On the characteristics of subtropical fronts in the North Atlantic

摘要: [1] The characteristics of surface temperature (SST) fronts in the subtropical frontal zone (STCZ) North Atlantic were investigated using a time series front data produced by an edge-detection algorithm applied to 18 years 9.3 km resolution NOAA/NASA AVHRR Pathfinder SST imagery. Front probability, averaged over subregions STCZ, varies seasonally with highest probability early spring western part region. In eastern region, maximum occurs late summer, and annual cycle is far less robust, being nearly absent prior 1991. The location strength across entire STCZ strongly season, moving southward (northward) strengthening (weakening) winter/spring (summer). From estimates cross-frontal step gradient, scale variability at estimated be approximately 30 km. monthly mean total meridional partitioned into component due pixels background gradient nonfrontal pixels, 30% attributable fronts. While largest winter heat flux, contribution lags 2 months or more STCZ. This suggests frontogenesis mechanism requiring presence rather than one arising from flux gradients alone.