New York University
70 WASHINGTON SQUARE S
NEW YORK, NY
CLIMATE & LARGE-SCALE DYNAMICS
Program Reference Code(s):
Program Element Code(s):
The first goal of this research is to assess and attribute the response of the Southern Hemisphere jet stream to anthropogenic forcing in comprehensive climate models in the Coupled Model Intercomparison Project Phase 5 (CMIP5). The Principal Investigator (PI) suggests a simple method to partition the impact of ozone and greenhouse gas induced changes on the jet stream will be sugg. It will allow to better quantify uncertainty in climate projections, separating differences in the thermal response to greenhouse gases and ozone from differences in the sensitivity of the jet stream to changes in atmospheric temperature. Analysis of CMIP5 models to previous generation climate models from the Coupled Model Intercomparison Project Phase 3 (CMIP3) and Chemistry Climate Model Validation Activity 2 (CCMVal2) will be undertaken to assess the impact of model improvements on climate projection.
The second goal of this research is to understand the mechanism(s) causing changes in the jet stream, using a series of controlled experiments with an idealized general circulation model. Preliminary analysis of CMIP3 and CCMVal2 models suggests that the jet is sensitive to the temperature gradient in the upper troposphere and lower stratosphere, so that the response is similar when the tropics are warmed or the high latitudes are cooled. This hints at a common mechanism behind greenhouse gas and ozone induced changes. In addition, stratospheric ozone induced changes have a strong seasonal footprint. The PI will explore interactions between the background seasonal cycle in the stratosphere and troposphere with a seasonally localized ozone-like forcing. Observed trends in the midlatitude circulation of the atmosphere are stronger in the Southern Hemisphere summer than in other seasons (or in the Northern Hemisphere), due to the combined effect of greenhouse gases and ozone. This has had significant impacts on precipitation throughout the Southern Hemisphere, even the tropics. Thus this project will increase our understanding of how changes in model configuration, e.g. representation of the stratosphere, impact a model's response.
This research will involve a graduate student and postdoctoral scientist, providing opportunity for their development as a research scientists.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
Some links on this page may take you to non-federal websites. Their policies may differ from this site.
Cohen, N. Y., E. P. Gerber, and O. Bühler. "What drives the Brewer-Dobson Circulation?," J. Atmos. Sci., v.71, 2014, p. 3837.
Li, X., E. P. Gerber, D. H. Holland, and C. Yoo. "A Rossby Wave Bridge from the Tropical Atlantic to West Antarctica," J. Climate, v.28, 2015, p. 2256.
Li, X., D. H. Holland, E. P. Gerber, and C. Yoo. "Impacts of North and Tropical Atlantic Ocean on the Antarctic Peninsula and Sea Ice," Nature, v.505, 2014, p. 538-542.
Gerber, E. P. and S.-W. Son. "Quantifying the Summertime Response of the Austral Jet Stream and Hadley Cell to Stratospheric Ozone and Greenhouse Gases," J. Climate, v.27, 2014, p. 5538.
Zurita-Gotor, P., J. Blanco-Fuentes, and E. P. Gerber. "The impact of baroclinic eddy feedback on the persistence of jet variability in the two layer model.," J. Atmos. Sci.,, v.71, 2014, p. 410-429.
Manzini, E. and 22 Coauthors including E. P. Gerber. "Northern winter climate change: Assessment of uncertainty in CMIP5 projections related to stratosphere ? troposphere coupling," J. Geophys. Res. Atmos., v.119, 2014.
Li, X., D. H. Holland, E. P. Gerber and C. Yoo. "Rossby waves mediate impacts of tropical oceans on West Antarctic atmospheric circulation," J. Climate, v.28, 2016, p. 8151.
Sheshadri, A., R. A. Plumb, and E. P. Gerber. "Seasonal variability of the polar stratospheric vortex in an idealized AGCM with varying tropospheric wave forcing," J. Atmos. Sci., v.72, 2015, p. 2248.
Wenzel, S., V. Eyring, E. P. Gerber and A. Yu. Karpechko. "Constraining Future Austral Jet Stream Position and Shifts in the CMIP5 Ensemble by Process-oriented Multiple Diagnostic Regression," J. Climate, v.29, 2016, p. 673.
Oberlaender-Hayn, S., E. P. Gerber, J. Abalichin, H. Akiyoshi, A. Kerschbaumer, A. Kubin, M. Kunze, U. Langematz, S. Meul, M. Michou, O. Morgenstern and L. D. Oman. "Is the Brewer-Dobson circulation increasing, or moving upward?," Geophys. Res. Lett., v.43, 2016.