ESTIMATING OVERWATER CONVECTIVE BOUNDARY-LAYER HEIGHT FROM ROUTINE METEOROLOGICAL MEASUREMENTS FOR DIFFUSION APPLICATIONS AT SEA

On the basis of hourly measurements of wind and air and sea surface te mperatures for at least 6 yr at three buoy stations in the eastern Gul f of Mexico, the onset of the free convection regime, which coincides with the commencement of stability class C (for slightly unstable cond itions in the Pasquill stability classification) at approximately R-b = -0.03, -Z/L = 0.4, and -Z(i)/L = 5, is verified over the ocean, wher e R-b is the bulk Richardson number, Z (= 10 m) is the height above th e sea, L is the Monin-Obukhov stability length, and Z(i) is the height of the convective boundary layer (CBL). Datasets for the CBL are anal yzed in the context of the boundary layer physics of Garratt. It is fo und that Z(i) is linearly proportional to the surface buoyancy flux-th at is, (w'theta(upsilon)')(0), where w is the vertical velocity and th eta(upsilon) is the virtual potential temperature. For operational dif fusion applications, a statistical formula is proposed-that is, Z(i) = 369 + 6004(w'theta(upsilon)')(0). A method to compute this buoyancy f lux from routine meteorological measurements is also provided.