(University of Virginia)
Do mid-latitude jet shifts cause cloud feedbacks?
|What||Meteo Colloquium Homepage GR|
Feb 10, 2016 03:30 PM
Feb 10, 2016 04:30 PM
Feb 10, 2016
from 03:30 pm to 04:30 pm
|Contact Name||Sukyoung Lee|
|Add event to calendar||
In response to increasing atmospheric greenhouse gas concentrations, most global climate models project that the mid-latitude jet streams will shift poleward over the 21st century. Consequently, the tracks of mid-latitude low-pressure systems and their associated cloud features are also anticipated to shift poleward over this time. As these cloud features move from a lower to a higher latitude, they will move from a latitude of greater incoming solar radiation to one of less incoming solar radiation. Thus, it seems logical to assume that such poleward movement in the clouds will lead to a warming feedback, as the clouds will be reflecting less solar radiation when they move to higher latitudes.
In this talk, I will challenge this notion using satellite observations from the NASA CERES mission. By looking at interannual variability in the jet location and cloud-radiative effects, I will show that a poleward jet shift is not associated with cloud-radiative warming in the Southern Hemisphere and is only associated with cloud-radiative warming in some seasons in the Northern Hemisphere. Most global climate models are incapable of capturing these patterns, particularly in the Southern Hemisphere, where many models indicate robust cloud-radiative warming effects with a poleward jet shift. Reasons for these model-observational differences will be diagnosed, and the implications of these model biases for future climate projections will be explored.