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Preface: Special Issue on Probing the Open Ocean With the Research Sailing Yacht Eugen Seibold for Climate Geochemistry

JGR–Atmospheres - Thu, 08/29/2024 - 13:09
Abstract

The 72-foot sailing yacht Eugen Seibold is a new research platform for contamination-free sampling of the water column and atmosphere for biological, chemical, and physical properties, and the exchange processes between the two realms. Ultimate goal of the project is a better understanding of the modern and past ocean and climate. Operations started in 2019 in the Northeast Atlantic, and will focus on the Tropical Eastern Pacific from 2023 until 2025. Laboratories for air and seawater analyses are equipped with down-sized and automated state-of-the-art technology for a comprehensive description of the marine carbon system including CO2 concentration in the air and sea surface, pH, macro-, and micro-nutrient concentration (e.g., Fe, Cd), trace metals, and calcareous plankton. Air samples are obtained from ca. 13 m above sea surface and analyzed for particles (incl. black carbon and aerosols) and greenhouse gases. Plankton nets and seawater probes are deployed over the custom-made A-frame at the stern of the boat. Near Real-Time Transfer of underway data via satellite connection allows dynamic expedition planning to maximize gain of information. Data and samples are analyzed in collaboration with the international expert research community. Quality controlled data are published for open access. The entire suite of data facilitates refined proxy calibration of paleoceanographic and paleoclimate archives at high temporal and spatial resolution in relation to seawater and atmospheric parameters.

Geodetic Matched Filter Slow Slip Event Detection Along the Northern Japan Subduction Zones

JGR–Solid Earth - Thu, 08/29/2024 - 12:24
Abstract

We apply a template matching method on GNSS data for stations located in Honshu, Japan, to detect slow slip events associated with the subducting Philippine Sea and Pacific plates during the period from 1997 to 2020. A measure of the minimum detectable moment magnitude is proposed, from which we infer that the method could potentially detect SSEs as small as M w 5.2 on the westernmost part of the Philippine Sea plate and M w 6 on the Pacific plate below Honshu eastern coastline. We find 12 slow slip events on the Philippine Sea plate, among which eight are located on the known Boso slow slip event asperity and the four others are located offshore north-east relative to the Boso SSEs, at the transition with the Pacific plate. We find 9 SSEs on the Pacific plate, mainly on the northern section, offshore Iwate prefecture. A clear gap with no SSEs coincides with the main asperity that broke during the 2011 Tohoku earthquake. Most event locations correlate with low locking areas. We do not find any clear temporal pattern apart from the regular occurrence of the largest Boso SSEs.

Inhomogeneous Magnetization of Tyrrhenian Seamounts Revealed From Gravity and Magnetic Correlation Analysis

JGR–Solid Earth - Thu, 08/29/2024 - 12:10
Abstract

We perform a joint analysis of gravity and magnetic data sets in the Tyrrhenian Sea region to infer the rock physical properties of several volcanic seamounts. We propose a moving-window application using Poisson's theorem, which relates the total gradient of the magnetic field to the total gradient of the first-order vertical derivative of the gravity field data. In volcanic environments, where strong intensity of remanent magnetization is expected, the total gradient of the magnetic field is particularly useful since it is almost independent on the direction of the total-magnetization. The moving-window approach resulted necessary due to the heterogeneous magnetization distribution of the volcanoes. First, we perform synthetic tests based on realistic seamount models which exhibit inhomogeneous magnetization intensity and orientation. Using the total gradients, we demonstrate that our approach can provide an appropriate magnetization-to-density ratio in different subareas of seamounts. The results of the correlation analysis for the Palinuro, Marsili, Vavilov, and Magnaghi seamounts provide interesting information on the variability of magnetization associated with different epochs of formation and demagnetization effects due to hydrothermal alteration processes.

Near‐Source Waveform Modeling to Estimate Shallow Crustal Attenuation and Radiated Energy of Mw 2.0–4.5 Earthquakes

JGR–Solid Earth - Thu, 08/29/2024 - 12:00
Abstract

Estimating the radiated energy of small-to-moderate (M w < 5) earthquakes remains challenging because their energy decay significantly during wave propagation. Even when near-source records are available, seismic waves pass through the shallow crust with strong attenuation, which can bias energy estimates. This study evaluated the degree of energy dissipation in the crust through modeling near-source (<12 km) waveform data in northern Ibaraki Prefecture, Japan. High-quality waveforms recorded at a downhole sensor confined by granite with high seismic velocity helped to investigate this issue. We first estimated the moment tensors for M1–4 events and computed their synthetic waveforms, assuming a tentative one-dimensional attenuation (Q −1) model. We then modified the Q −1-model in the 5–20 Hz range such that the frequency components of the synthetic and observed waveforms of microearthquakes (M w < 1.7) matched. The results show that the Q s-value is as low as 55 at depths of <4 km with no obvious frequency dependence. Using the derived Q −1-model, we estimated the moment-scaled radiated energy (e R ) of 3,884 events with M w 2.0–4.5. The median e R is 3.5 × 10−5, similar to the values reported for M w > 6 events, with no obvious M w dependence. If we use an empirically derived Q s-model, the median e R becomes a one-order underestimation (2.0 × 10−6). More than 70% of the energy is dissipated in the shallow crust for events with M w < 4. These results demonstrate the need for an accurate understanding of shallow crustal attenuation for energy estimation of small events, even with near-source high-quality data.

Assimilating Morning, Evening, and Nighttime Greenhouse Gas Observations in Atmospheric Inversions

JGR–Atmospheres - Thu, 08/29/2024 - 09:15
Abstract

Improved urban greenhouse gas (GHG) flux estimates are crucial for informing policy and mitigation efforts. Atmospheric inversion modeling (AIM) is a widely used technique combining atmospheric measurements of trace gas, meteorological modeling, and a prior emission map to infer fluxes. Traditionally, AIM relies on mid-afternoon observations due to the well-represented atmospheric boundary layer in meteorological models. However, confining flux assessment to daytime observations is problematic for the urban scale, where air masses typically move over a city in a few hours and AIM therefore cannot provide improved constraints on emissions over the full diurnal cycle. We hypothesized that there are atmospheric conditions beyond the mid-afternoon under which meteorological models also perform well. We tested this hypothesis using tower-based measurements of CO2 and CH4, wind speed observations, weather model outputs from INFLUX (Indianapolis Flux Experiment), and a prior emissions map. By categorizing trace gas vertical gradients according to wind speed classes and identifying when the meteorological model satisfactorily simulates boundary layer depth (BLD), we found that non-afternoon observations can be assimilated when wind speed is >5 m/s. This condition resulted in small modeled BLD biases (<40%) when compared to calmer conditions (>100%). For Indianapolis, 37% of the GHG measurements meet this wind speed criterion, almost tripling the observations retained for AIM. Similar results are expected for windy cities like Auckland, Melbourne, and Boston, potentially allowing AIM to assimilate up to 60% of the total (24-hr) observations. Incorporating these observations in AIMs should yield a more diurnally comprehensive evaluation of urban GHG emissions.

Call of the wild

Science - Thu, 08/29/2024 - 05:58
Science, Volume 385, Issue 6712, Page 939-939, August 2024.

The dawn of climate security

Science - Thu, 08/29/2024 - 05:58
Science, Volume 385, Issue 6712, Page 940-940, August 2024.

Vocal labeling of others by nonhuman primates

Science - Thu, 08/29/2024 - 05:58
Science, Volume 385, Issue 6712, Page 996-1003, August 2024.

Dryland self-expansion enabled by land–atmosphere feedbacks

Science - Thu, 08/29/2024 - 05:58
Science, Volume 385, Issue 6712, Page 967-972, August 2024.

Grain boundaries are Brownian ratchets

Science - Thu, 08/29/2024 - 05:58
Science, Volume 385, Issue 6712, Page 980-985, August 2024.

A smart mask for exhaled breath condensate harvesting and analysis

Science - Thu, 08/29/2024 - 05:58
Science, Volume 385, Issue 6712, Page 954-961, August 2024.

In Other Journals

Science - Thu, 08/29/2024 - 05:58
Science, Volume 385, Issue 6712, Page 947-948, August 2024.

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