Abstract:

The Asian Summer Monsoon is the most pronounced atmospheric weather system during boreal summer, consisting of a large-scale anticyclone extending from Asia to the Middle East.  Moist air masses are transported via strong convection or general tropical upwelling to altitudes where the coldest temperatures in the atmosphere are found.  Thin cirrus clouds that consist only of ice crystals form at these cold temperatures.  In addition, thick ice clouds are carried into the upper troposphere in deep convective thunderstorms.

The ice clouds over the Asian monsoon can have either a warming or a cooling effect. Also, they affect the amount of water vapour in the tropical upper troposphere, from where the water vapour is further transported into the stratosphere as far as the Arctic Circle. Because water vapour is a strong greenhouse gas, it causes a warming directly in the tropics up to the Arctic stratosphere.

Understanding the overall effect of ice clouds on this chain of processes is a focus of recent  research. Here, unique aircraft-based observations of ice clouds and water vapour over the Asian monsoon are presented.  In particular, ice cloud properties, formation and evolution will be shown and investigated based on simulations.