Nitric Acid Trihydrate Particle Formation in the Polar Stratosphere and Its Effect on Nitric Acid Transport to the Troposphere

抄録

Growth and sedimentation of type-I polar stratospheric clouds (type-I PSCs) particles including nitric acid are examined using a numerical model. The PSCs particles which grow in the upper particle layer have enough large size (-10μm) to descend rapidly to the tropopause within several days. In the lower part of PSCs layer, evaporation of HNO₃ from particulate matter occurs and acts as source of HNO₃ vapor. From view point of stratospheric HNO₃ distribution, the particle sedimentation effectively functions as vertical transport mechanism of HNO₃ vapor from the upper PSCs layer to the lower layer and/or to the troposphere.