PICE Talk by Xiaoming Zhai

Title: Cold Anticyclonic Eddies and Warm Cyclonic Eddies in the Ocean

Mesoscale eddies are ubiquitous features of the global ocean circulation and play a key role in transporting ocean properties and modulating air–sea exchanges. Anticyclonic and cyclonic eddies are traditionally thought to be associated with positive and negative temperature anomalies, respectively. Using satellite altimeter and microwave data, we show that surface cold-core anticyclonic eddies (CAEs) and warm-core cyclonic eddies (WCEs) are surprisingly abundant in the global ocean—about 20% of the eddies inferred from altimeter data are CAEs and WCEs. Idealized numerical model experiments highlight the key role of relative wind-stress-induced Ekman pumping, surface mixed layer depth, and vertical entrainment in the formation and seasonal cycle of these unconventional eddies in the tropical oceans.

Speaker: Xiaoming Zhai, University of East Anglia