Brix¹, Holger, Nicholas R. Bates², John E. Dore³, Nicolas Gruber⁴, David M. Karl³, Charles D. Keeling⁵, Roger Lukas³ and Daniel W. Sadler³

¹University of California, Los Angeles, CA, Tel: 310-825-4526, Fax: 310-206-3051, E-mail: hbrix@igpp.ucla.edu, ²Bermuda Biological Station for Research, Bermuda, ³University of Hawaii, Honolulu, HI, ⁴University of California, Los Angeles, CA and ⁵Scripps Institution of Oceanography, La Jolla, CA

Interannual to decadal variability in the oceanic carbon cycle: lessons from BATS and HOT

We synthesize investigations of long-term physical and biogeochemical time-series measurements in the subtropical North Pacific (HOT) and North Atlantic (BATS, Station 'S'). We have been able to determine some common processes that control variability at both sites (e.g., the control of air-sea gas exchange modulations by SSTs). Part of the variability is associated with regional forcing (e.g., a prolonged drought in the HOT region has had a significant impact in reducing the magnitude of the CO₂ flux into the ocean). However, a substantial fraction of the observed variability is connected to basin-scale climate patterns. For instance, the magnitude of net community production and air-sea CO₂ fluxes in the North Atlantic can be attributed to the influence of the NAO on convection and SST during winter. CO₂ uptake by subtropical mode waters at BATS contributes substantially to interannual variability in oceanic CO₂ uptake. It would not have been possible to achieve these and other valuable insights by using isolated process-oriented field studies. Long-term time-series studies have thus proven to be indispensable for the investigation of low-frequency climate variations.