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Posted (edited)

It's come up a few times recently that ever since the weather warmed up, the NOAA page for the Massachusetts Bay Data Buoy (numbered 44029 by NOAA) has been showing water temperatures that are strangely cold – where "strange" means "couldn't possibly be true". At the time of this post, the page above shows a water temperature of 44.8ºF. All the other regional buoys (including buoys well north of this in the Gulf of Maine) are showing temps in the 60-65ºF range. We recently had a paddler show up for a warm-water paddle with a heavy wetsuit because—to their great credit!—they had checked the buoy reading and dressed for immersion in 45 degree water. But the North Shore water is indeed warm, as I can attest from having taken several recent swims, not all of them intentional.

At first I thought the buoy was broken somehow. I dashed off an email to NOAA, and they responded that they do not operate the buoy but merely use its data. They told me to contact the actual buoy owner and operator, known as—long acronym warning—NERACOOS, the Northeastern Regional Association of Coastal Ocean Observing Systems. NERACOOS has its own website, so I promptly went there to see if they were reporting the same weird sea temperature for this buoy as NOAA.

It turns out that they were, and yet they were not...

The NOAA website reports water temperatures without specifying any particular depth. In most cases, where a buoy measures temperature at multiple depths (and most do), NOAA supplies the water temperature at or near the surface.  However, in this particular case, the buoy doesn't have a surface sensor. Here's what NERACOOS shows this morning for the buoy on their own web page (the buoy is known as A01 Massachusetts Bay in their system):

Water temperature (20m) 45 ° F (7.1 ° C)
Water temperature (50m) 43 ° F (5.9 ° C)
Water temperature (51m) 43 ° F (5.9 ° C)

This buoy doesn't even measure the surface temperature, it only measures temps at depth. So NOAA just glommed up the temperature at the depth nearest the surface... which is 65 feet down. Pretty darn cold down there.

By the way, how about the fact that NOAA shows 44.8º and NERACOOS shows 45º? This is just a rounding issue. NERACOOS apparently measures to the nearest 0.1ºC. If you convert 7.1ºC to ºF, you get 44.8 (rounding to 1 decimal place) or 45 (rounding to the nearest whole number).

Edited by Joseph Berkovitz
  • 3 weeks later...
Posted

I noticed those odd temperature readings at that buoy too.  Fortunately there are surrounding buoys in Massachusetts Bay (44013) and Jeffery's Ledge (44098) that also give water temperature readings that are more accurate.  Thank you for the explanation.  It's reasonable to think that the Cape Ann water temperature is somewhere between that of the 44013 and 44098 buoys.

NOAA has since removed the water temperature reading from their reports of the 44029 buoy.  NOAA must have recognized that people think the water temperature readings are sea surface readings.

Posted

Please send some of that refreshing cool water to southeast Florida. It's about 86 F down here now. I have the opposite of a cold water gasp when I practice rolling.

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