests
the major observed spatial patterns are a result of long term warming not a shifting
temperature distribution. The differing spatial patterns suggest that there
are different physical influences in the main stem of the Bay and in the tributaries.
This work affirms that satellite data can be an effective tool for studying
marine heatwaves in estuaries and enables similar studies in other estuaries.