The Characteristics of Traveling Planetary Waves in the Troposphere and Mesosphere on Mars

Abstract

Using the temperature provided by the Mars Global Circulation Model (MGCM) reanalysis data from Mars Year 30–32, we investigate the global characteristics of eastward traveling planetary waves (TPWs) with different periods in the Martian atmosphere. Based on the wavenumbers and frequencies, the TPWs in the Martian atmosphere are mainly divided into three modes: quasi‐3‐sol waves with eastward wavenumber 2, quasi‐6.5‐sol waves with eastward wavenumber 1, and quasi‐20‐sol waves with eastward wavenumber 1. The temporal, latitudinal, and altitudinal distributions of TPWs are revealed. The amplitudes of these TPWs are all stronger in the Northern Hemisphere than those in the Southern Hemisphere and are annually enhanced during autumn and winter. Quasi‐3‐sol waves are strongest in the lower troposphere from 40°N to 70°N. Quasi‐6.5‐sol waves dominate in the upper troposphere at the latitude from 55°N to 80°N. Quasi‐20‐sol waves exhibit a double‐peak structure in the upper troposphere and the mesosphere from 55°N to 82.5°N in autumn. Additionally, the features of solsticial pause are observed in the quasi‐3‐sol waves at the surface, in the quasi‐6.5‐sol waves from the surface to the middle troposphere, and in the quasi‐20‐sol waves in the lower troposphere. Our analysis suggests that the appearance of the solsticial pause is mainly related to the lack of strong wave sinks or wave sources during the winter solstice.

A Unique Vertical Structure of Quasi‐20‐sol Waves Observed by the MCS on the Martian Atmosphere

“…According to previous studies, Q20SWs in the Martian atmosphere are dominant at around 60°N (Gong et al, 2023;Hinson & Wilson, 2021). In this study, we focus on investigating the characteristics of the Q20SWs at a latitude range from 55° to 65° in the Northern Hemisphere.…”

“…Aside from the satellite observations, neutral winds and temperatures provided by the Mars Global Circulation Model (MGCM) data set are also used in the present study to derive the Eliassen-Palm (EP) flux in tracing the source and propagation of the Q20SWs. Details of the MGCM database can be found in Gong et al (2023) and Streeter et al (2020). Because of the similarity of the atmosphere of Earth and Mars, the EP flux is also used in the analysis of atmospheric waves on Mars (Kuroda et al, 2007;Wang et al, 2013).…”

“…Planetary‐scale traveling waves in the Martian atmosphere have been observed using theoretical and observational data for many years (Banfield et al., 2004; Gong et al., 2023; Hinson & Wilson, 2021; Kuroda et al., 2007; Wang, 2017; Wang & Toigo, 2016; Wang et al., 2013; Wilson et al., 2002). Distinguished from the westward‐traveling planetary waves dominated on Earth, eastward‐traveling planetary waves with periods of 2–30 sols and zonal wavenumbers 1–3 are typically the most prominent on Mars (Banfield et al., 2004; Wang & Toigo, 2016; Wang et al., 2013).…”

“…Using reanalysis data, Gong et al. (2023) presented an analysis of temporal and spatial characteristics of traveling planetary waves with wavenumber 1 and periods of 10–30 sols (quasi‐20‐sol waves, Q20SWs). Their results showed that a two‐cell structure in the Q20SW amplitudes existed in the lower atmosphere.…”

“…However, their study did not focus on the investigation of the two‐cell structure and its formation mechanisms have not been discussed. Compared with the other planetary waves with shorter periods, the Q20SW exhibits stronger amplitudes (Banfield et al., 2004; Gong et al., 2023; Wilson et al., 2002), which potentially exerts a strong influence on the Martian atmosphere. However, the generation and decaying mechanisms of the Q20SW are not well understood, and the interactions between the Q20SW and the background atmosphere have not been discussed.…”