12.2
Persistent imprints of mid-latitude ocean fronts high into the atmosphere
PAPER WITHDRAWN
W. Timothy Liu, JPL, Pasadena, CA; and X. Xie
The ocean has long memory and its feedback to the atmosphere governs climate changes. The coupling of the small and slow processes of the ocean to the transient and large-scale processes of the atmosphere, particularly in the extra-tropical latitudes and for long time periods, has been controversial. Over the global ocean, areas associated with ocean fronts are particularly interesting, because they have extremely high mean kinetic energy, and the smaller scale variation of wind convergence and evaporation may produce localized buoyancy and energetic vertical motion that could propagate the ocean effects far up into the atmosphere. Three years of data from International Cloud Climatology Project (ISCCP), from Atmospheric Infrared Sounders (AIRS). QuiksCAT, and Advanced Microwave Scanning Radiometer (AMSR) from 2002 to 2005 were examined over major mid-latitude ocean fronts, the Aqulhas, Kuroshio, and Gulf Stream Extensions. While surface wind stress divergence are found in quadrature with sea surface temperature (SST) anomalies as expected, significant spatial coherence between cloud top temperature (CTT) and SST are also found. The temperature sounding measured by AIRS is consistent with the spatial coherence SST and CTT, from the surface up to 500-300 mb, for periods longer than 10 days. Thus ocean mesoscale SST anomalies associated with the persistent current meanders may have long-term effect well above the mid-latitude atmospheric boundary layer, an observation not addressed in the past. Experimental investigation of air-sea interaction near ocean fronts has been mostly on synoptic time scales and within the boundary layer; the validations of spacebased observations are mostly made at synoptic time scales. The results of this study show potential effects of surface anomalies near the ocean front, in long periods and high into the atmosphere; the effects are important to climate changes and radiation balance in the atmosphere. Present numerical weather prediction models may not have the physics to simulate the long term, penetrating effects, making spacebased observations (e.g., ISCCP and AIRS) all the more important in the characterization, understanding, and prediction of climate changes and improving numerical models.
Session 12, Land and Ocean Observations
Wednesday, 23 January 2008, 4:00 PM-5:30 PM, 204
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