Abstract
<title>Abstract</title> <p>This study investigates the influence of El Nino Southern Oscillation (ENSO) and monsoon rainfall on kharif-season vegetation condition and terrestrial carbon fluxes across all 33 Rajasthan districts from 2000–2024. Four MODIS products, MOD13Q1 (NDVI/EVI, 250 m), MOD17A2H (8-day GPP), MOD17A3HGF (annual NPP), and MCD12Q1 (LULC) are combined with IMD 0.25° gridded rainfall and NOAA ONI indices in a fully non-parametric statistical framework (Mann-Kendall, Sen slope, Kendall tau, Spearman rho, iterative Theil-Sen regression, 1000-replicate bootstrap CI, LOOCV). The results shows that El Nino events suppress kharif NDVI by 3.6% and GPP by 7.0% on average, with maximum deficits of 14.3% (NDVI) and 21.6% (GPP) in hyper-arid Jaisalmer while La Nina surpluses of 3–18% mirror these anomalies. RF-NDVI Spearman correlations are significant in all 33 districts (mean ρ = 0.935, range 0.85–0.98). Independent ONI effects on GPP after controlling for RF are significant in six arid and semi-arid west districts. Significant positive Mann-Kendall trends in NDVI and GPP are detected in 16 of 33 districts (Sen slope: +0.003–0.007 NDVI yr⁻¹, + 1.5–7.3 g C m⁻² yr⁻¹). District-level Theil-Sen models achieve mean LOO-MAPE of 17.4% for GPP and 6.2% for NDVI, with best skill in the sub-humid SE (< 12% MAPE). With ONI = -0.1 (FMA) in 2026, state-mean kharif GPP is forecast at 249.5 g C m⁻² (anomaly − 3.2%, 90% CI: 212–284), with 30/33 districts NEAR NORMAL and three arid-zone districts BELOW NORMAL.</p>