| description abstract | An observational study of mesoscale cellular convection occurring over vast regions of the North Atlantic and North Pacific has been done for the period 1 January 1969 through 30 June 1970. Satellite cloud photography from the ESSA 7, ESSA 9 and ATS 3 satellites and conventional rawinsonde data have been analyzed for a total of 38 cases, consisting of 25 open and 13 closed convective patterns. Computations have shown that: 1) the average diameter for open cells is 30 km and for closed cells 32 km; 2) the average convective depth for open cells is 2.3 km, greater than the 1.3 km average for closed cells; 3) the average aspect (diameter-to-depth) ratio for open cells, 15:1, is less than that for closed cells, 28:1; 4) the aspect ratio is inversely proportional to increasing convective depth; 5) sea surface temperature exceeds the air temperature on the average by 2.1C in open cells but is 0.4C less in closed cells; 6) directional and magnitude shear (in the vertical) of the horizontal wind is small, less than 7° km?1 and 2 m sec?1 km?1, respectively, but indicative of backing or cold air advection in open cells and veering or warm air advection in closed cells; 7) a characteristic lapse for the convecting layer of 8.2C km?1; and 8) a strong total heat flux of 218 1y(4 hr) ?1 from the sea to the atmosphere in regions of open cell and a weaker total heat flux of 65 1y(4 hr) ?1 from the air to the sea in regions of closed cells. Open cellular patterns which preferably occur in cyclonic synoptic-scale flow portray the oceans as a major energy source for driving the atmosphere's circulation. Closed cellular patterns, on the other hand, usually occurring under conditions of anticyclonic synoptic-scale flow, portray the oceans as a weak sink for the atmosphere's energy. | |
