Relationship between the Scavenging Coefficient for Pollutants in Precipitation and the Radar Reflectivity Factor. Part II: Applications

Abstract

The power-law dependences between the scavenging coefficient ? for pollutants in precipitation and the radar reflectivity factor Z, theoretically derived in Part I, are discussed here from the point of view of applications. Possible problems in their use are related mainly to the uncertain characteristics of the pollutants involved and to common error sources in weather radar measurements of precipitation. The greatest usefulness of the ??Z relationships probably is obtained when the hydrometeor population that is producing the radar signal is the same as the population that is scavenging the pollutants. Because radar estimates Z in real time, the relationships can be utilized in short-term forecasts of the cleansing effect of precipitation and of wet deposition. This use is illustrated in the current paper with the aid of radioactivity and radar measurements in Finland following the Chernobyl accident. The ??Z relationships yielded estimates of radioactive fallout that were in good agreement with observations: a logarithmic correlation coefficient of 0.67 was found between gamma radiation dose rates and radar-derived estimates for the time integral of ?, a quantity that is approximately proportional to the accumulated wet deposition.