Think about it this way, to be able to say that it takes place annually instead of i.e. biannually or monthly, you need a lot more than one sample per year. You

Think about it this way, to be able to say that it takes place annually instead of i.e. biannually or monthly, you need a lot more than one sample per year. You need enough samples to know when it is or isn't occurring. https://www.earth.com/news/unprecedented-collapse-panamas-ocean-upwelling-fails-for-the-first-time-in-40-years/ https://www.earth.com/news/unprecedented-collapse-panamas-oc... mentions a lot of date oriented measurements which suggest they probably have at least 52 samples per year, if not daily samples: > The 40-year record makes the 2025 failure stand out. Average historical onset around January 20 contrasts with a March 4 threshold crossing in 2025. > The cool season shrank from roughly nine weeks to less than two weeks. Minimum sea surface temperature (SST) rose from historical lows near 66.2°F to about 73.9°F.