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Monday, June 13, 2016

Planetary Boundary Layer, Moist Air Envelope, Ocean Asymmetry

Planetary Boundary Layer, Moist Air Envelope, Ocean Asymmetry - all things I have mentioned a few times here.

As far as heat capacity goes, you have the oceans then the moist air envelope then ice and land.  The greenhouse effect and global warming start with dry air which isn't on my list, then assumes that an increase/decrease in dry air temperature will have wondrous amplifying feedback on carbon forcing.  Originally, this was carbon dioxide forcing, but shifted to more carbon generic forcing most likely because things were not going quite as planned.  In thermodynamics it is all about the heat which depends on the energy and energy storage capacity which really drive the bus.

The last post I had on the planetary boundary layer emphasizes the difference between being in and out of the moist air envelope.  With moist air you have a thicker, deeper and higher heat capacity planetary boundary layer which decreases the temperature response to any forcing.  You can heat up a potato chip or crisp a lot faster than you can a whole fresh potato.  Since this particular planet has more whole potatoes in the southern hemisphere and more crisps in the northern hemisphere, they aren't going to cook uniformly.

To add to that, the thermal equator and the physical equator are different and that damn thermal equator can move.  Right now the thermal equator or Inter-Tropical convergence Zone (ITCZ) is about 6 degrees north of the real equator.  Climate models often indicate there should be twin ITCZs which is obviously wrong and that warming should be more uniform.

To someone with a basic knowledge of thermodynamics, the models are friggin' wrong because they don't realistically consider heat capacity.  When you have an entire field of science starting with screwed up assumptions which should be obvious, you would be surprised how hard it is to get the giants in that field to listen.  These asshats, er giants, want a completely new theory most likely because their collective butts are on the line.

This completely new theory should "project" all of the things they think are relevant to a superior degree of precision, because they have over simplified a problem with poor assumptions and actually believe their model.  Since their model is obviously screwed up, they should have no reason to be so confident, but since they are humans you should expect flawed logic.

The sad thing about this situation is that in a multi-disciplinary approach, you have an exponential increase in the number of Prima Donnas.  Prima Donna are great at pointing out the flaws in others but not so great at introspection.  The normal thing to do is let these Pima Donna fade, but a false sense of urgency screws up the whole scientific process of advancing one funeral at a time.

The moist air envelope and moist air model were my attempts to get people to focus on the more significant part of the atmospheric portion of the problem.  There is no ideal way to set the problem up, so you have to consider the more significant parts.  If it turns out that what you consider to be more significant has issues, then you have to consider other parts that appear to be significant.  Basically, quit recycling your same failing set of assumptions.

The minions of the great and powerful carbon always revert to the basic playbook the way the choir reverts to their favorite hymns.  A dynamic open system with a planetary scale will likely require thinking outside of the box.  A large number of simplified models designed to avoid assumption inbreeding could be considered outside of the box.  Regional sensitivity and how that sensitivity changes with time, outside the box.  Subsurface reference instead of lower troposphere reference, outside the box.  If you keep your head inside the box, you may never realize that the box is up some idiot's butt, possibly your own.

Take clouds.  Clouds are a regulating mechanism.  If you focus on heat capacity instead one single likely flawed metric, Global Mean Surface Temperature, it is pretty obvious.  You can convert all those individual temperatures that make up GMST into equivalent energy and you have a simple weighting method.  Is that energy equivalent absolutely, perfectly accurate?  No, but it is useful, especially since it is assumed that effective surface energy is directly related to effective radiant energy.  You cannot convince the choir of that though.

Kimoto's equation, is that absolutely, perfectly accurate?  No, but energy is fungible and if you can figure out the solution to a wicked set of partial differential equations it could be.

Energy balance estimates of sensitivity, are they perfect?  No, but if you can figure out the right combination of regional energy balance estimates they could be.

As all Rednecks know there is more than one way to skin a catfish.  The best way is letting someone else do the work, it is the bones you need to worry about anyway.

End of rant

Saturday, June 11, 2016

Finally a paper on the Planetary Boundary Layer and relative heat capacity.

Differences in the efficacy of climate forcings explained by atmospheric boundary layer depths by Richard Davy and Igor Esau (Nature Communications no. 7) explains a few things I have been harping on for a while.  When you have low heat capacity you get bigger temperature response.  Pretty simple really.  There is a bit of a disconnect between the simplified GMST and change of actual energy in the system at the extremes of heat capacity.  Well worth a few minutes of your time to peruse and worth more time if you are confused about cloud forcing/feedback.

I have tried explaining it with effective radiant energy and heat capacity to show how the zeroth law of thermodynamics rears its ugly head when you attempt to use an average temperature based a range from -80C to +50C combing "surface" air temperature with bulk ocean temperature which is about as huge a range of heat capacity you can find, but Davy and Esau have an approach that is much more likely to be acceptable in the climate science community.

Because most of the positive cloud long wave feedback is in low heat capacity situations and most of the cloud negative short wave feedback is in high heat capacity situations, it should be pretty obvious that overall cloud feedback is most likely negative if you are concern with increased warming in a thermo relevant way.

So if you have wondered about the planetary boundary layer aka atmospheric boundary layer impact on estimates of sensitivity, this part is a got start.  Unfortunately, it doesn't delve into the issue of longer term impact on "global" heat capacity.  When you have high latitude warming in winter that doesn't result in heat storage below the "surface", that warming is actually cooling if you consider Ts=lambaRF +dQ, because dQ can be negative.  Ignoring the dQ just implies a higher sensitivity than actually exists.  Since solar in the lower latitudes has the largest impact on heat capacity, it would have a higher forcing efficacy.

Friday, June 10, 2016

The War for the Tropical Oceans

There is an interesting battle going on between ocean proxy groups.  Personally I have become a G. Ruber fan and am a bit skeptical of the coral fans, but both have their strengths and weaknesses.  Since both are based on biological organisms that have survival instincts, it is anyone's guess how well they would deal with extreme conditions so both likely have divergence issues.  In addition to the proxies having divergence issues, the instrumental data also has divergence issues early in the records.  

Robust global ocean cooling trend for the pre-industrial Common Era, McGregor et al. 2015 includes Delia Oppo as a coauthor and I use Oppo et al. 2009 quite a bit of the time as a reference.  While this paper is "global" and not just tropical, the tropical reconstructions carry considerable weight as they should.  They tend to consider the volcanic impacts starting around 800 CE, though the major impact should be around 1200 CE.  They also consider some ocean dynamic mechanisms,   but on time scales greater than 200 years, the volcanic forcing would be enough to reasonably explain the cooling, i.e. the Little Ice Age.

Tropical sea-surface temperatures for the past four centuries reconstructed from coral archives,  Tierney et al. 2015,  also finds pre-industrial cooling, but up to circa 1830 and don't get into mechanisms.

The war really is over how much cooling and when did it end.  McGregor et al. are in the 1700 CE minimum while the corals show a minimum about 130 years later.  Since the lowest minimum was likely in 1700, the corals could be missing a bit of the range, and Tierney et al. mentions that secular trends isn't a coral strong point.

Rob Wilson has a previous tropical corals reconstruction (30S-30N) that started in 1750 that didn't indicate much pre-industrial cooling and Emile-Geay has a Nino 3.4 reconstruction of corals that indicated some of the pre-industrial cooling with a minimum around 1750.  Corals can have a 30 year recovery time frame from either a warm or cold event which is one reason I am not a big fan.  G. Ruber proxies can be a bit on the cold side because G. Ruber is mobile, unlike corals, but their cold nature wouldn't explain the peak around 1150 CE. Both Oppo 2009 and Emile-Geay 2012 are single location reconstructions, but the Indo-Pacific Warm Pool (Oppo 2009) has a strong correlation with global temperature and NINO 3.4 has a strong correlation with El Nino related variability.  If we are looking for a proxy for GMST, I would go with Oppo 2009.  This makes me question the practice of throwing multi-proxy reconstructions together when they different strengths and weaknesses.

Saturday, June 4, 2016

Clouds are still cloudy

Around 80% of the reflectivity of the Earth is due to clouds or about 77 Wm-2 depending on which energy budget you like.  If you assume albedo (reflectivity) is magically fixed and completely separated from the "Greenhouse Effect" by some strange magic, you are missing a huge portion of the picture.  The atmosphere also absorbs in the ballpark of 77 Wm-2 of sunlight mainly due to clouds and water vapor.  Clouds, water vapor, convection, precipitation and albedo are all interconnected because of water in its three states.

Warmer air can hold more water and warmer more moist air condenses at a higher temperature.  Since temperature decreases with altitude, that would mean clouds would start forming at a lower altitude unless lapse changed to offset the change in dew point.  That is unlikely because the mechanical forcing of convection, buoyancy, becomes stronger with increased water vapor.  As buoyancy increases the rate of falling colder dry air that replaces the warmer moist air.  That colder dry air, which should be colder and dryer thanks to increased GHE would stimulate more condensation, stimulating more convection and more precipitation.

The keys to all this activity are the convective triggering mechanisms, temperature, moisture and pressure differential. One of the odd things about this combination is the role of saturation vapor pressure of water.  Colder dry air would have a higher pressure inducing flow toward warmer moist air but the warmer moist air has a higher saturation vapor pressure meaning water vapor would tend to flow from lighter more buoyant air to less buoyant air.  This is wonderfully counter intuitive to most folks :)  It is also just one of the mechanisms that makes modeling clouds and water vapor a serious bitch.

Mechanisms for convection triggering by cold pools

 Abstract Cold pools are fundamental ingredients of deep convection. They contribute to organizing the subcloud layer and are considered key elements in triggering convective cells. It was long known that this could happen mechanically, through lifting by the cold pools’ fronts. More recently, it has been suggested that convection could also be triggered thermodynamically, by accumulation of moisture around the edges of cold pools. A method based on Lagrangian tracking is here proposed to disentangle the signatures of both forcings and quantify their importance in a given environment. Results from a simulation of radiative-convective equilibrium over the ocean show that parcels reach their level of free convection through a combination of both forcings, each being dominant at different stages of the ascent. Mechanical forcing is an important player in lifting parcels from the surface, whereas thermodynamic forcing reduces the inhibition encountered by parcels before they reach their level of free convection.

I am still trying to digest this paper but it looks like it is on the right path.

Friday, June 3, 2016

Marcott v Rosenthal

"To the extent that our reconstruction reflects high-latitude climate conditions in both hemispheres,
it differs considerably from the recent surface compilations, which suggest ~2°C MWP to LIA cooling in the 30°N to 90°N zone, whereas the 30°S to 90°S zone warmed by ~0.6°C during
the same interval (24). In contrast, our composite IWT records of water masses linked to NH and
SH water masses imply similar patterns of MWP to LIA cooling at the source regions The inferred
similarity in temperature anomalies at both hemispheres is consistent with recent evidence from
Antarctica (30), thereby supporting the idea that the HTM, MWP, and LIA were global events."

Rosenthal et al. 2015

Fig. 2. Comparison between Holocene reconstructions of surface and intermediate-water temperatures.
(A) Global (red) and 30°N to 90°N (green) surface temperatures anomalies, (B) 30°S to
90°S surface temperature anomalies (24), (C) changes in IWT at 500 m, and (D) changes in IWT at
600 to 900 m. All anomalies are calculated relative to the temperature at 1850 to 1880 CE. Shaded
bands represent +/- 1 SD. Note the different temperature scales.

Panels A and B are from the Marcott et al 2013 paper and include the spurious uptick caused by lack of data and their method.  btw, that +/- 1 SD should not be confused with actual uncertainty because there are huge unknowns, but this is about as good as it gets for now.

A denizen posted the Marcott cartoon as a sort of gotcha then asked what I thought was a better reconstruction.  I offered Rosenthal et al. 2015 even though it has issues because there isn't a paleo reconstruction that doesn't have issues.  The Rosenthal, Oppo and Lindsey crew just happened to take a polite counter opinion of Marcott et al which carries a bit more weight than any of my ramblings.  Kind of entertaining that the denizen liked the Rosenthal paper because he thought the Marcott et al. reconstructions matched Marcott et al. reconstructions :)  Hopefully that denizen will get around to reading the text.

Fig. 3. Temperature anomaly reconstructions for the Common era relative to the modern data (note
that the age scale is in Common era years with the present on the right). (A) Change in SST from the
Makassar Straits [orange, based on (26) compared with NH temperature anomalies (27, 28)]. (B) Compiled IWT anomalies based on Indonesian records spanning the ~500- to 900-m water depth (for individual records,  see fig. S7). The shaded band represents +/- 1 SD.

They also include a comparison of Oppo et al. 2009 with Mann and Moberg similar to comparisons I have made but with a less dramatic scale, in the left hand figure.

Depending on which product you prefer and the current state of adjustment, the IPWP correlates well with global SST which is 70% of the GMST product.  Since HADSSTi uses less creative interpolation it is a better match for the reconstruction in the region of the reconstruction 3S-6S and 107E to 110E.

Since there are tons of issues in paleo to deal with, every reconstruction will need some time to resolve them, but Rosethal and crew appear to be ahead of the learning curve.