Kelvin‐Helmholtz instability around the tropical tropopause observed with the Equatorial Atmosphere Radar

In November 2001, the Equatorial Atmosphere Radar (0.20°S, 100.32°E) observed a continuous strong eastward wind shear (10–50 m s −1 km −1 ), westward wind (2–27 m s −1 ), and the radar echo layer tilted downward to the west in the region 0–1 km above the tropopause. During the same period, the Richardson number calculated with hourly‐averaged horizontal wind and radiosonde temperature data was almost continuously <0.5 and sometimes <0.25, which seems to indicate that the Kelvin‐Helmholtz instability (KHI) frequently occurs in that region. The existence of the tilted radar echo layer can be explained by KHI billows. A spurious updraft caused by the KHI‐induced tilted echo layer and by the strong westward wind was also observed in the region.