Although the Brown mathematical model is the standard model for waveform retracking over open oceans, coastal waveforms usually deviate from open ocean waveform shapes due to inhomogeneous surface reflections within altimeter footprints, and thus cannot be directly interpreted by the Brown model. Generally, the two primary sources of heterogeneous surface reflections are land surfaces and bright targets such as calm surface water. The former reduces echo power, while the latter often produces particularly strong echoes. In previous studies, sub-waveform retrackers, which use waveform samples collected from around leading edges in order to avoid trailing edge noise, have been recommended for coastal waveform retracking. In the present study, the peaky-type noise caused by fixed-point bright targets is explicitly detected and masked using the parabolic signature in the sequential along-track waveforms (or, azimuth-range echograms). Moreover, the power deficit of waveform trailing edges caused by weak land reflections is compensated for by estimating the ratio of sea surface area within each annular footprint in order to produce pseudo-homogeneous reflected waveforms suitable for the Brown model. Using this method, Jason-2 altimeter waveforms are retracked in several coastal areas. Our results show that both the correlation coefficient and root mean square difference between the derived sea surface height anomalies and tide gauge records retain similar values at the open ocean (0.9 and 20 cm) level, even in areas approaching 3 km from coastlines, which is considerably improved from the 10 km correlation coefficient limit of the conventional MLE4 retracker and the 7 km sub-waveform ALES retracker limit. These values, however, depend on the coastal topography of the study areas because the approach distance limit increases (decreases) in areas with complicated (straight) coastlines.

Consisting of charged particles originating from the Sun, the solar wind carries the Sun’s energy and magnetic field outward through interplanetary space. The solar wind is the predominant source of space weather events, and modeling the solar wind propagation to Earth is a critical component of space weather research. Solar wind models are typically separated into coronal and heliospheric parts to account for the different physical processes and scales characterizing each region. Coronal models are often coupled with heliospheric models to propagate the solar wind out to Earth’s orbit and beyond. The Wang-Sheeley-Arge (WSA) model is a semi-empirical coronal model consisting of a potential field source surface model and a current sheet model that takes synoptic magnetograms as input to estimate the magnetic field and solar wind speed at any distance above the coronal region. The current version of the WSA model takes the Air Force Data Assimilative Photospheric Flux Transport (ADAPT) model as input to provide improved time-varying solutions for the ambient solar wind structure. When heliospheric MHD models are coupled with the WSA model, density and temperature at the inner boundary are treated as free parameters that are tuned to optimal values. For example, the WSA-ENLIL model prescribes density and temperature assuming momentum flux and thermal pressure balance across the inner boundary of the ENLIL heliospheric MHD model. We consider an alternative approach of prescribing density and temperature using empirical correlations derived from Ulysses and OMNI data. We use our own modeling software (Multi-scale Fluid-kinetic Simulation Suite) to drive a heliospheric MHD model with ADAPT-WSA input. The modeling results using the two different approaches of density and temperature prescription suggest that the use of empirical correlations may be a more straightforward, consistent method.

This study intends to integrate heterogeneous remote sensing observations and hydrological modelling into a simple framework to monitor hydrological variables in the poorly gauged Congo River basin (CRB). It focuses on the possibility to retrieve effective channel depths and discharges all over the basin in near real time (NRT). First, this paper discusses the complexity of calibrating and validating a hydrologic–hydrodynamic model (namely the MGB model) in the CRB. Next, it provides a twofold methodology for inferring discharge at newly monitored virtual stations (VSs, crossings of a satellite ground track with a water body). It makes use of remotely sensed datasets together with in-situ data to constrain, calibrate and validate the model, and also to build a dataset of stage/discharge rating curves (RCs) at 709 VSs distributed all over the basin. The model was well calibrated at the four gages with recent data (Nash-Sutcliffe Efficiency, NSE> 0.77). The satisfactory quality of RCs basin-wide (mean NSE between simulated discharge and rated discharge at VSs, NSEmean = 0.67) is an indicator of the overall consistency of discharge simulations even in ungauged upstream sub-basins. This RC dataset provides an unprecedented possibility of NRT monitoring of CRB hydrological state from the current operational satellite altimetry constellation. The discharges estimated at newly monitored locations proved to be consistent with observations. They can be used to increase the temporal sampling of water surface elevation (WSE) monitoring from space with no need for new model runs. The RC located under the fast sampling orbit of the SWOT satellite, to be flown in 2022, will be used to infer daily discharge in major contributors and in the Cuvette Centrale, as soon as data is released.

Due to heavy urbanisation, approaches in greener cities are required. This is addressed by a number of initiatives, including seeing the city as an ecosystem, and the dialogue between economy and ecology. Sustainable and resilient cites mean connection between the city and the landscape, bringing the landscape into the city, for example through nature based solutions such as green walls or through more open spaces which are green, such as urban parks. In this context the landscape quality of the city can be judged. The renewable energy in the city can relate to solar energy of the passive house which can be a house of heavy geomaterials. In this contribution the authors present their approach to sustainable and resilient cities, including the first author’s approach to renewable energy and landscape quality. The first author would like to thank the Inclusiveness Target Countries grant scheme for supporting participation in the conference to represent the COST Action TU1401 (http://www.cost-rely.eu/).

Our increasingly robust history of ancient climates indicates that high latitude glaciation is the ultimate product of an episodic cooling trend that began about 100-million years ago rather than a result of a yet-to-be identified modal change. Antarctic geography (continent surrounded by ocean) allowed ice to develop prior to significant glaciation in the Northern Hemisphere (ocean surrounded by land), but global ice volume generally increased as Earth cooled. The question of what caused the Ice Ages should be reframed as to “What caused the Cenozoic Cooling?” Records tell us that changes in temperature and CO2 levels rise and fall together, however it is not clear when CO2 acts as a driver versus when it is primarily an indicator of temperature change. The episodic nature of the cooling trend suggests other more dynamic phenomena are involved. It is proposed that oceanic meridional overturning circulation (MOC) plays a significant role in regulating Earth’s surface temperature. Robust MOC has a cooling effect which results from its sequestration of cold waters (together with their increased heat-absorbing potential) below the surface. Unable to better absorb equatorial insolation for great lengths of time, oceanic deep waters are not able to fully compensate for the heat lost by warm-water transport to Polar Regions. A lag-time between cooling and subsequent warming yields lower operating temperatures commensurate with the strength of global MOC. The long-term decline in global temperatures is largely explained by the tectonic reshaping of ocean basins and the connections between them such that MOC has generally, but not uniformly, increased. Geophysically Influenced MOC (GIMOC) has caused a significant proportion of the lowering of global temperatures in the Cenozoic Era. Short-term disruptions in MOC (and subsequent impacts on global temperatures) were likely involved in Late Pleistocene glacial termination events and may already be compounding present anthropogenic CO2 induced warming. The immediate impacts of AMOC strength on North Atlantic and European temperatures coupled with the delayed and opposing effects on global temperatures offer explanations for phenomena including: Younger Dryas, Little Ice Age and the bipolar seesaw. (Please see supplemental file: Oceanic Geophysics & History of Climate(ver #02).pdf listed below.)

Klinkenberg-corrected gas permeability (k) estimation in tight-gas sandstones is essential for gas exploration and production in low-permeability porous rocks. Most models for estimating k are a function of porosity (ϕ), tortuosity (τ), pore shape factor (s) and a characteristic length scale (lc). Estimation of the latter, however, has been the subject of debate in the literature. Here we invoke two different upscaling approaches from statistical physics: (1) the EMA and (2) critical path analysis (CPA) to estimate lc from pore throat-size distribution derived from mercury intrusion capillary pressure (MICP) curve. τ is approximated from: (1) concepts of percolation theory and (2) formation resistivity factor measurements (F = τ/ϕ). We then estimate k of eighteen tight-gas sandstones from lc, τ, and ϕ by assuming two different pore shapes: cylindrical and slit-shaped. Comparison with Klinkenberg-corrected k measurements showed that τ was estimated more accurately from F measurements than from percolation theory. Generally speaking, our results implied that the EMA estimated k within a factor of two of the measurements and more precisely than CPA. We further found that the assumption of cylindrical pores yielded more accurate k estimates when τ was estimated from concepts of percolation theory than the assumption of slit-shaped pores. However, the EMA with slit-shaped pores estimated k more precisely than that with cylindrical pores when τ was estimated from F measurements.

Tikhonov’s regularization method is the standard technique applied to obtain models of the subsurface conductivity dis- tribution from electric or electromagnetic measurements by solving UT (m) = ||F(m) - d||^2 + P(m): The second term correspond to the stabilizing functional, with P(m) = ||m||^2 the usual approach, and the regularization parameter. Due to the roughness penalizer inclusion, the model developed by Tikhonov’s algorithm tends to smear discontinuities, a feature that may be undesirable. An important requirement for the regularizer is to allow the recovery of edges, and smooth the homogeneous parts. As is well known, Total Variation (TV) is now the standard approach to meet this requirement. Recently, Wang et.al. proved convergence for alternating direction method of multipliers in nonconvex, nonsmooth optimization. In this work we present a study of several algorithms for model recovering of Geosounding data based on Inmal Convolution, and also on hybrid, TV and second order TV and nonsmooth, nonconvex regularizers, observing their performance on synthetic and real data. The algorithms are based on Bregman iteration and Split Bregman method, and the geosounding method is the low-induction numbers magnetic dipoles. Non-smooth regularizers are considered using the Legendre-Fenchel transform.

We have used empirical models for electric potentials and the magnetic fields in both space and on the ground to obtain maps of the height-integrated Pedersen and Hall ionospheric conductivities at high latitudes. This calculation required use of both “curl-free” and “divergence-free” components of the ionospheric currents, with the former obtained from magnetic fields that are used in a model of the field-aligned currents. The second component is from the equivalent current, usually associated with Hall currents, derived from the ground-level magnetic field. Conductances were calculated for varying combinations of the Interplanetary magnetic field (IMF) magnitude and orientation angle, as well as the dipole tilt angle. The results show that reversing the sign of the Y component of the IMF produces substantially different conductivity patterns. The Hall conductivities are largest on the dawn side in the upward, Region 2 field-aligned currents. Low electric field strengths in the Harang discontinuity lead to inconclusive results near midnight. Calculations of the Joule heating, obtained from the electric field and both components of the ionospheric current, are compared with the Poynting flux in space. The maps show some differences, while their integrated totals match to within 1%. Some of the Poynting flux that enters the polar cap is dissipated as Joule heating within the auroral ovals, where the conductivity is enhanced, confirming the Poynting Flux theorem proposed by Richmond in 2010, for the first time using realistic electric fields, ionospheric currents, and conductivity.

Wildfires are one of the main sources of disturbance in boreal forests. Post-fire changes to soil temperature and moisture regimes can have wide-ranging impacts on boreal forests including the depth at which permafrost is found, vegetation recovery, and carbon and nitrogen cycling. Surface soil temperatures increase following fire, due to loss of shading from tree canopies and a thinner surface organic layer. Post-fire soil temperature and moisture regimes also change due to reduced transpiration and changes in surface albedo. The duration of these changes depends on factors such as region, fire intensity, and soil texture. Here we present results from a long-term (1999 to present) dataset of soil conditions for four black spruce boreal forest sites located in Interior Alaska across burn and permafrost gradients: 1) burned, no permafrost, 2) unburned, no permafrost, 3) burned, with permafrost, and 4) unburned, with permafrost. The data from these sites demonstrate how both burning and the presence of permafrost influence soil temperature and moisture, as well as the timing of seasonal changes, for over twenty years. In addition, we discuss the challenges of maintaining and collecting data from field instruments deployed for decades in harsh conditions. All data discussed in this presentation will be available on the Bonanza Creek Long-term Ecological Research (LTER) website and is available for future studies.

The National Water Center (NWC), part of the National Weather Service’s (NWS) Office of Water Prediction (OWP), seeks to provide forecast flood inundation maps (FIM) as services at the national scale along 2.7+ million river reaches. The National Water Model (NWM) forecasts stream discharges along these reaches at varying time horizons. Building on the methodology of previous versions, OWP FIM 3.0 seeks to map NWM stream discharges to inundation extents with a modified version of the Height Above Nearest Drainage method for mapping stages. FIM 3.0 produces required datasets for generation of FIMs, which are relative elevations, reach-level catchments, rating curves and crosswalk tables, to convert the NWM discharge forecasts to inundation extents as a post-processing step. Computational tests estimate that producing these FIM required datasets for the continental U.S. will be around 600 total CPU hours. Only publicly available input datasets from the NWM or NHDPlusHR are required. The latest methods leveraged within FIM 3.0 include the use of consistent reach lengths and deriving FIM outputs at lower stream densities (downstream of River Forecast Center forecast points) to mitigate catchment boundary limitations. FIM 3.0 is primarily parallelized across Hydrologic Unit Codes (HUC) 4, 6, or 8 as processing units which can be selected by the user at run time. FIM capability improvements were measured by comparisons to engineering scale maps using contingency statistics. Future versions will support NWM geospatial dataset production, usage of Lidar elevations, and more advanced hydrological methods. FIM 3.0 is highly configurable, modular, and portable due to its software architecture and containerization. All software dependencies are open-source including GDAL/OGR, TauDEM, and RichDEM. The source code and Docker container are expected to be made available publicly for community review and development.

A magnetic field measurement suite intended for CubeSat and ground-based geomagnetic applications is presented. The system is composed of commercial-off-the-shelf sensors (COTS), which include four PNI RM3100 magnetometers, a Bosch BMI270 inertial measurement unit (IMU), and a TMP36 thermal sensor. The instruments are collectively operated by a Texas Instrument’s MSP430FR5949 microcontroller. The novel measurement principle employed by the magnetometers permits a low fabrication cost, power consumption, and footprint; in turn, this enables the incorporation of four magnetometers (theoretically many more), reducing the magnetic noise floor and increasing the resolution by a factor of two in this case. Additionally, the inclusion of a COTS IMU allows us to reliably establish the orientation of the sensor package, thus permitting a better understanding of the geometry of the surrounding magnetic field under static or dynamic conditions. The system has been tested and characterized in a controlled laboratory environment with the intent of flying aboard the PR-CuNaR2 CubeSat, set to launch early next year. This mission will raise the technology readiness level (TRL) of the system (current TRL is approximately 4/5) and provide us with valuable measurements of the magnetic environment at Low-Earth-Orbit.

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.

We measured during the MOSAiC field experiment the snow microstructure on sea-ice from early winter to the melt season, and continued measurements with the surface scattering layer. We could measure every week 1-2 full snow profiles between 0.1-0.3 m. We extracted, mostly in-situ, cores of 48-78 mm diameter and of about 0.1 m length, and scanned with 18-28 µm resolution. The goal of these measurements is to understand the formation and metamorphism of the snowpack in detail, and to derive detailed geometrical and physical properties from the samples. We will present first examples and and overview of characteristic snow profiles from leg 1 - 4, spanning the winter, spring and melt season.

Ion temperature is a key parameter that influences dynamics in the magnetosphere, such as particle transport and wave-particle interactions. Measurements of ion heating and energization yields information about phenomena such as magnetic reconnection, bursty bulk flows, and ion injections. Taking advantage of the global view provided by energetic neutral atom imaging, a database of ion temperature maps during geomagnetic storms occurring throughout the NASA TWINS mission has been created. These ion temperature maps and relevant metadata are publicly available on CDAWeb to facilitate comparison to in situ measurements and model output, for use as boundary conditions for simulations, and for other relevant studies. A preliminary study of average plasma sheet ion temperatures calculated from these maps has revealed a common occurrence of decreasing ion temperature concurrent with a sharp negative gradient in the IMF B. A preliminary case study for one storm is presented.

Magnetospheric sawtooth oscillations are observed during strong and steady solar wind driving conditions. The simulation results of our global MHD model with embedded kinetic physics show that when the total magnetic flux carried by constant solar wind exceeds a threshold, sawtooth-like magnetospheric oscillations are generated. Different from previous works, this result is obtained without involving time-varying ionospheric outflow in the model. The oscillation period and amplitude agree well with observations. The simulated oscillations cover a wide range of local times, although the distribution of magnitude as a function of longitude is different from observations. Our comparative simulations using ideal or Hall MHD models do not produce global time-varying features, which suggests that kinetic reconnection physics in the magnetotail is a major contributing factor to sawtooth oscillations.

Haptophytes and Dinoflagellates are two cosmopolitan algae associated with dimethylsulfoniopropionate (DMSP) synthesis, which regulates the marine biogenic flux of dimethylsulfide (DMS) to the atmosphere and subsequently affects marine aerosols. Attempting to reveal the potential impact of atmospheric deposition on the growth of main DMSP producers, four bioassay experiments were conducted in the western North Pacific (WNP) by adding aerosols, nutrients and trace metals. Our results showed that the percentage of main DMSP producers increased substantially from coastal regions (<1%) to the open ocean (~17%) with the dominance of Dinophyceae and Haptophyceae, respectively. Aerosol additions largely increased the percentage of DMSP species in the open WNP. Specifically, atmospheric DIN and soluble Cu, and Fe promoted Chrysochromulina, and Phaeocystis and E. huxleyi, respectively. It is very likely that atmospheric deposition could lift the relative abundance of main DMSP producers in the vast oligotrophic oceans and contribute to the climate change.

Alteration of mantle peridotite in the Samail ophiolite forms secondary minerals, mainly serpentine and Mg-rich carbonates. Magnesium accounts for approximately 25 to 30% of peridotite mass and its mobility can be used to trace this alteration. We report the first set of Mg isotope measurements from peridotites and their alteration products in Oman. Partially serpentinized peridotites have Mg isotope ratios that are indistinguishable from estimates for the average mantle and bulk silicate earth (d26Mg =-0.25±0.04‰). However, more extensively altered peridotite samples show large shifts in Mg isotopic composition. The range of d26Mg values for our suite of alteration products from the mantle section is ~4.5‰;, or ~60% of the total range of terrestrial variability in d26Mg values. Serpentine veins are typically enriched in Mg (up to 0.96‰) whereas Mg-carbonate veins are associated with low Mg/Mg ratios (magnesite d26Mg =-3.3‰, dolomite d26Mg =-1.91‰). Our preferred explanation for the range in d26Mg values involves co-precipitation of serpentine and carbonates at water-to-rock ratios >10^3. The coincidence of alteration products characterized by d26Mg values that are both lower and higher than bulk silicate Earth and the finite C ages of the carbonates suggest that both serpentinization and carbonation are ongoing in Oman. Rates of calcite precipitation in travertines inferred from D26Mgcal-fl suggest that travertine formation in Oman sequesters a total of 10^6-10^7 kg CO/yr, consistent with previous estimates.

Traditional finite difference method for electromagnetic simulation is based on staggered grid, whilst researches on collocated grid are few. We present a high-order collocated-grid finite-difference method for modelling electromagnetic waves with a topographic ground surface by solving 2D time-domain Maxwell equations in curvilinear coordinates. The proposed method, incorporating curvilinear coordinates, collocated grids and MacCormack finite-difference scheme techniques, can describe the geometry of the irregular interface better and avoid the numerical scattering caused by the staircase approximation in the conventional finite-difference method for electromagnetic wavefield modelling. The first-order 2D Maxwell equations on curvilinear grids are solved by an optimized MacCormack finite-difference scheme, first presented by Hixon (1997). As the collocated grids are implemented, in which the electric and magnetic fields are discretized at the same grids, the interfacial boundary conditions need to be considered. Therefore, a novel effective interface method is presented to handle the conditions. The proposed method is verified by a series of ground penetrating radar application models, such as homogeneous space, multilayered media and buried cavity models, by comparing synthetic waveforms with independent reference solutions, such as the analytical solution, the generalized reflection/transmission method and an open-source program gprMax. Comparisons show that the proposed method does well in handling multiple reflections and curved interfaces.