A Brief Overview of Gravity Wave Retrieval Techniques From Observations

Abstract

Atmospheric gravity waves (GWs) are important in driving the middle and upper atmosphere dynamics on Earth. Here, we provide a brief review of the most common techniques of retrieving gravity wave activity from observations. Retrieval of gravity wave activity from observations is a multi-step process. First, the background fields have to be removed as the retrieval of the wave activity highly depends on this. Second, since a broad spectrum of internal waves contributes to atmospheric fluctuations, the contribution of GWs has to be extracted carefully. We briefly discuss the strengths, limitations/barriers, and applications of each technique. We also outline some future research questions to improve the treatment of these wave extraction methods.

Impacts of Gravity Waves in the Martian Thermosphere: The Mars Global Ionosphere‐Thermosphere Model Coupled With a Whole Atmosphere Gravity Wave Scheme

“…The full 7 years worth of NGIMS density observations could be employed in a future study to try to better optimize the GW scheme within the model under different conditions. In general, it is challenging to validate modeled gravity wave activity with respect to observations, since there are a number of different gravity wave retrieval techniques and they can yield different results depending on how the background fields are determined (Sakib & Yiğit, 2022). One of the challenges that remains in using a GW parameterization scheme is that the source GW spectrum is still not well known at Mars, but is likely more complex than the Gaussian used here and may be time-varying.…”

The Propagation of Gravity Waves in Titan's Stratosphere

“…Such procedure has been widely used in Earth's and Mars's atmosphere. There are also reviews and studies evaluating different methods to fit the background T , such as spectral filtering, moving average, and polynomial fit (John & Kumar, 2013; Sakib & Yiğit, 2022; Starichenko et al., 2021; Wu et al., 2022). Lorenz et al.…”

“…Besides, no matter what background trend is removed, the wave signal in the residue profile only becomes significant for altitudes above 60 km. More details on the evaluation of different extraction methods of GWs can be found in the review by Sakib and Yiğit (2022). The structure of temperature perturbations δT can be fitted by GWs with multiple vertical wavelengths:…”

“…Such procedure has been widely used in Earth's and Mars's atmosphere. There are also reviews and studies evaluating different methods to fit the background T, such as spectral filtering, moving average, and polynomial fit (John & Kumar, 2013;Sakib & Yiğit, 2022;Starichenko et al, 2021;Wu et al, 2022). Lorenz et al (2014) calculated a background trend by taking the moving average over the original observations with a window of 41 data points (around 10 km in altitude).…”

Scale separation for gravity wave analysis from 3D temperature observations in the MLT region

“…The coordinates of Equation 1 refer to the geometry of the MATS tomography output, where x refers to the along-track distance, y the across-track distance, z the height and t the time. Different methods for background removal have been discussed by Sakib and Yigit (2022). The separation of scales is typically made based on research interests and/or measurement limitations.…”