Response of Global Surface Ozone Distribution to Northern Hemispheric Sea Surface Temperature Changes: Implication for Long-Range Transport
Kan Yi1, Junfeng Liu1, George Ban-Weiss2, Jiachen Zhang2, Wei Tao1, and Shu Tao11Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing, China 2Sonny Astani Department of Civil and Environmental Engineering, University of Southern California, USA
Received: 10 Nov 2016 – Accepted for review: 29 Nov 2016 – Discussion started: 05 Dec 2016
Abstract. The response of surface O3 concentrations to basin-scale warming and cooling of Northern Hemispheric oceans is investigated using the Community Earth System Model (CESM). Idealized spatially uniform sea surface temperature (SST) anomalies of ±1 ºC are superimposed onto the North Pacific, North Atlantic, and North Indian oceans, individually. Our simulations suggest seasonal and regional variability of surface O3 in response to SST anomalies, especially in boreal summer. Increasing (decreasing) SST by 1 ºC in one of the regions of focus induces decreases (increases) in surface O3 concentrations, ranging from 1 to 5 ppbv. With fixed emissions, SST increases of a specific ocean in the Northern Hemisphere tend to increase summertime surface O3 concentrations over upwind continents, accompanied with a widespread reduction over downwind regions. We implement the integrated process analysis (IPR) in CESM and find that meteorological O3 transport in response to SST changes is the key process causing surface O3 perturbations in most cases. During boreal summer, basin-scale SST warming facilitates vertical transport of O3 to the surface over upwind regions while significantly reducing vertical transport over continents that are downwind. This process, as confirmed by tagged CO tracers, implicates a considerable suppression of O3 intercontinental transport due to increased stagnation at mid-latitudes induced by SST increases. Changes in O3 chemical production associated with regional SST increases, on the other hand, can increase surface O3 over highly polluted continents except for South Asia. In South Asia, intensified cloud loading in response to North Indian SST warming depresses both surface air temperature and solar radiation, and thus photochemical production of O3. Our findings indicate a robust linkage between basin-scale SST variability and continental surface O3 pollution, which should be taken into account for regional air quality management.
Yi, K., Liu, J., Ban-Weiss, G., Zhang, J., Tao, W., and Tao, S.: Response of Global Surface Ozone Distribution to Northern Hemispheric Sea Surface Temperature Changes: Implication for Long-Range Transport, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-1001, in review, 2016.