Spatiotemporal Dynamics of Vegetation Greenness and Drought in West Java and Their Relationship with El Nino Southern Oscillation and the Indian Ocean Dipole

Abstract

This study focuses on the West Java region and integrates MODIS NDVI-based vegetation drought assessment with a quantitative analysis of the lagged vegetation response to ENSO and IOD variability during the 2015–2024 period. Data were obtained from the Terra and Aqua MODIS sensors with spatial and temporal resolutions of 250 m and 16 d, respectively. Monthly NDVI anomalies were calculated relative to long-term monthly climatology to assess vegetation stress and drought indices. The ENSO and IOD data were obtained from the National Oceanic and Atmospheric Administration Physical Sciences Laboratory. A delayed correlation analysis was conducted to examine the monthly and seasonal responses of vegetation to ENSO and IOD. The drought level was quantified using the NDVI anomaly classification. The strongest correlation between the cumulative influence of ocean-atmosphere interactions on terrestrial vegetation was observed at lag times of 2 and 4 months for ENSO and 4 months for IOD. The Indian Ocean climate variability strongly influences the MAM season with a vegetation response time of 6 months, whereas the Pacific Ocean strongly influences the SON season with a vegetation response time of 2 months. The ENSO phase influences vegetation stress and drought in West Java more rapidly than the IOD phase. Drought spread in the northern coastal areas of West Java, bordering the Java Sea, experienced higher drought than the southern coast adjacent to the Indian Ocean.