The Impact of Ozone-Depleting Substances on Tropical Upwelling, as Revealed by the Absence of Lower-Stratospheric Cooling since the Late 1990s
Abstract
The impact of ozone-depleting substances on global lower-stratospheric temperature trends is widely recognized. In the tropics, however, understanding lower-stratospheric temperature trends has proven more challenging. While the tropical lower-stratospheric cooling observed from 1979 to 1997 has been linked to tropical ozone decreases, those ozone trends cannot be of chemical origin, as active chlorine is not abundant in the tropical lower stratosphere. The 1979–97 tropical ozone trends are believed to originate from enhanced upwelling, which, it is often stated, would be driven by increasing concentrations of well-mixed greenhouse gases. This study, using simple arguments based on observational evidence after 1997, combined with model integrations with incrementally added single forcings, argues that trends in ozone-depleting substances, not well-mixed greenhouse gases, have been the primary driver of temperature and ozone trends in the tropical lower stratosphere until 1997, and this has occurred because ozone-depleting substances are key drivers of tropical upwelling and, more generally, of the entire Brewer–Dobson circulation.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Apr 01, 2017
- Source ID
- 10.1175/jcli-d-16-0532.1
Entities
People
- Darryn W. Waugh
- Lei Wang
- Lorenzo M. Polvani
- Valentina Aquila
Organizations
- Columbia University
- Johns Hopkins University
- National Aeronautics and Space Administration
- National Oceanic and Atmospheric Administration
- National Science Foundation
- Office of Naval Research