Zonal temporal dispersion relations of the equatorially confined wave solutions with (black) and without (red) the nontraditional Coriolis terms (NCTs). Except the last frame of the animation, sound of piano is played at a sound frequency proportional to the effective buoyancy frequency used to plot every frame. (From Ong and Roundy 2020)

NCTs represent components of Coriolis force that turn eastward motion upward and upward motion westward, and vice versa.

Motivation

Atmospheric waves are known to impact global weather and climate. Traditional atmospheric models often neglect the nontraditional Coriolis terms (NCTs) due to scale analyses of extratropical atmospheric motion. However, the effect of NCTs on atmospheric waves has been a subject of concern.

Modeling approaches

To address this, I developed a model hierarchy incorporating NCTs into the modeling framework. The hierarchy, from simple to complex, included models with linearized physics that are 1D vertical (Ong & Roundy 2020a), 2D (Ong & Roundy 2020b), and 3D Model for Prediction Across Scales (MPAS) (Skamarock, Ong, & Klemp 2021). I have also explored the effects of NCTs with full physics in a 2D setting using the System for Atmospheric Modeling (SAM) (Ong & Yang 2022). In addition, I created schematic illustration for teaching about atmospheric Rossby waves (Ong & Yang 2025).

Main findings

My research revealed that omitting NCTs results in errors in the height of pressure levels in the tropical atmosphere (Ong & Roundy 2020a). Furthermore, incorporating NCTs in models can affect the speed and behavior of convective systems (Ong & Roundy 2020b; Ong & Yang 2022). In addition, I proposed a right-hand rule for distinguishing the westward traditional planetary Rossby waves and the eastward nontraditional compressional Rossby waves (Ong & Yang 2025).

Models evolved

My work has directly contributed to the advancement of MPAS (Skamarock, Ong, & Klemp 2021) and SAM (Ong & Yang 2022), integrating NCTs into their frameworks.

Modeling peers inspired

My research has inspired other scientists to explore the effects of NCTs in atmospheric models, as evidenced by their work on models like the Regional Atmospheric Modeling System (RAMS, Igel & Biello 2020) and the weak temperature gradient framework (Marsico et al. 2023; 2024).

Broader Impact and Prospects

The significance of NCTs in tropical large-scale atmospheric dynamics with full physics for global atmospheric circulation remain unexplored. My ongoing commitment is to collaborate with modeling peers to further investigate the effects of NCTs on global atmospheric circulation and expand their inclusion in models.

Honors and Awards

Three of my honors and awards are directly related to this project.

Climate and Global Change Postdoctoral Fellowship, NOAA (2020-2022) (Declined)

Government Scholarship to Study Abroad, Ministry of Education, Taiwan (2019-2020)

Student Presenter Award - Poster 1st Place, Annual Meeting, AMS (2019)

Video

Recorded PhD Dissertation Defense:

Project Status

My ongoing main project (2018-)

Publication

Ong, H., & Roundy, P. E. (2020). Nontraditional hypsometric equation. Q. J. R. Meteorol. Soc., 146(727), 700-706.

Ong, H., & Roundy, P. E. (2020). The compressional beta effect: Analytical solution, numerical benchmark, and data analysis. J. Atmos. Sci., 77(11), 3721-3732.

Skamarock, W. C., Ong, H., & Klemp, J. B. (2021). A fully compressible nonhydrostatic deep-atmosphere-equations solver for MPAS. Mon. Weather. Rev., 149(2), 571-583.

Ong, H., & Yang, D. (2022). The compressional beta effect and convective system propagation. J. Atmos. Sci., 79(8), 2031-2040.

[Ong, H., & Yang, D. (2025). Westward-or eastward-propagating Rossby waves: Schematic illustrations. J. Atmos. Sci., Accepted.](https://doi.org/10.22541/essoar.173238571.17307721/v1)