Water/Hycean Worlds & Oceanography

Unlocking Clearer Views Of Water Worlds: A Landsat Legacy

By Keith Cowing
Press Release
Aerospace Information Research Institute, Chinese Academy of Sciences
March 27, 2024
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Unlocking Clearer Views Of Water Worlds: A Landsat Legacy
Earth, a water world — NASA

Editor’s note: we are finding worlds orbiting other stars that may well be water worlds. These worlds may similar in some ways to our own and most likely different at the same time. Our first observations of these exoplanets will be from light years away. Understanding how our water world works – with both orbital data and ground truth calibration will help us develop further develop models to understand what might be happening on other water worlds – and what that may have to say in terms of those worlds’ habitability.

A study highlights the significant advancements in water environment analysis facilitated by the Landsat missions. This research, for the first time, offers a comprehensive global assessment of cloud-free observations (NCOs) from Landsat, underscoring its pivotal role in environmental and hydrological studies.

Satellite remote sensing is vital for monitoring marine and freshwater ecosystems, leveraging missions like SeaWiFS, MODIS, MERIS, Landsat, and Sentinel for tracking water parameters such as chlorophyll, sediment, and temperature. The dynamic nature of water bodies demands high-frequency observations for accuracy, with limitations highlighted by factors like clouds and sunglint. Despite its longer revisit cycle, Landsat’s observations are invaluable for inland and coastal waters, emphasizing the need for more frequent data to effectively monitor the dynamic changes in aquatic ecosystems.

A recent study (doi: 10.34133/remotesensing.0110) published in the Journal of Remote Sensing on 22 February 2024, advancements in analyzing water environments via Landsat missions are revealed. For the first time, this research offers a global assessment of cloud-free observations (NCOs) from Landsat, emphasizing its critical contribution to environmental and hydrological studies, marking a significant leap in our capability to monitor and understand water bodies on a global scale.

The study embarked on an ambitious journey to unravel the intricacies of NCOs via the Landsat missions. By meticulously analyzing over 4.8 million Landsat images spanning from Landsat 5 through Landsat 8, they uncovered striking spatial and temporal variations in cloud-free data across the globe. Their research illustrated Landsat-8’s superior performance, offering nearly double the mean annual NCOs compared to its predecessors. This leap in data quality is particularly pronounced in areas with orbital overlaps, especially above the 45°N latitude, where observation quality is significantly enhanced. Furthermore, this work delves into the vital role of these overlaps in augmenting the quantity and quality of observations, presenting a game-changer in how we monitor and understand the dynamics of the Earth’s water environments.

The study’s lead researcher emphasized, “Our analysis not only showcases Landsat-8’s superior capability in providing nearly twice as many mean annual NCOs as its predecessors but also highlights the importance of adjacent orbit overlaps in improving observation quality, particularly above 45°N latitude.”

The findings hold profound implications for enhancing the accuracy of long-term environmental change detection and monitoring. By leveraging improved NCOs, researchers and policymakers can make more informed decisions, particularly in managing water resources and addressing ecological challenges.

Quantifying Cloud-Free Observations from Landsat Missions: Implications for Water Environment Analysis, Journal of Remote Sensing (open access)


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