### Eryn Cangi, Ruth Lieberman, Astrid Maute

#### for 2016 REU in solar and space physics at Laboratory for Atmospheric and Space Physics, Boulder, CO

A more formal write up for this project is coming soon! For now, please see the abstract and poster below.

## Abstract

Comparison of two methods of quantifying lunar contribution to atmospheric tides In periods of Sudden Stratospheric Warming (SSW), large atmospheric disturbances caused by planetary wave forcing in the winter polar stratosphere propagate upwards to the ionosphere, causing plasma density changes between 50 – 150%. Understanding SSW and the coupling of atmospheric layers is vital for the prediction of space weather. Part of this understanding includes being able to quantify the contributions of the solar and lunar semidiurnal tides. In this study, we first remove the solar contribution before fitting a function to extract the lunar amplitude and phase. We then compare the results of this method to an earlier method used by Maute et al. [2016], using data from TIME-GCM. Results from testing our method for accuracy on known synthetic data show that the percent error of M2 amplitudes is 0.33% for data resolution of 30 minutes, and 1.42% for data resolution of 1 hour. When compared to the results of Maute et al., we see good agreement in amplitudes of M2 in the Northern Hemisphere. However, in the Southern Hemisphere, significant deviation occurs, likely due to unaccounted for background effects from, for example, $$F_{10.7}$$ data. With further work on phase recovery and incorporation of other factors affecting the Southern Hemisphere, we believe our method has promise as a clear way to extract M2 amplitudes that yields similarly accurate results as existing methods.

tides-poster