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The rise in global mean sea level (GMSL) is a critical indicator of climate change. Hong Kong Polytechnic University (PolyU) researchers have utilized advanced space geodetic technologies to deliver the first precise 30-year (1993–2022) record of global ocean mass change (also known as barystatic sea level), revealing its dominant role in driving GMSL rise.

Sustainable energy: 'Fairy circles' can provide clues to depth of natural hydrogen sources

Phys.org: Earth science - Mon, 09/01/2025 - 17:00

Natural hydrogen from deep underground could be an important building block for the sustainable energy system of the future, but it is currently still difficult to predict where and at what depth elevated concentrations are located. New study results from the Department of Geology at the University of Vienna could make such predictions easier in the future. So-called "fairy circles"—round patches with vegetation damage—could be helpful indicators. This is because these "fairy circles" subside due to the seepage of natural hydrogen.

Rare oceanic plate delamination may explain Portugal's mysterious earthquakes

Phys.org: Earth science - Mon, 09/01/2025 - 15:20

One of the worst earthquakes in European history ripped through Portugal in 1755, causing a tsunami, fires and shaking that killed tens of thousands of people and caused widespread destruction. Another less well-documented earthquake occurred in the same region in 1356, and a more recent 7.9 magnitude earthquake occurred in 1969. The most recent event was recorded by seismic instruments and has been found to have originated from the flat Horseshoe Abyssal Plain, which is not near any known major tectonic faults.

The Pacific's united front on climate action is splintering over deep-sea mining

Phys.org: Earth science - Mon, 09/01/2025 - 14:26

In recent years, Pacific island nations have earned global credibility as champions of climate action. Pacific leaders view sea level rise as an existential threat.

Seaweed on sandy coastlines contributes to greenhouse gas emissions, study shows

Phys.org: Earth science - Mon, 09/01/2025 - 14:08

A team of researchers from Monash University has made a discovery that could reshape our understanding of greenhouse gas emissions from coastal ecosystems. Published in Nature Geoscience, the study reveals sandy coastlines, which make up half the world's continental margins, are a previously overlooked source of methane.

The top hot spots in Tokyo: Revealing the impact of climate change through data fusion

Phys.org: Earth science - Mon, 09/01/2025 - 13:57

Global climate change is making temperatures hotter, particularly in densely populated cities, which can adversely affect the health of residents. While mitigation efforts are urgent, it is hard for urban planners to identify exactly where to target as accurate, long-term climate records created over fine spatial scales have been unavailable.

Landsat 9 sees Buccaneer Archipelago

Phys.org: Earth science - Mon, 09/01/2025 - 12:48

The Operational Land Imager on Landsat 9 captured this image of Buccaneer Archipelago on June 11, 2025.

Seafloor fiber optical cable repositioning using Target Motion Analysis on Distributed Acoustic Sensing of underwater acoustic noise

Geophysical Journal International - Mon, 09/01/2025 - 00:00

SummaryDistributed Acoustic Sensing (DAS) is a recent technology that turns optical fibers into multi-sensor arrays. In the marine environment, it offers new possibilities for measuring seismic and environmental signals. While DAS can be applied to existing fiber optic cables used for communications, a major limitation of such efforts is that the position of the cable is not always known with sufficient accuracy. In particular, for submarine telecommunication cables, the positioning accuracy decreases with increasing depth. This problem affects the accuracy of earthquake locations and source parameters based on DAS signals. This limitation calls for methods to retrieve the cable’s position and orientation. Here, we propose a method for relocating a linear section of cable “or multiple connected segments” using incidental acoustic sources, particularly boats moving in the vicinity of the cable. The method is based on Target Motion Analysis (TMA) for sources in uniform rectilinear motion. We consider Bearing-Only TMA (BO-TMA) and the Bearing and Frequency TMA (BF-TMA), which respectively use changes in back azimuth (called bearing in navigation) and changes in both back azimuth and Doppler frequency shift as the source moves. We adapt these methods to the 3D case to account for the difference in depth between the fiber and the sources. Both cases lead to a non-linear inverse problem, which we solve by the Levenberg-Marquardt method. On synthetic data, we test both TMA techniques on single and multiple source trajectories and evaluate their accuracy as a function of source trajectory and velocity. We then test the BO-TMA on real DAS recordings of acoustic signals produced by passing ships near a 42 km-long fiber optic cable off the coast of Toulon, southeastern France. In this study case, the position and characteristics of the acoustic source are known. While the Doppler frequency shift at low frequency (30 Hz) is difficult to measure with sufficient accuracy (<0.1○), we demonstrate that effective cable location can be achieved by BO-TMA using multiple ship passages with a variety of trajectories. Once the linear sections of the cable have been relocated, the stage is set to reconstruct the entire cable configuration. More generally, the three-dimensional TMA on linear antennas developed here can be used to locate either the sources or the antenna situated at different depths.

The climate case for planting trees has been overhyped—but it's not too late to fix it

Phys.org: Earth science - Sun, 08/31/2025 - 11:10

The climate benefits of planting trees may have been greatly overestimated, but swift action could ensure reforestation meets its potential to curb dangerous emissions, new research has found.

A Systematic Review of Martian Image Segmentation Techniques for Mars Exploration (from 2019 to 2025)

Recent articles in Advances in Space Research - Sat, 08/30/2025 - 19:10

Publication date: Available online 22 August 2025

Source: Advances in Space Research

Author(s): Yingyi Qu, Chee-Onn Chow, Joon Huang Chuah, Kian Lun Soon

Controller-matching-based robust model predictive control for spacecraft rendezvous and docking

Recent articles in Advances in Space Research - Sat, 08/30/2025 - 19:10

Publication date: Available online 21 August 2025

Source: Advances in Space Research

Author(s): Dae-Eun Kang, Youngho Eun, Hancheol Cho, Sang-Young Park

Monsoon changes accelerate glacier loss across High Mountain Asia, study finds

Phys.org: Earth science - Sat, 08/30/2025 - 09:57

Glaciers across High Mountain Asia are losing more than 22 gigatons of ice per year—the equivalent to nearly 9 million Olympic swimming pools, according to research from the University of Utah and Virginia Tech. The impact of a warming climate on glacial loss is undisputed—this new study provides the first evidence that seasonal shifts in rainfall and snowfall patterns, particularly of the South Asian monsoons, are also exacerbating glacier melting across the region.

Scientists track lightning 'pollution' in real time using NASA satellite

Phys.org: Earth science - Sat, 08/30/2025 - 09:52

Picture this: You're stuck in traffic on a summer afternoon, checking the weather app on your phone as dark storm clouds roll in. You might think about power outages or possible flooding, but you probably don't think about how every lightning bolt that flashes across the sky also emits a gas, nitrogen oxide (NO), that is also emitted in the exhaust from your car's engine.

Full-Waveform Inversion of borehole seismic data to delineate salt bodies: a new method using a level-set function applied to a weakly deformable mesh

Geophysical Journal International - Sat, 08/30/2025 - 00:00

SummaryWe present a full-wave inversion algorithm (FWI) to accurately delineate the subsalt body using seismic borehole data. This ill-posed inverse problem is constrained by introducing geological a priori information through the parameterization of the salt boundary using a level set function. The implicit level set function is spanned by a set of B-spline basis functions for their ability to represent a wide range of shapes. Furthermore, the proposed FWI algorithm combines a meshed discretization with the implicit representation of shapes throughout the inversion process. A weak deformation of the mesh is applied at each iteration of the inversion to maintain the explicit discretization of the shapes when the level set boundary is updated. This method is very accurate when it comes to modelling the scattered wavefields and computing the Fréchet derivatives at interfaces. Three numerical examples using synthetic borehole seismic data illustrate the ability of the method to accurately retrieve the size, location and shape of the salt body when the density and seismic velocities are known.