Abstract :
Accurate knowledge of the coefficients of molecular diffusivity (D) of trace gases, the kinematic viscosity of air (ν) and the thermal diffusivity of air (k) has important application to modeling and observational studies of atmosphere–biosphere interactions. For example, leaf boundary-layer resistances are often parameterized in term of the Schmidt number for mass exchange and the Prandtl number for heat exchange. This study reviews and re-analyzes the historical data and some modeling results for D for Hg vapor in air, N2 and O2 and recasts results of an independent review of dynamic viscosity and thermal conductivity of air in a form that are consistent with one another and with this author’s previous study of D for simple gases and air, N2 and O2 near STP. Because D, ν and k are functions of temperature and pressure, all modeling results and data are corrected to 1 atmosphere pressure and then used with a one- and two-parameter regression model to determine optimal values for the temperature exponent and the value of D, ν and k at 0°C. Statistical/regression methods for treating data and modeling results follow this author’s previous study of D, except that data for D for Hg vapor is not restricted to values below 100°C.
