Abstract Marine heatwaves (MHWs), prolonged periods of anomalously warm ocean temperatures, pose significant threats to marine ecosystems. While MHWs in coastal and estuarine systems have been studied separately, their spatial coherence remains significantly understudied. Here we analyze over 2 decades of high‐frequency in situ temperature data from 54 stations across 20 U.S. estuaries and 13 coastal buoys to assess MHW co‐occurrences. We find that estuarine and coastal MHWs co‐occur only ∼21% of the time, a 57% decrease compared to co‐occurrence within estuaries (∼49%). Maximum co‐occurrence occurs at zero lag, suggesting synchronous synoptic‐scale atmospheric forcing, likely via air–sea heat fluxes. Co‐occurrence shows strong seasonality, peaking in fall and weakening in summer, and declines exponentially with distance, with an e‐folding scale O(100 km), consistent with synoptic‐scale atmospheric forcing. This study offers the most comprehensive assessment to date of estuarine‐coastal MHW co‐occurrence and offers a baseline for understanding and forecasting these extreme events.

Read original article

Read original article