The Blob and Queen Charlotte: Predicting Ocean Properties in an
Upwelling System during Anomalous Conditions
Abstract
From 2014 to at least 2018, ecosystem health in the eastern boundary
upwelling system along the west coast of North America was significantly
impacted by a combination of a marine heatwave known as The Blob and an
El Niño event, as well as by ongoing climate change. At the northern
limit of this upwelling system, in Queen Charlotte Sound on the highly
productive central coast of British Columbia, we have demonstrated that
changing conditions on the continental shelf and in coastal waters may
be skillfully predicted based on observed open-ocean and large-scale
atmospheric conditions on seasonal to interannual timescales. In this
work, we build on our understanding of this predictability by presenting
a statistical model that relates physical and biogeochemical ocean
properties in this region to conditions at and beyond the shelf break
and large-scale forcing metrics. The model is based on statistical
relationships developed using a multi-decadal archive of hydrographic
and biogeochemical data in combination with high-temporal-resolution
mooring records collected in Queen Charlotte Sound, and is supported by
a conceptual understanding of the upwelling and downwelling regimes in
this region. We next use the model to examine specifically how the
arrival of The Blob and the subsequent El Niño modified ocean conditions
on the continental shelf during both upwelling and downwelling,
including impacts on nutrient concentrations, dissolved oxygen levels,
stratification, and warming. Our results suggest it may be possible to
predict changes in this upwelling system caused by future anomalous
events and climate change using readily available large-scale data
products such as the Argo dataset and NOAA Upwelling Index.