Stephen Wilde comments
Stephen Wilde says:
Now that the sun is slowly coming out of its minimum the strength of the solar wind is increasing.
That produces more solar photons reaching the mesosphere which then cools a little from increased ozone destruction to increase the temperature gradient right down to the tropopause. The tropopause then rises a little and the jets move a little more poleward to produce a stronger upward energy flux from the surface.
Thus energy is leaving the Earth system a little faster than it was when the sun was quieter and at the same time the developing La Nina is denying energy to the air with the result that the air is cooling from two directions. That should at last put a solid end to the late 20th century tropospheric warming trend after the past ten years or so of mere cessation of warming.
As per my interpretation of the recent Haigh data an active sun cools the mesosphere and stratosphere for a stronger upward energy flux and a quiet sun does the opposite.
For a while the solar minimum held more energy within the system and combined with the recent El Nino to achieve the recent tropospheric warmth. Both processes have now reversed hence the more noticeable cooling that we are observing.
Stephen Wilde says:
October 29, 2010 at 12:06 pm
If the cause of current warming is “integration” of the ENSO (by that I assume you mean that the release of heat from ocean to atmosphere in the past 50 years during El Nino phases has exceeded the recapture of that heat during the various La Nina phases), the n the ocean should show a definite cooling. Nicht wahr?”
Interesting point, Owen.
Bob has often mentioned the discharge / recharge process with which I agree but in the absence of any other factor that should have resulted in a decline in ocean heat content during the recent warming spell but in fact ocean heat content actually rose until recently.
Now with stronger La Ninas the ocean heat content is declining which again is opposite to Bob’s proposition.
So my conclusion is that a separate influence is operating to dictate the longer term ENSO trends from the background thereby overriding the discharge / recharge process on longer than interannual timescales.
My proposition is that the background trend is provided in part by internal ocean cycles but also by solar variability so that the more active sun draws the jets and their associated cloud bands poleward to let more energy into the oceans just like opening a pair of window blinds.
The quieter sun pushes the jets back equatorward to reduce the energy input to the oceans just like closing the blinds again.
Thus are the tiny variations in solar output massively amplified via albedo changes to explain the much larger global tropospheric temperature changes that we observe. And in the process they also skew the relative intensities of El Nino and La Nina especially on timescales longer than the 60 years or so of the Pacific Decadal Oscillation.
One is forced to propose something of that sort in order to explain the even longer climate cycling from MWP to LIA to date.