I liked this part:
According to the study an important issue remains as to why the poleward expansion is largest in autumn, and there is still uncertainty about the role of external forcings – such as greenhouse gases – as climate models underestimate the southward expansion of the Hadley cell edge.
From CSIRO Australia
Southern Hemisphere becoming drier
A decline in April-May rainfall over south-east Australia is associated with a southward expansion of the subtropical dry-zone according to research published today in Scientific Reports, a primary research journal from the publishers of Nature.
CSIRO scientists Wenju Cai, Tim Cowan and Marcus Thatcher explored why autumn rainfall has been in decline across south-eastern Australia since the 1970s, a period that included the devastating Millennium drought from 1997-2009.
Previous research into what has been driving the decline in autumn rainfall across regions like southern Australia has pointed the finger at a southward shift in the storm tracks and weather systems during the late 20th century. However, the extent to which these regional rainfall reductions are attributable to the poleward expansion of the subtropical dry-zone has not been clarified before now.
Mr Cowan said rainfall patterns in the subtropics are known to be influenced by the Hadley cell, the large-scale atmospheric circulation that transports heat from the tropics to the sub-tropics.
“There has been a southward expansion of the edge of the Hadley cell – also called subtropical dry-zone – over the past 30 years, with the strongest expansion occurring in mid-late autumn, or April to May, ranging from 200 to 400 kilometres,” Mr Cowan said. The CSIRO researchers found that the autumn southward expansion of the subtropical dry-zone is greatest over south-eastern Australia, and to a lesser extent, over the Southern Ocean to the south of Africa.
“The Hadley cell is comprised of a number of individual branches, so the impact of a southward shift of the subtropical dry-zone on rainfall is not the same across the different semi-arid regions of the Southern Hemisphere,” says CSIRO’s Dr Wenju Cai.
The researchers tested the hypothesis that the dry-zone expansion would give rise to a southward shift in the average rainfall during April and May, and questioned how rainfall across semi-arid regions, including southern-coastal Chile and southern Africa, would be affected.
“During April and May, when the dry-zone expansion is strong, rainfall over south-eastern Africa, south-eastern Australia and southern-coastal Chile is higher than over regions immediately to their north,” Dr Cai said.
Using high-quality observations and an atmospheric model the CSIRO team found that for south-eastern Australia, up to 85% of recent rainfall reduction can be accounted for by replacing south-eastern Australia rainfall with rainfall 400km to the north. Such a southward shift of rainfall can explain only a small portion of the southern Africa rainfall trend, but none of the autumn drying observed over southern Chile.
“For south-east Australia, autumn is an important wetting season,” Dr Cai explained. “Good autumn rainfall wets the soil and effectively allows for vital runoff from follow-on winter and spring rain to flow into catchments.”
According to the study an important issue remains as to why the poleward expansion is largest in autumn, and there is still uncertainty about the role of external forcings – such as greenhouse gases – as climate models underestimate the southward expansion of the Hadley cell edge.
This research was conducted through CSIRO’s Water for a Healthy Country Flagship, and was funded by the Goyder Institute for Water Research and the Australian Climate Change Science Programme. Wenju Cai, Tim Cowan and Marcus Thatcher are from CSIRO’s Marine and Atmospheric Research division.
UPDATE:
Some commenters can’t look beyond the title and see the bigger picture, so here’s an update just for them. Note that the study deals with the Hadley cell, which is NOT regional, but hemispherical. They looked not only at Australia, but also rainfall in southern-coastal Chile and southern Africa.
This is where I was coming from, which I thought would be obvious to anyone who’s been following the positive water vapor feedback issue for any length of time.
http://www.gfdl.noaa.gov/bibliography/related_files/hall0001.pdf
===============
Abstract. Using two versions of the GFDL coupled ocean-atmosphere model, one where
water vapor anomalies are allowed to affect the longwave radiation calculation and one
where they are not, we examine the role of water vapor feedback in internal precipitation
variability and greenhouse-gas-forced intensification of the hydrologic cycle. Without
external forcing, the experiment with water vapor feedback produces 44% more annualmean, global-mean precipitation variability than the one without.
We diagnose the reason for this difference: In both experiments, global-mean surface temperature anomalies are associated with water vapor anomalies. However, when water vapor interacts with longwave radiation, the temperature anomalies are associated with larger anomalies in surface downward longwave radiation. This increases the temperature anomaly damping through latent heat flux, creating an evaporation anomaly.
The evaporation anomaly, in turn, leads to an anomaly of nearly the same magnitude in precipitation. In the experiment without water vapor feedback, this mechanism is absent. While the interaction between longwave and water vapor has a large impact on the global hydrologic cycle internal variations, its effect decreases as spatial scales decrease, so water vapor feedback has only a very small impact on grid-scale hydrologic variability. Water vapor feedback also affects the hydrologic cycle intensification when greenhouse gas concentrations increase. By the 5th century of global warming experiments where CO2 is increased and then fixed at its doubled value, the global-mean precipitation increase is nearly an order of magnitude larger when water vapor feedback is present.
The cause of this difference is similar to the cause of the difference in internal precipitation variability: When water vapor feedback is present, the increase in water vapor associated with a warmer climate enhances downward longwave radiation. To maintain surface heat balance, evaporation increases, leading to a similar increase in precipitation. This effect is absent in the experiment without water vapor feedback. The large impact of water vapor feedback on hydrologic cycle intensification does not weaken as spatial scales decrease, unlike the internal variability case. Accurate representations of water vapor feedback are therefore necessary to simulate global-scale hydrologic variability and intensification of the hydrologic cycle in global warming.
=================
So if positive water vapor feedback were occurring, based on this idea, we’d see an “intensification of the hydrologic cycle”, i.e. more rainfall, runoff, and evaporation. That would apply to the southern hemisphere continents too.
And the researchers by their own admission can’t even fit GHG feedbacks into the Hadley cell migration equation successfully. It is just more evidence of uncertainty in the “settled science” of AGW.
To D Boehm,
That’s all you have to add to what I said in support of Mr. Huffman’s “proof” that there is no greenhouse effect operative on Venus and the Earth? And you still believe in Mr. Huffman’s “theory” concerning …………… what was it that it concerned other than a means of provided the sought for “bottom line” with no beef associate with it.
And by the way, I was not the one that claimed that Venus emits substantially more energy than it receives. That suggestion was made on this thread by Anthony Watts. So that is a point you should take up with him.
And concerning “religions experience” ? You wander too far from science, Sir, to take you seriously anymore. As you continue to try to save face on this thread, please do not be disappointed is I ignore your meaningless comments from here on. One of my shortcomings is that there is a limit to the extent to which I can suffer fools gladly.
ericgrimsrud,
Please, ignore my comments. Bravo! I absolutely approve of that decision.
Rest assured, however, that I will not ignore your comments. Casual readers of WUWT will not be misled by your pseudo-science while I am around to correct your climate alarmist nonsense. I have deconstructed your entire Belief system, and will continue to do so every time you comment.
For example, your underhanded attempt to pretend that Venus does not emit more radiation than it receives from the sun. By pointing the finger at Anthony, you tried to give the false impression that it isn’t so. But as usual, it is you who are emitting pseudo-scientific nonsense.
Venus is an enigma. Mars is not. Both have extremely high CO2 levels, over 95%. Venus is hotter than we can account for without assuming an internal heat source. But Mars is freezing cold. Not much of a greenhouse there.
Now, there may be a greenhouse effect, but if so it is too small to measure. On the other hand, you have stated your Belief in catastrophic runaway global warming due to rising CO2. The fact that you have no empirical evidence to support your Belief means that you have only a baseless opinion. A belief. That is not science, that is religion. And the planet itself is deconstructing your Belief. There is no sign of runaway global warming anywhere. You are only dreaming.
To Richardscourtney,
I have tried to respond to your last post – with a level of civility that matches your own – and with some relevant scientific comments. But they were blocked by the Mods. This is just to let you know that I tried and am not ignoring you. I am particularly interested to talking science without extensive use of one’s book of quotes. One can find anything one wishes to find on the bloggery.
Hoping this passes mustard with the PC cops.
Eric
(Reply: your snipped comment did not mention Mr Courtney at all. ~mod)
to Richardscourtney, Oh good, I am now again able to address you.
So here I have a scientific question for you. As you know, you take exception to my previous statement that the energy balance of the Earth is determined by just three things. They are the intensity of the sun, the Earth’s albedo and the GH Effect. You claim that this is not true and for proof pointed to a scientific reference without explaining what that reference had to say about the point under consideration.
So if you would, please tell us in your own words just one factor – that is not included in the three factors I listed – that affects the energy balance of the Earth.
Simple question, right? And one that most readily understand, right. So why do I now suspect that you will try to change to subject and / or lob a view personal insults without ever addressing this very simple and very relevant question. We’ll see.
Some person just said to me:
” For example, your underhanded attempt to pretend that Venus does not emit more radiation than it receives from the sun. By pointing the finger at Anthony, you tried to give the false impression that it isn’t so. But as usual, it is you who are emitting pseudo-scientific nonsense.”
All I know about the possibitity that Venus emits more radiation than it absorbs is what Mr Watts told me in his posts on Oct 14, 5;13 pm and Oct 15, 8:22 above. I have no reason to doubt what he said and, until I learn otherwise, will accept the possibility that it is true. All of this is documented on the transcripts above. So who is that loose cannon polutiing every conversation he can at WUWT? So if the Mods can not help, I will try even harder to ignor all of his frequent posts on this and other threads. All one can do is post occasional corrections to any content, if any, included in his personal spasms.
So ericgrimsrud has returned to unsubstantiated accusations of WUWT censorship, eh?
As fun as displays of slippery wriggling can be, I think this exercise in pig wrestling has run its course. As told by the old saying, the pig is enjoying it. Indeed, I can tell the pig is really enjoying it, as you’re wrestling a boar.
ericgrimsmud says:
“I will try even harder to ignor [sic] all of his frequent posts on this and other threads.”
You are simply not trying hard enough. You stated that you were going to ignore my comments. I approved of that decision. But you are weak.
Not only weak, but wrong. As I clearly stated, I will correct all your anti-science comments. To date you have not made a convincing case that CO2 has any measurable effect on temperature. Your opinions are only baseless conjectures, and thus easy to deconstruct.
Better run along back to your thinly-trafficked alarmist blogs. You need some new talking points, because the ones you have been parroting are old and busted.
BTW, how is your search for my CV coming along? If you keep at it, you should find it within the next few weeks. Even less, if you really put in some serious time searching.
Anthony, maybe ericgrimsmud may have enough science background (questionable) to understand the concept of potential temperature in a gravitational field better than the molecular example of carrying heat deeper into Venus’s atmosphere than the one you used even though you are correct. Potential temperature explains it all it seems:
Using the standard Φ = T ( p0 / p )^( R / cp )
T.sv is temperature of Venus’s surface
310K is temperature on Venus at one atmosphere
8.315 is the gas constant
37 is the specific heat capacity of CO2
You get T.sv = 310 * (92/1)^(8.315/37) = 856K, a bit high but close knowing that the exact temperature at one atmosphere is in question and the specific heat capacity varies with the pressure and this assumes only co2 is present and even the surface temperature is a bit fuzzy, but simple potential temperature explains the large surface temperature even if no radiation ever made it deeper than 50 km at all. Pressure is temperature in an atmosphere and tell him any meteorologist knows this well… and to forget the GHE meme on Venus (or Earth).
On Earth the ’76 standard atmosphere does not exactly follow this potential temperature parameter but roughly but also the our atmosphere, absorbing incoming radiation smoothly at all levels, has warmed each level more than if most of the temperature from absorption had originated high above as on Venus. That also explains that variance very clearly here, especially in the stratosphere’s case where potential temperature and actual temperature vary quite a bit.
ericgrimsrud:
At October 17, 2012 at 8:03 pm you write to me
THAT IS A LIE.
In the “claim” at October 17, 2012 at 11:18 am I wrote
If you had scrolled up to October 14, 2012 at 9:21 am you could have read
The quotation from Lindzen provides a complete explanation for everybody who knows anything about the thermolhaline circulation and knows radiative flux from a surface is proportional to T^4 so small changes in distribution of the Earth’s surface temperatures have large effect on the average global temperature.
Your knowledge of what is a “scientific question” is as lacking as your ability to understand a scientific answer.
Richard
D Böehm says:
October 17, 2012 at 6:34 pm
For example, your underhanded attempt to pretend that Venus does not emit more radiation than it receives from the sun. By pointing the finger at Anthony, you tried to give the false impression that it isn’t so. But as usual, it is you who are emitting pseudo-scientific nonsense.
Venus is an enigma. Mars is not. Both have extremely high CO2 levels, over 95%. Venus is hotter than we can account for without assuming an internal heat source. But Mars is freezing cold. Not much of a greenhouse there.
Not much of one but still measureable, percentage of CO2 in the atmosphere is not the relevant parameter, rather it is the partial pressure of CO2 and the influence of spectral broadening is very important, see a comparison between a portion of the CO2 IR spectrum under Earth conditions and Mars (note the large difference in transmittance):
http://i302.photobucket.com/albums/nn107/Sprintstar400/Mars-Earth.gif
D Böehm says:
October 17, 2012 at 6:34 pm
For example, your underhanded attempt to pretend that Venus does not emit more radiation than it receives from the sun. By pointing the finger at Anthony, you tried to give the false impression that it isn’t so.
Anthony referred to a 1980 note in New Scientist magazine as the basis for that statement, there’s more recent science on the subject. The one below should be ‘paywall’ free:
http://yly-mac.gps.caltech.edu/z_temp/venus_ref/Bullock_ClimateVenus_Icarus2001.pdf
Work over the last 20 years or so have shown that Venus does have a powerful greenhouse effect, the above paper gives a very clear exposition of the basics.
[snip – note above you’ve been given a 48 hour timeout – mod]
[snip – note above you’ve been given a 48 hour timeout -mod]
(Snip. ~mod)
(snip ~mod)
richardscourtney says:
October 18, 2012 at 2:31 am
If you had scrolled up to October 14, 2012 at 9:21 am you could have read
Richard Lindzen states the matter more clearly than I could so I quote his words from
http://www.glebedigital.co.uk/blog/?p=1450
“Recent work (Tsonis et al, 2007), suggests that this variability is enough to account for all climate change since the 19th Century.”
Although that is not a conclusion that Tsonis et al. draw themselves, they conclude:
“The standard explanation for the post 1970s warming is that the radiative effect of greenhouse gases overcame shortwave reflection effects due to aerosols [Mann and Emanuel, 2006]. However, comparison of the 2035 event in the 21st century simulation and the 1910s event in the observations with this event, suggests an alternative hypothesis, namely that the climate shifted after the 1970s event to a different state of a warmer climate, which may be superimposed on an anthropogenic warming trend.”