First International Satellite Land Surface Climatology Field Experiment 1987 sonde budget revisited

We recompute estimates of boundary layer top entrainment from the 1987 FIFE sonde data, using a better averaging method, and get a mean value for the entrainment parameter A R of 0.39 ± 0.19, about 10% smaller than before. We also show the dependence of A R on wind speed and time of day. The increase in entrainment with wind speed is quite marked. Our mean asymptotic value of A R , representative of free convection at low wind speeds, is now only 0.31.