By chance I stumbled across the remarkable US Standard Atmosphere Supplements 1966 documentation which contains a few surprises.
The first surprise was that the Second Isopycnic Level discovered by Allen Cole in 1961 was explicitly identified in the US Standard Atmosphere Supplements 1966.
The Second Isopycnic Level is located “just above 90 km where density profiles of all latitudes and seasons tend to converge or cross at a density roughly 10 percent greater than Standard”.
2.2.2 DENSITY AND PRESSURE
Density profiles for each of the Supplementary Atmospheres are shown in Figures 2.8 and 2.9 as percentage departure from Standard.
The region of minimum seasonal and latitudinal variability in density near 8 km represents the first isopycnic level where density remains relatively constant throughout the year regardless of location.
A second isopycnic level appears to exist just above 90 km where density profiles of all latitudes and seasons tend to converge or cross at a density roughly 10 percent greater than Standard (Cole, 1961; Champion, 1965).
This concept of a second isopycnic level near 90 km is supported by density observations and observed wind and temperature distributions between 60 and 100 km.
The levels of maximum seasonal and latitudinal variability in atmospheric density occur between 65 and 75 km and 100 to 120 km.
Seasonal variability is greatest at high latitudes.
To reduce the number of boundary conditions at 120 km the density profiles (Figures 2.6 and 2.7) have been arbitrarily drawn into three points.
The limitations discussed in the previous section on temperature also apply to density between 100 and 120 km.
Density profiles associated with typical warm and cold stratospheric and mesospheric thermal regimes observed at 60 and 75 N. in January are shown in Figures 2.8 and 2.9, also in terms of percentage departures from Standard.
The profiles for 60 N. in Figure 2.8 indicate that during January at 70 km, the warm regime density is approximately 80 percent greater than the cold regime density.
Although these atmospheres are intended to depict typical January conditions, similar conditions can occur in the arctic and subarctic during other winter months.
The pressure profiles in Figures 2.10 and 2.11 are similar to those for density.
A level of minimum seasonal pressure variability exists near 85 km which reflects the negative correlations between temperatures at altitudes above 70 km and below 60 km.
The limitations that apply to the density between 100 and 120 km owing to the assumption of only three sets of boundary conditions at 120 km also apply to the pressure at these altitudes.
Furthermore, actual density measurements at White Sands and Elgin indicated that the standard predominantly underestimated atmospheric density from 85 km to 120 km and this departure from standard could exceed 70 percent.
Sadly, by 1976, Atmospheric Science had effectively redacted the Second Isopycnic Level and was backing rapidly away from all that it implied.
However, by 1976 Allen Cole was probably a very despondent scientist when the US Standard Atmosphere 1976 described the Second Isopycnic Level as a “much less pronounced” level of “minimum variability” and very effectively redacted the graphical evidence via the strategic placement of a text label.
Atmospheric Science: The Second Level
The second surprise was that the US Standard Atmosphere Supplements 1966 contained information regarding the atmosphere above 120 kilometres.
The 1966 documentation clearly indicated that atomic Oxygen becomes the predominant atmospheric gas at an altitude of about 200 kilometres.
The exosphere temperatures from 1966 can be merged with the US Standard Atmosphere 1962 atmospheric temperatures [as promoted by Wikipedia] and the model Thermal Properties of the Continental Upper Mantle to provide a composite view of the Cooling Earth that appears to be remarkably lacking in the mainstream literature.
Evidently, the Earth’s Atmosphere [i.e. dry air plus water vapour] very effectively protects the Earth from incoming solar radiation whilst simultaneously cooling the Earth’s surface and lower atmosphere.
The Earth’s watery surface and wet lower atmosphere acts as a Heat Pump in cooling mode.
The third surprise was that the US Standard Atmosphere Supplements 1966 included exosphere density and temperature data from the Explorer I satellite in association with data relating to solar radiation and geomagnetic activity.
Evidently, Atmospheric Science only started to effectively implement Mushroom Management techniques after 1966.