bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving microbial quality assessment for irrigation water in ponds using the Environmental Fluid Dynamic Code
Authors: Kim Seongyun , Stocker Matthew , Sharma Manan , Pachepsky Yakov
Published: March 2022

Microbial quality of irrigation water is a public health concern. Management decisions are routinely based on concentrations of fecal indicator bacteria like Escherichia coli (E. coli) in water sources. In the case of irrigation ponds, water samples are often collected near the banks and at shallow depths due to convenient access. However, we hypothesized that water is drawn from locations far from the shoreline and far below the water surface during irrigation events. We used the Environmental Fluid Dynamic Code (EFDC) water quality model to test this hypothesis by simulating water and tracer movement in a working irrigation pond. The initial condition datasets included (1) setting the tracer concentration to zero at the shoreline and to unity in the interior and (2) setting the tracer concentration to zero at the surface water layer and to unity in the deeper layers. Tracer transport to the intake location was simulated with and without wind effect. The simulated concentrations at the intake were close to unity, indicating an insignificant contribution of the near-surface and nearshore layers to the intake concentrations. Four years of biweekly sampling of nearshore and interior locations in two irrigation ponds revealed statistically different average E. coli concentrations between nearshore and interior locations under various environmental conditions. Additionally, when three-dimensional monitoring was conducted, significantly different E. coli concentrations between water depth layers (e.g., 0 m to 0.5 m, 0.5 m to 1 m, 1 m to 1.5 m, etc.) were frequently observed. Mixing water from different depths or locations in the same water body in response to the initiation of irrigation did not homogenize the tracer in the pond. Hydrodynamic modeling showed that the E. coli concentration at the intake changed over the course of the irrigation event in response to the 3D spatial heterogeneity of concentrations measured in the pond water. The results of this work show that 1) water samples should be collected from the pond interior at depths close to the irrigation water intake, and 2) water must be sampled several times during irrigation events if samples are taken at the irrigated fields rather than in ponds.
Joint extremes of precipitation and temperature in Europe: seasonal trends and patterns
Authors: Gelati Emiliano , J. Bakke Sigrid , Tallaksen Lena M.
Published: March 2022

Co-occurring extremes of multiple climate variables can cause disproportionate damage to human activities and ecosystems. Their impacts may be larger than the combination of those caused by individual extremes. Moreover, associated risks may be compounded by dependence structures between climate variables, which enhance the frequency of joint extremes beyond the level that would be observed if variables were independent. Joint extremes of precipitation (P) and temperature (T) are of particular interest as they can simultaneously affect water resources, ecosystems, and agricultural and energy systems, all of which are closely interconnected.

We analyse non-parametric trends and spatial patterns in the occurrences of joint extremes of P and T in Europe using observational E-OBS daily data at 0.1° spatial resolution from 1950 to 2019. For each grid-cell and calendar month, we define low (high) extremes as values smaller (larger) than quantiles of empirical frequency distributions. These are obtained from times series smoothed using backward moving averages. Time averaging is used to detect extremes at  time scales relevant for the variable and type of hazard considered, e.g. we use longer windows for low precipitation extremes to represent reduced freshwater availability. We compute statistically significant trends in occurrence and spatial extent of both joint and univariate extremes, and investigate their correlations with analogous trends in P and T time series. Several quantile thresholds and different combinations of averaging window duration are used to evaluate the sensitivity of the results. The analysis is repeated on two sub-periods (1950-1984 and 1985-2019) to investigate whether there is a change in the strength of signals over time. Special attention is given to regions experiencing extended periods with zero precipitation, such as the Mediterranean, and regions with a seasonal snow climate, such as in the Alps and Northern Europe.

 

Acknowledgement: This work is funded by the Strategic Research Initiative “Land Atmosphere Interactions in Cold Environments” (LATICE) of the University of Oslo (project number: UiO/GEO103920).
The importance of interactions between intratidal processes for the evolution of stratification in a dynamic salt wedge estuary
Authors: Geraeds Marlein , Pietrzak Julie , Verlaan Martin , Katsman Caroline , Hulsen Lambèr
Published: March 2022

Strongly forced salt wedge estuaries are known to demonstrate significant variability in stratification, currents, and mixing within a tidal cycle. Such estuaries also show strongly spatially varying patterns of stratification and mixing, and the processes causing this spatial and temporal variability are known to interact. As a consequence, the dynamics of these estuaries are distinctly different from well-mixed and partially mixed estuaries, and intratidal processes may play a more central role in the evolution of stratification.

The Rhine-Meuse estuary is an example of a strongly forced salt wedge estuary. It is very dynamic, mesotidal, and stably stratified. In this study, we investigate how individual intratidal estuarine processes contribute to the evolution of stratification in the Rhine-Meuse estuary. Data from recent shipboard measurements are used to assess their relative influence and highlight the potential importance of interactions between these processes.

From measurements in the Rhine-Meuse estuary we find that the availability of salt is determined by tidal advection of the salt wedge. Additionally, exchange flows transfer salt from high-density to low-density regions such as harbour basins and side branches while the salt wedge is advected through the estuary. The combination of the barotropic tidal asymmetry imposed at the river mouth and turbulence damping at the pycnocline results in strong shear and subsequent formation of mid-depth jets at the onset of flood. These mid-depth jets contribute to the transfer of salt by transporting salt from regions of higher momentum to regions of lower momentum. Furthermore, the measurements suggest that several bathymetric transitions locally generate internal wave activity, although the resulting turbulent mixing is not strong enough to erode the persistent salt wedge structure.

These findings underline the importance of interactions between intratidal processes on different spatial scales and their effect on the evolution of stratification in the Rhine-Meuse estuary. As an extension to our findings, measurements in the Rhine region of influence (ROFI) are used to further examine the role of the seaside forcing on the individual physical processes and the resulting intratidal variability of stratification in the estuary.
Observational evidence for ocean feedback causing episodes of convective aggregation breakup in the tropical Pacific.
Authors: Adrian Mark Tompkins , De Vera Michie Vianca
Published: March 2022

Cloud resolving models run in idealized conditions of radiative convective equilibrium often show convective switching a state of random convection to a state in which the convection is clustered, leading to a much drier mean state. These simulations have shown that feedbacks with the ocean over thin mixed layers can delay or prevent clustering onset. Understanding convective aggregation is critical as it could alter our assessment of tropical climate sensitivity, and yet it has been difficult so far to even assess aggregation in observations, due to the lack of ability to observe convective core location from space until Doppler radar is available. Here, using a novel analysis method to examine a combination of state-of-the-art retrievals of clouds, water vapour, precipitation and sea surface temperature available since 2016, we present observations that demonstrate convective aggregation operates in the tropical western Pacific region on the sub-1000 km scale, in a region with very weak spatial gradients in sea surface temperature. Convection is generally seen to be in a highly aggregated state, but intermittently and rapidly flips to a random state when low wind conditions prevail, associated with thin mixed ocean layers which oppose aggregation. These events generally persist for a few days to a week or more before convection transitions back to a clustered state. We believe this to be the first direct evidence of this "switching" of clustering state occurring on the meso-scale in the tropics. Summary statistics of these random-convection episodes will be presented.
A hybrid computational Framework for 3D anisotropic full-Waveform inversion at a regional scale
Authors: Karakostas Foivos , Morelli Andrea , Molinari Irene , VanderBeek Brandon , Faccenda Manuele
Published: March 2022

Seismic anisotropy exists in various depths on Earth. However, computational complexities and limited data coverage often lead many seismic tomographic efforts to neglect it. This isotropic assumption can lead to various misinterpretations, which become more important when the spatial resolution is increased. 

In our project, we aim at constructing, through full-waveform inversion, a 3D seismic model of upper mantle anisotropic structure (approximately 500 km depth) below the Tyrrhenian Sea -- a region of great geodynamic interest mainly because of the Calabro-Ionian subduction zone. 

Here we present the framework and the forward modelling, based on the joint use of SPECFEM3D and AxiSEM software, for the implementation of the so-called "box tomography" [1]. By this, a 3D, anisotropic, model spans the region that we aim to resolve, whereas the rest of the globe is represented by a 1D model with lower resolution. This methodology allows the inclusion of teleseisms -- thus a much larger dataset than allowed by closed-domain modelling, as we can also use numerous seismic events out of the region of interest recorded by the dense network of stations within it. We show that this approach in fact highly improves the coverage of data, that can be used for inversion. 

We use SPECFEM3D for the region of interest and AxiSEM for the global simulation. We process the topography, seismic velocities and anisotropy, in order to construct a realistic 3D input model for the area of interest, that honours the Earth's curvature and transforms the geometry of an a priori model from geographical to Cartesian coordinates, with respect to a point of reference, situated in the middle of the top layer of the constructed mesh. We then process the waveforms, resulting from such forward simulation, with the application of a rotation from the Cartesian coordinates to the geographical ones, in order to perform the inversion with the use of real data of seismic recordings. The forward modelling is then to be used for computation of anisotropic Fréchet kernels and inversion. 

[1] Yder Masson, Barbara Romanowicz, Box tomography: localized imaging of remote targets buried in an unknown medium, a step forward for understanding key structures in the deep Earth, Geophysical Journal International, Volume 211, Issue 1, October 2017, Pages 141–163, https://doi.org/10.1093/gji/ggx141
Landslides, soil moisture, and land use changes in the mountainous Northern-western provinces of Rwanda: field-based research in a tropical environment
Authors: Sibomana Pascal , Vanmaercke Matthias , Nahayo Déogratias , Uwihirwe Judith , Bogaard Thom , Hubert Aurélia , Rukundo Emmanuel , Tychon Bernard , Dewitte Olivier
Published: March 2022

The mountainous environments of the Northern-western provinces of Rwanda are often affected by severe cases of rainfall-triggered landslides. Recent studies carried out in the region reveal that the peak in the occurrence of these new landslides is not associated with the highest monthly rainfall, but occurs at the end of the wet season when the antecedent soil moisture conditions seem to be the most favourable. The Northern-western provinces of Rwanda are also densely populated. This high demographic pressure is associated with significant land use/cover changes (e.g. deforestation) and land management practices (e.g. agricultural terraces). Recent studies in the region have demonstrated that deforestation initiates a landslide peak that lasts several years. Our field observations also show that agricultural terraces seem to play a role in the occurrence of landslides. Nonetheless, not only for Rwanda, but also in general, our insights on the impacts of land use/cover changes and land management practices on the soil moisture conditions that lead to rainfall-triggered landslides remain very poorly quantified. This is especially true in the tropics. The goal of our research is to make a contribution to the quantification of these interactions. More specifically, we work at the level of six experimental hillslopes that present similar topographic characteristics but contrasting soil types, namely clayey soils and sandy soils. For each soil type, three hillslopes with different land uses and land management practices are investigated: cultivated hillslope, terraced hillslope, and forest hillslope. In total, we installed sixty access tubes, eighteen sensors, five rain gauges and six piezometers to monitor/measure the spatial-temporal variation of soil moisture content, rainfall and groundwater fluctuations. Both automatic and manual measurements are carried out, bringing accurate daily to sub-daily data for all the sites. The acquisition of the data was initiated during the wet season that started at the end of 2021. Preliminary results show the occurrence of patterns of rainfall-soil moisture conditions. These data from the field measurements will be used to better link the landslide susceptibly of the region with the human-induced changes and the rainfall characteristics. Ultimately, this will serve to improve the prediction of spatial-temporal patterns of rainfall triggered landslides at local scale in this tropical and intensively cultivated environment.
What do oyster shells tell us about paleoclimatology?
Authors: Huyghe Damien , de Rafelis Marc , Emmanuel Laurent , Daëron Mathieu , Marlot Loïc , Lartaud Franck
Published: March 2022

In the context of the current global warming, it is crucial to acquire new paleoclimatic data around past analogues. For decades, bivalve shells have constituted one of the most common supports for paleoclimatic archives based on stable isotope approaches to constrain the seasonal gradient of temperature. One of the key points to conduct this kind of project reliably is to constrain precisely what the analyzed organisms do record and what it is possible to restore from their analysis? Thus, the prerequisite for any (paleo)climatic study is to determine the rhythms that govern the biomineralization of the analyzed organisms. Additionally, it is essential to verify the significance of their geochemical signal.

Thus, in this work, we present results combining a sclerochronological and geochemical approach applied to oyster shells. The shells were cultivated in sites from the French Atlantic coast where the environmental conditions (temperature, salinity, ...) were measured continuously during two years. The shells were chemically labeled (Mn2+) in order to obtain a precise time frame within each shell that can be revealed under cathodoluiminescence.

The results of the sclerochronological study indicate that oysters mineralize their shells with a rhythmicity following tidal cycles (2 calcite increments / day). A lunar and seasonal cyclicity is also highlighted. High resolution geochemical measurements (d18O) confirm that oysters can reliably reproduce seasonal temperature variations, even if geochemical drifts are observed during the first year of growth due to a very high growth rate. We also tested the new ∆47thermometer for these mollusks. Our results are consistent with a strong correlation between seawater temperature and ∆47 for all samples except for the juvenile samples that also exhibited an isotopic disequilibrium for the d18O. This correlation is consistent with earlier calibrations reprocessed in the recent I-CDES metrological scale, adding to the evidence that many different types of carbonates conform to statistically indistinguishable relationships between ∆47 and crystallization temperature.

Finally, these results are applied to reconstruct the paleoclimatic evolution around a hyperthermal event that occurred 40 Ma ago, the Middle Eocene Climatic optimum.
Sensitivity analysis of terrestrial carbon budget with changing land use land cover and climate by combining dynamic vegetation model and satellite observed data at high resolution over Austria- Eisenwurzen
Authors: Verma Arpita , Francois Louis , Jacquemin Ingrid , Lanssens Benjamin , Tölle Merja , Matej Sarah , Egger Claudine
Published: March 2022

The understanding of the terrestrial carbon budget depends on the development of the terrestrial carbon sink, which is influenced by the forest dynamics under climate change and environmental conditions. In this study, we choose a new approach combining the CARAIB-dynamic vegetation model (DVM) and satellite observed data at a high resolution of 3 km over the Austria-Eisenwurzen region for the year 1985-2020. Using machine learning techniques and remote sensing Landsat satellite data, we extracted the land use and land cover (LULC) over the study region. It is giving the precise estimation of spatial and temporal change of forest dynamic over the year 1985-2020. In addition, the geographical distribution of Eisenwurzen 80 % part is the Northern Alps, 11 % of the area belongs to the Northern Alpine Foothills and 9 % belong to the Central Alps. The objective of this study is to understand the model sensitivities and uncertainties in dynamic conditions which are necessary for a reliable and robust estimation of the terrestrial carbon budget. Here, we will conduct our simulation with CARAIB-DVM in different environments – with and without LULC change, no climate change (de-trending), climate change scenario, constant atmospheric CO2. Additionally, we are simulating our model over the course of >100 years for analysis of model sensitivity to climatic parameters. From, this study, we explore how the changes in these parameters affect the estimation of the terrestrial carbon sinks. Given that the parameters we are exploring in this analysis are highly uncertain, especially at the regional level and at high resolution, it is important to see how these adjustments affect the estimation of the carbon budget. Hence, with this study, we understand which input parameters are responsible for the uncertainty in the estimation of carbon sequestration. Further, we will calibrate the dynamic vegetation model to minimize uncertainty in the future projection (until 2070). In conclusion, this study allows us to understand the importance of changing land-use, climate, and environment scenarios and to constrain the model with an improved input dataset that reduces the uncertainty in the model evaluation of the regional carbon budget of terrestrial ecosystems.

 
Lack of Change in Atmospheric Blocking Duration in a Warming Climate
Authors: Nabizadeh Ebrahim , Lubis Sandro , Hassanzadeh Pedram
Published: March 2022

Most studies on blocking events have so far focused on changes in the frequency of blocking events and the resulting weather extremes. The duration of blocking events and its potential changes under climate change have received much less attention. Previous studies are uncertain and show slightly different changes in the duration of blocking events. Using three large-ensemble, fully coupled general circulation model simulations, and two different blocking indices, we show no noticeable change in the duration of blocks under future climate change. Based on the results from the 1D traffic jam, proposed by Nakamura and Huang in 2018, we have found that an increase in the mean flow (speed of the jet) or transient eddy forcing independently, cause a reduction in the duration of blocking events. However, in reality, the transient eddy forcing and the speed of the jet are varied dependently, and they are likely to covary through shear. To address this issue, we diagnosed the relationship between transient forcing and the meridional temperature gradient in the GFDL dry dynamical core. By substituting this relationship in the 1D model, we show no changes in the duration of blocking events consistent with a constant duration in the GFDL dry dynamical core simulations. The responses of transient forcing and mean flow under climate change in a comprehensive GCM explain the insignificant change in the duration of blocks. It is worth mentioning that we only focus on the duration of blocking events as one of the important factors in driving extreme weather events, however, the impacts of other essential factors such as thermodynamics and soil moisture are needed to be further investigated.
Assessment of spatiotemporal variations of groundwater recharge in the Upper Lerma River basin using a process-based hydrological model
Authors: Ortiz Febe , Zhang Zhechen , Maskey Shreedhar , Zhou Yangxiao , McClain Michael
Published: March 2022

Water resources are under high stress worldwide due to multiple factors. There is a general need to develop better and more efficient management practices. Understanding groundwater and surface water as one source is crucial for this determination. A clear comprehension of groundwater and surface water interactions as an integrated system requires a good knowledge of topography, geology, and climate. This research analyzes the spatiotemporal variation and availability of surface water resources and groundwater recharge in a highland basin using a comprehensive hydrological model. The hydrological model is based on the Soil and Water Assessment Tool (SWAT), allowing spatially distributed assessment using sub-basin and hydrological response units. The case study is the Upper Lerma River basin located in the central part of Mexico. Its location and topography (highland) have made its aquifer the second most source to satisfy the water demand of Mexico City since 1940. As a result, groundwater levels have declined, and springs in the surrounding mountainous regions have progressively disappeared over time. Although few studies attempted to estimate recharge and variability, a lot is unknown to analyze the declining water resources in the basin. This research contributes to understanding the basin water resources using the modeling approach, which integrates topography, land use, soil, and climate data to calculate different water cycle components in space and time. The analysis period is 1985-2017. Statistics of model calibration show a good correlation between the computed and measured discharges from 1995 to 2003 with a Nash-Sutcliffe Efficiency (NSE) value of 0.77, an R2 value of 0.79, and a PBIAS of -1%. The preliminary results show that the foothills and alluvial fans are the most extensive recharge areas, which agree with the piezometric data. Detailed analysis on recharge and surface runoff is ongoing.
Likely future(s) of global wildfires
Authors: Kelley Douglas I , Mathison Camilla , Burton Chantelle , Brown Megan , Sullivan Andrew , Baker Elaine , Kurvits Tiina
Published: March 2022

We show likely substantial increases in burning by 2100 in Boreal and Tropical Forests irrespective of future emissions and after accounting for the (often considerable) uncertainties and biases in global fire and climate modelling. Rather than projecting future fire regimes directly, we used the ConFire Bayesian framework to model the likelihood of all possible future burning levels given historic fire and climate model performance. Driving the framework with bias-corrected outputs from four ISIMIP2b GCMs run under RCP2.6 and RCP6.0 accounts for uncertainties in future emissions and climate model projections. 

While we forecast the potential for substantial shifts in fire regimes of much of the world by the end of the century, many show low likelihood given our confidence in the fire, vegetation and climate model projections. Tropical savannas show the largest potential for change, though without confidence in the direction of change due to uncertainty in future precipitation projections.  An increase in dry fuel drives an increase in burnt area in northern Australia. However, this is not significant against uncertainty associated with present-day veg/fire model performance. There is a significant agreement for decreased burning in Southern Brazil, Uruguay and northern Argentina, and the US east coast under RCP2.6, but not RCP6.0.

We do show a high likelihood of drying fuel loads driving an increase in burning in Indonesia, Southern Amazon, central and eastern Siberian Taiga and many Arctic areas across RCPs. These areas are of particular concern given the potential to release the high carbon content of forests and peatlands irrecoverable carbon. Mitigating from RCP6.0 to 2.6 will likely alleviate some though not all of this burning. This is important for future mitigation planning and determining likely temperature and emission targets to avoid the worst impacts of fire in our warmer world.
Crop water productivity studies of leading world crops in California utilizing advanced multispectral remote sensing and modeling on the Google Earth Engine (GEE) cloud
Authors: Foley Daniel , Thenkabail Prasad , Oliphant Adam , Aneece Itiya , Teluguntla Pardhasaradhi
Published: March 2022

As the global population expands in the 21st century, demand for food and water are increasing whereas supply of arable land and accessible fresh water are decreasing. A way to mitigate this looming problem is to increase agricultural Crop Water Productivity (CWP) by improving how much yield (e.g., grain, biomass) is produced per unit of water. To produce more crop with less water (more crop per drop) over large scales, a better understanding of measuring, modeling, and mapping CWP of major world crops utilizing multi-sensor remote sensing, meteorological data, crop yield statistics, and cloud based machine learning is needed.  This study aims to establish a novel methodology to measure evapotranspiration and CWP of select crops at 30m resolution. To accomplish this, a benchmark study area within the San Joaquin section of the Central Valley of California, USA was chosen to represent a diverse agricultural growing region. Within this area, leading and high-water consuming world crops were selected and mapped with respective growing seasons determined by NDVI analysis. Actual evapotranspiration (Eta) as a proxy for water use was determined with new methods to map Evaporative Fraction (Etf) and Reference Evapotranspiration (Eto) per crop type. Using the equation Eta = Eto x Etf, a novel approach for hot and cold pixel selection in image analysis was developed to determine Etf utilizing Landsat thermal bands in conjunction with Google Earth Engine (GEE).

This analysis determined CWP for nine major world crops (almonds, cotton, wheat, pistachios, grapes, barley, rice, corn, and walnuts) specific to individual crop growing seasons. This study also provides the quantum of water that can be saved if CWP is raised by 10, 20, and 30% relative to existing water use, thus establishing a pathway to create potential water banks from the saved water. Although this study focused on California, the application of methods used has potential to expand globally. This methodology provides insight to help ensure water security and potentially implement better water management strategies in the 21st century.
Advanced Prediction of the Outer Van Allen Belt Dynamics and a Prototype Service: the H2020 SafeSpace project 
Authors: Daglis Ioannis A. ,   SafeSpace Team
Published: March 2022

The European SafeSpace project has been implementing a synergistical approach to improve space weather forecasting capabilities from the current lead times of a few hours to 2-4 days. We have combined the solar wind acceleration model MULTI-VP with the heliospheric propagation models Helio1D and EUHFORIA to compute the evolution of the solar wind from the surface of the Sun to the Earth orbit. The forecasted solar wind conditions are then fed into the ONERA Geoffectiveness Neural Networks, to forecast the level of geomagnetic activity with the Kp index as the chosen proxy. The Kp index is used as the input parameter for the IASB plasmasphere model and for the Salammbô radiation belts code. The plasma density is used to estimate VLF wave amplitude and then VLF diffusion coefficients, while the predicted solar wind parameters are used to estimate the ULF diffusion coefficients. Plasmaspheric density and VLF/ULF diffusion coefficients are used by the Salammbô radiation belts code to deliver a detailed flux map of energetic electrons. Finally, particle radiation indicators will also be provided as a prototype space weather service of use to spacecraft operators and space industry. The performance of the prototype service will be evaluated in collaboration with space industry stakeholders. The work leading to this paper has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870437 for the SafeSpace (Radiation Belt Environmental Indicators for the Safety of Space Assets) project.
Solar wind conditions suppressing the production of magnetosheath jets during CME occurrence
Authors: Koller Florian , Plaschke Ferdinand , Preisser Luis , Temmer Manuela , Roberts Owen W.
Published: March 2022

Magnetosheath jets are dynamic pressure enhancements frequently observed in the Earth’s magnetosheath. They are significant coupling elements between the solar wind and the magnetosphere of the Earth and they can be geoeffective. Jets travel anti-sunward through the magnetosheath and can impact the magnetopause. The generation of these jets is generally linked to processes at the quasi-parallel bow shock and the foreshock. We analyzed how the appearance of these jets is linked to large-scale solar wind (SW) structures, in particular coronal mass ejections (CMEs) and stream interaction regions (SIRs) and their associated high speed streams (HSSs). In our statistical analysis, we use magnetosheath jets detected by the THEMIS spacecraft between 2008 to 2020. We found that the number of detected jets is lower during the passing of CMEs. Significantly more jets are observed during SIRs and HSSs. We analyze the difference in conditions during each SW structure and compare them to the SW conditions measured during the detection of jets. We focus on SW Alfvénic Mach number and IMF cone angle, which affect the presence of the foreshock and the position of the quasi-parallel shock front. We find that jets are unlikely to appear during a mix of low Alfvénic Mach numbers and high cone angles, which are SW conditions often found during CMEs and their associated sheaths.
Creating land use-land cover baselines for monitoring Land Degradation Neutrality in Switzerland
Authors: Akinyemi Felicia O. , Bär Valentin , Ifejika Speranza Chinwe
Published: March 2022

The non-availability of annual land cover maps for Switzerland at the national and local levels hampers setting a Land Degradation Neutrality (LDN) baseline (2000 – 2015) and monitoring until the year 2030. Land cover change is an LDN sub-indicator required to assess the proportion of degraded land to total land area (Sustainable Development Goal 15 indicator — SDG15.3.1). The Swiss version of the European CORINE Land Cover (CLC), which is available for the years 1990, 2000, 2006, 2012 and 2018, is often used to analyse land cover and land cover change. However, the approximately 6-year production cycle of the CLC is only partially in line with the internationally agreed LDN baseline and monitoring periods.

Yet, annual land cover maps are required not only for baseline setting but crucial for monitoring the SDG15.3.1 on an annual basis until 2030. Further, most studies evaluating the effects of land cover and change often do not consider the impact of differing annual land cover configurations and sizes on their analysis results. Doing so is important, especially for the LDN, because of the pervasive influence land cover and its changes have on other sub-indicators such as Land Productivity Dynamics (LPD) and the change in Soil Organic Carbon stock, whose computation is currently based on land cover change.

Aimed at contributing to the scientific basis for operationalizing LDN for Switzerland, this study developed and applied a remote sensing-based method for generating land cover data. It took advantage of the availability of big spatial data (e.g., Sentinel-1 and Sentinel-2 satellite images, digital elevation model — DEM, CLC) to map land cover for the years 2015 and 2020, with reference datasets created with high resolution images. For 2015 and 2020, 100 training and validation points were created for each of the seven land cover classes (Forest, Grassland, Cropland, Wetland, Artificial Surfaces, and Otherland). Land cover change was calculated for the baseline period of 2000 – 2015 and 2016 – 2020 for the monitoring period. DEM was used in land cover classification, as topography was one of the main limiting factors for identifying land use types, particularly the need to reduce misclassifications of shady mountainous areas.

The methodology and results provide a basis for periodic assessments of the land cover dimension of the LDN and for automating the production of annual land cover maps for Switzerland. Evaluating the changes in land cover both for the baseline and monitoring periods also enabled us to separately analyze how changes in land cover differed between both periods. The land cover change for the monitoring period until 2020 was compared to the baseline, based on which we identify and discuss some challenges relating to land degradation in Switzerland.
Contribution of SLR to combined hlSST+SLR solutions for bridging the gap between GRACE and GRACE-Follow On
Authors: Ebadi Sahar , Weigelt Matthias , Jäggi Adrian , Meyer Ulrich , Arnold Daniel , Mayer-Gürr Torsten
Published: March 2022

GRACE and GRACE-Follow On gravity field solutions form an unprecedented time series of time-variable gravity field which is indispensable for geosciences, water and climate monitoring. However, the GRACE and GRACE-Follow On time series suffer from a data gap of about one year. Thus, there is a need for an intermediate technique that will bridge the gap between the two missions and will allow 1) for a continued and uninterrupted time series of mass observations and 2) to compare, cross-validate and link the two time series. The most promising method for the long-wavelength part of the gravity field is a combination of high-low satellite-to-satellite tracking (hlSST) of low-Earth orbiting satellites by GNSS in combination with satellite laser ranging (SLR), where SLR is known to provide the highest quality time-variable gravity for the very low degrees (2-5) and hlSST is able to provide a higher spatial resolution at a lower precision in the very low degrees. In this contribution, we discuss the importance of the SLR contribution to the combined solution showing that a hlSST solution is underperforming and a considerable improvement and stabilization for the low degrees can be achieved by the inclusion of SLR for the very low degrees. We also shed light on different combination techniques on the normal equation level with and without variance component estimation and discuss their advantages and difficulties in the implementation.
Probing the structure of the flat subduction in Oaxaca, Mexico, using a temporal seismic array. 
Authors: Calò Marco , Solano Hernández Erika Alinne , Bernal Manzanilla Karina , García Gomora Luisa , Perez-Campos Xyoli , Iglesias Mendoza Arturo
Published: March 2022

Cocos plate assumes a peculiar flat subduction beneath Mexico. Oaxaca region is the part of Mexico where the trench is closest to the coastline and where a transition from flat to a more dipping subduction plane occurs.

The closest seismic broadband seismometers existing near the coast are managed by the Mexican National Seismological Service (SSN) and consist of three stations installed over a straight coastline of Oaxaca of more than 200 km. The limited number of stations makes it very      difficult to get a detailed study of the seismicity able to provide sufficient information to characterize the events of magnitude less than 4.0-4.5 in this portion of the subduction.

In this work we show the preliminary results of a temporary network of 11 stations (9 broadband and 2 Raspberry Shakes) installed since September 2021 on the Oaxaca coast and designed to complement the coverage of the SSN stations. The two networks are now able to provide enough information to obtain refined catalogs and carry out studies that can probe the structure of the crust and upper mantle of the region with unprecedented detail.

In particular we will show the first results of the refined event locations, focal mechanisms and 3D seismic velocity models. All this information is lighting several features unknown of this portion of the Cocos plate and the overlaying North America one, opening new questions about the tectonics and geodynamics of the region.

Work supported by the PASPA-DGAPA, UNAM program, as a sabbatical year at Universidad del Mar (UMAR), Puerto Angel, by the PAPIIT-DGAPA project: IN108221, and by the internal project of the UMAR: 2II2003 and PRODEP UMAR-PTC-181.
Common Era sea-level budgets of North America
Authors: Walker Jennifer , Kopp Robert , Shaw Timothy , Richards Geoff , Horton Benjamin
Published: March 2022

A sea-level budget improves understanding of driving processes and their relative contributions. However, most sea-level budget assessments are limited to the 20th and 21st centuries and are global in scale. Here, we estimate the sea-level budget on centennial to millennial timescales of the Common Era (last 2000 years). We expand upon previous analysis of sites along the U.S. mid-Atlantic coast (Walker et al., 2021) and produce site-specific sea-level budgets for all of the eastern and western North American coastlines and Gulf coast. This broader scope further improves understanding of the temporal evolution and variability of driving processes of sea-level changes in the past and present, and which will shape such changes in the future.

To produce the sea-level budgets, we use an updated global database of instrumental and proxy sea-level records coupled with a spatiotemporal model. Using the unique spatial scales of driving processes, we separate relative sea-level records into global, regional, and local-scale components. Preliminary results along the eastern North American coastline reveal that each budget is dominated by regional-scale, temporally-linear processes driven by glacial isostatic adjustment until at least the mid-19th century. This signal exhibits a spatial gradient, ranging from 1.0 ± 0.02 mm/yr (1σ) in Newfoundland to a maximum of 1.6 ± 0.02 mm/yr in southern New Jersey to 0.5 ± 0.02 mm/yr in Florida. Non-linear regional and local-scale processes, such as ocean/atmosphere dynamics and groundwater withdrawal, are smaller in magnitude and vary temporally and spatially. The most significant change to the budgets is the increasing influence of the global signal due to ice melt and thermal expansion since ~1800 CE, which reaches a 20th century rate of 1.3 ± 0.1 mm/yr, accounting for 43-65% of each budget.
Process-level differences between two PBL schemes used in NOAA’s GFS model
Authors: Bao Jian-Wen , Grell Evelyn , Michelson Sara , Hong Songyou
Published: March 2022

The behavior of two eddy-diffusivity mass-flux (EDMF) planetary boundary layer (PBL) schemes used in NOAA’s Global Forecast System is examined at the level of mixing processes.  The examination is performed by comparing the two schemes in 1-D simulations of convective PBL growth using the same physics configuration and two sets of initial atmospheric states extracted from three-dimensional (3-D) GFS initial conditions.  All simulations show that the TKE-EDMF scheme mixes more and leads to less CIN and CAPE than the Hybrid-EDMF scheme.  The excessive mixing of the TKE-EDMF scheme is consistent with that seen in the 3-D GFS forecasts compared with radiosonde data.  Diagnosis using process perturbation sensitivity experiments indicates that the mass-flux term is more dominant in the TKE-EDMF than in the Hybrid-EDMF scheme.  Quantitative aspects of the local eddy diffusivity are also different between the two schemes, pointing to uncertainty in the physical partition of local and non-local mixing in the EDMF formulation of the two schemes.  Additional sensitivity experiments show essential parameters that can be optimized according to observations and/or large-eddy-simulation results that provide a more realistic partition of local and non-local mixing.
Influences of temporal variability on the calibration of a hydrologic model  
Authors: Tigabu Tibebe , Wagner Paul , Narasimhan Balaji , Fohrer Nicola
Published: March 2022

Abstract: Parametrization is an important step to construct a reasonable hydrologic model for a catchment. However, selecting appropriate model parameters can be challenging, particularly in data scarce regions. Conventionally, hydrologic model parameters are selected through calibration assuming that catchment processes and model parameters are stationary over time. However, the assumption of stationarity may not be valid all the time due to temporal changes in the behaviors of catchments. Therefore, the purpose of this study is to investigate the influence of temporal variability on the SWAT model parametrization using different calibration periods. To this end, we calibrated the SWAT model based on daily and monthly streamflow data in the Adyar catchment, Chennai. Results showed that the SWAT model performance and parameter values differed when the calibration periods were shifted by one year. This is reflected in the KGE (Kling Gupta Efficiency) values that varied between 0.38 to 0.68 for calibration periods of 2004-2007,2005-2008, 2006-2009, 2007-2010, 2008-2011, 2009-2012 and 2010-2013. Likewise, the selection of values for sensitive model parameters varied even though the parameter values were chosen in the same ranges. Moreover, independent model evaluation for wet and dry years showed significantly different performance indices and model parameter values. The model efficiency of wet years (NSE = 0.59 and KGE= 0.68) was by far better than the model efficiency of dry years (NSE = -0.59 and KGE = 0.1). In general, this study provides a good insight into hydrologic model calibration under non-stationarity conditions.
Jovian Synchrotron Observations From The Juno Microwave Radiometer
Authors: Levin Steve , Adumitroaie Virgil , Santos-Costa Daniel , Bolton Scott ,   Juno Microwave Radiometer Team
Published: March 2022

The Juno Microwave Radiometer (MWR) is in a unique position to measure the synchrotron emission from Jupiter’s inner radiation belts. Juno is a spinning spacecraft in a highly eccentric polar orbit about Jupiter, with perijoves at about 5000 km above the cloudtops. From this unique vantage point, the Juno Microwave Radiometer (MWR) has measured the radio emission in 6 channels, at wavelengths ranging from approximately 1.4 to 50 cm, with 100 ms sampling throughout each spin of the spacecraft, since the first science pass in August of 2016. Synchrotron emission is emitted in a narrow cone about the electron’s direction of motion, so Earth-based observations are limited by our equatorial vantage point. The Juno data set provides a remarkable view of the Jovian synchrotron emission over a wide range of viewing angles, from inside the radiation belts.  While the MWR synchrotron data set is unprecedented, the size and variety of the data set also make analysis complex. We have therefore begun by extracting a limited subset of the data. For each channel during each perijove pass, we have determined the peak emission observed in the equatorial lobe and in the high-latitude lobes.  Using these data, we determine the spectral index of the synchrotron emission as a function of frequency, from 0.6 GHz to 22 GHz.  Results will be compared with models to examine the energy distribution of electrons.
Hazard assessment with SAR – What to expect from the NISAR mission
Authors: Jones Cathleen , An Karen , Staniewicz Scott
Published: March 2022

NASA’s NISAR mission, expected to launch in early 2023, will provide SAR observations of nearly all Earth’s land surfaces and selected ocean and sea ice areas on both ascending and descending orbits at a 12-day orbit repeat interval.  In this talk, mission plans to support both sustained and event-driven observations for hazard assessment are presented.  The NISAR satellite will carry both L- and S-band instruments, with the L-band instrument providing the near-global coverage and the S-band acquisitions concentrated in southern Asia and the polar regions.  In addition, the mission system will be capable of accepting and implementing requests for rapid processing to support disaster response.  Most land observations are part of the standard observation plan, so requested scenes will be marked for rapid processing and delivery, with the goal of providing information within hours of acquisition.  In the event that new acquisitions are needed, e.g., over the ocean as major tropical storms develop, the instrument can be retasked to acquire new scenes.

In addition, we present information about efforts on the part of the mission to enable realistic simulation of NISAR’s capabilities across a broad range of science and applications topics.  To that end, L-band quad-polarimetric and repeat pass SAR data acquired with the airborne UAVSAR instrument, which has ~3-m single look resolution, has been processed to be ‘NISAR-like,’ with the noise level and spatial resolution of NISAR’s planned acquisition modes.  To date, more than 400 NISAR-like products from 70 different UAVSAR scenes acquired in North America and Greenland have been produced, and the UAVSAR project is continuing to generate more products specifically to support hazard assessment for fires and landslides.  Examples of anticipated NISAR performance will be shown with comparison to results using the full resolution UAVSAR products. 

This work was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA.