tag:blogger.com,1999:blog-16612221.post512967443532322605..comments2024-03-19T03:14:04.172-04:00Comments on Rabett Run: An Odd Introduction to a New PaperEliRabetthttp://www.blogger.com/profile/07957002964638398767noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-16612221.post-79719902244186278982011-09-06T18:55:32.509-04:002011-09-06T18:55:32.509-04:00I posted this too at Tamino's
I have not seen...I posted this too at Tamino's<br /><br />I have not seen any of this before, but after reading the paper and this/Eli’s blog, I am surprised that the reactions to the article are not much more critical than they have been. I have no problems with the statistics, but getting data and calculating trends for CO2 or temperature as a function of time of day is rather trivial and would make a good undergraduate thesis for an end of semester project. But the climatological implications forwarded by this paper do not at all follow and their discussions of attribution (or what it means in the context of IPCC’s climate sensitivity estimates, etc) are borderline nonsensical. Even if some of the calculations are algebraically or statistically correct, this paper adds no insight into atmospheric physics or “climate of the past” and shouldn’t have published.<br /><br />They spend a page talking about how their T trend estimates are in line with the very large range you’d get from multiplying climate sensitivity by 5.35 ln(C/Co). So what? Given the uncertainties in CS, that would probably be true for an incredibly large number of individual stations. In any case, given that we are far out of equilibrium, it would have been better to use a transient climate sensitivity. They did not even compute dF correctly in the follow up to equation 1 , since you get about 0.86 W/m2 with their values (not 0.72), though I suspect that is a typo in what they used for their 2006 CO2 concentrations, which looks more like 2011 values. But a transient sensitivity closer to about 1.5 C for a doubling of CO2 is appropriate (see e.g., Table 4.1, Assessment of Climate Models: Strengths and Limitations, USCCP), in which case they’d get dT=(1.5/3.7)*(0.72) divided by the time interval ~0.009 C/yr. That is just on the edge (if not outside) of the low end of their value “dT/dt =0.021±0.011C/yr.” inally, how does a coincidental agreement with IPCC dT/dt estimates imply that the site is necessarily a global representative?<br /><br />Also, the radiative forcing for CO2 is not a globally uniform field, even though CO2 concentrations are well mixed. It tends to be higher at TOA in the tropics and lower in the tropics for downward radiation to the surface, per 2xCO2. To do the radiative transfer right you need to account for different temperature structures/tropopause heights and overlap with water vapor/clouds, which gives the forcing heterogenity.<br /><br />Their next section on DTR is meaningless and says nothing physical other than agreement or disagreement of Mauna Loa compared with other studies that do a spatial average. Again, so what?<br /><br />Their following discussion section is just qualitative hand-waving, there is no attribution. Mauna Loa is such a regional area, it should be affected by much more than just CO2 (they warn in section 3 that the PDO matters here, as if this means something). They ignore many other studies on global or regional DTR trends that show trends are largely the result of global dimming/brightening, clouds/humidity changes, or other regional influences and not necessarily CO2. Their high school level thought experiment about day vs. night mixing and back radiation is hopelessly unconvincing, and also ignores the top of the atmosphere perspective of the greenhouse effect people like raypierre have cautioned for in other studies of this sort, like<br />http://www.realclimate.org/index.php/archives/2005/11/busy-week-for-water-vapor/Chris Colosehttp://blog.timesunion.com/weather/author/chriscolose/noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-90588559454244100692011-09-02T18:05:46.527-04:002011-09-02T18:05:46.527-04:00DPM, Eli seems to remember that there is a project...DPM, Eli seems to remember that there is a project to digitize sea logs for climate info using crowd sourcing. This would fit right in but Steve Ryan at MLO is the guy with the dataEliRabetthttps://www.blogger.com/profile/07957002964638398767noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-29044986188327108242011-09-02T14:18:26.327-04:002011-09-02T14:18:26.327-04:00Just loverly! Great work and thanks.
Over at RC ...Just loverly! Great work and thanks.<br /><br />Over at RC somebody pointed out a satellite site (article about Glory) and I enjoyed mousing over the globe - at that time and height CO2 was noticeably higher (298 compared to 292-3 elsewhere) near Greenland in the area where planes fly from US-northern Europe. I have no idea what this means, but still ...<br /><br />Sorry about my lack of analytic skills.<br />(Susan Anderson)susanhttps://www.blogger.com/profile/16829151452002682271noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-76456409958395929102011-09-02T13:10:16.814-04:002011-09-02T13:10:16.814-04:00Interesting post. It is surprising that they were...Interesting post. It is surprising that they were not more aware of of the subjects covered by blogs, though with all the noise, it is easy to write blogs off as useless.<br /><br />As far as the temperature record of ML related to global, it does seem reasonable that tropical islands would be more useful for long term trends.Recovering in the Florida Keyshttps://www.blogger.com/profile/07913299764512464597noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-45340011432481244122011-09-01T23:49:09.857-04:002011-09-01T23:49:09.857-04:00"Those of you who have some spare time might ..."Those of you who have some spare time might think of organizing a project to digitize the data." <br /><br />I'm not sure I have 19 years of data worth of spare time, but I do have some tools for doing the dead trees to bits thing, and *some* time.<br /><br />I suppose I should write to Bruce?<br /><br /><br /><br />dark-pawed mouseAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-16612221.post-80003002451011389302011-09-01T18:28:01.535-04:002011-09-01T18:28:01.535-04:00Nice story about how science really works.
I'...Nice story about how science really works.<br /><br />I'm a little surprised by this sentence, however: "For the same reasons that this site provides excellent globally averaged CO2 data, it may provide temperature data with global significance." I agree that MLO is great for looking at global CO2 levels - it isn't immediately obvious to me that MLO should be good for matching global temperature trends. Eg, if I were to plop a dozen tall island mountains down randomly in oceans around the world, I'd expect them to all match in terms of CO2 to within a fairly small variation (and be much closer to each other than a measurement in a random forest or town), but I'd expect them to have temperature trends that vary one from the other almost as much as they would from a random ground level temperature station...<br /><br />-MAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-16612221.post-52449719317233582812011-09-01T15:11:25.098-04:002011-09-01T15:11:25.098-04:00From Steve Bloom:
Nice work all around! Thanks E...From Steve Bloom:<br /><br />Nice work all around! Thanks Eli! Next up:Samanta strikes again (this time against Zhao and Runner).EliRabetthttps://www.blogger.com/profile/07957002964638398767noreply@blogger.com