California Coast Ecological Conservation: Coupling Satellite Observations and Machine Learning to Understand Future Fog Prevalence Along the Coast Redwood Range

Fog engulfs the California coast during the dry summer months, serving as a vital water source for
coast redwoods (Sequoia sempervirens). The future of fog is uncertain, threatening redwoods and their functions:
carbon sequestration, ecosystem balance, and recreational value. Previous research has found mixed
outcomes, with some studies expecting a decrease in fog, while others predict stability or even an increase. To
address this uncertainty, NASA DEVELOP partnered with Save the Redwoods League to use satellite data
and machine learning to better understand the future of fog. Using new satellite products, we developed a
method for quantifying coastal fog presence. Then, we trained a machine learning model to use climate
projection and satellite-derived fog data to predict changes in fog through the year 2090. The model predicted
fog to increase along most of the coast redwood range, with an average increase of 3.4 hours of fog per day,
which would benefit redwood conservation and carbon sequestration. To more closely examine these
changes, we analyzed sea and land surface temperature trends over the last quarter-century, finding mixed
impacts on fog. This understanding of fog—past, present, and future—informs redwood conservation for
Save the Redwoods League and guides future research and monitoring efforts.