Satellite data fusion enhances the early detection of convective clouds
image:
Developing cumulus clouds
view moreCredit: Yang Gao
As global warming continues, convective weather events are becoming more frequent. The early stage of these storms, known as convective initiation (CI), can be monitored using geostationary satellites. However, detecting CI accurately remains a challenge. The current detection methods still have a high rate of false alarms and missed events. One key reason for this is that the resolution of existing geostationary meteorological satellites is not yet precise enough to meet the requirements for better detection.
To address this issue, researchers from the National Satellite Meteorological Center in China have proposed a new fusion method in which the high-resolution texture information provided by Gaofen-4 (GF-4), an Earth observation satellite, is combined with the multispectral data of Fengyun-4A (FY-4A), a geostationary meteorological satellite. This approach retains the detection advantages of each satellite, ensuring the accuracy of spectral information, while fully considering the early growth patterns of convective clouds, thereby significantly enhancing the capability to detect CI. The results have recently been published in Atmospheric and Oceanic Science Letters.
The fused data revealed a notable improvement in the detection of smaller-scale convective clouds, which often develop rapidly and can be difficult to capture using traditional observation methods. By leveraging high-resolution Earth observation satellites, forecasters gain the ability to identify these clouds much earlier in their formation.
"This early detection is particularly important as small convective clouds can quickly evolve into severe weather systems, such as thunderstorms or localized heavy rainfall", says the corresponding author, Prof. Xin Wang. "The integration of these detailed satellite data helps improve the timing of forecasts, allowing meteorologists to track cloud development with greater accuracy and issue earlier, more reliable warnings".
Beyond simply detecting clouds earlier, the integration of high-resolution satellite data enhances the precision of identifying where these clouds will form and intensify. This added spatial accuracy is crucial in understanding localized weather patterns, which may have been previously overlooked.
"For decision-makers, this means not only having a more detailed picture of the early stages of convective cloud development, but also having access to data that informs strategic responses," says Yang Gao, one of the other authors of the paper.
By pinpointing the exact locations of potential severe weather systems, this advanced detection method enables more targeted and efficient disaster preparedness and mitigation efforts.
"Ultimately, it improves our ability to safeguard communities from the impacts of extreme weather," Professor Wang concludes.
Journal
Atmospheric and Oceanic Science Letters
DOI
Who lives in the treetops? DNA-collecting drone provides insights
American Chemical Society
video:
This drone can release a specialized probe in the rainforest to collect environmental DNA from the trees’ branches and leaves.
view moreCredit: Adapted from Environmental Science & Technology 2024, DOI: 10.1021/acs.est.4c05595
Squinting into the treetops won’t reveal the tiny organisms up there. But these creatures leave clues, in the form of DNA, on the leaves and branches. Now, researchers report in ACS’ Environmental Science & Technology that they have developed a way to collect this genetic material: a drone with a specialized fabric probe. The team flew the drone above the rainforest and, based on DNA collected by the probe, identified the invertebrates in the canopy.
“If we want people to protect nature, we need to tell them what we are actually protecting — with our solution, we hope to better understand the life in the canopy,” says the study’s lead author, Steffen Kirchgeorg.
Drones go where people can’t or shouldn’t go, including remote, protected or inaccessible locations. So, researchers have started to use aerial robots to take pictures, deploy sensors and collect samples in the forest canopy. To identify the species living in and around trees, samples are taken of genetic material left on leaves and branches. This environmental DNA (eDNA) comes from mucus, feces and dead skin cells. However, if a drone outfitted with swabs to gently collect eDNA accidentally collides with a tree, both the robot and plant can be damaged. So, Kirchgeorg, Stefano Mintchev and colleagues wanted to design a sampling system that keeps the drone out of the vegetation.
They developed a drone sampling system with a specialized fabric probe that brushes against branches and leaves to collect eDNA. When a remote pilot activates a pully underneath the drone, a tether lowers and raises the probe through the canopy. The system includes a piece of fleece cloth cut into a circle, similar in shape to a coffee filter, with strips of fiberglass attached to provide structure. In addition, a sensor keeps the probe’s tether from tangling on branches: If it detects an impact, the researchers programmed the system to automatically shift position before completing the drop or retrieval.
In proof-of-concept demonstrations, the researchers flew their drone into a rainforest in Southeast Asia, sending it beyond their line of sight to retrieve genetic material from trees 10 different times. When the drone returned from the flights, the researchers removed the fabric and extracted eDNA from each probe before bringing the samples to a lab for analysis and species identification. Across the 10 separate samples, most of the organisms detected were arachnids and insects. Additional species of note, according to the researchers, include the long-tailed macaque (monkey), multiple ant and termite species, and a type of fly called the gall midge. The study presents another way to study biodiversity in remote habitats, which the researchers say is critical for conservation and restoration initiatives.
The authors acknowledge funding from the Swiss National Science Foundation through an Eccellenza Grant and a Bridge Discovery Grant, the European Research Council through the European Union’s Horizon 2020 research and innovation program, Rütli-Stiftung, the ETH Foundation, the XPRIZE Foundation, and the Alana Foundation.
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The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, e-books and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.
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Journal
Environmental Science & Technology
Article Title
“eProbe: Sampling of Environmental DNA within Tree Canopies with Drones”
Using satellite images to understand changes in river flow
Since 1953, an equation has been used to explain the relationship between hydraulic parameters (river width, depth, and velocity) and river discharge, the volume of water that flows through a river channel. This relationship is called at-a-station hydraulic geometry (AHG). Understanding this relationship is important for hydraulic engineering, predicting flooding, navigation, and more.
Though this equation has been studied extensively through field research, this has limited sample size and study areas and is not enough to fully explain the variety of factors beyond hydraulic parameters that impact river discharge. The ability to use satellites to monitor the surface of the earth through remote sensing may provide an option to expand the way AHG is understood. The data was presented in a paper published in the Journal of Remote Sensing.
“Understanding the response of width to changing discharge in different rivers is crucial for hydraulic modeling and river management. However, previous research is limited in spatiotemporal coverage by field measurements and only offers a fragmentary understanding in confined areas. This study introduces new data sources—multi-temporal river width data derived from Landsat and global discharge observations built upon years of progresses by the community —to provide a more comprehensive scope,” said Zimin Yuan, a researcher at the Institute of Remote Sensing and Geographic Information Systems at Peking University in Beijing, China. By using several data sets covering years ranging from 1979 to 2020 and matching data against Google Map Images to find limitations, researchers were able to derive an unprecedented global samples of AHG.
18 variables relating to AHG were identified from a vast range of factors, which could be divided into six categories that included: hydrology, physiography, climate, land cover, geology, and human influences. To focus the list of variables, researchers looked at the relationship between each variable and how it impacts the AHG. Then, because AHG is also closely related to the planform river pattern, researchers also factored in whether a river was meandering, anabranching, straight, or braided.
Understanding how these identified factors are related is essential for predicting river width changes, which can have impacts on the land and communities around the river. “We found that a 1% increase in discharge will result in a median of 0.2% increase in river width worldwide. Reaches characterized by cohesive soil, high forest coverage, and less human influences typically exhibit weaker response of width to discharge changes. River planform patterns are correlated with width response, and the relationship can be well correlated by climatic conditions,” said Yuan.
Looking ahead, researchers are hoping to understand the changes in river width over time, which is impacted by channel shape. They also plan to explore the abilities of remote sensing to find other factors that influence river discharge. “We plan to explore the depth response to discharge using remote sensing in the future. We also hope to reconstruct global channel shape on the basis of the samples and knowledge obtained in this and following studies,” said Yuan.
Other contributors include Peirong Lin of the Institute of Remote Sensing and Geographic Information Systems at Peking University; Xiwei Guo at the Department of Geosciences at The Pennsylvania State University; Kai Zhang at Geovis Environment Technology Co. Ltd.; and Hylke E. Beck at the Physical Science and Engineering Division of King Abdullah University of Science and Technology.
The National Natural Science Foundation of China, the Beijing Nova Program, and the Yunnan Provincial Science and Technology Project at Southwest United Graduate School funded this research.
Journal
Journal of Remote Sensing
Method of Research
Imaging analysis
Subject of Research
Not applicable
Article Title
Revisiting At-a-Station Hydraulic Geometry Using Discharge Observations and Satellite-Derived River Widths
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