[工程科技]Destabilization of the thermohaline circulation by transient perturbations to the hydrologi.pdfVIP

4 0 0 2 Destabilization of the thermohaline circulation l u J 9 by transient perturbations to the hydrological 2 ] h p- cycle o a . s c Valerio Lucarini ∗ i s y h Dipartimento di Matematica ed Informatica, p [ Universit´a di Camerino 1 v 7 Via Madonna delle Carceri, 62032 Camerino (MC), Italy 4 1 7 0 4 0 Sandro Calmanti and Vincenzo Artale / s c i ENEA-CLIM-MOD s y h Via Anguillarese 301, 00060 S. Maria di Galeria (Roma), Italy p : v i February 2, 2008 X r a ∗lucarini@alum.mit.edu. Please address correspondence to: Valerio Lucarini, Via Pale- stro 7, 50123 Firenze, Italy. Tel: +393488814008. 1 Abstract We reconsider the problem of the stability of the thermohaline circulation as described by a two-dimensional Boussinesq model with mixed boundary conditions. We determine how the stability properties of the system depend on the intensity of the hydrologi- cal cycle. We define a two-dimensional parameters’ space descrip- tive of the hydrology of the system and determine, by considering suitable quasi-static perturbations, a bounded region where mul- tiple equilibria of the system are realized. We then focus on how the response of the system to finite-amplitude surface freshwa- ter forcings depends on their rate of increase. We show that it is possible to define a robust separation between slow and fast regimes of forcing. Such separation is obtained by singling out an estimate of the critical growth rate for the anomal