Guest Post by Willis Eschenbach
The TAO buoy array is an array of moored buoys in the equatorial tropical Pacific ocean. Here’s a map showing their locations along with the average sea surface temperature.
Figure 1. Locations of all active and historical TAO buoy sites.
And here is what a typical buoy setup looks like:
Figure 2. Details of the TAO moored buoy and sensor arrays.
I like the TAO buoy data because we can be sure that it is free of urban heat islands, changes in location, instrumentation changes, and many of the other problems that plague land-based stations. It is also measured very frequently, typically every ten minutes. This lets us explore the daily cycles of air and sea temperature, solar radiation, longwave radiation, humidity, and the like.
The eight buoys located on the Equator between 165°E and 95°W have the most data covering the longest time, so I’ve looked most at those locations.
The coldest of these eight buoys is the one at 95° W longitude, near the Americas at the far right of the map above. Average sea surface temperature (SST) there is 23.8°C (75°F). The warmest is the buoy at the other side of the Pacific at 165° East longitude. Average SST there, near the warmest part of the Pacific, is 29.2°C (85°F).
Now, something that I like to look at and consider are the differences between the buoys. The buoys at the colder eastern edge of the Pacific are often different from the buoys at the warmer western edge of thePacific. Here are the daily air temperatures from each of the eight buoys:
Figure 3. Daily cycle of air temperatures at eight equatorial TAO buoys.
Next, here are the same eight buoy air temperature records, expressed as anomalies about their respective means.
Figure 4. Daily cycle of air temperature anomalies at eight equatorial TAO buoys.
Note that the daily air temperature cycles at the warmest buoys (reds) have a very different shape and amplitude than do the coolest buoys (blue), particularly during daylight hours.
I’ve mentioned before that what I like best about science is getting surprised by what I find. Here’s my surprise for today. I got to thinking about what is called “delta T”, usually written as “∆T”. The “delta” means “difference”, and the “T” means temperature. For example, winds on the ocean are often driven by temperature differences.
One of the important ∆T’s in the climate system is the difference between the surface temperature and the air temperature. Over the ocean, the air is generally cooler than the sea surface. When the difference between the surface and the air temperature (∆T) gets large enough, when the ocean gets significantly warmer than the air or the air cools significantly below the sea temperature, we start to see things like cumulus clouds and thunderstorms.
So let me start with the absolute values of the differences between sea surface temperature and air temperature at the eight TAO buoys. I’ve used the same color coding as above. Light blue is the coolest buoy at 95°W, and red is the warmest buoy at 165°E.
Figure 5. Daily cycle of differences between sea temperatures and air temperatures at eight equatorial TAO buoys.
This was the first surprise. The overall difference between the sea temperatures and the air temperatures was not in any order by temperature. The coolest and the warmest buoys had the widest differences between sea and air temperatures … odd.
But the real surprise came when I plotted the delta T values as anomalies around their respective means, as I’d done in Figure 4 above …
Figure 6. Daily cycle of anomalies of differences between sea temperatures and air temperatures at eight equatorial TAO buoys.
How interesting. All along the Equator across the Pacific, from the cold edge to the warm edge, the sea-to-air temperature difference anomaly is just the same in every location—lowest at eight AM, peak at one PM, trough at five PM, peak at six PM, trough at nine PM, highest point at about three in the morning.
Not only that, but the temperature swings have the same amplitudes, to within a few hundredths of a degree. Given that these are eight totally different results from sixteen independent temperature datasets (eight air temperature, eight sea temperature), this is an astounding degree of agreement.
I must say that I do not have any coherent explanation for the afternoon and evening peaks and troughs. All I can conclude from this is that all across the Equatorial Pacific, the daily temperature swings are strongly constrained by some unknown combination of natural phenomena, such that the average daily swings are identical in both timing and amplitude regardless of the average temperature of the location …
Go figure … the joys of settled science.
AS ALWAYS: Let me politely request that when you comment, you QUOTE THE WORDS YOU ARE DISCUSSING so that everyone can understand just what you are referring to. I can defend my own words. I can’t defend your vague restatement of something you think I said. Quote what you are talking about, it’s the only way to refute what someone says.
FURTHER READINGS: Here are some of my previous posts about the TAO buoy data:
The Tao That Can Be Spoken … 2011-08-14
As I mentioned in an earlier post, I’ve started to look at the data from the TAO/TRITON buoy array in the Pacific Ocean. These are an array of moored buoys which collect hourly information on a variety of environmental variables. The results are quite interesting, because they relate directly to…
Pinatubo and the Albedo Thermostat 2011-08-21
I got to thinking that the eruption of Mount Pinatubo should provide a good test case for my theory that changes in albedo help regulate the temperature and keep it within a narrow range. When a big volcano erupts, it throws both black and reflective particles and aerosols high into…
TAO/TRITON TAKE TWO 2011-08-25
I wrote before of my investigations into the surface air temperature records of the TAO/TRITON buoys in the Pacific Ocean. To refresh your memory, here are the locations of the TAO/TRITON buoys. Figure 1. Locations of the TAO/TRITON buoys (pink squares). Each buoy is equipped with a sensor array measuring…
Cloud Radiation Forcing in the TAO Dataset 2011-09-15
This is the third in a series ( Part 1, Part 2 ) of occasional posts regarding my somewhat peripatetic analysis of the data from the TAO moored buoys in the Western Pacific. I’m doing construction work these days, and so in between pounding nails into the frame of a building I continue to…
TAO Buoys Go Hot And Cold 2015-06-16
I got to thinking about how I could gain more understanding of the daily air temperature cycles in the tropics. I decided to look at what happens when the early morning (midnight to 5:00 AM) of a given day is cooler than usual, versus what happens when the early morning…