Table 1 Coastal locations of (in situ) water temperature measurements used in this study. The sites were selected to represent the broad range of Patella vulgata’s southern distribution. Temperatures were recorded by Maxim DS1922 iButton loggers deployed in the intertidal at 0–1 m below Mean Sea Level (MSL) at a particular frequency (in minutes, t_x). Daily values were obtained by averaging data collected by one of multiple sensors (N loggers). These in situ measurements were used to calculate a Thermal Upwelling Index (UI, in °C) for each location, defined as the magnitude of the cold anomaly (i.e. cold bias) between upwelled coastal waters and the warmer offshore waters^47,66. Manufacturer reported logger accuracy and resolution for the iButton loggers were both 0.50 °C.

From: Coastal upwelling generates cryptic temperature refugia