El Niño is a complex part of the climate system with extreme events occurring every 15 to 20 years that have major impacts on global water supplies. This study combined data derived from on-the-ground measurements and a suite of global datasets to determine where impacts on soil moisture from such events were most severe in the tropics and to explore possible links of these changes to other large-scale weather patterns.
The study will provide a better understanding of where changes in moisture availability for plants are most severe in the tropics during El Niño to enable better predictions of impacts on the food supply and feedbacks of water from land back to the atmosphere through evapotranspiration. This can be used to guide decisions on where changes need to be made to water management systems during El Niño to offset expected decreases in moisture availability for crops and to improve global Earth system model predictions.
El Niño is an important part of the climate system that has widespread impacts on global water resource availability. This study employed a combination of modeled soil moisture datasets and on-the-ground measurements to determine what changes to expect for soil moisture during severe El Niño events. Supplemental datasets of evapotranspiration and precipitation were used to explore the possible link of these changes to non-El Niño related weather events. The analysis was focused on the humid tropics, which is important not only because of the higher severity of impacts due to its closer proximity to the El Niño source region, but also because historical observations in this region are generally sparse, which limits the ability to predict what will happen during an El Niño. Results indicate that the northern Amazon basin, as well as maritime regions of southeastern Asia, Indonesia and New Guinea will experience the largest reductions in soil moisture during the next severe El Niño. Information gleaned from the study can be used to develop better predictions of potential impacts on plants or the food supply so mitigation measures can be implemented, or to improve the understanding of tropical moisture feedbacks and how this might impact regional water supplies or the climate system.
Figure. Cluster analysis of mean October to December soil moisture changes during “Super El Niño” events. Red cell colors indicate regions where decrease was most severe.
Contacts (BER PM): Daniel Stover, SC-23.1, Daniel.Stover@science.doe.gov (301-903-0289)
PI Contact: Jeffrey Chambers, Lawrence Berkeley National Laboratory, firstname.lastname@example.org (510-495-2932)
This project was supported as part of the Next-Generation Ecosystem Experiments – Tropics, funded by the United States Department of Energy Office of Science Office of Biological and Environmental Research through the Terrestrial Ecosystem Science program.
Solander, B.D. Newman and C. Xu, et al., “The pantropical response of soil moisture to El Niño.” Hydrology and Earth System Sciences 24, 2303-2322 (2020). https://doi.org/10.5194/hess-24-2303-2020.
Associated data that was used for this research was uploaded to the Next-Generation Ecosystem Experiments – Tropics online data archive (NGT0132-NGT0146 & NGT0148: https://ngt-data.lbl.gov/)