REGIMES OF NONISOTHERMAL SCAVENGING OF SOLUBLE GASEOUS POLLUTANTS BY RAIN IN THE ATMOSPHERE WITH NON-UNIFORM CONCENTRATION AND TEMPERATURE DISTRIBUTIONS

We suggest a one-dimensional model of precipitation scavenging of gaseous pollutants with arbitrary solubility by rain that is valid for nonuniform initial vertical distributions of soluble trace gases and temperature in the atmosphere. We investigate the influence of a nonstationary inhomogeneous temperature distribution in the atmosphere on the rate of gas scavenging by precipitation. It is showed that when gradients of temperature and soluble trace gases concentration in the atmosphere are small, evolutions of altitudinal temperature and concentration distributions under the influence of rain are governed by linear wave equations that describe propagation of temperature and scavenging wave fronts. Scavenging coefficient and the rates of precipitation scavenging are calculated for wet removal of methanol (CH₃OH) using measured initial distributions of methanol and temperature in the atmosphere. It is shown that scavenging of gases with low and high solubility by precipitation in the inhomogeneous atmosphere can be analyzed assuming a homogeneous temperature distribution or by solving equations of mass transfer in the atmosphere with stationary inhomogeneous temperature distribution, correspondingly. Theoretical predictions for the values of the scavenging coefficient during sulphur dioxide washout by rain and for the dependence of the scavenging coefficient on rain intensity agree with the atmospheric measurements.