Strong Green‐Up of Tropical Asia During the 2015/16 El Niño

• Published in: Geophysical research letters Vol. 51; no. 8
• Main Authors: Satriawan, T. W., Luo, X., Tian, J., Ichii, K., Juneng, L., Kondo, M.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28-04-2024; Wiley
• Subjects: Anomalies; Climate; Climate and vegetation; Climate change; Climate variability; Climatic extremes; El Nino; El Nino phenomena; El Nino-Southern Oscillation event; ENSO; geostationary satellite; Interannual variability; Leaf area; Leaf area index; leaf area index (LAI); Leaves; Moisture content; Remote sensing; Satellite data; Soil moisture; Soil temperature; Soil water; Southeast Asia; Southern Oscillation; Sunlight; tropical forest; Tropical forests; Vegetation; vegetation dynamics; Asia
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2023GL106955

El Niño/Southern Oscillation (ENSO) is the main climate mode that drives the interannual variability in climate and consequently vegetation greenness. While widespread green‐up has been reported and examined in tropical America during El Niño, it remains unclear how vegetation in tropical Asia changes during the period. Here, we used four remote sensing‐based leaf area index (LAI) products to investigate changes in vegetation greenness during the 2015/16 El Niño in tropical Asia. We found a strong green‐up during the 2015/16 El Niño in tropical Asia, with its regional average LAI stronger than that of tropical America. The drivers for the green‐up vary across the region, with radiation being the main driver for continental tropical Asia, and temperature and soil water anomalies in the west and east parts of maritime tropical Asia, respectively. These findings provide important insights into the response of tropical Asia's vegetation to extreme climate anomalies.
Plain Language Summary
El Niño is a climate pattern that is associated with warm and dry conditions in tropical forest regions. Significant climatic changes during El Niño thus affect vegetation greenness (i.e., growth, size of canopy, amount of leaves). While an increase in vegetation greenness has been reported in tropical America during El Niño, it remains unclear how vegetation in tropical Asia changes during the period. Here, we used satellite data to investigate changes in vegetation greenness during El Niño in 2015–2016 in tropical Asia. We found a strong increase in vegetation greenness in tropical Asia during this period. The cause of this increase in greenness varied across different parts of tropical Asia. In mainland tropical Asia, sunlight was the main driver, while in maritime Southeast Asia, temperature or soil moisture was the main driver. These findings help provide better understanding of how vegetation in tropical Asia responds to extreme climate events like El Niño.
Key Points
Tropical Asia experienced strong green‐up during the 2015/16 El Niño, stronger than that of tropical America
In continental tropical Asia, green‐up was mostly driven by anomalously high shortwave radiation
In maritime tropical Asia, green‐up was primarily driven either by anomalously warmer temperatures or drier soil moisture from the west to east