“Seen & Heard” is a monthly feature of GPS World magazine, traveling the world to capture interesting and unusual news stories involving the GNSS/PNT industry.
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HOW BIG IS THAT BEAR?
Monitoring the weight of polar bears — an important health factor — usually means tranquilizing them from the air and lifting them with a tripod attached to a scale. However, technology might provide a non-invasive solution. Various zoos and sanctuaries are testing the accuracy of lidar scanners to measure the weight of polar bears, reports Geo Week News. The scans could be done using drones and mobile mapping equipment and techniques, according to Joel Cusick, a GIS specialist for the National Parks Service.
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SLIP SLIDING AWAY
Researchers used a combination of GNSS and interferometric synthetic aperture radar (InSAR) data from Sentinel-1 satellites to determine subsidence in
99 cities around the world between 2015 and 2020. Subsidence rates in Tianjin, Semarang and Jakarta exceed 30 mm per year. Even in mostly stable cities, areas are sinking faster than sea level is rising, with Istanbul, Lagos, Taipei, Mumbai, Auckland and Tampa sinking faster than 2 mm per year in some areas. Besides climate change, causes include groundwater extraction, mining, reclamation of natural wetlands, infrastructure projects and ecological disturbances. The study is published in Geophysical Research Letters.
Photo: NOAA Fisheries/Raymond BolandPhoto:
FINDING NEMO
National Oceanic and Atmospheric Administration (NOAA) ocean mapping ship Rainier completed a five-month expedition to the Mariana Islands in September, combining mapping and charting with coral-reef ecosystem surveying. Collection of high-resolution mapping data in near real time improved the effectiveness of the traditional marine science data collection as the combined team mapped 4,000 square nautical miles of seabed and conducted 1,800 SCUBA dives. The data will improve navigation safety through updated NOAA nautical charts and increase understanding of coral reefs through the National Coral Reef Monitoring Program. Besides charts, the seabed mapping data supports marine protected areas, sustainable fisheries, and offshore wind siting — and, in the Marianas, is important for tsunami modeling.
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GRAVITY DOWN UNDER
An airborne gravity sensor is flying above 80,000 square kilometers of New South Wales (NSW), Australia, collecting data that will improve the accuracy of real-world heights from GNSS positioning to just a few centimeters. Data for the 18-month NSW Gravity Model project will be captured in five stages, starting in Western NSW. The resulting model is expected to enable better resource management, infrastructure planning and natural hazard preparation. It is also a critical building block for developing digital twins, replacing datasets that predate GNSS positioning.