Geography 257 Topics in Climatology Fall 2008

This semester’s topic: Extratropical influences on the tropical circulation

Instructor: Prof. John Chiang

Time: Wednesdays 1p-4p, 575 McCone. First meeting will be Wed 8/27 at that time and location.

Synopsis: The goal for this semester is to explore the emerging topic of how extratropical eddies influence the tropical circulation, with an eye towards trying to understand how they might be usefully applied to past and future climates. We'll start with some basics: general circulation review from Holton, and the Held and Hou, and Lindzen and Hou papers. The inadequacies of the Held and Hou type thinking led some to understand the role of eddies in the Hadley circulation, of which we cover 3 papers (Trenberth and Stepaniak 2003, Kim and Lee 2001, and Walker and Schneider 2006]. From here, we'll read papers on more 'practical climates', including the possible role of eddies in monsoons (Schneider and Bordoni 2008; Bordoni and Schneider 2008), Hadley circulation in Global warming ( Lu et al. 2007), and the tropical response to the 'interhemispheric gradient' (Rotstayn and Lohmann 2002, Kang et al. 2008). We'll end of with some papers on the 20^th century and LGM climates.

Website (schedule updated weekly): http://www.atmos.berkeley.edu/~jchiang/Geog257/geog257.html

Prerequisites: Atmospheric physics and dynamics at the level of the upper division 'Atmospheric Physics and Dynamics' course (GeogC139 / EPS181); this is the website for that course: http://geography.berkeley.edu/ProgramCourses/CoursePagesFA2006/GEOGC139/geogC139.html

Class Schedule (red is preliminary and subject to change):

Week and date	Topic	Reading	Notes and posts
1 (8/27)	Logistics
2 (9/3)	General circulation - review	Holton Ch10 (first half)
3 (9/10)	Symmetric Hadley circulation	[Held and Hou, 1980], as summarized in Ian James’ book, Ch4 (first half)
4 (9/17)	Asymmetric Hadley circulation	[Lindzen and Hou, 1988]
5 (9/24)	No class – JC away	[Dima and Wallace, 2003]
6 (10/1)	Poleward energy transports	[Trenberth and Stepaniak, 2003]
7 (10/8)	Feedback of eddies on the Hadley circulation	[Kim and Lee, 2001]
8 (10/15)	Feedback of eddies on the Hadley circulation	[Kim and Lee, 2001] AGAIN
9 (10/22)	Feedback of eddies on the Hadley circulation	[Walker and Schneider, 2006]
10 (10/29)	Feedback of eddies on the Hadley circulation	[Walker and Schneider, 2006] AGAIN
11 (11/5)	Eddies and monsoons	[Schneider and Bordoni, 2008]
12(11/12)	Eddies and monsoons	[Schneider and Bordoni, 2008] AGAIN; and [Bordoni and Schneider, 2008]
13 (11/19)	Eddies and Hadley circulation in general circulation models	[Frierson, et al., 2007] and [Caballero, 2008]
14 (11/26)	No class
15 (12/3)	Tropics and interhemispheric gradients	[Kang, et al., 2008]

References

Bordoni, S., and T. Schneider (2008), Monsoons as eddy-mediated regime transitions of the tropical overturning circulation, Nature Geosci, 1, 515-519.

Caballero, R. (2008), Hadley cell bias in climate models linked to extratropical eddy stress, Geophysical Research Letters, 35.

Dima, I. M., and J. M. Wallace (2003), On the seasonality of the Hadley cell, Journal of the Atmospheric Sciences, 60, 1522-1527.

Frierson, D. M. W., J. Lu, and G. Chen (2007), Width of the Hadley cell in simple and comprehensive general circulation models, Geophysical Research Letters, 34.

Held, I., and A.-Y. Hou (1980), Nonlinear axially symmetric circulations in a nearly inviscid atmosphere, Journal of the Atmospheric Sciences, 46, 163-174.

Kang, S. M., I. M. Held, D. M. W. Frierson, and M. Zhao (2008), The response of the ITCZ to extratropical thermal forcing: idealized slab-ocean experiments with a GCM Journal of Climate.

Kim, H. K., and S. Lee (2001), Hadley cell dynamics in a primitive equation model. Part II: Nonaxisymmetric flow, Journal of the Atmospheric Sciences, 58, 2859-2871.

Lindzen, R. S., and A. Y. Hou (1988), Hadley Circulations for Zonally Averaged Heating Centered Off the Equator, Journal of the Atmospheric Sciences, 45, 2416-2427.

Rotstayn, L. D., and U. Lohmann (2002), Tropical rainfall trends and the indirect aerosol effect, Journal of Climate, 15, 2103-2116.

Schneider, T., and S. Bordoni (2008), Eddy-mediated regime transitions in the seasonal cycle of a Hadley circulation and implications for monsoon dynamics, Journal of the Atmospheric Sciences, 65, 915-934.

Trenberth, K. E., and D. P. Stepaniak (2003), Seamless poleward atmospheric energy transports and implications for the Hadley circulation, Journal of Climate, 16, 3706-3722.

Walker, C. C., and T. Schneider (2006), Eddy influences on Hadley circulations: Simulations with an idealized GCM, Journal of the Atmospheric Sciences, 63, 3333-3350.