The Snow Water Equivalent (SWE) describes the amount of water stored in snow. The SWE is a key parameter for various applications including meteorological information systems, run-off predictions for hydro power plants, and roof load monitoring. The SWE as well as the snow height and liquid water content can be determined with Global Navigation Satellite System (GNSS) signals. The set-up consists of two GNSS antennas where as one antenna is placed on the ground below the snow and the second one is placed on a pole above the snow, and serves as reference antenna. The differential GNSS signals are affected by the relative position between the antennas, the snow and the GNSS carrier phase ambiguities. The GNSS signals are refracted at the air-snow interface, and attenuated and delayed in the snow pack. The contribution of this talk is three-fold: First, we have extended our snow parameter estimation [2,3] from a single-frequency, dual constellation (GPS + Galileo) solution to a multi-frequency, triple-constellation (GPS + Galileo + Beidou) solution [1]. Secondly, we have used a Kalman filter to continuously estimate the SWE and carrier phase ambiguities [1] instead of a least-squares estimation. Third, the float ambiguity estimates are now fixed to integer numbers with the Least-Squares Ambiguity Decorrelation Adjustment (LAMBDA) method. The first results are very promising and indicate that the measurement period for snow parameter estimation can be reduced from several hours to less than 30 minutes. References: [1] Julian Weiss: “Snow Parameter Estimation with Multi-Frequency and Multi-Constellation GNSS”, Master thesis, Techn. Univ. Muenchen, Germany, 2021. [2] Patrick Henkel, Franziska Koch, Florian Appel, Heike Bach, Monika Prasch, Lino Schmid, Juerg Schweizer, and Wolfram Mauser: “Snow Water Equivalent of Dry Snow Derived from GNSS Carrier Phases“, in: IEEE Transactions on Geoscience and Remote Sensing, vol. 56, issue 6, pp. 3561 – 3572, Jun. 2018. [3] Franziska Koch, Patrick Henkel, Florian Appel, Lino Schmid, Heike Bach, Markus Lamm, Monika Prasch, Juerg Schweizer, and Wolfram Mauser: “Retrieval of snow water equivalent, liquid water content, and snow height of dry and wet snow by combining GPS signal attenuation and time delay“, in Water Resources Research, vol. 55, issue 5, pp. 4465 – 4487, May 2019.

The science community’s progression toward Python as a primary programing language, facilitated NASA’s Global Precipitation Measurement (GPM) Ground Validation (GV) Program to develop a Python-based radar processing system, GVradar. GVradar consists of two modules: Dual-Polarimetric Quality Control (DPQC) and dual-polarimetric precipitation product generation (dp_products). Both modules take full advantage of the open-source Python Atmospheric Radiation Measurement (ARM) Radar Toolkit (Py-ART) and Colorado State University’s Radar Tools (CSU Radar Tools). Within DPQC, parameter threshold gate filters are utilized to identify and remove non­-precipitating echoes based on freezing level, beam height, or by user defined sector. Additional DPQC capabilities include unfolding of Differential Phase (Φdp), Specific Differential Phase (Kdp) retrieval, velocity de-aliasing, and application of calibration offsets. Precipitation products generated with CSU Radar Tools include HIDRO Rain Rate (RC) and Hydrometeor Identification (FH). Additional products include GPM-GV’s mass weighted mean diameter (Dm) and normalized intercept parameter (Nw). Dm and Nw retrievals were computed from empirical equations using disdrometer derived Zdr data obtained during GPM field experiments. The recommended method of executing GVradar is to use a user designated parameter dictionary, however the code will run with default settings. The use of a dictionary allows the user to optimize QC thresholds, specify fields to generate, and select output and plotting options. The ability of GVradar to retrieve sounding data from the Rapid Refresh (RAP) model allows DPQC to be applied and dp_products to be generated in near real-time. NASA’s Dual Polarimetric (NPOL) radar is currently using GVradar to display data in near real-time. GPM-GV developed GVradar as a user-friendly open-source radar processing tool that is freely available to the scientific community.

Light absorption in the photosynthetically active (400 – 700 nm) spectral region is necessary for plant CO2 fixation via photosynthesis. Light absorption in excess of that which can be used for photosynthesis may result in photoinhibition and/or other processes detrimental to normal plant function. Plants have evolved several photoprotective mechanisms to reduce light absorption under stressful conditions. For example, leaf-level reflectance and transmittance increased as a result of chloroplast movement within leaf cells in response to water stress in greenhouse-grown maize and soybean. This has implications for detecting (as a signal and noise) diurnal and stress-related changes in canopy reflectance in field-grown crops. These changes were recently investigated in the field using newly developed instrumentation systems and software. Two hyperspectral spectrometers, an Ocean Optics QE Pro (0.3 nm resolution in the 650 - 813 nm range) and a Flame (2.0 nm resolution in the 340 - 1028 nm range) are coupled through optical shutters to a downward looking fiber (25° field of view) and an upward looking fiber with cosine corrector. The spectrometers can be configured to see sky or surface targets concurrently or separately. This new configuration offers concurrent measures of derived solar induced fluorescence (SIF), and visible and near infrared reflectance on a mobile platform, acquiring spatially averaged responses. Our goal is to use SIF as an indicator of the level of photosynthetic activity in comparison to reflectance-derived indication of photoprotective response. In conducting data acquisition, several technical issues arose. Different spectrometer integration times, due to differing radiometric sensitivities and changing sky conditions, causes differences in measured reflectance between the two spectrometers. Also the approach highlighted the difficulty of obtaining reliable system calibration under varying sky conditions when using near-Lambertian reference panels. While results are promising in detecting SIF along with more conventional remote sensing spectral resolution, further research is needed to refine data acquisition to ensure quality reflectance measurements. We report on technical issues and on our success in tying photoprotection to changes in photosythentic activity.

This study is motivated by the observation that after a wave breaking event in the ocean, the residual surface foam left in the wake of the breaker rapidly cools down. The relationship between the cooling foam and the characteristics of the breaking wave such as bubble plume dynamics, visible surface foam, and energy dissipation is investigated experimentally. Previous studies have suggested that the decay time of the visible foam can be used to determine the dynamics of the subsurface bubble plume, and to estimate the energy dissipation by the breaking process. But the foam decay process can be greatly affected by the surfactant concentration in the ocean and this effect need to be accounted for independently. We present a new approach that utilizes the thermal signature of the cooling foam to infer the breaking characteristics and is less sensitive to surfactant concentration. The experiments are conducted in a wave flume that is equipped with a piston-type wavemaker and is filled with salt water. In order to study the effects of surfactants on the cooling of the residual foam, two sets of experiments are carried out; In the first set clean salt water is used and in the second set, Triton X-100 at a concentration of approximately 200 mg/L is added to the water. Breaking waves are generated using the focusing wavepacket technique and are designed to cover a wide range of slopes and breaking intensities. The bubble plume and the surface foam are imaged using visible cameras and the surface temperature is captured using an IR camera with an overlapping field of view with the visible foam camera. It is observed that the average temperature of the foam initially increases after the passage of a breaking wave due to the disruption of the cool skin layer, but the foam starts to cool down soon after the bubble plume has subsided, and the foam regeneration is not sustained by the bubbles anymore. It is found that the time from the start of the breaking process to the onset of cooling of the foam (τcool) scales with the decay time of the bubble plume (τplume), energy dissipation, and the wavepacket slope of the breakers. It is also observed that the foam decay time is prolonged greatly by the presence of additional surfactants (consistent with the literature), but the bubble plume decay time and the onset of cooling of the foam are not significantly affected.

Many disciplines within the geosciences require computational skills to access, analyze, and visualize data. These are skills students need to be competitive in the work environment. Applying computational thinking and basic coding into the classroom can diversify student learning, develop 21st century skills, and demonstrate real world applications through project based learning. Teaching students to have a broad base of knowledge and a range of skills is paramount in developing career ready-students. Working in collaboration with members of the Earth Science Information Partners (ESIP) Education committee, education professionals from UNAVCO, NOAA, Cooperative Institute for Mesoscale Meteorological Studies and teachers from schools around the country are exploring the use of basic coding and programmable robots as a springboard to learn computational thinking and skills within an Earth science context. By encouraging teachers to learn how to code, we help them to encourage their students to be creators, more than just consumers, of the technology around us and to foster curiosity that whets their appetites to learn more!. This presentation will elaborate upon coding in the classroom initiatives these partners are facilitating from workshops, learning materials, and insights from workshop feedback.

Following the radioactive fall out of the 2011 Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, radiocesium (Cs-137) contaminated soils of forests, uplands, rice paddies and other land uses released contaminated sediments onto neighboring areas and into the creeks and rivers in Iitate Village, Japan. The study used conventional and Cs-137 fingerprinting techniques to determine runoff and suspended sediment discharges to assess the small and large-scale soil redistribution dynamics within contributing areas in two watersheds. Also, we attempted to use Cs-137 fingerprinting to identify spatial and temporal patterns of erosion, transport and sedimentation on hillslopes within those watersheds. Tributaries near the outlet of the 30 km2 Hiso watersheds were simulated at the hillslope and watersheds using the process-based Water Erosion Prediction Project (WEPP) model and the Geospatial Interface for WEPP (GeoWEPP). Besides the simulation of historic soil redistribution events, a particular emphasis was the identification and assessment of various land use and cover changes on the past soil redistribution. Results of the analysis in the post-fallout landscapes enables scientists and farmers as well as natural resources and disaster managers to investigate the consequences of active and passive land use and cover changes on the runoff and sediment dynamics at the plot, hillslope and watershed scales. Especially the behavior of Cs-137 contaminated clay particles in soils and sediments seem to be the key for the success of the measurement, modeling and management techniques. The result of this study has the potential to assist decision and policymaking for stakeholders not only in areas that were impacted by the contamination through radioactive fallout.

The roles of heavy ions have long been an important subject in the magnetospheric physics since the first discovery of O+ ions in the magnetosphere as it hinted to the connection between the ionospheric and magnetospheric plasma. Albeit limited, several observations show the importance of ionospheric N+ and molecular ions, including NO+, N2+ and O2+, in the high-altitude ionosphere and magnetosphere. However, the mechanisms responsible for accelerating the ionospheric heavy ions from eV to keV energies are still largely unknown. Developed from the Polar Wind Outflow Model (PWOM), the Seven Ion Polar Wind Outflow Model (7iPWOM) solves the gyrotropic transport equations for all relevant species (e-, H+, He+, N+, O+, N2+, NO+ and O2+) along open magnetic field lines and therefore, has the capability to assess the role of heavy ions in the supersonic ionospheric outflow. However, the hydrodynamic approach is limited to the region where collisions are important. For the altitudes above the collision-dominated region, the hydrodynamic solution becomes increasingly inadequate. Thus, the 7iPWOM applies a kinetic particle-in-cell (PIC) approach that enables the inclusion of wave-particle interactions (WPI) and Coulomb collisions. The simulation results showed that the N+ ions play a key role in the polar wind solution under all conditions. The mechanisms responsible for the energization of outflowing N+ ions are different than those of O+, not only in the collision-dominated region but also at high-altitudes. This means that the local heating sources to O+ and N+ in the polar wind, even in small amounts, can lead to plasma instability and could possibly affect the large-scale transport properties. In addition, the relative abundance of molecular ions, and how they change the polar wind solution, reveals the link between lower thermosphere and the ionosphere. Therefore, tracking the molecular ions helps understand how the “fast ion outflow” acquires sufficient energy in such a short time scale, compared with the dissociative recombination lifetime of the molecular ions, and assess the role of molecular ions in the overall dynamics of the polar wind outflow.

In this work we examine the seismicity of Montefeltro, a historical region of central Italy located between the northern Apennines and the Republic of San Marino towards the northern Adriatic coast. The seismicity of the northern Apennines region is mainly concentrated along the chain within a seismogenic layer that extends from about 5 to 15 km depth. Recently, important seismic sequences occurred in the central-northern Apenninic chain with magnitudes exceeding 5.5 (Colfiorito 1997, Mw 6.0; L’Aquila 2009 Mw 6.3; Emilia 2012, Mw 6.1; Amatrice 2016, Mw 6.5). Instead, the seismicity of Montefeltro, as recorded in the past three decades, appears quite widespread and discontinuous over time, except in some phases of intense activity. The magnitudes detected so far vary essentially from low to moderate, lower than 4.5 for the largest events. Unfortunately, the region that includes the Montefeltro is still not adequately monitored, therefore a detailed analysis of the background seismicity, the calculation of focal mechanisms for low magnitude events, and a more reliable estimate of the b-value is limited. To better define these parameters, a temporary seismic network has been set up starting from December 2018 to integrate the instrumental coverage provided by the Italian National Seismic Network (RSN). The analysis of the seismic activity occurred in the period January 2005 – up to now shows a sporadic, rather diffuse background seismicity marked by small magnitude seismic sequences strongly clustered in time and space. The most important sequences occurred in September-October 2005 (M=3.2) and August-September 2006 (M=3.7), nearby the towns of Macerata Feltria and Casteldelci, respectively. The spatio-temporal evolution of these main episodes highlights an energy release consistent with swarm-like activity. Others clusters of less intensity and duration were observed in January 2011 (ML 2.2, 15 events), September 2012 (ML 2.8, 6 events), and July 2015 (ML 2.3, 10 events). These bursts are confined in the upper crust contrary to the swarm-like seismicity which extends up to ~25 km depth. Another major feature of the seismicity pattern is represented by the occurrence of events even in the lower crust and in the upper mantle down to at least 50 km depth.

The rapid retreat of tropical glaciers in the Cordillera Blanca, Peru, results in significant changes to the quality and quantity of the streamflow below. Debris-covered glaciers are a common feature in this region but have previously only been studied in terms of their geomorphology and surface characteristics. Short term studies have used hydrochemical mixing models to estimate contributions of melting glaciers to down valley streams. The progressive impact that these glaciers have on streamflow and water chemistry as climate change continues to force glacier loss has yet to be examined. Here we analyze a 16-year dataset (2004-19) of water samples collected from glacierized tributaries of the Santa River draining the Cordillera Blanca, Peru to evaluate inter-annual to decadal differences in hydrochemistry in the outflows below debris-covered glaciers and debris-free glaciers. This unique dataset consists of annual dry season samples from 48 sites within 20 tributaries with different amounts of glacier coverage that provide the isotopic and ionic composition of the water, allowing for analyses of patterns within catchments and comparisons between them over time. Within the Llanganuco catchment, the Kinzl glacier tongue descending from Peru’s highest summit of Huascaran is heavily debris covered (4350-5200 m). Samples directly from the Kinzl effluent stream show the most negative (δ18O = -16.79‰) and variable isotope values (δ18O difference = 3.84‰) compared to less glacierized points within the watershed. In contrast, the Broggi drainage displays the least negative (δ18O = -14.10‰) and variable isotope values (δ18O difference = 2.80‰). Finally, to gain a regional perspective we use the synoptic samples throughout the Callejon de Huaylas watershed to provide a comparison to previous estimates of specific discharge from glacier melt.

Upscaled transport models are needed to address regional-scale groundwater quality degradation in major aquifers worldwide, and these models must accurately characterize anomalous (non-Fickian) transport (e.g., early solute arrival due to preferential flow, and late time tailing). Although it is well known that seasonal pumping and recharge can cause vertical hydraulic gradient values to exceed horizontal gradients by 10-100 times, the relationship between large shifts in vertical to horizontal gradient ratio (VHGR) and plume migration is less understood. We simulate flow and transport of a conservative solute in a heterogeneous alluvial aquifer under varying VHGR representative of typical seasonal hydraulic gradient fluctuations and find that VHGR strongly impacts anomalous transport, plume migration, and mass transfer rates between hydrofacies. At low VHGR (e.g., ambient hydraulic gradient conditions corresponding to a more horizontal flow direction), low-K facies are diffusion-dominated, resulting in low mass transfer rates out of low-K material, increased spatial spreading along the mean flow direction, and tortuous particle trajectories. In contrast, at high VHGR (e.g., representative of pumping and recharge, and corresponding to an increasingly vertical mean flow direction), results in increasingly Fickian transport, explained by a shift from diffusion- to advection-dominated mass transfer in low-K facies, and illustrated by relatively non-tortuous, vertically oriented particle trajectories. We conclude that seasonal fluctuations in VHGR in a typical alluvial aquifer system may create oscillating transport behavior, with implications for contaminant transport and cleanup. The strong dependence of anomalous transport on VHGR implies that approaches to upscale anomalous transport may benefit from incorporating information about the VHGR, and highlights specific hydrogeologic forcings that cause upscaled transport methods to fail under transient boundary conditions.

Convective dynamo action may be fundamentally different between low-mass and high-mass stars due to a dichotomy in their bulk electrical conductivities relative to kinematic viscosity as characterized by the magnetic Prandtl number, Pm (Augustson et al., 2019, https://doi.org/10.3847/1538-4357/ab14ea). Magnetic Prandtl values less than unity are expected in low-mass stars with convective envelopes, while larger Pm values are more relevant for high-mass stars with convective cores. Here we investigate how the fluid’s electrical conductivity alters the behavior of a given dynamo system through a suite of 3D, spherical shell dynamo models in the strongly-forced convective regime with varied magnetic Prandtl number. We find that the fluid motions, the pattern of convective heat transfer, and the mode of dynamo generation all differ across the range 0.25 ≤ Pm ≤ 10. For example, we show that strong magnetohydrodynamics effects cause a fundamental change in the surface zonal flows: the equatorial zonal jet reverses direction for sufficiently large values of the electrical conductivity. Thus, our work further supports the importance of bulk electrical conductivity for not only sustaining dynamo action, but also for the characteristics of the large-scale convective flows that generate those dynamo fields.

This paper presents some pre-earthquake and coseismic water-level and stream-flow changes observed in Japan and Taiwan. The results suggest that: (1) Hydrological precursors do occur; (2) they can be observed at a relatively few sensitive sites; (3) these “sensitive” sites consistently show coseismic changes; (4) the mechanisms of these precursors can be understood, if crustal heterogeneity and pre-earthquake slow-slip events are included in their mechanism consideration. In Japan, the monitored well was sensitive, because it tapped a permeable aquifer connected to a nearby fault, which was under a hydraulic –pressure gradient caused by pumping activity in an underground gallery on the other side of the fault. Also, the fault was in a near-critical condition, such that leakage could be caused by a small crustal disturbance, such as seismic shaking, in the case of coseismic changes, or a stress increment, in the case of precursory changes. In Taiwan, both the sensitive well and the stream gauge were located on the hanging wall of the seismogenic fault of the magnitude-7.6 Chi-Chi earthquake in 1999. The hanging wall probably bulged before the earthquake, causing opening up of fractures along some secondary faults, and allowing stored groundwater to flow down to the monitored stream and caused the observed pre-earthquake stream-flow increase. The continued fracture-opening process toward greater depth then caused down-flow of water into greater depth of the crust and triggered the occurrence of slow-slip events, which propagated down-dip to where these faults met the seismogenic fault and caused slow-slip events to propagate up-dip the seismogenic fault toward the hypocenter, triggering the earthquake and the observed water-level precursor at a well located near the tip of the wall.

Aloft Sensing, Inc. (Aloft) is developing a breakthrough compact radar system for deployment on high-altitude long-endurance (HALE) stratospheric platforms. These emerging platforms offer the unmatched ability to persistently observe science targets and capture the dynamics of rapidly evolving surface vegetation and topographic phenomena. Aloft’s radar system is specifically designed to overcome the challenges associated with synthetic aperture radar (SAR) and interferometric SAR (InSAR) operation from these platforms in the stratosphere, maintaining coherence over the minutes-long collection apertures and tolerating the non-linear flight trajectories to generate high-quality imaging and interferometric products. The large fractional bandwidth of Aloft’s radar system, combined with innovative motion compensation techniques, enable high-precision repeat-pass interferograms to be generated despite the coarse trajectory control of HALE platforms. Furthermore, Aloft’s patent-pending positioning, navigation, and timing (PNT) technique supports coherent multistatic operations, such that a new type of cross-platform interferometric and volumetric radar products is possible. This presentation describes the current state of Aloft’s payload development and demonstrates, via system performance models, that millimetric surface changes, centimetric topography, and decametric volumetric resolutions can be obtained from this 7 kg HALE radar system.

Inspired by the AAHE Assessment Forum’s Principles for good practice for assessing students’ learning, the author has generated Ten Steps (1992) to Promote a Stronger Emphasis on Student Learning in a Hydrology–Fluid Mechanics Course. Student-Learning must not be focused only about making the connections initially. Instead it should concentrate more about maintaining those connections in the long run. Student learning is fundamentally about a strong bond between the academic establishment and the student citizens of the entire community. Student-Learning is enhanced by the environment. It should take place in the context of a compelling situation that balances curiosity, challenge and opportunity. Student-Learning should have an active search for meaning by the learner – constructing knowledge rather than passively delivering it or receiving it. In other words one should create a Concept Mapping Model instead of a Structured Content Model. Student-Learning is developmental. In other words, it is a cumulative process involving the whole person, who is capable of integrating the new with the old. The settings, the surroundings, the influences of others contribute to successful accomplishments. Student-Learning should be viewed as an effort promoted by individuals who are intrinsically tied to others as social beings, actually interacting as collaborators. Student-Learning is strongly influenced by the educational climate in which learning achievements takes place. Student-Learning requires Action, Communication, Ownership, Reflection and Nurture (ACORN) as suggested by Hawkins and Winter (1997). Student-Learning in reality aims at an educational experience that takes place informally and incidentally, beyond explicit teaching in the lecture hall. Student-Learning is grounded in particular contexts and individual experiences, requiring effort to transfer specific knowledge and skills to other citizens. Student-Learning involves the ability of individuals not only to monitor their own learning, but also be able to enhance learning through collaboration and cooperation. References: Hawkins, P., & Winter, J. (1997). Mastering change: Learning the lessons of the enterprise in higher education initiative. London: Department for Education and Employment.

It is now widely understood that seasonal snow cover in the Western United States is melting earlier than in past decades. This could have significant consequences for human populations and ecosystems dependent on regularity in timing and magnitude of downstream flows that originate as snow. However, while earlier melt is well established, less is known about intra-annual changes in the spatial and temporal distribution of accumulation and ablation (melt) cycles in the core winter months and spring months, i.e. the ‘persistence’ of seasonal snow cover. This is significant because changes to the persistence of seasonal snow in the winter and spring could have important implications for other snow cover characteristics such as albedo, as well as ancillary hydrologic factors such as soil moisture and runoff. To understand these changes in persistence, this project focuses on study basins in different climatic zones of the Columbia river basin, capturing the shift from maritime snowpack in the west to alpine snowpack in the east. The research relies on a combination of time series analysis of NRCS SNOTEL stations and snow courses and use of an optical remote sensing product which is based on the MODIS MOD10A1 dataset. To compensate for significant winter and spring cloud cover, particularly in the Pacific Northwest, a temporal and spatial gap filling approach utilizing higher spatial resolution products (e.g. Landsat and Sentinel 2) is implemented primarily in Google Earth Engine. The seasonal snow persistence from the MODIS-based product is evaluated using additional Landsat, Sentinel 2 and Planet Labs data, as well as data from the in situ monitoring stations. Finally, changes in intra-annual seasonal snow cover persistence are characterized for core winter, spring and early summer months along an elevational gradient and across study sub-basins.

In support of our ongoing program to measure coronal magnetic fields using Faraday rotation (the rotation of the plane of polarization when linearly polarized light propagates through a magnetized plasma), we report on measurements of angular broadening of cosmic radio sources as they were occulted by the corona. Angular broadening results from plasma density irregularities elongated along the coronal magnetic field that cause radio wave scattering. In radioastronomical observations, the measured intensity (power per unit area per unit solid angle along the path to the detector) is the convolution of the true radio source intensity with a point spread function (PSF, the effective response of an imaging system to a point-like source). In most radio interferometric applications, the PSF is simply the synthesized beam; however, when observing through a turbulent plasma like the corona, the PSF is the convolution of the synthesized beam with the power pattern of the angular broadening. The angular broadening acts to reduce the measured intensity of a radio source. This can have important consequences for coronal Faraday rotation studies because the error associated with measuring the polarization angle is inversely proportional to the intensity of the linearly polarized light. We made full-polarization observations at 1 – 2 GHz frequencies using the Karl G. Jansky Very Large Array of 21 linearly polarized cosmic radio sources occulted by the solar corona in July and August, 2015. The radio sources were scattered over a range of heliocentric distances; however, sources within a heliocentric distance of 10 solar radii experienced the most pronounced angular broadening. The observed angular broadening is consistent with a 15% - 35% decrease in intensity. We discuss the implications of these angular broadening measurements on the observed coronal Faraday rotation as well as potential methods to correct for this phenomenon in mapping the radio sources.

Formal data citation is a growing practice increasingly required by scientific journals. Roughly a decade ago, the Federation of Earth Science Information Partners (ESIP) began developing formal guidelines for data citation including acknowledgement of authors and archives and careful use of persistent identifiers (PIDs). Many Earth science data centers now provide formal citation text and PIDs for their data sets, typically a Digital Object Identifier (DOI). A central purpose of data citation (amongst many) is to aid scientific reproducibility through direct, unambiguous reference to the precise data used in a particular study, i.e., to aid provenance tracking. How has that worked in practice? ESIP is now in the process of revising and updating their guidelines and seeks to ensure that data citation meets its stated purpose. This presentation explores whether and how formal citation and the the use of PIDs for data sets has improved the tracking of data provenance. For example, is there is some commonality in the nature and granularity of objects that are assigned PIDs? We review how the guidelines are being revised to further enhance the transparency and reusability of data.

Oceans are known to have complex and nuanced effects on seismic wave propagation; changing the behaviour of phases which propagate in the solid Earth, supporting the propagation of new classes of hydroacoustic waves, and acting as the source of the dominant ambient noise, the ocean microseism. Simulations with realistic ocean layers have historically been challenging, due to the need to explicitly mesh the low-sound-speed ocean and the challenge in implementing bathymetry with a conformal mesh. This has led to a number of simplifications becoming commonplace, including modelling the ocean as a ‘weight load’, and restriction to purely axisymmetric or local-scale domains. Such approximations are not appropriate in a high-frequency global seismology context, motivating us to develop a code capable of supporting realistic ocean layers with accurate bathymetry. Here, we present such an implementation of AxiSEM3D which should provide useful modelling output for comparison with new and exciting datasets from OBSs and Mermaids. We use this method to perform a high-frequency evaluation of the oft-used ‘ocean loading’ formulation, and find that it breaks down well above the 5-10 seconds period routinely suggested. Bathymetry is found to have a particularly substantial impact on surface-reflected phases (e.g. PP), and on the generation of ocean microseismic noise. We also consider the use of this method for interpreting observed water depth phases, and intend to work toward direct comparison to data.