Erik Johansson, PhD student at MISU and SMHI.
Erik Johansson, PhD student at MISU and SMHI.


Erik Johansson
PhD student at SMHI and MISU


How does cloud overlap affect the radiative heating in the tropical upper troposphere / lower stratosphere?


This talk is about the cloud radiative heating from cirrus clouds and in the upper troposphere / lower stratosphere. Most of the upward transport from the troposphere into the stratosphere takes place in the Tropical Troposphere Layer (TTL). Several mechanisms are believed to play an active role in this transport whereof cirrus clouds in and around the TTL is one of them. By radiatively heating the air in the TTL the cirrus clouds can support the upwelling motion of the air masses. However, if an underlying cloud-layer is present that is optically thick and has a sufficient cold cloud top it can alter the radiative effect of the cirrus cloud. The radiative heating usually produced by cirrus clouds can instead turn into radiative cooling.

The talk will deal with several questions, such as:
What is the net radiative heating resulting from cirrus clouds in the TTL?
How does this heating differ between single layer cirrus and cirrus clouds under overlap condition?
What role do the optical depth and physical properties of both the cirrus cloud and the underlying cloud plays?


Time and Place

Thursday June 7th 2018, 14.15
Rossbysalen C609, Arrhenius Laboratory, 6th floor