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Deep Sea Instruments May Solve Missing Energy Mystery

08.10.2014 12:53 Age: 3 yrs

New research from NASA this week showed that the deep ocean may be cooling and highlighted the mystery over so called missing energy. Scientists hope that a new generation of deep sea instruments will help to resolve the issue.

Click to enlarge. Deep Argo float deployment. Scientists and technicians deploy the first of two Deep Argo floats from RV Tangaroa in June 2014 over the 5.5km deep abyssal plain east of New Zealand, a deep ocean region where bottom waters that spread north after sinking near Antarctica have exhibited significant warming over recent decades. These floats, designed and built at the Scripps Institution of Oceanography, are capable of profiling to depths of 6 km, allowing sampling of almost all of the ocean volume. The orange plastic case covers a glass flotation sphere containing machinery, circuitry and batteries, and a GPS and Iridium antenna is pointed away from the ship. Part of the scientific sensor package is visible to the left of the black plastic cylinder. Courtesy: Nature Climate Change, NOAA and LEARNZ — part of CORE Education

Click to enlarge. Gregory C. Johnson, NOAA oceanographer. Courtesy: NOAA

Click to enlarge. R/V Tangaroa. Scientists aboard R/V Tangaroa, operated by New Zealand’s National Institute of Water and Atmospheric Research, deployed Deep Argo floats in June 2014. Courtesy: NOAA and LEARNZ — part of CORE Education


However, NASA's suggestion that the deep oceans have been cooling since 2005 is implied from evidence about what is happening in the ocean above 2km rather than from direct measurement and also the uncertainties in the data are huge.

Water expands as it warms and it contracts as it cools, so careful measurements of sea level that take into account how much fresh water has entered the oceans from, for example, melting ice sheets, and other sources, should enable scientists to estimate the amount ocean warming that has taken place using the expansion of sea water as a measure.

A group led by William Llovel of the Jet Propulsion Laboratory in the US used satellite radar altimetry data to determine that sea level has been rising at a global average rate of 2.78 mm yr from 2005 to 2013. Over that period, ocean expansion from warming in the upper 2 km has accounted for 0.9 mm yr of that rise, according to in situ ocean measurements, and a transfer of freshwater into the ocean 2.0 mm yr-1.

This latest study is the first to test the idea using satellite observations, as well as direct temperature measurements of the upper ocean. Scientists have been taking the temperature of the top half of the ocean down to a depth of 2km since 2005, using a network of 3,000 floating temperature probes called the Argo array.

Harder to measure


The solution is to deploy a fleet of deep diving ocean instruments that can provide direct measurements of what is happening in the deep ocean below 2km and down as deep as 6km. This would follow the template of the successful Argo programme. Unsurprisingly it has been dubbed Deep Argo.

This project is a proposed global array of profiling floats capable of measuring temperature and salinity to high accuracy and to depths of 6 km. In June 2014, scientists deployed two prototype Deep Argo floats (see image) east of New Zealand. Deep Argo pilot arrays in other areas have exhibited large abyssal and deep-ocean temperature and salinity variability, including the Southern and North Atlantic oceans, according to Johnson and Lyman.

The hunt for the missing energy is on. If it is hiding in the deep oceans then Deep Argo is designed to find it.

Here is the text of the feature published on the NOAA wesbite regarding this research and the Deep Argo project (the pictures on the right accompany the feature):

Deep Argo will help unlock mystery of deep ocean effects on climate

Monday, October 06, 2014End of NOAA feature.


Nature Climate Change

Deep-ocean contribution to sea level and energy budget not detectable over the past decade by W. Llovel, J. K.Willis, F.W. Landererand and I. Fukumori published in nature Climate Change. DOI: 10.1038/NCLIMATE2387

Read the abstract and get the paper here.


Varying planetary heat sink led to global-warming slowdown and acceleration by Xianyao Chen, Ka-Kit Tung published in Science 22 August 2014: Vol. 345 no. 6199 pp. 897-903 DOI: 10.1126/science.1254937

Read the abstract and get the paper here.


NOAA feature here.

NASA news release here.

Judith Curry's Climate Etc blog here.

Nature Climate Change article by Gregory Johnson and John Lyman here


Our report on the latest NASA research published in Nature Climate Change here

And our report on the Science research into heat storage in the Atlantic ocean here.