Seasons Can Fool Satellites: Land Cover Maps Change With the Time of Year

Camp Misty Mount Dining Hall, Catoctin Mountain Park, in early December. NPS / Kelsey Graczyk.

Same land, different map

Remote sensing — images of the Earth taken from satellites or aircraft — shows what covers the land and how people use it: forest, urban development, farmland. That helps in studying water quality, climate change and more.

But the season matters. Scientists found that data from the same area produced different land use/land cover (LULC) classifications depending on the time of year: more buildings and fewer trees in one season than another — although the land use hadn't changed. They report it in the December 2024 issue of Hydrology and Earth System Sciences.

Why it matters

• Researchers feed LULC data into mathematical models that analyze or predict real-world outcomes under different scenarios.
• Land managers base natural-resource decisions on those results.
• Models using LULC data from different seasons could give wrong results, and so weaker decisions.

The authors offer tips for getting more accurate results from LULC data gathered in different seasons.

Study: Myers and others, 2024, "Seasonal variation in land cover estimates reveals sensitivities and opportunities for environmental models," Hydrology and Earth System Sciences 28: 5295–5310.

Sources

Based on "Seasonal Variations in Remotely Sensed Data," by the editors of Park Science magazine, Research Roundup, Volume 39, Number 1, Winter 2024-25 (January 15, 2025), National Park Service; a work of the United States government in the public domain.