Clouds - Positive And Negative Feedback Discussion

[Chris Knight]

Paper* by Dietmuller et al (2008) apparently refuting Travis et al (2002, 2004) that shows that contrails (and high clouds in general if I am reading it correctly) do not have a significant impact on the diurnal temperature range (DTR).

The probability distribution of the DTR showed no

significant change, even in regions of the strongest aviation.

On the other hand, the climate model reproduces

the main features of the observed DTR variability as

well as its correlation with natural cloud coverage and

cloud radiative forcing. An important detail is that the

DTR appears to be rather insensitive to high cloud

changes in both the model and the ERA-40-observed

data (see section 4). This suggests that the impact of

contrails on DTR is also small.

If this is correct "high clouds warming - low clouds cooling" needs to be rethunk!

In both ECHAM4 and ERA-40 data, the

correlation of cloud coverage or cloud radiative forcing

with the DTR is mainly apparent for low clouds.

Edit: *J. Climate

Edited January 26, 2009 by Chris Knight