GEE based Multi-Sensor Remote Sensing Data (1987-2025) and R Analysis Scripts for Sikkim Snow Cover Dynamics

This repository contains the complete analytical workflow, datasets, and resultant figures for the study "Long-Term Decline in Snow Cover Area of Sikkim, Eastern Himalaya (1987–2025)." The provided materials ensure full reproducibility of the research, featuring Google Earth Engine (GEE) JavaScript code used to process 39 years of Landsat and Sentinel-2 surface reflectance imagery to extract annual snow cover area (SCA) utilizing a Normalised Difference Snow Index (NDSI) threshold. Additionally, the repository includes the finalized SCA time-series data, generated summary tables, high-resolution manuscript figures, and the comprehensive R scripts (for R v4.5.1) utilized for all downstream analysis. The R code encompasses non-parametric trend assessments (Mann–Kendall, Theil–Sen), PELT structural change-point detection, machine learning model evaluation via Leave-One-Out Cross-Validation (LOOCV), and the construction of an inverse-RMSE weighted ensemble to project continuous regional snow cover decline out to the year 2100.