ENSO-modulated heat source and moisture sink of Asian monsoon and its impact on rice production

Asian monsoon dynamics modulated by ENSO (El Niño-Southern Oscillation) exert a strong influence on rice production across Asia. This study quantifies the role of major high-pressure systems, Tibetan High (heat source and moisture sink), Mascarene High and West Pacific High (moisture sources), and Siberian High (heat sink) in regulating rice yield variability. Canonical correlation analysis between rice yield (Asia, China, India) and climate variables (temperature and pressure) reveals a pronounced seasonal asymmetry, with ocean-driven monsoon dominance in summer transitioning to continental impact during winter. The leading summer canonical mode is highly robust (r ≈ 0.51, p < 10⁻¹⁴), reflecting strong ocean-atmosphere coupling, while the dominant winter mode (r ≈ 0.46, p < 10⁻⁸) highlights land-atmosphere interactions. Regression and trend analyses show that La Niña years exhibit the strongest climate-yield coupling (R² ≈ 0.4-0.9), with detrended rice yield anomalies increasing (Sen's slope 6.54). In contrast, El Niño years show declining detrended yields (Sen's slope - 6.06) despite strong increases in total yield, indicating adverse climatic effects masked by technological advancement. Neutral years display weak and insignificant climate-crop relationships. Overall, only La Niña conditions provide a robust, technology-independent positive climatic influence on Asian rice production.