Guest Post by Willis Eschenbach
I’ve been thinking about the Argo floats and the data they’ve collected. There are about 4,000 Argo floats in the ocean. Most of the time they are asleep, a thousand metres below the surface. Every 10 days they wake up and slowly rise to the surface, taking temperature measurements as they go. When they reach the surface, they radio their data back to headquarters, slip beneath the waves, sink down to a thousand metres and go back to sleep …
At this point, we have decent Argo data since about 2005. I’m using the Argo dataset 2005-2012, which has been gridded. Here, to open the bidding, are the ocean surface temperatures for the period.
Figure 1. Oceanic surface temperatures, 2005-2012. Argo data.
Dang, I like that … so what else can the Argo data show us?
Well, it can show us the changes in the average temperature down to 2000 metres. Figure 2 shows that result:
Figure 2. Average temperature, surface down to 2,000 metres depth. Temperatures are volume-weighted.
The average temperature of the top 2000 metres is six degrees C (43°F). Chilly.
We can also take a look at how much the ocean has warmed and cooled, and where. Here are the trends in the surface temperature:
Figure 3. Decadal change in ocean surface temperatures.
Once again we see the surprising stability of the system. Some areas of the ocean have warmed at 2° per decade, some have cooled at -1.5° per decade. But overall? The warming is trivially small, 0.03°C per decade.
Next, here is the corresponding map for the average temperatures down to 2,000 metres:
Figure 4. Decadal change in average temperatures 0—2000 metres. Temperatures are volume-averaged.
Note that although the amounts of the changes are smaller, the trends at the surface are geographically similar to the trends down to 2000 metres.
Figure 5 shows the global average trends in the top 2,000 metres of the ocean. I have expressed the changes in another unit, 10^22 joules, rather than in °C, to show it as variations in ocean heat content.
Figure 5. Global ocean heat content anomaly (10^22 joules). Same data as in Figure 4, expressed in different units.
The trend in this data (6.9 ± 0.6 e+22 joules per decade) agrees quite well with the trend in the Levitus OHC data, which is about 7.4 ± 0.8 e+22 joules per decade.
Anyhow, that’s the state of play so far. The top two kilometers of the ocean are warming at 0.02°C per decade … can’t say I’m worried by that. More to come, unless I get distracted by … oooh, shiny!
Regards,
w.
SAME OLD: If you disagree with something I or anyone said, please quote it exactly, so we can all be clear on exactly what you object to.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
The best analysis of the changing OHC is at
http://www.pmel.noaa.gov/people/gjohnson/OHCA_1950_2011_final.pdf
Look at table1. This shows that the heat flux from 0-100 m dropped 90% when the period 1983 – 2011 is compared with 2004-2011. The flux at deeper levels also declined substantially. Trenberth’s hidey hole for the “missing ” heat is in reality non existent. This shows that, as one might expect on a cooling earth, the oceans are cooling from the top down.
Willis Are you familiar with all this modeling activity- it seems right up your alley
http://www.gewex.org/gewexnews/Nov2013.pdf
@Dale Rainwater Norman Page at 1:22 pm
Thank you for that report.
http://www.pmel.noaa.gov/people/gjohnson/OHCA_1950_2011_final.pdf
I want to draw people’s attention to Figure 5 at line 750.
It is a very useful chart of the uncertainty in OHC as a function of time and Depth Interval.
Very useful… and unbelievably optimistic in accuracy.
The authors of this chart say that for the period 1970-1990, the uncertainty in OHCA is in the range of 20-25 ZJ for 0-1800 meters. That means our uncertainty in the deep ocean temperature, before ARGO, before ALACE is less than 0.01 deg C.
SHOW ME THE DATA of where and when NOAA made temperature measurements of the 1000-2000 meters interval, particularly in the southern hemisphere and away from the submarine patrol zones. A measured accuracy of 0.01 deg C for 0-1800 meters in 1970 is fantasy. Even with ARGO in 2013, Willis’s Figure 2 in the head post shows average NH at 6.7-6.8 deg C, SH at 5.7-5.8, Tropic of 7.1-7.2 deg C depending upon season.
○ See Discussion at ClimateEtc Starting at March 4 to March 6.
○
See also Figure 1 (b 1960) and (c 1985) maps in Abraham, J. P., et al. (2013) (pdf).
Thank you Dr. Norman Page and Stephen Rasey for bringing this discussion (and me) up-to-date. As Dr. Page says, that NOAA paper from Lyman and Johnson clearly demonstrates recent ocean cooling, consistent with the less comprehensive paper by Knox and Douglass that I mentioned above. It’s a little old now, but I touched on this question among many others in my 2012 book “Global Warming False Alarm”.
@Michael Whittemore March 5, 2014 at 11:25 pm : Bob Tisdale’s work would be a good start. Brett Keane
The Abraham paper mentioned by Stephen Rasey above is a good discussion of Argo float accuracy issues, including a warming bias not reported until 2011 that perhaps should call into question papers before then.
“When APEX float pressure is uncorrected, Barker et al. [2011] found a net global positive temperature bias, although the signal was mitigated through compensating pressure drifts from floats utilizing different pressure sensor models. Globally averaged temperature bias reached a magnitude of 0.02°C at the base of the mixed layer.”
http://onlinelibrary.wiley.com/doi/10.1002/rog.20022/full