Spatial variability of marine heatwaves in the Chesapeake Bay

Abstract

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 a rms that satellite data can be an effective tool for studying marine heatwaves in estuaries and enables similar studies in other estuaries.