Monsoon Model Indicates Potential for Abrupt Transitions

[phantom power]

"Our analysis shows on the basis of observations that there could be two stable states for monsoon systems and the possibility of abrupt transitions from one to the other," says Levermann.

The driving force of monsoon systems depends on different air temperatures. In spring, the air over land is warmed up more rapidly than the air over the sea. The warmer air rises and moist and cooler air from the ocean flows landwards and yields precipitation, which has two effects: the rainfall cools the land surface, but also releases latent heat, when water vapour condenses to raindrops. The more moist air is transported landwards, the more latent heat is released through rainfall and the more moist air is drawn towards land. This self amplification, named moisture-advection feedback, sustains the temperature difference and the entire circulation. However, the self-amplification is vulnerable and may lead to abrupt changes in response to relatively weak external perturbations, the authors state.

The PIK researchers now present a conceptual model that captures the self-amplification feedback. The basic equations show that there is a critical value of irradiation from the sun for a monsoon circulation to start. If irradiation falls below the critical value, for instance due to high air pollution, no conventional monsoon can develop. Above the critical value, one state with and one state without a monsoon circulation exist.

This allows for an abrupt transition to occur in one of two different ways. First, climatic shifts can push the system across the critical threshold. The transition would occur from one season to the other and last as long as the climatic shift prevails. The second possibility is abrupt transitions between the two stable states, when the system is -- as current monsoon circulations are -- in the bi-stable regime above the critical threshold. Within one rainy season weakening of monsoon winds and latent heat release could decrease the temperature difference between land and sea until the circulation is disrupted

http://www.sciencedaily.com/releases/2009/10/091029152301.htm

[excess_3]

1. the violent 2009 Atlantic hurricane season continues

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x204325

[Strelnikov_]

2. Your point? n/t

[XemaSab]

3. Abrupt, you say?

:shrug:

[phantom power]

4. I suppose the upper limit of FTE is where the gradient becomes a Dirac delta?

Even I can't expect anything faster than that. Unless we fuck up so badly that we actually violate causality.

That would be something to be proud of!