Topographic Amplification of Pressure Gradients Across Atmospheric States in East Asia

This repository presents a **preliminary** state-based analysis of ERA5 sea-level pressure (SLP) over East Asia. The main focus is how terrain systematically amplifies atmospheric pressure gradients across different large-scale circulation states. The study uses principal component analysis (PCA) for dimensionality reduction, K-means clustering to identify discrete atmospheric states, and spatial gradient analysis to examine the structural relationship between large-scale pressure patterns and topography. **This is Version 1.0**, based only on one year (2025) of daily ERA5 data. Future versions will extend the temporal coverage to multiple decades, replace proxy masks with actual elevation (orography) data, and apply metric-based gradient calculations. The current results demonstrate a consistent topographic amplification of pressure gradients (ratio ≈ 2.33) across identified atmospheric states. ### Data Sources**ERA5 Reanalysis** Sea-level pressure data from the European Centre for Medium-Range Weather Forecasts (ECMWF) via Copernicus Climate Data Store (CDS). License: CC-BY 4.0 **NASA POWER** (optional) https://power.larc.nasa.gov/api/temporal/daily/point