We present X-ray observations of the upper atmospheric density disturbance caused by the explosive eruption of the Hunga Tonga-Hunga Ha’apai (HTHH) volcano on 15 January 2022. From 14 January to 16 January, the Chinese X-ray astronomy satellite, Insight-HXMT, was observing the supernova remnant Cassiopeia~A. The X-ray data obtained during Earth’s atmospheric occultations allowed us to measure neutral densities in the altitude range of $\sim$90–150\,km. The density profiles above 110\,km altitude obtained before the major eruption are in reasonable agreement with expectations by both GAIA and NRLMSIS~2.0 models. In contrast, after the HTHH eruption we found a severe density depletion at 500–1,000\,km away from the epicenter, and a relatively weak depletion extending up to $\sim7,000$\,km for over 8\,hr after the eruption. In addition, density profiles showed wavy structures with a typical length scale of either $\sim$20\,km (vertical) or $\sim$1,000\,km (horizontal). This may reflect gravity waves triggered by the volcanic eruption.

A document by Ayako Yamamoto. Click on the document to view its contents.

Deep (>20 km) crustal seismicity is typically associated with cold Precambrian lithosphere. However, previous studies have reported that the depth above which 90% of seismicity occurs (D90) in the Southland region of New Zealand is 30-35 km, even though it is situated in relatively young Mesozoic crust at the eastern edge of the transpressive Pacific-Australian plate boundary. To examine this unusual lower crustal seismicity further, we deployed 19 short period seismometers between October 2022-2023 through the Southland Otago Seismic Array (SOSA). Supplemented by the permanent GeoNet network and an ongoing array to the west in Fiordland, SOSA provided a station spacing of ~30 km across this 150 km wide region. In total, SOSA recorded 85 events in and around Southland. These events are not uniformly distributed, with an abrupt decrease in seismicity east of Fiordland. We also identified six spatial-temporal clusters of elevated seismicity across eastern Fiordland and Southland. The distribution of SOSA event depths confirms the presence of lower crustal seismicity in Southland (D90 = 32 km). This D90 estimate is significantly deeper than suggested by event depths to the north in Otago (D90 = 14 km). Using 1D lithospheric strength profiles, we suggest that the embrittlement of Southland’s mid-lower crust reflects the emplacement of mafic terranes in this region during Mesozoic subduction at the Gondwana margin. Our study therefore highlights that a mafic lower crust can lead to deep seismicity within a region undergoing transpression.

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Based on outcrop observations in the National and State Parks, the present study demonstrates that the white mass in “White Pocket” is a thick blanket of weathering crust developed in arid region (desert crust), composed of minerals, deposited from uprising groundwater. “Cauliflower Rock” and surface mounds are erosional remnants cored with undisturbed stratified sandstone mass. Large scale soft sediment deformation involved in the formation of “Cauliflower Rock” is not supported by the current study and the reported “contorted formation” can be simply attributed to the appearance of undisturbed cross-bedding sets exposed on erosional surfaces with different curvatures and orientations.

A document by Rosa Isabella Cuppari. Click on the document to view its contents.

11 12 Corresponding author: Niko Fedkin ([email protected]) 13 Key Points: 14 • Satellite NO2 records and trends of urban, coastal and deep water areas from 2005 to 15 2022, are presented 16 • Classifying NO2 over the Gulf of Mexico (GOM) under various wind conditions 17 highlights typical patterns in average NO2 values 18 • GOM NO2 hotspots from deepwater platforms were identified by TROPOMI under calm 19 wind conditions, the largest of which is over Mars/Olympus 20 21 Abstract 22 The Outer Continental Shelf of the Gulf of Mexico (GOM) is populated with numerous 23 oil and natural gas (ONG) platforms which produce NOx (NOx = NO + NO2), a major component 24 of air pollution. The Bureau of Ocean Energy Management (BOEM) is mandated to ensure that 25 the air quality of coastal states is not degraded by these emissions. As part of a NASA-BOEM 26 collaboration, we conducted a satellite data-based analysis of nitrogen dioxide (NO2) patterns 27 and trends in the GOM. Data from the OMI and TROPOMI sensors were used to obtain 18+ year 28 records of tropospheric column (TrC) NO2 in three GOM regions: 1) Houston urban area, 2) near 29 shore area off the Louisiana coast, and a 3) deepwater area off the Louisiana coast. The 2004-30 2022 time series show a decreasing trend for the urban (-0.027 DU/decade) and near shore (-31 0.0022 DU/decade) areas, and an increasing trend (0.0019 DU/decade) for the deepwater area. 32 MERRA-2 wind and TROPOMI NO2 data were used to reveal several NO2 hotspots (up to 25% 33 above background values) under calm wind conditions near individual platforms. The NO2 34 signals from these deepwater platforms and the high density of shallow water platforms closer to 35 shore were confirmed by TrC NO2 anomalies of up to 10%, taking into account the monthly TrC 36 NO2 climatology over the GOM. The results presented in this study establish a baseline for future 37 estimates of emissions from the ONG hotspots and provide a methodology for analyzing NO2 38 measurements from the new geostationary TEMPO instrument. 39 40 Plain Language Summary 41 Oil and natural gas operations emit nitrogen oxides (NOx), which are major air pollutants and 42 precursors to ground-level ozone. The Bureau of Ocean Energy Management (BOEM) agency is 43 responsible for managing planned oil and natural gas (ONG) activity on the outer continental 44

Glacier flow is typically modeled using a power law rheology known as the Glen–Nye flow law, with the power n assumed to be 3. However, recent research and past observations suggest that n=4 may better represent ice flow in some locations. We lack a quantitative understanding of how much this exponent affects ice loss projections, and its significance relative to other sources of uncertainty. Here, we test the effect of n=3 versus n=4 in a series of 300-year forward simulations of the Amundsen Sea Embayment, West Antarctica. We find that in periods of rapid grounding line retreat, uncertainty in n leads to a larger spread in ice loss projections than the spread due to uncertainty in climate forcing. The spatial sensitivity of n is generally proportional to the change in strain rates, so we expect regions undergoing more moderate dynamic change to be less sensitive to n.

A document by Avelon Gerritsma. Click on the document to view its contents.

Measurements of riverine dissolved inorganic carbon (DIC), total alkalinity (AT), pH, and the partial pressure of carbon dioxide (pCO2) can provide insights into the biogeochemical function of rivers including the processes that control biological production, chemical speciation, and air-water CO2 fluxes. The complexity created by these combined processes dictates that studies of inorganic carbon be made over broad spatial and temporal scales. Time-series data like these are relatively rare, however, because sampling and measurements are labor intensive and, for some variables, good measurement quality is difficult to achieve (e.g., pH). In this study, spectrophotometric pH and total alkalinity (AT) were quantified with high precision and accuracy at biweekly to monthly intervals over a four year period (2018-2021) along 216 km of the Upper Clark Fork River (UCFR) in the northern Rocky Mountains, USA. We use these and other time-series data to provide insights into the processes that control river inorganic carbon, with a focus on pCO2 and air-water CO2 fluxes. We found that seasonal snowmelt runoff increased pCO2 and that expected increase and decrease of pCO2due to seasonal heating and cooling were likely offset by an increase and loss of algal biomass, respectively. Overall, the UCFR was a small net source (0.08 ± 0.14 mol m-2 d-1) of CO2 to the atmosphere for all four years of our study with highly variable annual averages. The highly dynamic, seasonally correlated, offsetting mechanisms highlight the challenges in predicting pCO2 and air-water CO2 fluxes in rivers.

High-resolution ionospheric structure estimation with low latency is essential for the stable maintenance of various future services. However, no papers have yet addressed this issue. In this paper, a new algorithm for real-time high-resolution ionospheric tomography within a large area is developed. The algorithm uses the property that the ionospheric electron number density does not change significantly in 30 seconds, the observation interval of the Total Electron Content (TEC), to estimate the unknown distribution using the known immediately preceding distribution as the initial solution. The conjugate gradient method is used to search for the solution, but it is converged very quickly by using a diagonal scaling matrix, which is a very simple preprocessing step. Using the algorithm on actual ionospheric data, we found that it is possible to estimate the electron number density distribution with an unprecedentedly high resolution of 0.25° square for TEC data within a 1-minute interval. The algorithm also reconstructed the ionospheric structure during the occurrence of Medium Scale Traveling Ionospheric Disturbances (MSTID), and was able to estimate the detailed its horizontal and vertical structures. This indicates that this algorithm is useful for real-time estimation of the three-dimensional structure of ionosphere. Further development of a system utilizing this algorithm will lead to further studies of the ionospheric mechanisms.

The process of two-phase fluid displacement in the porous medium is still poorly understood partly due to the absence of effective reconstruction methods featured in a 3D real-time fashion. This manuscript proposes the application of thermoacoustics (TA) imaging, an emerging real-time imaging technique, to reconstruct the dynamic surfactant-enhanced imbibition process into the oil-saturated sand. It is both theoretically and experimentally demonstrated that a significant TA contrast exists between the water-saturated sand and oil-saturated sand under the same microwave power. In the experiment, a U-shaped infiltration path is embedded 20mm underneath the oil-saturated sand as the ground truth profile of the water flow. A calibration process is conducted to account for the amplitude attenuation and velocity dispersion effects of the TA wave in the sand, and a two-layered medium sensing matrix is built for the inversion process. The reconstructed images match well with the infiltration path, which makes it feasible to monitor the subsurface 3D water-oil displacement in non-transparent porous sand in a real-time fashion.

Dotson Ice Shelf has resisted acceleration and ice-front retreat despite high basal-melt rates and rapid disaggregation of the neighboring Crosson Ice Shelf. Because of this lack of acceleration, previous studies have assumed that Dotson is durable. Here we show clear evidence of Dotson's vulnerability as it decelerates, contrary to the common assumption that ice-flow deceleration is synonymous with increased ice-shelf buttressing. Ungrounding of a series of pinning points initiated acceleration in the Upper Dotson in the early 2000s, which subsequently plugged ice flow in the Lower Dotson. Discharge from the tributary Kohler Glacier into Crosson increased, but non-proportionally. Given current surface-lowering rates, we estimate that several remaining pinning points in the Upper Dotson could unground within one to three decades.

Robust increases in temperatures will occur globally across the twenty-first century; however, for some regions, sign changes in rainfall remain uncertain. Navigating this uncertainty is crucial in addressing drought-related challenges faced by climate-exposed sectors. New Zealand represents these challenges, exhibiting significant model uncertainty in warm-season rainfall change. Here, we examine how temperature-driven increases in potential evapotranspiration interact with contrasting storylines of future rainfall to explore drought outcomes for New Zealand. In our drying storyline, we find that increasing temperatures accompanied by less rainfall bring forward the onset of drought several months and delay its termination. In the wetting storyline, increases in rainfall partly offset the temperature-induced drying effect, leading to minor reductions in soil moisture. Examining extreme years, the average hydrological year in the future becomes comparable to the driest years of the current climate, while the worst future events exhibit unprecedented drought severity.

Besides the forces described by Newtonian dynamics, there is an additional cosmological force in the Universe, which is observed in experiments, but does not follow from Newton's law of gravitation. The additional cosmological force was not represented in Newtonian dynamics. The law of cosmological force Fcos = (mc^2)√Ʌ is derived. The law of cosmological force makes it possible to obtain the extended law of universal gravitation. The extended law of universal gravitation includes two laws of gravitation: Newton's law of gravitation and the law of cosmological force. The extended law of universal gravitation does not have the limitations of Newton's law of gravitation. It describes the full force of gravitational interaction both on small scales and on the scale of the Universe. The coupling constants in the extended law of universal gravitation are two constants: the Newtonian constant of gravitation G and the cosmological constant Ʌ. The equation of the extended law of universal gravitation without using the gravitational constant G is given. The extended law of universal gravitation gives an explanation of the Galaxy rotation curve and the Pioneer anomaly. Extended Newtonian dynamics is able to provide solutions to the problems of astrophysics and cosmology without expecting (and instead of) quantum gravity.

As wildfire pervasiveness increases with a changing climate, there is a need to develop new techniques with emerging technologies to understand the interaction between wildfires and the surrounding atmosphere at a high spatiotemporal resolution. The Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) experiment conducted in 2019 focused on wildfires using several measurement platforms aboard aircraft. In this study, we interpret wind measurements across a boundary layer (BL) trapped smoke plume from an airborne Doppler lidar (DL). Flight transects parallel and perpendicular to the orientation of the plume enabled the characterization of key features such as a fire-induced spanwise vortex, large downdrafts that modified the smoke plume, and the evolving velocity structure at different distances downwind of the fire-induced convergence zone (FICZ) at an unprecedented horizontal and vertical resolution of 10s of meters.

In the nightside region of Earth’s magnetosphere, buoyancy modes have been associated with low entropy bubbles. These bubbles form in the plasma sheet, particularly during substorm expansion, and move rapidly earthward and come to rest in the inner plasma sheet or inner magnetosphere. They often exhibit damped oscillations with periods of a few minutes and have been associated with Pi2 pulsations. In previous work, we used the thin filament approximation to compare the frequencies and modes of buoyancy waves using three approaches: magnetohydrodynamic (MHD) ballooning theory, classic interchange theory, and an idealized formula. Interchange oscillations differ from the more general MHD oscillations in that they assume a constant pressure on each magnetic field line. It was determined that the buoyancy and interchange modes are very similar for field lines that extend into the plasma sheet but differ for field lines that map to the inner magnetosphere. In this paper, we create a small region of entropy depletion in an otherwise stable entropy background profile of the magnetotail to represent the presence of a plasma bubble and determine the properties of the buoyancy modes using the same 3 approaches. In the bubble region, we find that in some regions the interchange and buoyancy modes overlap resulting in frequencies that are much lower than the background. In other regions within the bubble, we find interchange unstable modes while in other locations MHD normal mode predicts an MHD slow mode wave solution which is not found in the pure interchange solution.

A document by Doris Voina. Click on the document to view its contents.