Marine heatwaves and marine cold-spells on the Yucatan Shelf-break upwelling region

Abstract

Since the historic marine temperature has been changing and consequently the ecological processes, this work studies the presence and magnitude of anomalous events at the sea surface temperature (SST) from a climate change perspective in a Non-eastern upwelling system. Concepts and metrics for Marine Heatwaves (MHW) and Marine Cold–Spell (MCS) were applied over the marine region of the Yucatan continental shelf and Yucatan Channel. To calculate the MHW/MCS and climatology between 1982 and 2019, a remote historic dataset of SST was used. Temporal differences of MHW/MCS events were calculated to assess the increase of MHW reported at a global scale in the last 10–20 years, splitting the resulting metrics of the study period. Furthermore, a frequency-domain cross-correlation analysis between SST and Chlorophyll-a was conducted to analyze a temporal relationship among those anomalies and the Red tide that struck the coastal region, in the year 2011. Results indicate that MHW/MCS have varied spatially and temporarily over the marine region of the Yucatan shelf, and have become more frequent and longer in the last twenty-years, tending to keep increasing in some sub-regions. MCS events are of equal or greater significance than MHW, mainly in the inner–shelf sub-region, where more than 110 days of MCS were recorded in 2011. The extreme biological event reported that year could be explained by MCS. Variability of the Yucatan current and upwelling, as well as large-scale synoptic atmospheric events are discussed as possible drivers for MHW/MCS.