Thermodynamic characteristics of air flowing into and out of precipitatingconvection over the west Pacific warm pool

Aircraft data from the Tropical Ocean/Global Atmosphere Coupled Ocean-Atmos phere Response Experiment (TOGA-COARE) indicate the validity of current con ceptual models used in cumulus parametrization theories. This study makes u se of 1 s (similar to 100 m) measurements of temperature, dew-point tempera ture and pressure taken along the aircraft flight tracks and airborne radar data. The radar data are used to determine the location, depth and horizon tal extent of the convection and to categorize the thermodynamic data accor ding to whether the measurements were obtained in precipitation areas or in regions of inflow to convection. Inflow regions had the highest values of equivalent potential temperature ( theta(e)), both in the boundary layer and lower free atmosphere, where the convection was deepest and most horizontally extensive, implying a relation ship of theta(e) to both the depth and breadth of convection. The observati ons suggest that the thickness of the layer of high-theta(e) air may determ ine the sustainability and, therefore, the horizontal extent of warm-pool c onvection. The spectrum of values of theta(e) in the boundary layer of infl ow regions was broad, indicating that the field of theta(e) was highly non- uniform at the 1 s (similar to 100 m) scale sampled by the aircraft. The boundary-layer air in precipitating regions also exhibited a broad spec trum of theta(e) values, indicating the presence of both outflow from downd raughts and a significant amount of air with characteristics similar to inf low regions. The lowest values in the distribution were about 345 K, sugges ting that air parcels transported down into the boundary layer originated f rom no higher than about 1500 m, or that they underwent substantial mixing.