Recorded presentation6A.2
The possible role of hurricanes in the climate system
Aixue Hu, NCAR, Boulder, CO; and G. A. Meehl
To address the possible role of hurricanes in the climate system, hurricanes are specified in the Atlantic basin in 100 year simulations with a global coupled climate model. First the climatological effects of hurricane winds are included by prescribing a number of time evolving hurricanes that repeat each summer season. Then a second experiment includes the torrential rain associated with those hurricanes. This fresh water source is compensated in the coupled model by proportionately enhancing evaporation over the domain of the Atlantic trade winds, the climatological source of evaporation and fresh water flux that contributes to hurricanes that form near the ITCZ. The effect of the prescribed hurricane winds is to mix heat into the thermocline as observed, and northward heat transport and meridional overturning circulation (MOC) in the Atlantic are strengthened. The combination of hurricane winds and associated torrential rainfall also mix heat into the thermocline, but reduce northward heat transport because MOC is weakened due to consequent density variations in the North Atlantic. The climatological changes in ocean heat transport and MOC due to the hurricanes are small (on the order of a few percent), indicating present models that do not resolve hurricanes are likely not missing a major climatological element. But regional systematic salinity errors and upper ocean temperature errors in some regions could be improved if hurricanes were resolved. Additionally, the results suggest a possible feedback of hurricanes on multi-decadal MOC and SST variability, such that hurricanes themselves could be active contributors to their own multi-decadal variability.
Session 6A, Ocean-atmosphere interactions and influences on tropical and extratropical storms: Part 1
Tuesday, 13 January 2009, 1:30 PM-3:00 PM, Room 128A
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