{"id":26991625,"url":"https://github.com/limeo131/ssw-topography","last_synced_at":"2026-04-29T17:03:08.118Z","repository":{"id":285873994,"uuid":"959543590","full_name":"Limeo131/ssw-topography","owner":"Limeo131","description":"This project explores the hemispheric asymmetry of Stratospheric Sudden Warmings (SSWs) using climate model simulations and data analysis. It demonstrates that topography plays a dominant role in shaping the frequency and dynamics of SSWs by enhancing eddy heat flux through increased wave amplitude and phase alignment.","archived":false,"fork":false,"pushed_at":"2025-04-03T05:41:38.000Z","size":27966,"stargazers_count":0,"open_issues_count":0,"forks_count":0,"subscribers_count":1,"default_branch":"main","last_synced_at":"2025-04-03T06:26:43.430Z","etag":null,"topics":["climate-model","climate-science","python"],"latest_commit_sha":null,"homepage":"","language":"Jupyter Notebook","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":null,"status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/Limeo131.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":null,"code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null}},"created_at":"2025-04-03T00:37:34.000Z","updated_at":"2025-04-03T05:41:41.000Z","dependencies_parsed_at":"2025-04-03T06:37:20.523Z","dependency_job_id":null,"html_url":"https://github.com/Limeo131/ssw-topography","commit_stats":null,"previous_names":["limeo131/ssw-topography"],"tags_count":0,"template":false,"template_full_name":null,"repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/Limeo131%2Fssw-topography","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/Limeo131%2Fssw-topography/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/Limeo131%2Fssw-topography/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/Limeo131%2Fssw-topography/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/Limeo131","download_url":"https://codeload.github.com/Limeo131/ssw-topography/tar.gz/refs/heads/main","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":248067040,"owners_count":21042218,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["climate-model","climate-science","python"],"created_at":"2025-04-03T22:16:21.826Z","updated_at":"2026-04-29T17:03:03.096Z","avatar_url":"https://github.com/Limeo131.png","language":"Jupyter Notebook","funding_links":[],"categories":[],"sub_categories":[],"readme":"## 📘 Topography Dominates the Hemispheric Asymmetry of Stratospheric Sudden Warmings\n\n**Author**: Siming Liu  \n**Affiliations**: The University of Chicago  \n**Contact**: smliu01@uchicago.edu\n\n### 🔍 Overview\n\nThis repository contains the code and analysis for the study:\n\n\u003e **Topography dominates the hemispheric asymmetry of Stratospheric Sudden Warmings**  \n\u003e Liu, S., Shaw, T. A., \u0026 Garfinkel, C. I. (2025). accepted by Geophysical Research Letters.\n\nThe study investigates why **Stratospheric Sudden Warmings (SSWs)** occur almost exclusively in the Northern Hemisphere (NH). Using climate model simulations, the paper shows that **topography is the dominant factor** in creating this hemispheric asymmetry through its control of eddy heat flux.\n\n---\n\n### 📄 Paper\n\n- **Main Manuscript**: [`manuscript.pdf`](./result/manuscript.pdf)  \n- **Supporting Information**: [`supplementary.pdf`](./result/supplementary.pdf)\n\n---\n\n### 📂 Notebooks\n\nThe analysis is broken into several Jupyter notebooks:\n\n| Notebook | Description |\n|----------|-------------|\n| `ssw_onset_dm.ipynb` | Detects the onset of SSW events following the Charlton \u0026 Polvani (2007) method. |\n| `tropos_ssw_v_t_vint.ipynb` | Calculates and visualizes vertically integrated meridional eddy heat flux (`v*T*`) in both hemispheres. |\n| `v.t.daily.ipynb` | Computes and analyzes daily zonal deviations of meridional wind (`v`) and temperature (`T`). |\n| `vtpdf_100_ssw.ipynb` | Generates probability distributions of wave amplitudes and phase differences at 100 hPa, 60°N. |\n| `vt_amp.phase.pdf.ipynb` | Decomposes `v` and `T` into wave components and calculates amplitude and phase differences. |\n| `u_z.lat.ipynb` | Analyzes zonal mean zonal wind structure as a function of height and latitude. |\n\n---\n\n### 📊 Key Findings\n\n- **Topography dominates** the hemispheric asymmetry in SSWs.\n- Flattening NH topography nearly eliminates SSWs in climate model simulations.\n- Topography amplifies eddy heat flux by:\n  - Increasing the amplitude of eddy meridional wind and temperature.\n  - Decreasing their phase difference, enhancing vertical wave propagation.\n\n---\n\n### 🗂️ Data\n\nThe analysis uses the following datasets:\n\n- **ECHAM6 Climate Model Simulations**  \n  - ALL: Realistic topography and surface energy fluxes  \n  - FLAT: Flattened topography  \n  - SYMS: Symmetrized surface energy fluxes  \n  - F+S: Flattened topography + symmetrized fluxes  \n  - 60-year integrations with monthly and daily outputs  \n  - Developed in Shaw et al. (2022)\n\n- **ERA5 Reanalysis** (1958–2022)  \n  - Zonal and meridional wind, temperature  \n  - Used to evaluate model performance and calculate SSW frequency\n\n---\n\n### 🛠️ Environment \u0026 Dependencies\n\nThis project was developed using:\n\n- Python 3.x\n- Jupyter Notebook\n- Common scientific libraries: `numpy`, `matplotlib`, `scipy`, `xarray`, `cartopy`, `netCDF4`\n\n*Note: You may need to configure access to climate model output or reanalysis datasets used in the analysis.*\n\n---\n\n### 🧑‍🔬 Reproducibility\n\nIf you’d like to reproduce the analysis:\n\n1. Clone the repository.\n2. Make sure you have access to the model output files used in the simulations.\n3. Run the notebooks in the order listed above, starting with `ssw_onset_dm.ipynb`.\n\n---\n\n### 📘 Citation\n\nIf you use this code or analysis in your work, please cite:\n\n```\nLiu, S., Shaw, T., \u0026 Garfinkel, C. I. (2025). Topography dominates the hemispheric asymmetry of stratospheric sudden warmings. Geophysical Research Letters, 52, e2024GL113051.\nhttps://doi.org/10.1029/2024GL113051\n```\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Flimeo131%2Fssw-topography","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Flimeo131%2Fssw-topography","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Flimeo131%2Fssw-topography/lists"}