In the tropical ocean, diurnal heating and the formation of atmospheric convection cells associated with local precipitation events, cold pools and wind bursts, have been shown to impact air-sea exchange and the structure of the ocean surface layer. Here, we use a high-resolution regional ocean model, forced by an atmospheric Large Eddy Simulation (LES) that explicitly resolves these processes in a realistic scenario in the tropical north-east Atlantic Ocean, to study their impact on the ocean surface layer and parameterized air-sea fluxes. We find that the oceanic heat loss is, unexpectedly, reduced in the presence of cold pools by on average 30 W m-2 due to the higher air humidity, weaker mean winds, and increased cloud cover. Our results also show that the total non-solar heat flux is dominated by the diurnal cycle of the trade winds, rather than by diurnal heating. In the ocean surface layer, local wind bursts, rain layers, and cloud shading induce a strong lateral variability in the strength and depth of Diurnal Warm Layers, questioning the local applicability of available bulk parameterizations. From a series of numerical tracer experiments, we identify a new shear-dispersion mechanism, induced by the Diurnal jet, that is reflected in an extreme anisotropy of horizontal dispersion with diffusivities of order 10-100 m2 s-1.

Thomas C. Harmon1,2,3, Humberto Flores3, Lorenzo Booth4, Emily R. Waring2,Emily Gomez1, and Stefano Carpin4,51Department of Civil & Environmental Engineering, University of California Merced2Sierra Nevada Research Institute, University of California Merced3Enivronmental Systems Graduate Program4Electrical Engineering & Computer Science Graduate Program, University of California Merced5Department of Computer Science, University of California MercedPoster presentation GC51P-0859 at the Fall 2023 Meeting of the American Geophysical Union, San Francisco, CA, December 12-16, 2023

Mirror mode structures are born from a plasma instability driven by a large temperature anisotropy and appear downstream of planetary and interplanetary shocks, in their magnetosheath. As magnetic bottles imprisoning dense and hot plasma, they are usually observed downstream of their region of formation, where the anisotropy is large and free energy is available, implying that they are advected with the plasma flow to the detection region. At Earth and other planets, the quasi-perpendicular shock provides the plasma with the necessary heating along the perpendicular direction to the local magnetic field. At Mars, which boasts an extended exosphere, an additional source of temperature anisotropy exists, through unstable ring-beam velocity distributions, that is, through ions locally ionised and subsequently picked up by the local electric fields. We report here for the first time an example of near locally-generated mirror mode structures at Mars using the full plasma instrument suite on board the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. We present three events in quasi-perpendicular and quasi-parallel shock conditions with a variable exosphere, discuss the locality of the mirror modes excited and show that, in addition to the classic quasi-perpendicular source of anisotropy, another source exists, that is, unstable pickup protons. The existence at Mars of this extra ion anisotropy-generating mechanism is reminiscent of comets.

A document by Jeffrey P. Morgenthaler. Click on the document to view its contents.

Differences in slab dehydration and fluid transport influence the distribution of magmatism and seismicity in subduction zones. Southwest Japan, particularly Kyushu and Shikoku/Chugoku, exhibits significant along-arc variation in the spatial distribution of Quaternary arc volcanoes and adakites as well as sub-arc tectonic tremors. Using two-dimensional numerical modeling, we quantitatively evaluate melting and fluid transport via a weak hydrous layer on the slab interface since the subduction initiation to clarify the observed key differences. In Kyushu, our model shows that dehydration of the colder subducting slab is mostly completed at sub-arc depths of 80–120 km, triggering intense flux melting in the mantle wedge without slab melting for adakite and an absence of sub-forearc fluid percolation for tremors. Whereas, the model for Shikoku/Chugoku shows shallower sub-forearc dehydration of the warmer slab (<80 km), allowing less flux melting, slab melting for adakite, and sub-forearc fluid percolation for tremors.

Unsustainable rates of groundwater (GW) depletion make GW management a priority. Effective GW management is hindered by the uncertainty in the predictions of aquifer models, but the increase of geodetic surface deformation data can improve aquifer characterization. We integrate surface deformation measurements into a Bayesian inference framework to infer aquifer permeability in a poroelastic model. We demonstrate the applicability of this technique using a Nevada pumping test with both Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) surface deformation data. We infer the lateral permeability variations in the aquifer with high spatial resolution and identify the information content of each data set. For the Nevada case, a single InSAR surface deformation map provides significantly more information than multiple GPS time series. As the availability of global InSAR data continues to grow, geomechanical inversion of geodetic surface deformation data will become a valuable technique for aquifer characterization and management.

Turbulence and sound are important cues for oyster reef larval recruitment. Numerous studies have found a relationship between turbulence intensity and swimming behaviors of marine larvae, while others have documented the importance of sounds in enhancing larval recruitment to oyster reefs. However, the relationship between turbulence and the reef soundscape is not well understood. In this study we made side-by-side acoustic Doppler velocimeter turbulence measurements and hydrophone soundscape recordings over 2 intertidal oyster reefs (1 natural and 1 restored) and 1 adjacent bare mudflat as a reference. Sound pressure levels (SPL) were similar across all three sites, although SPL > 2000 Hz was highest at the restored reef, likely due to its larger area that contained a greater number of sound-producing organisms. Flow noise (FN), defined as the mean of pressure fluctuations recorded by the hydrophone at f < 100 Hz, was significantly related to mean flow speed, turbulent kinetic energy, and turbulence dissipation rate (ε), agreeing with theoretical calculations for turbulence. Our results also show a similar relationship between ε and FN to what has been previously reported for ε vs. downward larval swimming velocity (wb), with both FN and wb demonstrating rapid growth at ε > 0.1 cm2 s-3. These results suggest that reef turbulence and sounds may attract oyster larvae in complementary and synergistic ways.

Household air pollution accounts for about 4 million premature deaths annually worldwide with Ghana recording about 8,800 deaths each year amidst the HAP-influenced diseases resulting in increasing health expenditure. Clean Cook solutions such as the adoption of LPG and ICS can be used to mitigate household air pollution and save lives. This study sought to estimate the BCR and NPV of LPG and ICS over a 10-year and 3-year period respectively and assess Ghana's policy context on the phenomenon. The study found a lack of a comprehensive national policy on the phenomenon and the need for a national strategy and policy in addressing these as there currently exist policy gaps and a disjointed efforts between the relevant state institutions. The study also found the LPG intervention to be the most beneficial and having more health and environmental benefits as it recorded higher BCRs and NPVs than the ICS. However, considering the average annual household expenditure, the ICS had a higher chance of public acceptance due to its affordability than the LPG. Considering the high adoption cost of LPG as compared to the ICS, it is recommended that the government gives tax holidays to local manufacturers of methane stove and LPG cylinders to reduce the cost of production and sales price and place subsidies on LPG to minimize the cost of operation to encourage households to adopt this cleaner option. It is also recommended that the government invests in research into innovative clean cook solutions that consider the economic inequities.

A document by Timothy Scheibe. Click on the document to view its contents.

The forward simulation of radar reflectivity requires details of clouds and precipitation from general circulation models (GCMs). But such details are represented as sub-grid processes that involve parameterizations and assumptions about the spatial coverage and thus depend on the GCM. In this research, we propose the use of a statistical method to generate sub-grid precipitation for generic use. In addition, the proposed method can be used to provide uncertainty estimates on the signals. The sub-grid variability is obtained from simulation with a global storm-resolving model called NICAM (non-hydrostatic icosahedral atmospheric model). The proposed method first generates precipitation probabilities for the possible scenarios and then sub-grid precipitation rates are generated from the generalized gamma distribution for the given cloud fraction and grid-scale precipitation rates. Compared to the standard method (which neglects the probabilities) that overestimates the precipitation fraction, our method well reproduces the NICAM dataset profiles of both the precipitation fraction and the radar-based cloud fraction. The in-cloud signal frequencies are also reproduced, although less accurately over a tropical region. Inclusion of sub-grid variability in precipitation rates was particularly important for the tropical region to obtain agreement of the precipitation fraction. Application of the two methods to a GCM shows it to have a robust bias for low-level liquid clouds. The proposed method can be used to identify uncertainty in the signals associated with sub-grid variability in the precipitation processes, indicating an effective way to use a global storm-resolving model to evaluate conventional GCMs.

Precise knowledge of geocenter motion, i.e., the relative motion between the Earth's center of mass (CM) and the center of figure of the Earth's surface (CF), is crucial to high-stakes geodetic applications such as sea level rise monitoring with satellite altimetry or the establishment of regional and global mass budgets with satellite gravimetry. The computation of the latest release of the International Terrestrial Reference Frame, ITRF2020, involved the estimation of a field of seasonal motions for a global network of geodetic stations, expressed with respect to CM, as sensed by Satellite Laser Ranging, from which the translational part represents seasonal geocenter motion. This paper presents two different methods to isolate seasonal geocenter motion from the field of ITRF2020 seasonal station motions, among which a new method based on a direct weighted average of seasonal station motions, with station-specific weights chosen so as to provide a better approximation of CF than the standard network shift approach. The ITRF2020 annual geocenter motion model thus obtained is then compared with other recent geodetic and geophysical estimates. Although different subgroups of estimates with relatively good internal consistency may be identified, the overall scatter of recent geodetic estimates remains at the level of several mm, i.e., close to the amplitude of annual geocenter motion itself. Efforts toward reconciling seasonal geocenter motion estimates therefore still appear necessary. Meanwhile, it would seem safe to assume that seasonal geocenter motion models, in particular those currently used in satellite altimetry and satellite gravimetry, are still uncertain.

A document by Dustin Roten. Click on the document to view its contents.

Large language models are moving into a multi-modal space covering text, images, audio, and other media, yet scientific datasets possess features that are not represented by this paradigm. In cosmology, for instance, galaxies are embedded within dark matter-dominated collapsed objects, termed halos. A galaxy can be described in many ways: star formation history (SFH) characterizing the evolution of stellar content, magnitudes describing luminosity across different wavelengths (MAG), images, or matter distribution of the hosting halo. Despite their differences, these descriptions represent the same cosmological object. We propose the Object Foundation Model (OFM) to learn disparate representations of objects in scientific domains. OFM learns the general underlying representation of sparse and indeterminate data and facilitates robust predictions on diverse inputs. Unlike traditional deep learning with architecture-specific predictions, the OFM predictions are requested via a language-based key that varies with the user query. 

Patrick Naple1, S. McKenzie Skiles1*, Otto I. Lang1, Karl Rittger2, Sebastien J.P. Lenard2, Annie Burgess3, Thomas H. Painter4,5

We estimated the mineralogy of the effusive and explosive units at the Gardner shield volcano using Chandrayaan-1 Moon Mineralogy Mapper (M3) data and Lunar Reconnaissance Orbiter (LRO) Diviner data. We present a high-resolution 3D morphological map of the shield based on LRO Camera (LROC) Narrow Angle Camera (NAC) and Wide Angle Camera (WAC) images and LOLA SLDEM data. The shield shows evidence of caldera subsidence with downsag and possible trapdoor style subsidence, including a central normal fault, partially developed fault-ring structure, resurgence, and subsidence blocks, two sinuous rilles, graben, lineaments, a parasitic cone SE of the central caldera. The shield comprises 5 prominent voluminous and 10 thinner effusive basaltic flow units, and one explosive unit displaying pyroclastic material at the center of the caldera. North of the caldera is Gardner crater, which is a simple bowl-shaped impact crater, formed after the shield, revealing fresh mineralogy from the shield and highlands, including high calcium pyroxene, olivine, and Fe-spinel. The crater has a dark debris flow on its eastern wall, landslides, a boulder cluster, boulder tracs, and lineaments. The shield presents a unique lava river channel originating from a secondary oblique fault ~ 5 km wide and spreading tens of kilometers at the northern part of Mare Tranquillitatis. Our volcano-tectonic study indicates that the Gardner shield is a science rich site with exploration potential to study basaltic caldera-forming volcanoes with in-situ pyroclastic resources as it comprises almost all the major compositional and structural aspects to understand lunar thermal, tectonic, and geological evolution.

We have carried out a statistical study of neutral atmospheric parameters in the mesosphere lower thermosphere (MLT) region, by utilizing simultaneous measurements from the EISCAT VHF radar and sodium LIDAR collocated at  Tromsø , Norway. This study focuses on the incoherent scatter (IS) spectral width, which is a function of the ion-neutral collision frequency, ion temperature, (equal to neutral temperatures in the D-region), and ion mass. Using the neutral temperatures obtained from LIDAR, and ion mass estimated using a chemistry model, we have measured the ion-neutral collision frequency in the 80-100 km altitudes by fitting the spectral width. The study shows that the current widely used formulae underestimate the ion-neutral collision frequency on average by 1.53\(\pm\)0.24 in comparison to the measurements. Also, the measured collision frequencies showed large temporal variations due to neutral density fluctuations, indicating the presence of atmospheric waves. The amplitudes of these waves are found to be as large as 50% of the background densities. This suggests that individual spectral width measurements are likely influenced by these random neutral density fluctuations, which can have a significant impact on the IS temperature fits. In addition, for altitudes below 85 km, the ion mass increases drastically indicating the presence of heavy cluster ions. The dominance of heavy ions makes it further challenging to extract the temperature values from the spectral width at these altitudes. In light of these observations, the inherent limitations of inferring temperatures from IS spectral width in the MLT altitudes are studied.

The knowledge of the composition and dynamics of eruption columns is very important because tephra dispersal strongly depends on it. Few measurements on the vertical distribution of volcanic particles within the eruption column are available. In this work, we analyze data from the X-band radar that were located 75 km far from the crater of Grímsvötn (Iceland) during the eruption in 2011 and propose a first attempt to characterize how the mass eruption rate and the particle size are distributed within the eruption column. We find that both quantities are not uniformly distributed along it. In particular, a greater percentage of particle size and mass eruption rate is confined in the convective region with respect to the umbrella region. We think that this work can make new advancements in the characterization and dispersal of explosive eruptions.

A manuscript prepared for Water Resources ResearchbyYun Yang 1, Hongbin Zhan 3, Haibo Feng 2, 4, Zhongxia Li 1, 4, *, Junwei Wan 1, Xianshuo Yang1, Shuai Yuan 1, Kun Huang 11 School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China.2 School of Geography and Information Engineering, China University of Geosciences, 430074 Wuhan, China.3 Department of Geology and Geophysics, Texas A & M University, College Station, TX 77843-3115, USA.4 Key Laboratory of Mine Ecological Effects and Systematic Restoration, Ministry of Natural Resources, Beijing, 100081.* Corresponding authors: