Mammatus‐Like Echo Structures Along the Base of Upper‐Tropospheric Outflow‐Layer Clouds of Typhoons Observed by Cloud Radar

Abstract

AbstractUpper‐tropospheric clouds in the outflow layer of typhoons can affect the track of typhoons (tropical cyclones) through radiation effects. In this study, the microstructure of the outflow‐layer clouds of several typhoons was examined. Cloud radar observations of three typhoons around Japan revealed numerous protuberances in echoes along the base of the upper‐level clouds, which are referred to as mammatus‐like echoes. The horizontal and vertical scales of these mammatus‐like echoes were 0.5–3.0 and 0.3–1.5 km, respectively. Vertical observations revealed downward (upward) Doppler velocities in (between) the hanging echo regions. Upward and downward velocity maxima were estimated at 3 m s−1 around the mammatus‐like echoes. Neutral stratification developed in the dry layer beneath the cloud base in which the mammatus‐like echoes formed. These mammatus‐like structures may promote mixing along the cloud base that contributes to dissipation of the outflow‐layer clouds.