View Full Version : Interesting climate change paper..

John Hill
14th Dec 2013, 08:34
An short interesting paper showing how climate change could come about by changes to air circulation which might be induced by ocean temperature and other changes.

The atmosphere transports heat throughout the globe extremely well, but present-day atmospheric characteristics prevent heat from being carried directly from the equator to the poles. Currently, there are three distinct wind cells - Hadley Cells, Ferrel Cells, and Polar Cells - that divide the troposphere into regions of essentially closed wind circulations. In this arrangement, heat from the equator generally sinks around 30 latitude where the Hadley Cells end. As a result, the warmest air does not reach the poles. If atmospheric dynamics were different, however, it is plausible that one large overturning circulation per hemisphere could exist and that wind from the low-latitudes could transport heat to the high-latitudes. As an explanation for equable climates, Brian Farrell presented this idea in 1990 and advocated that during equable climates, the Hadley Cells extended from the equator to the poles (Farrell, 1990).


Based off of Venus' atmosphere's behavior, Farrell argues that another way to extend the Hadley Cells would be to increase the height of the tropopause. This change would increase the poleward moving air's Rossby number. The Rossby number describes the importance of the Coriolis force in atmospheric dynamics. A higher Rossby number means that the Coriolis force has a smaller impact on a particle, so if the height of the tropopause increased enough, the Rossby number would become high enough to make the Coriolis force negligible. As a result, particles would not diverge from their path as they moved poleward, and the Hadley Cells would reach the poles. To explain how the tropopause height could increase, Farrell states that the height is correlated to surface temperature and that a 1C increase in sea surface temperature causes the tropopause potential temperature to rise by roughly 7.5C. Raising the average equatorial sea surface temperature to 32C from its current 27C would increase the potential temperature of the tropopause by 37C. There temperature increases would almost double the static stability at the tropopause. For the height to increase, the stratosphere would also have to become less stable. If CO2 concentrations increased and if stratospheric ozone concentrations decreased, the stratosphere would cool substantially, and this change would destabilize the stratosphere. As a result of the alterations to tropospheric and stratospheric stability, the tropopause height would increase. Farrell estimates the height would have doubled under Cretaceous conditions, and as a result, the Rossby number would have doubled. This change would have allowed the Hadley Cells to extend to the poles and would have made equable climates more likely.

Hadley Cells (http://www.seas.harvard.edu/climate/eli/research/equable/hadley.html)

14th Dec 2013, 08:45
Just what I was thinking.

B Fraser
14th Dec 2013, 08:48
Just how high would the trop have to be for the Rossby number to have the right value ? There's only so much atmosphere up there. The tropical trop (or the trop trop as we called it) can be at 70,000 feet plus.

I checked the calendar and it isn't April yet.

14th Dec 2013, 08:50
What language is "based off of"?

Takan Inchovit
14th Dec 2013, 08:57
I still think its the sun.

14th Dec 2013, 10:42
Yar. http://sdo.gsfc.nasa.gov/assets/img/latest/latest_256_0304.jpg