The relationship between inclinometry spikes and temperature gradients

SUMMARY
The expected relationship between thermal gradients within the antenna structure and inclinometry spike height is not well seen.

Justin's theory that the 'spikes' in inclinometry difference spectra (and thence the symmetry of the antenna) are caused by wheel loadings occasionally reaching zero, has a corallary that the effect will be exacerbated by large thermal differences between the upper antenna structure and the lower members. If the lower A-frame beams remain at constant temperature while the upper A-frame members contract under cooling, then the A-frames will 'curl up' and the wheel loadings will diminish.

The inclinometry data are accompanied by temperature readings, in volts (V), from the third channel in each inclinometer. Examination of the data confirms the manufacturer's specification that the temperature = 0.1 * the voltage - with an undetermined (unspecified) zero point. I adopt T_incl = 0.1*V - 6.0 as a determinant of temperature (deg C). The 1998 inclinometry were examined for T_incl from both left and right A-frame inclinometers, and the weather station data were examined for the simultaneously recorded antenna leg temperatures. The means of the inclinometry and the means of the leg data then allow the construction of the temperature difference (T_incl - T_meanleg), a time history of which is plotted below :

It was hoped that this plot would resemble the asymmetry plot, but such a resemblance is not obvious.