Improving harmful algal bloom predictions in the Middle East: how submesoscale physics disrupt food and water security.

Coastal regions of the Arabian Sea frequently experience HABs, disrupting food and water security in surrounding countries.

While large-scale processes triggering blooms off-shore are well understood, it is the complex eddy-topography interactions and localized upwelling which are responsible for onshore transport and triggering blooms in the coastal margins. These small scales processes (0.1-10km, hours-days) are not resolved by current HAB monitoring systems.

Furthermore, the mechanisms responsible for when and how an algal bloom becomes harmful, either through toxicity or intensity, are not understood.We aim to understand how submesoscale physical processes trigger harmful algal blooms on the shelf and set the conditions for harmful impacts.

We will directly measure submesoscale ocean mixing processes along with changes in organic carbon, dissolved oxygen, nitrate and sulfide concentrations at high spatial and temporal resolution across an entire year using autonomous underwater vehicles and a mooring array.

This dataset, in tandem with a coupled physical-biogeochemical model and existing HAB predictive models, will be used to determine weaknesses in existing systems, key priorities for development, and parameterizations for processes not resolved in models.This knowledge will underpin the development of a novel monitoring framework to deliver improved spatio-temporal understanding of key HAB drivers and deliver improved early-warning capacity in the Middle East.