Lomb periodogram :
The Lomb periodogram is a type of spectral estimation method used to identify significant periodic signals in a time series data set. It is based on the concept of least-squares fitting of sinusoidal functions to the data, and is commonly used in fields such as astronomy, geophysics, and signal processing.
One of the key advantages of the Lomb periodogram is that it is able to accurately detect and estimate the strength of periodic signals even in the presence of noise and other non-periodic components in the data. This is because the method uses a combination of windowing, detrending, and least-squares fitting to isolate and estimate the power of the periodic signals.
Here are two examples of how the Lomb periodogram can be used:
Example 1: In astronomy, the Lomb periodogram is often used to search for periodic signals in the light curves of stars. A light curve is a plot of the brightness of a star over time, and can reveal information about the star’s behavior, such as its rotation rate or the presence of any orbiting planets. By applying the Lomb periodogram to the light curve data, astronomers can identify any periodic signals and use them to make inferences about the star.
Example 2: In geophysics, the Lomb periodogram can be used to study the periodic signals present in geophysical data such as earthquakes, tides, or ocean currents. By applying the method to this type of data, geophysicists can identify and analyze the periodic signals, and use them to gain insight into the underlying processes that generate the signals. For example, the presence of periodic signals in earthquake data can provide clues about the structure and behavior of the earth’s crust, while the periodic signals in ocean current data can reveal information about the circulation patterns of the oceans.