Spatiotemporal and Machine Learning-Based Prediction of Tropospheric Formaldehyde in Nigeria
# Spatiotemporal Analysis of Formaldehyde (HCHO) over Nigeria (2019–2025) and Machine Learning Forecasting (2026–2030)
An undergraduate research dissertation codebase performing spatiotemporal characterization, hotspot detection, meteorological/fire driver attribution, machine learning predictive modeling, and a 5-year spatial forecast (2026–2030) of tropospheric Formaldehyde (HCHO) column densities over Nigeria.
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## 📌 Executive Summary
Tropospheric Formaldehyde (HCHO) is a primary indicator of volatile organic compound (VOC) emissions, air pollution, and precursor activity for ground-level ozone. This project leverages **Sentinel-5P TROPOMI satellite data (2019–2025)** combined with **NASA MERRA-2 reanalysis meteorology** and **MODIS FIRMS biomass burning data** across Nigeria's ecological zones.
### Key Headline Results:
- **Study Horizon:** 84 monthly grids (2019–2025) at $0.1^\circ \times 0.1^\circ$ spatial resolution across Nigeria.
- **Top Machine Learning Model:** **LightGBM** achieved the highest test performance (**$R^2 = 0.841$**, RMSE $= 0.142 \times 10^{-4} \text{ mol/m}^2$) on the 2025 hold-out year, beating the seasonal Climatology Baseline ($R^2 = 0.832$).
- **Key Atmospheric Drivers:** Temperature at 2m (`T2M`) and Fire Radiative Power (`FRP`) were identified as primary drivers explaining dry-season HCHO peaks.
- **5-Year Spatial Forecast:** 60 monthly spatial grids generated for **2026 to 2030** using a recursive multi-step machine learning ensemble.
- **Independent Cross-Satellite Validation:** Validated against independent **OMI (Aura)** satellite sensor observations ($r = 0.258$, 16 overlapping months).
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## 🎯 Research Objectives
| Obj | Scope | Key Findings / Highlights |
|---|---|---|
| **1. Spatiotemporal Analysis** | Monthly & seasonal trend characterization (2019–2025) | Strong dry-season peaks; highest concentrations localized over southern industrial/oil-producing regions. |
| **2. Hotspot Detection** | Getis-Ord $G_i^*$ …