Cellular convection over the north‐eastern Atlantic

Abstract

AbstractConvective clouds over the ocean frequently exhibit organized meso‐scale patterns. A statistical evaluation of 4 years of NOAA satellite images over the north‐eastern Atlantic yields climatological data of the appearance of these patterns and shows that open cellular convection is most abundant. For this convection type, surface and radiosonde data from Weathership M have been analysed. Open convection cells appear at a wide range of positive sea‐air temperature differences up to 12°C and at wind speeds up to 25 m s−1. All diameters have been found to be less than 80 km (average 41 km). Larger diameters are, on average, associated with slightly larger convection heights and, thus, with larger aspect ratios.The scene‐averaged brightness temperature of AVHRR channel 4 exhibits a definite correlation with the sea‐air temperature difference and, less well expressed, with the sensible and latent heat flux. This, in turn, provides a possibility of estimating those quantities by using easily accessible AVHRR satellite data.