Changing Sea-to Air Flux of Aerosol Chemical Material and the Positive Feedback with Planetary Scale Ocean and Atmospheric Dynamics
Tuesday, July 28, 2015
Oliver W Wingenter1, Oluwaseun O Ogunro1, Stephanie N. Nance1, Scott Elliott2, Donald Ray Blake3 and Nicola J Blake4, (1)New Mexico Tech, Socorro, NM, United States, (2)Los Alamos National Laboratory, Los Alamos, NM, United States, (3)University of California Irvine, Irvine, CA, United States, (4)University California Irvine, Vineyard Haven, MA, United States
Abstract:
The Southern Westerly Winds (SWW) are important in determining the Earth’s climate state, and have been strengthening and shifting southward. Loss of Antarctic stratospheric ozone and global warming have contributed to an increase in temperature difference (DT) between the southern mid and high latitudes but these may not be the only mechanisms to increase DT. To investigate the possibility of a contribution from oceanic emissions of dimethyl sulfide (DMS) we perform here new simulation of DMS fluxes, based on wind and sea surface temperature data going back to 1950. Our analysis shows a substantial increase in the summer DMS sea-to-air flux, as a result of changes in the SWW. Dimethyl sulfide is oxidized in the atmosphere where it can form new particles or add to existing ones, enhancing cloud reflectivity. Consistent with this observation, the cloud albedo over the Southern Ocean (SO) region around Antarctica has been getting brighter, leading us to conclude that increased DMS fluxes maybe contributing to the changing air temperatures that are driving the observed poleward movement of the SWW as part of a positive feedback loop to increase T. The southward shift of the SWW results in greater wind stress acting on the Antarctic Circumpolar Current and moves more water northward, pulling warm-salty, high in nutrient Circumpolar Deep Water to the surface, which contributes to Antarctic ice shelf loss and vents CO2 to the atmosphere, while creating more Subantarctic Mode Water and Antarctic Intermediate Water (AAIW). Increasing AAIW in turn displaces North Atlantic Intermediate Water (NAIW). Displacement of NAIW, along with increasing freshwater from melting of Arctic ice, may have been responsible for the onset of the last glacial maximum.
