The Melting Arctic Causes UK Snow?
Posted 20 March 2013 - 20:15
The reality is that there will be winners and losers in any change of world climate however it is caused. Trying to make computer models fit the synoptics is just as crafty as trying to make the temperature record fit the curve!
Posted 20 March 2013 - 20:45
For definitive or near precise values, concur. Its the problem of figuring out the functions first. So far most models are large scale top/down. I figure we need a bit more empirical work first. The problem it costs tax money to perform a field campaign. I can just imagine being in one of the leading Climate Science teams knowing you're, "dammed if you do and dammed* if you don't"... (*Note: Misspelling of explictive on purpose.)
(Done right we need some form of Argo buoy for the atmosphere. Kind of like a helium balloon that captures/dumps condensed water vapor to vary altitude. The problem is finding the right materials and not impacting air traffic.)
Posted 20 March 2013 - 20:53
Posted 20 March 2013 - 23:11
Posted 21 March 2013 - 07:42
All in all this is something to watch for the simple reason that it brings major problems to agriculture, which in turn could lead to substantial hikes in food prices on top of those already experienced, which are more a reflection of the massive increase in global oil prices in recent years. My advice is start growing your own, if you have not already, and get good at it!
Posted 21 March 2013 - 10:56
The issue is not that the speed has dropped; but, that meanders have developed. In addition, though the surface level Summer temperatures have risen, the Winter time and Upper Level air has not warmed. At least the warming that has occurred has in essence radiated out into space and is greatly diminished in the Polar cell return flow. That I think is the main issue, the thermal increase at the surface has increased the amount of air parcels in the Arctic which ends up expanding the Polar Cell pushing the UL winds into the Hadley Cell region. The interaction at the edges is what is giving rise to both the "wild weather" and the meanders.
The Ferrel cell has always been a, " if come, maybe " kind of feature. Similar to the " feeding jet " of a blackhole, it has the character of existing mainly where there was a clean Hadley/Polar convergence, where the in essence "outer layer scud" mixed and rotated above the convergence acting as a form of UL bridge. The more erratic the convergence the greater the outer layers were shed and in essence fed a secondary circulation cell. At the current erratic flow the Ferrel cell really is not an observable feature as the strong counter rotating features are driven by the thermal UL differences between the higher latitudes and the surface level in the lower latitudes. In essence, in the past the circulation cells were more like a closed system, very little energy was exchanged. (Any exchange was purely the energy transferred at the surface or ground level by ocean surface currents.).
Once the convection energy changed the Ferrel cell broke down, and the interaction at the Polar/Hadley convergence increased. It is the energy transferred at the convergence zone, further pushed by the added convection in the former polar region caused by higher sea surface temperatures that is responsible for most of what we are seeing. At the same time that the upper level of the Polar cell has pushed South the surface level of the Hadley cell has pushed North. In essence, no more closed cell convergence; but, constant convection cells both rising and the return flow.
Posted 21 March 2013 - 11:34
That's the point, they aren't right. The wind speeds within the Polar Jet Stream have not diminished. The only real effect is that the ground speed has changed. Increase the ground to be covered under a wind speed that has not changed and yes you could interpret that as a reduction in ground speed; but, that is disengenerous at best and fraud as a possibility. This is the type of science that infuriates the reasonable against the cause of the "warmists" pov. A little tweek here a contentious interpretation there and it is clear that the conspiracy against honest examination of the facts feeds my personal anger over conclusions which misrepresent the facts and fuels my personal disgust. That both sides use similar misrepresentation does not absolve either party, they simply expand the disdain of the public at large.
Posted 21 March 2013 - 12:25
Its simple really, if there was a reduction in the UL wind speed I could accept their "years of expertise". No they were not measuring wind speed ; but, the progress of an air parcel as it advance on the circumference of the Earth, please... Read the paper and the examination if you question my interpretation. If you are that concerned that they are being honest brokers have the folks at Skeptical Science have them submit a guest article. I will be surprised one if they will open their examination methods beyond the public satellite monitoring of UL cloud features and their advance over the ground. This is not a valid measure of a body of air, it is a measure of the effects of its passing. Its like trying to measure the speed of a passing lorry by the displacement or wind speed of its passing...
I find that disengenerous at best! I really cannot express my full displeasure in a public forum, which is probably a good thing...
Put another way, if the exhaust of a car exits the muffler at a rate of 100km/hr how fast is the car moving...?
Posted 21 March 2013 - 12:30
This graphic depicts how the drop in high-altitude winds in autumn over the past 30 years has closely tracked the decline in Arctic sea ice (dashed line). The rapid warming of the Arctic has reduced the temperature difference between the Far North and temperate regions, slowing down the jet stream and leading to more persistent, or “stuck,” weather patterns. (Jennifer Francis, based on data from the National Center for Environmental Prediction, National Center for Atmospheric Research, and National Snow and Ice Data Center)
Posted 21 March 2013 - 12:44
Fields of 500 hPa heights are selected for this analysis because they are constrained by observations from numerous radiosondes and satellite retrievals, they are relatively free from surface effects, and they capture upper-level wave patterns.
I find this holds time and again when figuring out shear profiles in thunderstorm forecasting.
Posted 21 March 2013 - 12:59
So is standing on the side of the road going to be a measure of the passing lorry. Move further away from the road and the wind speed will drop. Increase the average atmospheric turnover from a 10-12km height to a 14-16km height and what do you think happens to the measured wind speed. I'm so sorry; but, 500mb is not the jet stream. Matter of fact on the SRRS server for nesdis I have watch over the last 10 years as the 300mb measures have narrowed and the 250mb measures have broadened. Certainly there used to be a seasonality, Winters were broader at 300mb and narrower at 250mb. Then we started seeing around 2006 that both seemed about he same breadth. Now we begin to see the 300mb narrow and the 250mb broaden year round.
The point is, BINGO, they were not measuring the Jet Stream rate, period!
Posted 21 March 2013 - 13:29
Daily fields of 500 hPa heights from the National Centers for Environmental Pre-diction Reanalysis are analyzed over N. America and the N. Atlantic to assess changes in north-south (Rossby) wave characteristics associated with AA and the relaxation of pole-ward thickness gradients. Two effects are identified that each contribute to a slower eastward progression of Rossby waves in the upper-level flow: 1) weakened zonal winds, and 2) increased wave amplitude.
What they are saying is that 500 hPa observations can characterise how Rossby Waves are behaving. I see no problem with this. For example, compare these three charts:
You can see that the 200 hPa and 300hPa windfields, including strengths and positions of jetstreams, are well reflected by the 500hPa pattern.
Posted 21 March 2013 - 14:50
What do you think a Rossby wave is?
I'll share my thought, it is the point of interaction between the Polar and the Hadley Cell. If the energy balance favors convection it's a cyclonic wave if the energy favors subduction its an anti-cyclonic wave. If there is a "greater" thermal imbalance by surface latitude, the Polar cross zonal flow increases, if the circulations are closed as when the polar air mass reserves are balanced both gravitationally and in vapor pressure, then the cross zonal flow is minimal or reduced. Just the opposite of current theorms, it is in the NH Winter that the Polar air masses move over the NA continent, not Summer.
However, the point is the Jet Stream has not slowed, its gotten longer. I agree that Rossby wave progression between 20-60N have slowed. However, that does not reflect on the speed of the Jet Stream though. Instead of suggesting a weaker Jet Stream it makes more sense to suggest a stronger N/S meridional flow, driven by circulation change caused by thermal/climatic zone overlapping.
The global atmospheric circulation is the driver of the meanders, the blocking and cutoff conditions, which are symptoms of gravitational changes related to thermal changes in the thermodynamic balance at the global boundary layer where advection and convection merge. In a balanced system most energy would be advected away from a point of excess towards a point of stasis. If the energy at the point of excess exceeds the ability to be advected away we get increased convection, the combination of which changes atmospheric circulation.