Thursday, September 01, 2011

An Odd Introduction to a New Paper



O, wonder!
How many goodly creatures are there here!

How beauteous mankind is!
O brave new world,

That has such people in't!







Note: Moved up to take account of cross posting

Just less than two years ago Eli (well there was another name on his tag, but let us not go there even in the comments) was wandering through the poster forest at the AGU National Conference in San Francisco when he came across a presentation by Bruce D. Malamud and Donald L. Turcotte.
Temperature trends at the Mauna Loa Observatory, Hawaii: A direct measurement of global warming?

Observations at the Mauna Loa Observatory, Hawaii, established the systematic increase of anthropogenic CO2 in the atmosphere. Here, we examine the hourly temperature records at this observatory for the 30-year period (1977-2006). We determine the linear trends in the annual averaged data as a function of the time of day. For night-time data (22:00 to 6:00 local time) we find a near uniform warming trend, dT/dt ≈ 0.04 °C/yr. During the day, the warming trend moderates to a slight cooling, with dT/dt ≈ -0.01 °C/yr at 12:00 (noon). Our hourly data shows that there is a mean daily warming trend dT/dt = 0.022 °C/yr for this period.
It looked interesting, was about temperature trends at the Mauna Loa Observatory (MLO), something Eli has a passing interest in, and so he paused and looked and started to discuss the poster with the two presenters, Bruce Malamud and Don Turcotte. . . . . . and then Eli blurted

"I've seen this somewhere"

Which was a considerable shock to Bruce and Don. Where? How? and slowly it came back, somewhere on the net. . . Oh yes, I've blogged about this. Huh? Yeah, your presentation can be downloaded. Much consternation.

Turns out, there was a PowerPoint version at York University which Eli had found. The search was motivated by a post of Tim Curtin's on Marohasy's (nil nisi) that claimed there was no relationship between the temperatures measured at MLO
The temperature data at Mauna Loa from 1955 do not support the conclusions of the paper, of extreme warming at ‘high altitude Hawaii” to the extent of 0.268 C per decade since 1975. Actually as the graph shows there is a slight declining trend in the annual increases in temperatures at Mauna Loa.
and the ensuing bun fight. In any case, Eli found the Malamud and Turcotte presentation which showed a +0.22 C per decade trend. But there was something else confusing about Curtin's take on the matter
Note that this regression is for only the 1959 (first full year of [CO2] measures) to 1992 period, as the Mauna Loa Slope Obervatory ceased regular daily recording of temperature on cold days from the day Al Gore took up residence next door to Bill.
The answer is that MLO itself is not part of the US Historical Climate Network, but there have been other stations on the mountain for which data can be found. Or go here and search for Mauna Loa. This turned out to be a strong hint that Tim was not looking at the records for MLO, but for other stations on the mountain which closed down/moved/got spotty after 1992, and indeed the Malamud and Turcotte work used the hourly MLO data which are continuous to today. Indeed there are a few such hourly records which can be downloaded from the NOAA Earth System Research Lab, which is what Malamud and Turcotte did
bld - Boulder - Jan. 1, 1994 to Present
brw - Point Barrow - Jan. 1, 1977 to Present
mlo - Mauna Loa - Jan. 1, 1977 to Present
smo - Samoa - Jan. 1, 1977 to Present
sum - Summit - Aug. 12, 2005 to Present
spo - South Pole - Jan. 1, 1977 to Present
thd - Trinidad Head - Jan. 11, 2007 to Present
Eli wrote to Bruce Malamud the next day while huddling in the snow in Chicago.
For another, a good summary of ML meteorology is Ryan, S. (2001), Estimating volcanic CO2 emission rates from atmospheric measurements on the slope of Mauna Loa, /Chem. Geol., 177/, 201-211 and Quiescent Outgassing of Mauna Loa Volcano 1958-1994. You can find an on line copy of this

The paper says that there are measurements of wind direction, humidity, etc going back to 1958, but that the early data, before 1977 is still on paper. Also, winds blow up from the base during the afternoon. Ryan is still there, I interchanged some Email with him a couple of months ago and he knows where all this data is. At least some of it can be found on NOAA data servers.
Those of you who have some spare time might think of organizing a project to digitize the data. It is important to (and Rabett Run has permission) to quote the reply for what it shows about the intersection between blogs and climate science, or at least the parts of it that are not concerned with climate change
It is now one day later since your e-mail, and Don and I have now had a chance to go through your blogs and then the corresponding blog of Jennifer Marohasy with all the communications from Tim Curtin, Louis Hissink, etc. All I can say is 'wow'! We're still going through all the comments.

Neither Don or myself had any idea this was out there in the internet [neither of us keeps up with blogs in the climate community], and we are now going through all the 'constructive' comments, to see how they correspond to the current paper that we are getting ready to submit, pulling out major objections and criticisms to see if we have responded to them [already] or whether we need to respond to them (or just leave it be, as we might not agree).

One thing I was genuinely confused about was comments that we could not have data after 1992. {-See above - Eli} I pulled it off the internet, and then corresponded with the people at Mauna Loa, and the data seemed real. One of the reasons we went for this particular data set, is it is very difficult to get long records that are records to 0.1 degrees [either F or C] hourly--most are to the nearest integer. This makes a large difference in the overall statistics we look at. And yes, there were gaps in the hourly data (missing values), which I interpolated, using some fairly standard techniques. I'm pretty up front about this. But, I don't understand why people think we could not have had data after 1992. . . . . . .

Although I am of course interested in how this all relates to climate change, I at the beginning was more interested in working with data and then we found an extremely nice looking curve. In other words, I (we) worked with the hourly trend data first, with definitely no set agenda or expectations of what it would come up with.
We exchanged Emails again in early 2010. Fishing a comment out of the interchange
I'm having a lot of fun introducing Don Turcotte to the idea of blogs (he had never seen one before, and had no idea they existed).
And that was that until an Email fluttered into the mailbox today from Bruce Malamud
I hope you are well!

I thought I'd better wait to respond to you until the final Mauna Loa Observatory (MLO) paper was published in Climate of the Past, which it now has been today.

Donald Turcotte, Sue Grimmond {-Joined the team soon after AGU - Eli} and myself spent a number of days back in December 2009 going through all the blogs you pointed us to (there were many hundreds of comments in different blogs), and tried to 'answer' as many of the [constructive] critical comments as we could in the paper that we submitted in 2010. Our submission went through a discussion phase (all online) including our detailed responses to those people (it was open to anyone) who wrote in with comments.

After the discussion phase and our response, we then received the go ahead to prepare a final manuscript, which we did, along with another set of detailed reply to editor and reviewer comments (along the lines of what we published online) and the final paper was published today (and is attached). The paper is open access so others can post it if they want; the link is available

Malamud BD, Turcotte DL, and Grimmond CSB (2011) Temperature trends at the Mauna Loa observatory, Hawaii, Climate of the Past, 7, 975-983, doi:10.5194/cp-7-975-2011.

I would of course appreciate your blogging about this paper and the ideas in it if you are willing and feel it would still be of interest to the general community. I know it was controversial before, without even being a paper but rather a talk. Hopefully we've taken on board many of the comments from the blogs and the reviewers in our significantly revised version of the context of how we presented our original research (but the main facts remained, although slightly elaborated for the seasons), and that the scientific information presented in the attached will be taken in appropriate context of whatever 'arguments' people decide they wish to make.

It has been a reasonably long journey to this point, but am pleased to finally see it published. Thanks again for introducing yourself to us in December 2009 at AGU, as your help was invaluable. If you have any ideas about other appropriate publicity for this paper (e.g., places we should 'make it known') that would of course be appreciated.
In every way this has been a very satisfying experience for the staff at Rabett Run and Eli thinks an interesting and useful one for Drs. Malamud, Turcotte and Grimmond. Discussion of the published paper is now open here (and hopefully elsewhere). Some of the authors might join in.

To get started, here are the two abstracts





AGU Talk Abstract

Observations at the Mauna Loa Observatory, Hawaii, established the systematic increase of anthropogenic CO2 in the atmosphere. Here, we examine the hourly temperature records at this observatory for the 30-year period (1977-2006). We determine the linear trends in the annual averaged data as a function of the time of day. For night-time data (22:00 to 6:00 local time) we find a near uniform warming trend, dT/dt ≈ 0.04 °C/yr. During the day, the warming trend moderates to a slight cooling, with dT/dt ≈ -0.01 °C/yr at 12:00 (noon). Our hourly data shows that there is a mean daily warming trend dT/dt = 0.022 °C/yr for this period. The global temperature trend inferred from CO2 data by the IPCC in 2007 was dT/dt = 0.017(+0.009, -0.006) °C/yr. The direct measurement from our observations is in quite good agreement with the IPCC value. A decrease in the diurnal temperature range (DTR) is a direct signature of a greenhouse effect of CO2. For the Mauna Loa Observatory data we find a relatively large decrease in DTR with a yearly DTR change of d(DTR)/dt = -0.051 °C/yr over the 30 year period under consideration. It is of interest to compare the high altitude Mauna Loa data with the sea level data at the Tutuila Observatory, American Samoa, for the same period. At Tutuila, the mean temperature trend is dT/dt = -0.013 °C/yr and d(DTR)/dt = -0.051 °C/yr. The greenhouse effect is the same at the two observatories, but the temperature trend is quite different. The latter can be attributed to the buffering effect of the ocean. We suggest that the temperature trends observed at the Mauna Loa Observatory are consistent with the observed increases in CO2 concentrations at the observatory, and the role of CO2 as a greenhouse gas.
Climate of the Past Paper Abstract

Observations at the Mauna Loa Observatory, Hawaii, established the systematic increase of anthropogenic CO2 in the atmosphere. For the same reasons that this site provides excellent globally averaged CO2 data, it may provide temperature data with global significance. Here, we examine hourly temperature records, averaged annually for 1977–2006, to determine linear trends as a function of time of day. For night-time data (22:00 to 06:00 LST (local standard time)) there is a near-uniform warming of 0.040 °C yr−1. During the day, the linear trend shows a slight cooling of −0.014 °C yr−1 at 12:00 LST (noon). Overall, at Mauna Loa Observatory, there is a mean warming trend of 0.021 °C yr−1. The dominance of night-time warming results in a relatively large annual decrease in the diurnal temperature range (DTR) of −0.050 °C yr−1 over the period 1977–2006. These trends are consistent with the observed increases in the concentrations of CO2 and its role as a greenhouse gas (demonstrated here by first-order radiative forcing calculations), and indicate the possible relevance of the Mauna Loa temperature measurements to global warming.






7 comments:

EliRabett said...

From Steve Bloom:

Nice work all around! Thanks Eli! Next up:Samanta strikes again (this time against Zhao and Runner).

Anonymous said...

Nice story about how science really works.

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...

-M

Anonymous said...

"Those of you who have some spare time might think of organizing a project to digitize the data."

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.

I suppose I should write to Bruce?



dark-pawed mouse

Dallas said...

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.

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.

susan said...

Just loverly! Great work and thanks.

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 ...

Sorry about my lack of analytic skills.
(Susan Anderson)

EliRabett said...

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 data

Chris Colose said...

I posted this too at Tamino's

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.

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?

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.

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?

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
http://www.realclimate.org/index.php/archives/2005/11/busy-week-for-water-vapor/