ATMOSPHERE-OCEAN INTERACTION ON WEEKLY TIMESCALES IN THE NORTH-ATLANTIC AND PACIFIC

Large-scale atmosphere-ocean interaction over the North Atlantic and N orth Pacific during winter using a 14-yr record of weekly sea surface temperature and atmospheric circulation fields is examined. Singular V alue Decomposition is used to quantify objectively: the degree of coup ling between the sea surface temperature and 500-mb geopotential heigh t fields as a function of time lag, from -4 weeks to +4 weeks. The aut hors show that the air-sea coupling is strongest when 500-mb height le ads sea surface temperature by 2-3 weeks-twice as strong as the simult aneous covariability and nearly four times as large as when sea surfac e temperature leads 500-mb height by a few weeks. The authors believe the 2-3-week timescale may be a reflection of high-frequency stochasti c forcing by the atmosphere an the ocean mixed layer in line with the theoretical model of Frankignoul and Hasselmann. Sensible and latent e nergy fluxes at the sea surface are shown to be an important component of the atmospheric forcing. The close spatial and temporal correspond ence between the fluxes and SST tendencies on weekly timescales is a t estament to the quality of the datasets.