Surface Fluxes of Trace Gases Derived from Convective - Profiles

Non-local gradient and variance functions relating the surface and entrainment fluxes of a passive scalar to the mean mixing ratio and variance profiles in the cloud -free, convective boundary layer have been determined from large eddy simulations. These functions can be used to calculate the surface and entrainment fluxes of trace gases over a large area, given profile measurements within the convective boundary layer. This dissertation develops the convective layer gradient technique for estimating fluxes and demonstrates two potentially valuable applications. An attempt is made to verify the large eddy simulation gradient functions with aircraft observations from the First ISLSCP Field Experiment and the San Joaquin Valley Air Quality Study. Results show general agreement with the simulated gradient functions but precise comparison is made difficult by scatter in the aircraft derived functions. The gradient functions are used to estimate forest emissions of nonmethane hydrocarbons using tethered balloon profiles. Mean emission estimates from profiles collected during the Amazon Boundary Layer Experiment 2A and the Rural Oxidants in the Southern Environment I experiment show good agreement with estimates made from budget arguments. Daytime isoprene emissions from the dry season Amazon are estimated to be 3860 +/- 1380 mu g m^{-2} hr ^{-1}. Summer, daytime isoprene emissions from an Alabama pine-oak forest are estimated to be 4040 +/- 3200 mu g m^{-2} hr ^{-1}, alpha-pinene emissions 1750 +/- 1060 mug m^{-2} hr^ {-1}, and beta-pinene emissions 770 +/- 560 mug m ^{-2} hr^{ -1}. Fluxes from individual profiles are very scattered and expected diurnal cycles in emission rates are not distinguishable. This technique provides a valuable means of measuring biogenic hydrocarbon emissions, a precursor to photochemical ozone production. The convective layer gradient technique holds the potential for remote estimation of surface fluxes over large areas using remote profiling technology, such as Differential Absorption Lidar (DIAL). An attempt to estimate ozone deposition rates using an ozone DIAL system was unsuccessful. The minimum signal-to-noise ratio for successful ozone deposition estimates using this DIAL system and the convective layer gradient technique was derived and is less than the signal -to-noise level in the analyzed DIAL observations.