|Fig. 1 Ocean Depth Levels|
"Why does Dredd Blog have a '>3000m' level in its graphs and reports" the notorious blogger was asked, "Because that is where the water is" answered the blogger.
"The average depth of the ocean is about 12,100 feet [3,688 m] " (NOAA), and some 90% of ocean water is below 200m.
The modified graphic at Fig. 1 (see link there) shows the depth levels used by Dredd Blog.
They are designated as "L1-L7", which equate to:
L1 0-200 mIn other words, Dredd Blog analysis uses World Ocean Database measurements from every depth measured and placed in the CTD and PFL datasets (Databases Galore - 18).
L2 201-400 m
L3 401-600 m
L4 601-800 m
L5 801-1000 m
L6 1001-3000 m
L7 >3000 m
Some scientists issue a caution about anything less:
"Despite recent advances in the state of the global ocean observing system, estimating oceanic variability on basin-wide to global scales remains difficult. Errors in such estimates can be large and often go unreported in the literature. In order to make the most accurate estimates of oceanic variability, it is necessary to combine different types of data into a single consistent field."Willis et al. 2004, J. Geophys. Res., 109, PDF). One of the IPCC editors/authors, Nathan Bindoff, indicates:
"The data used for temperature and heat content estimates are based on the World Ocean Database 2001." - p. 389(Bindoff et al., 2007, PDF). That is a robust number of measurements but it leaves out the deeper waters:
"Approximately 7.9 million temperature profiles were used in constructing the two longer time series."- p. 390
"Figure 5.1. Time series of global annual ocean heat content (1022 J) for the 0 to 700 m layer." - p. 390(ibid, Bindoff et al. 2007). Regular readers of Dredd Blog know that I use measurements from the World Ocean Database to analyze temperature and salinity measurements at all depths for which measurements have been taken and recorded.
"Figure 5.2. Linear trends (1955–2003) of change in ocean heat content per unit surface area (W m–2) for the 0 to 700 m layer..." - p. 391
Those data are arranged in various configurations (year, day-of-year, and month) then combined, as suggested by the scientist quoted above who wrote:
"In order to make the most accurate estimates of oceanic variability, it is necessary to combine different types of data into a single consistent field."(ibid, Willis et al. 2004). That is what I like to do too (On Thermal Expansion & Thermal Contraction - 15).
If one wants to analyze all of the ocean, then all of the measurements available should be used.
This is not always the case, and in fact the practice seems to be to only use measurements in the upper half, or less, of the total ocean depths.
Here is one reason why it is important to consider the generally colder, deeper water:
"Sea level will rise if the ocean warms and fall if it cools, since the density of the water column will change." - p. 414(ibid, Bindoff et al. 2007, emphasis added). In other words, as I have written over and over, there is both "thermal contraction" and "thermal expansion" (On Thermal Expansion & Thermal Contraction)..
"Global ocean heat content observations show considerable interannual and inter-decadal variability superimposed on the longer-term trend. Relative to 1961 to 2003, the period 1993 to 2003 has high rates of warming but since 2003 there has been some cooling." - p. 387
Yet, sea level is not rising or falling because thermal expansion and contraction are the major factors (The Bathtub Model Doesn't Hold Water, 2, 3, 4).
Hopefully, the IPCC establishment scientists will discover the ghost water they have been utterly clueless about, because like its source gravity, it is especially invisible when we are not looking for it (The Ghost-Water Constant, 2, 3, 4, 5, 6, 7; The Gravity of Sea Level Change, 2, 3, 4).
If they stop scratching the surface and really look close into the depths, they will find out why the surface can cool some without a decrease in overall heat quantity contained in the oceans:
"The oceans are warming. Over the period 1961 to 2003, global ocean temperature has risen by 0.10°C from the surface to a depth of 700 m. Consistent with the Third Assessment Report (TAR), global ocean heat content (0–3,000 m) has increased during the same period, equivalent to absorbing energy at a rate of 0.21 ± 0.04 W m–2 globally averaged over the Earth’s surface. Two-thirds of this energy is absorbed between the surface and a depth of 700 m. Global ocean heat content observations show considerable interannual and inter-decadal variability superimposed on the longer-term trend. Relative to 1961 to 2003, the period 1993 to 2003 has high rates of warming but since 2003 there has been some cooling."(ibid, Bindoff et al. 2007, emphasis added). Those upper levels can 'cool' even as the overall ocean heat content increases.
Why? ("The first statement of the 2nd law of thermodynamics - heat flows spontaneously from a hot to a cold body ..." - On Thermal Expansion & Thermal Contraction - 9).
Some of the heat flows from the shallower depth levels they tend to solely focus on (<700 m) into the deeper waters (>3000m) which is where the most ocean water is.
The amount of heat in the ocean is not diminished just because some of that heat moves out of those shallower depths and into the deeper depths.
But, the temperature will drop at depths where the heat flows away from those shallower depths (<700 m) into deeper, cooler water (>3000m, where the temperature will rise unnoticed unless it is measured).
Remember that the changes I reported in the previous post of this series are about changes in temperature and salinity taking place at various depths at various latitude layers.
It is not about a decrease of heat content in the oceans.
The reality is that temperatures and salinity at one depth will change as the heat leaves that depth and flows to a deeper depth, without any diminution of the total ocean heat content.
The previous post in this series is here.