Temperature vs. Latitude

The satellite lower troposphere temperature data available from the University of Alabama, Houston, provides monthly temperature values for eight Latitude zones, namely Global: 90°S to 90°N, Northern Hemisphere: 0° to 90°N, Southern Hemisphere: 0° to 90°S, Tropics: 20°S to 20°N, Northern Extension: 20°N to 90°N, Southern Extension: 90°S to 20°S, North Pole: 60°N to 90°N and South Pole: 90°S to 60°S. The data for this study came from five of these zones over the period December 1978 to July 2018.

Linear regression applied to the zones gave the following annual rates of change:
North Pole: +0.02522 degrees C per annum, standard error 0.00216,
Northern Extension: +0.01776 degrees C per annum, standard error 0.00098,
Tropics: +0.01185 degrees C per annum, standard error 0.00118,
Southern Extension: +0.00886 degrees C per annum, standard error 0.00081,
and South Pole: +0.00023 degrees C per annum, standard error 0.00250.

These results show that, while the rate for the South Pole is not significantly different from zero, there is a definite increase in the rate of temperature change in going from the South Pole to the North Pole zone over the 40 year period. That is, the rate of warming is not symmetrical about the Equator as might be expected for a uniform Earth heated from a Sun directly above the Equator. This may be partly due to the fact that the Earth is not symmetrical but has the approximate shape of an oblate spheroid with some flattening at the South Pole. However this does not explain why the rate at the North Pole is greater than the rate at the Tropics.

Here are the time series of the satellite lower troposphere temperature for five of the zones:

NoPole_tempLinear Fit North Pole temperature: -50.3213+0.0252202 x

NthnExt_tempLinear Fit Northern Extension temperature: -35.4403+0.0177596 x

Tropics_tempLinear Fit Tropics temperature: -23.6657+0.0118531 x

SthnExt_tempLinear Fit Southern Extension temperature: -17.673+0.008855 x

SoPole_tempLinear Fit South Pole temperature: -0.444813+0.000227886 x

A comparison of the five time series can be seen in their variance after detrending :-
Probability detrended Nth Pole and Nthn Extn variances equal:  2.97999*10-61
Probability detrended Nth Pole and Sth Pole variances equal:  0.00131376
Probability detrended Nthn Extn and Sthn Extn variances equal:  0.000129001
Probability detrended Tropics and Nthn Extn variances equal:  0.0551014
Probability detrended Tropics and Sthn Extn variances equal:  3.27242*10-8
Probability detrended Sth Pole and Sthn Extn variances equal:  6.77165*10-62

Not only are the rates of warming all different but so are the variances indicating that all five time series arose from different populations in spite of the Sun being the primary source of the temperature.

Another form of comparison is the individual Fourier Amplitude spectra :-

NoPole_temp_DFT

NthnExt_temp_DFT

Tropics_temp_DFT

SthnExt_temp_DFT

SoPole_temp_DFT

While some dominant spectral lines are common to a few adjoining zones, their differences are evident. In particular the North Pole and South Pole zones display far more high frequency activity than elsewhere. The North Pole zone displays a prominent amplitude at frequency x = 121, which represents a period of 129 days, that is, a period of 0.353 years.

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