Previous page: Measuring temperatures and composition in the ionoshere

How to Get the Temperatures and Ion Composition from the Spectra

If the actual spectra that the radar measures from the ionosphere consisted of continuous smooth curves, and if it was necessary to measure only two quantities, say the width and the total power, then one could use a ruler and get pretty good answers. However, the measured spectra are noisy data points like the red circles on the graph below, and the idea is to get all of the temperatures and ion compositions "right". Two ideal, or theoretical, spectra are shown in purple and blue. They have different electron temperatures and number of electrons. There is no simple way to get from the data points to the best answers, but one would say that one spectrum is much better than the other. How does one find the best match? The method has several steps and illustrates how a lot of work is done in science.



First of the four pages: How does a radar work?