bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrated Climate Radiative Forcing from Arctic-Boreal Fires
Authors: van Gerrevink Max J. , Veraverbeke Sander , Cooperdock Sol , Potter Stefano , Moubarak Michael , Goetz Scott J. , Mack Michelle C. , Randerson James T. , Turetsky Merritt R. , Rogers Brendan M.
Published: March 2022

Fire is a major disturbance mechanism in arctic-boreal ecosystems and results in warming and cooling feedbacks to the climate system. Greenhouse gas emissions from fires are a major positive feedback, yet post-fire carbon sequestration in recovering ecosystems partly offsets this. In addition, fire removes part of the organic soil layer and may result in permafrost thaw and consequent greenhouse gas emissions. Yet, fire-induced changes in ecosystem structures result in a larger spring-time snow cover compared to unburned areas, and this imposes a negative climate feedback through increased surface albedo. These various climate forcings are spatially and temporally heterogeneous and depend on various landscape components and fire regime characteristics. Understanding the net climate forcing effect is crucial in managing and mitigating climate change impacts on carbon cycling. We applied the concept of radiative forcing in a quantitative spatial assessment of the net climate feedbacks induced by arctic-boreal North American fires. We capitalize upon the state-of-the-art carbon combustion estimates by the Arctic Boreal Vulnerability Experiment Fire Emissions Database (ABoVE-FED) and a novel climate forcing framework to predict fire-driven changes in net forcing under historical and future climate scenarios. In our analyses we incorporated all fires between 2001 and 2019, evaluating the net fire-induced forcing over the regrowth successional phase (at 20-years after fire) and after full succession (at 80-years after fire). Our results highlight the spatial and temporal heterogeneity in climate forcings from arctic-boreal fires, and in future work we plan to characterize spatiotemporal patterns of the net climate feedback.
Assessing global macroalgal carbon dioxide removal potential using a high-resolution ocean biogeochemistry model
Authors: Berger Manon , Bopp Laurent , Ho David T. , Kwiatkowski Lester
Published: March 2022

Carbon dioxide removal (CDR) has become part of the portfolio of solutions to mitigate climate change. In combination with emission reductions, CDR may be critical to achieving the goal of limiting global warming to below 2°C, as outlined in the Paris Agreement. Due to its potential high productivity and environmental co-benefits, macroalgae cultivation has recently become a prominent ocean-based CDR strategy. However, estimates of the CDR potential of large-scale deployment are highly limited. Here we simulate idealized global deployment of macroalgae-based CDR using the NEMO-PISCESv2 ocean biogeochemical model at high spatial resolution (0.25° nominal horizontal resolution). Macroalgae growth is confined to the upper 100m of the water column in Exclusive Economic Zones (EEZ) free of sea ice and with an appropriate nitrate/phosphate regime. Although the loss of dissolved inorganic carbon (DIC) through macroalgal growth enhances the flux of atmospheric carbon into the ocean, this increase in carbon uptake is less than the rate of macroalgal production. In the absence of any nutrient limitation on growth, the enhancement in ocean carbon uptake is only 73-77% of the carbon lost from the water column due to macroalgal production. However, when macroalgae nutrient limitation/uptake is additionally accounted for, the increase in ocean carbon uptake accounts for only 41-42% of the potential carbon lost through macroalgae production. These inefficiencies are due to ocean transport replacing part of the DIC lost in the upper water column with DIC from depth, the influence of local nutrient concentrations on the vertical profile of macroalgal production, and feedbacks on the nutrient resources available for phytoplankton net primary production. CDR efficiency is shown to scale near-linearly between scenarios assuming 1% to 10% of the global EEZ area is cultivated for macroalgae. The efficiency of macroalgal CDR shows significant regional variability, with much of the enhancement in ocean carbon uptake (43%-46%) occurring outside EEZs, posing potential difficulties to national scale accounting.
Experimental study on sediment deposition and water level surge under unsteady sediment supply
Authors: Zhou Qihang , Wang Lu , Liu Xingnian , Nie Ruihua
Published: March 2022

Storms often cause serious rainfall runoff in mountain river areas, which results large amounts of sediment form upstream hills to downstream channels, leading to a reconstruction of the riverbed and finally water and sediment disasters. High concentration sediment transport may exist during flash floods, and performs unsteady supply process in channels. Based on laboratory experiments, this paper analyzed the responses of riverbed elevation and water level to unsteady sediment supply. The unsteady sediment supply is described as a single triangular sediment process. The sediment supply rate of all tests is greater than the sediment transport capacity of the flow. Results show that the riverbed deposits and water level rises continuously during sediment supply, while the flow depth decreases correspondingly. The greater the rate of sediment supply, the faster the rising of riverbed elevation and water level. After the sediment supply ended, the deposited bed degraded and the rising water level decreased. Compared with the constant sediment supply, the riverbed elevation and water level under unsteady sediment supply rise greatly. In addition, it is found that the flow discharge with saturated sediment supply is much less than that without sediment supply in the same water level. Because the concentration sediment transport increases the flow resistance and then makes the water level sharply rise. The study highlighted the important effects of the unsteady sediment supply on bed morphology and water level surge in water and sediment disasters, and enhanced the understanding of the mechanism caused by the sharply rise of water level in flash floods.
Water Towers of the Pamirs: II. Cryosphere dynamics and implications for runoff and livelihoods
Authors: Sidle Roy C , Caiserman Arnaud , Salazar Álvaro , Khojazoda Zulfiqor T
Published: March 2022

Cryosphere components in the Pamirs play an important role in the release of water to the Vakhsh and Panj river systems where both mountain and downstream communities rely on sustainable water supplies for their agriculture, potable water, and hydropower. Of the three primary cryosphere sources of water (glacial, snow, and permafrost melt), glacial melt is the most predictable and constitutes and intermediate supply of runoff to streams, while almost no estimates of permafrost contributions are available. Snowmelt is highly variable from year to year and because it is the largest water supply to these rivers, understanding the potential amount and timing of snowmelt is critical for local communities.  

Based on our remote sensing investigations during the past 20 years, we water found wide interannual variations in snow water, snowline elevation, and snow persistence throughout the Vakhsh and Paji basins, but no clear evidence of basin-wide climate change trends. Specific locations of the central Pamirs appear to be shifting from snow to rain due to climate warming, approximately offsetting each other, but likely producing more runoff in late spring to early summer and less in mid to late summer. In the high, glaciated Vakhsh basin, temperature increases have been offset by higher snowfall, resulting in little glacial ice change. By overlaying maps of glaciers on a digital elevation model (Alos Palsar 12.5 m) containing stream networks, we estimated that about 75% of the glaciers were closely connected to first-order or larger channels; however, this may be a liberal estimate because some first-order streams are not connected to major river systems. Based on the TTOP model nearly 24,000 km2 of continuous permafrost terrain exists throughout the Panj and Vakhsh basins, the majority of which is located at elevations > 3577 m. Streamflow contributions from permafrost thaw during the summer were estimated as subsurface flux from streambanks; ≈ 638 x 106 m3 each summer, which represents about 1.5% of the average annual river discharge for both basins.

The climate variability and localized changes we observed pose challenges for predicting runoff from high elevation cold regions due to the altered patterns of the timing of snow, glacier, and permafrost accumulation and melt, including temporal changes, interannual variability, and hydrological connectivity of sources. The various water sources will respond differently in a changing climate, generating complex runoff scenarios and socioeconomic consequences downstream.
Microphysical retrieval for stratiform precipitation: Global statistics from the Dual-frequency Precipitation Radar
Authors: Mroz Kamil , Battaglia Alessandro
Published: March 2022

Stratiform rain and the overlying ice that generates it are leading components of the Earth's climate system. From a microphysics perspective, it’s the ice mass concentration and its size that exert first-order control on the mass flux through the cloud, and by extension the underlying rain rate. The Dual-frequency Precipitation Radar (DPR) on NASA's core Global Precipitation Measurement satellite is the first space-borne instrument that offers the opportunity of a dual-wavelength radar retrieval of these variables.

Our focus is placed on DPR observations over the precipitation columns with a confidently identified bright band.  The analysis indicates a sharp increase in retrieved mass flux from ice to rain phase in the current algorithm, which is inconsistent with the expectation that mass flux varies little across the bright band under conditions of stratiform rain.

The algorithm proposed here imposes a continuity of the precipitation rate across the bright band which additionally helps in deriving bulk ice density. It is based on Bayes' rule with riming parameterized by the “fill-in” model. The radar reflectivities are simulated using the scattering models corresponding to realistic snowflake shapes. The algorithm is validated using the co-located polarimetric radar data collected for the GPM ground validation program. In future, this dataset will be used for multi-frequency radar studies that aim at constructing high quality training datasets for artificial intelligence algorithms that are necessary to analyse huge data volumes that will be generated by upcoming space-borne radar missions.
Topological structure, fractal characteristic of fault network system and their relationship with hydrocarbon migration：Taking Wenchang 9/8 area in the Pearl River Mouth Basin as an example
Authors: Ma Saiting , Wu Zhiping , Wang Di
Published: March 2022

Abstract: To clarify the relationship between the complexity of the fault network systems and hydrocarbon migration in petroleum basin, 3D seismic data and hydrocarbon migration data from T50, T60 and T70 horizon in Wenchang 9/8 area were analyzed. The complexity and connectivity of the fault network system at different horizons in Wenchang 9/8 area are quantitatively characterized based on the topology and fractal theory. The relationship between the distribution characteristics of the complexity of the fault network system and hydrocarbon migration at different horizons in Wenchang 9/8 area was revealed combined with hydrocarbon migration data in typical zones. It indicates that the fractal dimension high value areas, and the topological high value areas and hydrocarbon migration area shave a good coupling relationship in the fault network system. The results showed that: there has a good coupling relationship among the fault interaction zone (fracture tip, structural transition zone, etc.), the fractal dimension high value areas and the topological high value areas. The peak values of the number of nodes (Nc) in T50, T60 and T70 horizons are in the range of 1-2, 6-8 and 5-7, respectively. The peak values of the fractal dimension (D) in T50, T60 and T70 horizon are among 1.4-1.6, 1.6-1.8 and 1.5-1.8, respectively. There is a good coupling relationship between fault interaction zone and hydrocarbon migration zone. Comparing with other structural area, the fault interaction zone has higher topological value and fractal dimension value. The topological high value area has good connectivity, and the fractal high value area has more faults, which is conducive to the formation of fault traps. Therefore, the overlapping zone with high topological value and high fractal dimension value are the dominant channels for oil and gas migration, which are favorable for the formation of favorable oil and gas reservoirs.
Energy Export from the Tropical Pacific via the Atmosphere - a Lagrangian Perspective
Authors: Baier Katharina , Duetsch Marina , Bakels Lucie , Mayer Michael , Haimberger Leopold , Stohl Andreas
Published: March 2022

The El Niño-Southern Oscillation (ENSO) is linked with energy exchange between the ocean, atmosphere and space. It has a global impact on weather, agriculture and the economic system. In association with ENSO, we analyse the atmospheric energy export from the Tropical Pacific with the particle dispersion model FLEXPART using meteorological input data from the ERA5 reanalysis. In this Lagrangian model, the atmosphere was filled homogeneously with five million particles, which were traced forward in time and represent the global atmospheric mass transport. From this Lagrangian reanalysis dataset covering the years 1979-2017, air masses residing within the Nino3.4 + Nino3 region and below 1 km are selected and followed 30 days forward in time. We found that some of these relatively warm air masses are transported to the Atlantic Ocean where they are mainly located at upper layers. Furthermore, we found strong correlations between the mass transport and the Nino3.4 Index, thus more air is exported to the Atlantic Ocean during El Niño conditions. This transported air further releases energy, as shown by a negative energy divergence. Even over the Sahel zone there is a significant signal, which indicates a direct atmospheric connection between West Africa and the Tropical Pacific. Based on our findings, the transported air might support drier surface conditions during El Niño in that region. In summary, the Lagrangian technique provides new insights into how energy is exported from the Tropical Pacific via the atmosphere and clarifies the relevance of atmospheric transport associated with ENSO.
Sorptivity of dual-permeability soils
Authors: Lassabatere Laurent , Yilmaz Deniz , Di Prima Simone , Abou Najm Majdi , Stewart Ryan D. , Fernández-Gálvez Jesús , Pollacco Joseph , Angulo-Jaramillo Rafael
Published: March 2022

Sorptivity is a crucial parameter for modeling water infiltration into soils. Many works have related sorptivity to the soil hydraulic functions, i.e., the water retention and unsaturated hydraulic functions. Parlange's  (1975) formulation is one of the most used to relate sorptivity to the soil hydraulic functions, allowing the direct computation of sorptivity as a function of the soil hydraulic parameters and initial and final water contents. On this basis, several works investigated the possibility of direct analytical relationships between sorptivity and the hydraulic shape and scale parameters  (e.g., Lassabatere et al., 2021). So far, most of the studies have focused on single permeability soils with monomodal water retention and unsaturated hydraulic functions. However, the use of dual- or multi-permeability approaches is increasing in relation to the necessity to account for preferential flows in soils. The approach developed by (Gerke and van Genuchten, 1993) or (Pollacco et al., 2017) are examples of dual-permeability approaches and allow the modeling of preferential flows in soils. In the proposed study, we apply the formulation proposed by Parlange (1975) for the computation of sorptivity for dual-permeability soils, considering the approaches proposed by Gerke and van Genuchten (1993) and Pollacco et al. (2017). Our developments lead to a relation between the bulk sorptivity of the dual permeability soils to those of the matrix and the fast-flow compartments, plus additional terms. We end with the scaling of the proposed relation for investigating the effects of the matrix and fast-flow shape and scale parameters and the volumetric content occupied by the fast-flow compartment.

References

Gerke, H. H. and van Genuchten, M. T.: A dual-porosity model for simulating the preferential movement of water and solutes in structured porous-media, 29, 305–319, 1993.

Lassabatere, L., Peyneau, P.-E., Yilmaz, D., Pollacco, J., Fernández-Gálvez, J., Latorre, B., Moret-Fernández, D., Di Prima, S., Rahmati, M., Stewart, R. D., Abou Najm, M., Hammecker, C., and Angulo-Jaramillo, R.: Scaling procedure for straightforward computation of sorptivity, 2021, 1–33, https://doi.org/10.5194/hess-2021-150, 2021.

Parlange, J.-Y.: On Solving the Flow Equation in Unsaturated Soils by Optimization: Horizontal Infiltration, 39, 415–418, 1975.

Pollacco, J. A. P., Webb, T., McNeill, S., Hu, W., Carrick, S., Hewitt, A., and Lilburne, L.: Saturated hydraulic conductivity model computed from bimodal water retention curves for a range of New Zealand soils, 21, 2725–2737, https://doi.org/10.5194/hess-21-2725-2017, 2017.
First results from the AQG-B07 absolute quantum gravimeter
Authors: Dykowski Przemyslaw , Arnal Maxime , Menoret Vincent , Sękowski Marcin , Karkowska Kamila , Wilde-Piórko Monika , Kryński Jan
Published: March 2022

In October of 2021 the AQG-B07 absolute quantum gravimeter has been installed at the Borowa Góra Geodetic Geophysical Observatory. Since its installation the instrument is under ongoing evaluation performance and testing at Borowa Góra as well as in other locations in Poland.

Within the first months of the AQG-B07 operation periodic continuous measurements were conducted at Borowa Góra as well as multiple gravity determinations on gravity stations at the gravimetric laboratory. Gravity values obtained with the AQG-B07 were compared with those from the A10-020 absolute gravimeter using the record of the iGrav-027 superconducting gravimeter to evaluate the offset between those absolute instruments. Continuous gravity records allowed to evaluate the short term stability of the AQG-B07 against the expected behaviour of the instrument. By the end of 2021 a 12 day record have been collected with a broadband seismometer recording side by side which allowed to evaluate the noise characteristic of residual gravity values collected with the AQG-B07 gravimeter.

In January of 2022 the gravimeter was operating in Warsaw in the premises of the Institute of Geodesy and Cartography located in an urban area. Gravity measurements conducted in more active micro seismic environment allowed to gain a better perspective on the performance of the AQG-B07. Absolute gravity determinations were simultaneously done with the A10-020 gravimeter at the same location.

Evaluations of noise as well as analysis against the seismometer, in particular to test the ability of the AQG-B07 to record earthquakes for determination of the seismic structure of the Earth's mantle from the analysis of surface waveforms, were performed in the framework of the research project No. 2017/27/B/ST10/01600 financed from the funds of the Polish National Science Centre.
Are ocean reanalyses useful for Earth rotation research?
Authors: Börger Lara , Schindelegger Michael
Published: March 2022

Oceanic circulation and mass-field variability play important roles in exciting Earth’s wobbles and changes in length-of-day (ΔLOD), on time scales from days to several years. Quantifying these effects require estimates of ocean angular momentum (OAM), which are typically drawn from numerical forward models or coarse-resolution ocean state estimates. A little-tested alternative in this regard is the emerging suite of ocean reanalyses, operating at eddy-permitting horizontal resolution (1/4°) and with sequential data assimilation (DA) schemes. Here, we compute geophysical excitation series from three identically configured global ocean reanalyses that are based on the same hydrodynamic core and input data (e.g., altimetry, Argo, sea surface temperature) but different DA schemes. The resulting OAM time series are compared both with each other and with atmosphere-corrected geodetic excitation from 2007 to 2011. For periods less than 120 days, the reanalyses series typically explain 40–50% of the residual observed polar motion excitation, somewhat less than a widely used ocean state estimate. By contrast, the reanalyses’ skill in accounting for oceanic signals in ΔLOD is more varied, particularly when seasonal and longer time scales are included in the comparison. This result points to a misclosure of the global mass balance constraint among atmosphere, ocean, and terrestrial hydrology, in part depending on whether or not a specific reanalysis considers the discharge of continental freshwater into the ocean. Together, our analyses provide insight into the kinematic consistency of newly available ocean reanalyses and give a quantitative understanding of the influence of different DA schemes on OAM estimates.
Recharge sources, flow regime, and hydrogeochemical evolution of saline groundwater in an arid inland basin, northwestern China
Authors: Lei Yujuan , Sun Ziyong , Zou Changjian
Published: March 2022

Uneven water resources distribution and saline groundwater have become urgent concerns in inland arid areas because they pose difficulties for managing water resources. Policies and decisions depend on understanding the recharge sources, flow patterns, and hydrogeochemical evolution of groundwater systems. A comprehensive approach of hydrogeochemistry and environmental isotopes (δD, δ18O, 3H, 14C) was used to assess the groundwater recharge sources and hydrogeochemical evolution, and the Aksu River Basin was taken as the study area, which is located in the northwestern Tarim Basin, NW China. Results indicate that groundwater was originated from precipitation and meltwater in mountainous areas of Tianshan Mountain. Modern groundwater was found in the mountain front area and shallow groundwater locality near the surface area, while the deep confined groundwater was recharged by the paleo precipitation during the last glacial period. In the lowest discharge area, groundwater was recharged by the lateral flow from both the south desert and north Mountain areas. Along the flow path, groundwater evolves from freshwater to brine water and saline water, with a shift in hydrochemistry type from Na·Ca·Mg-HCO3·SO4 and Na·Ca·Mg-HCO3·SO4·Cl to Na-Cl. Mineral dissolution dominates the groundwater chemistry in the alluvial fan. The groundwater in the flow-through area is dominated by mineral (halite, gypsum) dissolution and cation exchange due to the longer residence times, leading to an increase in solute inputs along the flow paths and thus the evolving trend from freshwater to brackish water and finally saline water. On the contrary, infiltration of surface water decreases the salinity of groundwater partly. In the discharge area, the mineral dissolution and reverse cation exchange are the primary geochemical process controlling groundwater chemistry. This study could provide essential information for groundwater resource management.
Sedimentary calcite Zn isotope composition as a possible paleo pH proxy – a case study from eutrophic Lake Greifen, Switzerland
Authors: Vogel Hendrik , Engler Andrea , Bigalke Moritz
Published: March 2022

The pH is a fundamental determinant for physico-chemical reactions in aquatic environments but notoriously difficult to reconstruct in paleo records. Experimental studies have shown that the δ66Zn isotopic composition of calcite is strongly pH dependent in the 7.0 ≤ pH ≤ 8.0 range, with lower δ66Zn at higher pH, making it a suitable pH proxy in settings with endogenic calcite precipitation (Mavromatis et al. 2019). Here we applied the calcite δ66Zn pH proxy to a sediment core covering the recent anthropogenic eutrophication at Lake Greifen, Switzerland to test its applicability in a natural setting that has undergone a productivity-driven shift in surface water pH. Lake Greifen is a hard water lake with a surface water pH ranging between >8.5 during spring and summer algal blooms and ~7.5 in the remainder of the year. Sediments deposited in the center of the lake are predominantly composed of endogenic calcite (>75 %wt) with the remainder comprising varying amounts of organic matter and biogenic silica and only minor detrital matter. Pure calcite samples for this study were collected from sediments deposited during both the oligotrophic and eutrophic lake phases to capture a wide range in pH. Lake Greifen sedimentary calcite δ66Zn values relative to the JMC3-0749L standard range between 0.71 ± 0.05 ‰ in sediments deposited under oligotrophic conditions to 0.29 ± 0.01 ‰ in sediments deposited under eutrophic conditions. Lower δ66Zn values during the more recent eutrophic lake phase may thus be explained by a productivity-driven change in surface water pH. Interestingly, δ66Zn values around 0.3 ‰ have been reported for calcite precipitating at pH >8 in experimental studies, which is very close to Lake Greifen’s modern surface water pH recorded during spring and summer algal blooms. δ66Zn values around 0.7 ‰, reported in samples originating from the less productive oligotrophic phase of Lake Greifen, are indicative for a pH <7 in experimental studies. Additional data from other settings with varying δ66Zn water isotope compositions are required to further confirm our findings but the preliminary results of this study suggest δ66Zncalcite to be a promising pH proxy candidate in paleo records.

 

Reference

Mavromatis, V.; Gonzalez, A.G.; Dietzel, M.; Schott, J. (2019) Zinc isotope fractionation during the inorganic precipitation of calcite – Towards a new pH proxy. Geochimica et Cosmochimica Acta 244, 99 – 112.
Preliminary Geochemical Assessment of the Subglacial Environment of Beerenberg, the World’s Northernmost Active Stratovolcano
Authors: Graly Joseph , Engen Siri , Yde Jacob
Published: March 2022

As loci of the fresh formation of alkaline rock, volcanic islands are hotspots of geochemical activity. Collectively volcanic islands are responsible for approximately one third of the global long term CO2 drawdown from chemical weathering. Glaciers also form environments with substantial chemical weathering activity. Despite zero-degree temperatures, subglacial environments provide both freshly ground down mineral surfaces and highly dilute meltwaters, allowing chemical processes to occur at faster rates than in warmer settings where reactions occur near chemical saturation. Yet, the degree to which glaciation enhances weathering on volcanic islands has received relatively little study.

Beerenberg, Jan Mayen, Norway, is the world´s northernmost active stratovolcano. It is mostly glacierized, with 23 distinctly named glaciers descending from the top of the volcanic cone to the sea. Many of the Beerenberg glaciers release sediment-laden subglacial water, indicative of water-rock interaction in subglacial environments. In August 2021, we did a preliminary survey of the aqueous geochemistry and sediment composition of several subglacial outlets at Beerenberg’s largest glacier, Sørbreen. We also surveyed glacial surface streams, glacial ice and snow, non-glacial melt streams, springs, and proglacial lakes.

The subglacial waters of Sørbreen are strongly enriched in bicarbonate, with little chloride despite the marine location and only trace amounts of other anions. Cation composition is ~60% Na and K and 40% Ca and Mg by mole, suggesting a balance between divalent and monovalent cations reflective of local bedrock. Together this strongly suggests carbonation weathering of silicate minerals as the source of the vast majority of dissolved load in the subglacial waters. Non-glacial waters are more dilute and enriched in sea water derived ions (Cl, SO4, and Na) compared to subglacial waters.  

While a complete geochemical budget is not possible from our initial observations, these results imply that Beerenberg is a hot spot of chemical weathering. If our dissolved CO2 fluxes are representative of long-term averages, then atmospheric CO2 drawdown at Sørbreen is comparable to other glacierized mafic volcanic rock regions, such as those on Iceland and Disko Island. These atmospheric CO2 drawdown rates are approximately double the world average and a factor of five higher than the drawdown in non-glacierized high latitude regions.
Real-time global shear-traction model verification using atmospheric effects of radon activity
Authors: Pulinets Sergey , Vičič Blaž , Budnikov Pavel , Žalohar Jure , Potočnik Matic , Komac Marco , Dolenec Matej
Published: March 2022

Over the last 30 years, the Cosserat continuum has gained an importance in the description of physical properties of tectonic faulting. Using the sine-Gordon equation we show that kink and antikink solitary wave solutions can be used to describe propagation of the couple-stresses through the faulted medium of the Earth’s crust. Recently it was established that the shear-traction exerted on the tectonic faults by the couple-stresses correlates with radon degassing. Degassing is estimated through atmospheric effects due to air ionization expressed in the form of the atmospheric chemical potential (ACP), thus providing a direct and measurable proof for the existence propagating couple-stresses in the Earth’s crust. The positive and negative correlation corresponds to different faulting mechanism and thickness of the Earth’s crust. Positive correlation is observed in the regions characterized by thin crust, as well as in the normal and strike-slip faulting regimes. The negative correlation is observed in the regions characterized by thick crust as well as in the reverse faulting regimes, and along very long transform faults. Using together the shear-traction modeling and ACP measurements, we can identify critical zones prone to the earthquake triggering and calculate the time-dependent probability for the future earthquakes.
The (missing) erosional record of warm-based glaciation on early Mars
Authors: Grau Galofre Anna , Whipple Kelin , Christensen Philip
Published: March 2022

The lack of evidence for large-scale glacial erosion on Mars has led to the belief that any ice sheet that may have existed had to be frozen to the ground. We challenge this argument, suggesting instead that the fingerprints of Martian warm-based ice masses should be the remnants of their drainage systems, including channel networks and eskers, instead of the large scoured fields generally associated with terrestrial Quaternary glaciation. Our results use the terrestrial glacial hydrology framework to interrogate how the Martian lower surface gravity should affect the state and evolution of the glacial drainage system, ice sliding velocity, and the rates of glacial erosion. Taking as reference the scale and characteristics of the ancient southern circumpolar ice sheet that deposited the Dorsa Argentea formation, we compare the theoretical behavior of geometrically identical ice sheets on Mars and Earth and show that, whereas on Earth glacial drainage is predominantly inefficient, enhancing ice sliding and producing characteristically scoured glacial landscapes, on Mars the lower gravity favors the formation of efficient subglacial channelized drainage. The apparent lack of large-scale glacial fingerprints on Mars, such as scouring marks, drumlins, lineations, etc., is thus to be expected. 
Adaptation to extreme heat in the agricultural sector – SSP-dependent scenarios for mechanization deployment
Authors: van Maanen Nicole , Orlov Anton , Schleussner Carl-Friedrich
Published: March 2022

Climate change and increasing heat stress reduces labour productivity and supply all across the globe. In a global warming scenario of 3°C, effective labour (i.e., the combination of productivity and supply) is expected to decrease by up to 50 percentage points relative to the period 1986-2005. Central Africa, Southeast Asia and Latin America will be most affected. In these regions, the agricultural sector is still of paramount importance for livelihoods and food security and outdoor work is more common. When heat stress further increases, the capability for physical activity will reduce across a wide range of working places, primarily outdoors. Especially in low- and middle-income countries the effects of climate change will lead to a reduction in economic activity and decrease the capacity for economic growth.

 

Automation and mechanization of outdoor work could greatly reduce the economic costs of heat stress and counts as the most effective adaptation strategy in the agricultural- and construction sectors to climate change, but scenarios of potential future deployment of mechanization are in their infancy. Here we propose a Mechanization Deployment Index (MDI), which builds on the concept of constrained adaptative capacity reflecting a level of mechanization under the presence of socio-economic constraints compared to the maximum mechanization potential in the absence of constraints to adaptive capacity. By identifying socioeconomic variables within the framework of the Shared Socioeconomic Pathways (SSPs) that correlate with the current level of mechanization deployment, we are able to project five scenarios for future mechanization implementation alongside the SSPs. For the first time, we will be able to show how different socio-economic trajectories strongly modulate future heat stress impacts in the agriculture sector. These scenarios can be included in integrated assessments of climate change and improve the economic risk assessment in the 21st century.
The impact of COVID-19 pandemic preventing measures and meteorological conditions on the atmospheric air composition in Moscow in 2020
Authors: Kirillova Natalia , Skorokhod Andrey , Rakitin Vadim , Fedorova Eugenia
Published: March 2022

Changes in the atmospheric composition in different periods of 2020 in Moscow, associated with the COVID-19 pandemic preventing measures of varying intensity and with corresponding reduction in emissions of pollutants, were investigated. Surface concentrations of nitrogen dioxide NO2, carbon monoxide CO, ozone O3, aerosol fraction PM10 and meteorological parameters in different periods of 2020 are compared with similar data for the previous 5 years. The analysis of ground-based measurements, as well as high-resolution satellite distributions of CO and NO2, indicated that the content of major pollutants and its spatial distribution in the Moscow region were significantly affected by both restrictive measures and abnormal meteorological conditions in 2020. It is possible to obtain quantitative estimates of the contribution of both factors using transport and chemical modeling based on detailed inventory of anthropogenic emissions.

Additionally, some characteristics of atmospheric composition long-term trends in Moscow region are analyzed and discussed.

The study was supported by Russian Science Foundation under grant №21-17-00210.
Orographic Flow Influence on Precipitation During an Atmospheric River Event at Davis, Antarctica
Authors: Gehring Josué , Vignon Etienne , Billault--Roux Anne-Claire , Ferrone Alfonso , Protat Alain , Alexander Simon P. , Berne Alexis
Published: March 2022

Snowfall in Antarctica is the main input to ice sheet mass balance, which is heavily influenced by the frequency and intensity of maritime moisture intrusions from lower latitudes. The most intense moisture incursions often occur as narrow corridors of enhanced vapor transport, called atmospheric rivers (ARs). However, the fate of ARs depends on the state of the coastal boundary layer. For instance, katabatic or foehn winds can lead to a subsaturated boundary layer, which can cause total snowfall sublimation. In this study, we use recent data collected during the Precipitation over Land And The Southern Ocean (PLATO) campaign to investigate how the synoptic evolution and the local orography influenced the sublimation of snowfall during an AR event (08 – 10 January 2019) at Davis, East Antarctica. The dataset includes scanning polarimetric and vertically pointing Doppler radar, radiosounding, and Raman lidar measurements. We also make use of simulations from the Weather Research and Forecasting (WRF) model. Our analysis revealed that orographic gravity waves (OGWs), generated by a north-easterly flow impinging on the ice ridge upstream of Davis, were responsible for snowfall sublimation through a foehn effect. Despite the strong meridional moisture advection associated with the AR during this event, almost no precipitation reached the ground at Davis. We found that the direction of the synoptic flow with respect to the orography determined the intensity of OGWs over Davis, which in turn directly influenced the snowfall microphysics. We hypothesize that turbulence induced by the OGWs likely enhanced the aggregation process, as identified thanks to dual-polarization and dual-frequency radar observations. This study suggests that despite the intense AR, the snowfall distribution was determined by local processes tied to the orography. It also stresses the importance of studying local effects when interpreting the impact of ARs on the Antarctic surface masse balance. Finally, the mechanisms found in this case study could contribute to the extremely dry climate of the Vestfold Hills, one of the main Antarctic oases.
Evaluation of amplitude and phase scintillation impact on GPS and Galileo frequencies 
Authors: Christovam de Souza Ana Lucia , Oliveira Jerez Gabriel , de Oliveira Camargo Paulo
Published: March 2022

Global Navigation Satellite Systems (GNSS) has been widely used in aviation applications, nonetheless its accuracy and reliability are degraded under ionospheric scintillation. This effect on the radio wave signals causes a rapid fluctuation on both amplitude and phase of the signals, which may even lead to loss of lock in the worst case. The (Ground Based Augmentation Systems) GBAS based on GNSS signals is used for positioning improvement of aircraft landing. For safety-of-life applications, augmentation systems are necessary once reliability under all conditions is of great importance. Therefore, the evaluation of GNSS performance under amplitude and phase ionospheric scintillation is an important task when introducing a new safety-of-life technology such as GBAS. In this context, we present a quantitative analysis of the ionospheric amplitude and phase scintillation impact on the GPS and Galileo frequencies. Analysis considered S4 and σ_moraeφ60 behavior for the same frequencies between both systems (L1 = E1 and L5 = E5a signals). The data used in this study were measured by a station located in a region characterized by the occurrence of strong scintillations, station SJCU (23.1°S, 45.8°W). The analyzed data were collected from November 12 to December 12, 2014, a period with moderate to strong solar activity. S4 and σφ indices were estimated for satellites with elevation angle higher than 20° and indices values classified above 0.2 and 0.08, respectively. Considering GPS, amplitude and phase scintillation, the L5 signal had the greatest ionospheric impact in 91.7% and 98.4% of the epochs, respectively. Considering Galileo, for amplitude and phase scintillation, the E5a signal had the greatest ionospheric impact in 96.4% and 99.4% of the epochs, respectively. Those results indicate that lower frequencies are most affected under ionospheric scintillation. Similar behavior could be observed considering the same frequencies with GPS and Galileo, specially taking into account phase scintillation for L5 and E5 frequencies.
Dynamic leaf nitrogen and phosphorus under increasing nutrient co-limitation in a land surface model
Authors: Caldararu Silvia , Yu Lin , Nair Richard , Fleischer Katrin , Zaehle Sönke
Published: March 2022

Leaf nutrient contents, in particular nitrogen (N) and phosphorus (P), are key plant traits, linking to processes such as photosynthesis and respiration. Traditionally, plant traits are considered to be constant in time, but there is ample observational evidence that nutrient content varies with changes in environmental conditions. Specifically, increased atmospheric CO2 drives increased plant growth and potentially increases in plant nutrient limitation, while anthropogenic N deposition further drives an imbalance in the N and P available to plants. Therefore, being able to dynamically, and accurately, represent leaf N and P content in land surface models (LSMs) is critical to predicting future ecosystem response to global change.

Most LSMs that include dynamic leaf N and P do so through a set of empirical functions that balance out demand and supply of nutrients. However, such representations do not take into account the differing physiological roles of the two nutrients, with N being directly linked to photosynthetic compounds, while P has a much stronger control on new biomass growth and respiration. 

Using the QUINCY land surface model we represent physiologically-realistic dynamic leaf N and P content, using optimality theory, which assumes that plants alter their structure and function in order to maximize growth. We test the model using data from ICP Forests, a spatially extensive European network of sites with repeated, standardized measurements of leaf N and P content covering the period 1990 - present. We show that the new model representation performs better than the standard empirical functions, both in terms of spatial distribution of leaf nutrient content and its change through time, being able to reproduce the observed shift towards P limitation caused by increased N deposition. Most importantly, the model does not rely on the law of the minimum principle, being able to represent true co-limitation and allow leaf N and P to vary with different physiological and environmental pressures, thus creating more robust and realistic predictions.
Subduction invasion of the Atlantic by Mediterranean subduction zones
Authors: Duarte João C. , Riel Nicolas , Kaus Boris J.P. , Rosas Filipe M.
Published: March 2022

Subduction invasion has been referred to as the process by which subduction zones from a subducting ocean invade or trigger subduction initiation in a contiguous ocean. This can, in principle, happen in different ways that can vary from a direct migration by rollback along an oceanic corridor connecting the two oceans (e.g., the Gibraltar Arc into the Atlantic) or by polarity reversal across a narrow continental land bridge, potentially involving the collision of an ocean plateau with the pre-existent trench (the Scotia and the Caribbean arcs). This process is important because new subduction zones are difficult to start in the present plate tectonics context and most known examples of initiation seem to be forced by pre-existent subduction zones. The problem is that in internal Atlantic-type oceans there are no pre-existent subduction zones, and therefore, they must be introduced from the outside. Luckily, the Atlantic seems to be just passing through a phase of invasion, as evidenced by the three referred examples. But while the Caribbean and the Scotia arcs are already two fully formed Atlantic-subduction systems, the Gibraltar Arc is currently in the process of migrating between oceanic basins. In the future, the Arc can evolve according to two different scenarios. In the first, the Gibraltar Arc is stuck between Africa and Iberia and the subduction is waning. In the other scenario, after a period of quiescence, the arc manages to go through and invade the Atlantic. In order to understand which is more feasible, we have developed 3D numerical models using the code LaMEM to gain some insights into how this system may evolve. We have simulated the development of the Mediterranean arc-back-arc system, with rollback and the retreat of the subduction zones in a fully dynamic framework (no active kinematic boundaries). Our model shows that under the studied parameters, the Gibraltar subduction zone manages to invade the Atlantic, even in the cases of a very narrow oceanic corridor. However, this led to a very significant decrease in the subduction velocity, suggesting that in the natural prototype, a period of quiescence is expected before the Mediterranean subduction zone manages to go through and invade the Atlantic.

J.C. Duarte and F.M. Rosas acknowledge financial support by FCT through the project UIDB/50019/2020 – Instituto Dom Luiz (IDL)
The effects of global warming on flood properties in small-medium Mediterranean catchments
Authors: Rinat Yair , Armon Moshe , Morin Efrat
Published: March 2022

Climate change impact on floods and water resources is crucial for planning adaptation strategies. This is especially true in Mediterranean regions where a decrease in precipitation and an increase in extreme rain rates are projected.  Global climate models and common hydrological models are often too coarse to represent rainfall properties and hydrological processes in these regions due to their scale. Therefore, the current understanding of climate change's impact on hydrological properties and processes in Mediterranean catchments is missing. To resolve this, we utilize the high-resolution (1 km2) weather research and forecasting (WRF) model (abstract #EGU22-1996). Rainfall simulations were input to a distributed hydrological model (<60 s, 100 m2 GB-HYDRA). Explicitly, we apply spatially-shifted ensemble results for 41 couples of heavy precipitation events in historic (end of 20th century) and future (end of 21st century; RCP 8.5 scenario) climate conditions to 4 small-medium-size basins (18–69 km2) in the eastern Mediterranean. Ensemble average total precipitation decreased by 24% between historic and future events. This resulted in an average decrease in outlet peak discharge (-20%, non-significant), and a significant drop in the total flood volume (-27%) in future events. This change can be attributed to a significant (-25%) decrease in runoff contributing area (RCA); hillslope sections from which water flows, reaches the stream network, and consequently, the basin outlet and significant decrease of the averaged rainfall rates over them (-22%). The results of this study suggest that ongoing climate change in Mediterranean regions is expected to have a considerable impact on the flow regime, and thus, practical actions should be taken.
Englacial temperatures increase of Taconnaz glacier (Mont Blanc area) and consequences on glacier instability in the future.
Authors: Vincent Christian , Gilbert Adrien , Piard Luc , Gagliardini Olivier , Jourdain Bruno , Gimbert Florent , Christoffersen Poul
Published: March 2022

High elevation cold glaciers are experiencing important warming in response to on-going climate change. It could affect the ice/rock interface temperature and lead to avalanching glacier instabilities on steep slopes. Few of these glaciers are located in densely populated areas and could threaten inhabited areas in the future, when the ice/rock interface will become temperate. It is the case of Taconnaz hanging glacier (Mont Blanc area) with a large cold ice area located on a steep slope in the accumulation zone. This glacier is located above the valley of Chamonix. Modeling and measuring the progressive warming of this cold hanging glacier is critical to assess the evolution of its stability.The thermal regime of this glacier have been monitored over the last decades from deep boreholes observations.  We found clear englacial temperatures increase. For instance, measurements performed in deep boreholes between 1994 and 2021 reveal strong changes in englacial temperature reaching 2 °C increase at a depth of 50 m close to the summit of this glacier (4300 m a.s.l.). We also found that the current englacial warming is now reaching the glacier base at most location. Our numerical simulations, using a thermo-mechanical model, are able to capture the observed warming and show that a large volume of ice could become unstable within the 21th century and could lead to a large ice avalanche. Such break-off could have catastrophic consequences for life and property in the valley.