bluuebunny/crossref_metadata_2025 huggingface dataset:
Inferred bioavailability of pyrogenic organic matter in comparison to natural organic matter from global sediments and surface waters
Authors: Graham Emily , Song Hyun-Seob , Grieger Samantha , Garayburu-Caruso Vanessa , Stegen James , Bladon Kevin , Myers-Pigg Allison
Published: March 2021

Wildfires are increasing in frequency, severity, and area burned in response to pervasive hotter and drier conditions, creating a multitude of negative consequences for aquatic ecosystems. Pyrogenic materials generated by wildfires are transported across terrestrial landscapes into inland waters, where approximately 10% of organic matter pools is comprised of black carbon. While recent work suggests pyrogenic organic matter (PyOM) is more bioavailable than indicated by traditional paradigms, the heterogeneity of PyOM pools generated through various feedstocks and combustion scenarios complicates our efforts to understand its bioavailability. Here, we use a mathematical model to predict the energy content, metabolic efficiency, and rate of aerobic decomposition of representative PyOM compounds. We compare these metrics to model outputs derived from measured natural organic matter in global surface waters and sediments to assess differences in bioavailability. We find that PyOM generally has a similar range of bioavailabilities to that of natural systems. However, phenols and black carbon (defined as highly condensed molecules with high solubility) have lower metabolic efficiency than most representative PyOM classes and natural organic matter pools, denoted by higher lambda and lower carbon use efficiency. Rates of aerobic metabolism of phenols and black carbon are also less negatively impacted by oxygen limitation than any other group. Overall, our work suggests that PyOM may be more bioavailable than previously thought and could be an unrecognized contributor to global C emissions as the prevalence of wildfires increases.
Combined Migration of GPR data for layered media
Authors: Persico Raffaele , Morelli Gianfranco
Published: March 2021

In this contribution we will propose the combination of migration results achieved from the same GPR dataset, aimed to mitigate the effects of the nonuniformity of the propagation velocity of the waves throughout the investigated domain. The nonuniformity of the propagation velocity can be appreciated from the diffraction hyperbolas [1] possibly present in the data, or directly from the results of the focusing [2] achieved from different trial values of the propagation velocity. In ref. [3] an algebraic combination of two (but theoretically even more) migration results achieved from different migration parameters applied to the same data has been shown. In that paper, the case of a horizontal variation and the case of a vertical variation of the propagation velocity of the electromagnetic waves in the soil were considered. Here, we will consider the case of a layered medium with non-flat interface between two adjacent layers, which is a case of interest in several practical application, and is a case where we have both a vertical and a horizontal variation of the parameters. Analogously to ref. [3], we will consider both the aspect of the focusing and that of the combined time-depth conversion.

 

References

 

[1] R. Persico G. Leucci, L. Matera, L. De Giorgi, F. Soldovieri, A. Cataldo, G. Cannazza, E. De Benedetto, Effect of the height of the observation line on the diffraction curve in GPR prospecting, Near Surface Geophysics, Vol. 13, n. 3, pp. 243-252, 2015.

[2]G. Gennarelli, I. Catapano, F. Soldovieri, R. Persico, On the Achievable Imaging Performance in Full 3-D Linear Inverse Scattering, IEEE Trans. on Antennas and Propagation,  vol. 63, n. 3, pp. 1150-1155, March 2015.

[3] R. Persico, G. Morelli, Combined Migrations and Time-Depth Conversions in GPR Prospecting: Application to Reinforced Concrete, Remote Sens. 2020, Volume 12, Issue 17, 2778, open access, DOI 10.3390/rs12172778

 

 
Insights for Business Centric Earthquake Early Warning and Operational Forecasting Systems
Authors: Mulder Femke , Morga Mariantonietta , Jones Keith
Published: March 2021

A large part of Europe is at risk of earthquake disaster events. In the last decade, earthquakes in Europe led to direct economic losses of approximately €29 billion as well as close to 19,000 fatalities. As a result of public awareness campaigns, business organisations are increasingly cognisant of earthquake risks. However, to date there is limited support available to help them systematically manage these risks. Our research supports decision makers based at European business organizations in their efforts to prepare for and respond to earthquakes. We look at how earthquake early warning (EEW) systems and earthquake operational forecasting (OEF) systems can best support business disaster risk management (DRM). We focus hereby on EEW and OEF based decision support systems for preparedness and rapid response, and also their integration with business continuity planning. Our article is based on an extensive literature review of the state of the art in OEF and EEW systems. We have validated and built on these insights through participatory action research (PAR) with potential business users of EEW and OEF systems in Europe. There is great variability in the ways in which different European businesses currently manage earthquake risk. Our research has given us insights into business users’ needs and expectations of EEW and OEF systems. We have harmonized and integrated these insights towards the development of a common earthquake decision support protocol for business organisations. This protocol covers business considerations that extend beyond the prevention of fatalities and direct economic loss to long-term organisational resilience. Combining insights from facilities management, organization science and engineering, we present various considerations for the development of business centric EEW and OEF decision support systems. We outline barriers to the development and uptake of such systems and describe what opportunities they present for different stakeholders.
Understanding in and above canopy-atmosphere interactions by combining large-eddy simulations with a comprehensive observational set
Authors: Pedruzo-Bagazgoitia Xabier , Moene Arnold F. , Ouwersloot Huug , Gerken Tobias , Machado Luiz A.T. , Martin Scot T. , Patton Edward G. , Sörgel Matthias , Stoy Paul C. , Yamasoe Marcia A. , Vilà-Guerau de Arellano Jordi
Published: March 2021

The vegetated canopy plays a key role in regulating the surface fluxes and, therefore, the global energy, water and carbon cycles. In particular, vulnerable ecosystems like the Amazonia basin can be very sensitive to changes in vegetation that exert subsequent shifts in the partition of the energy, water and carbon in and above the canopy. Despite this relevance, most 3D atmospheric models represent the vegetated canopy as a flat 2D layer with, at most, a rough imitation of its effect in the atmospheric boundary layer through a modified roughness length. Thus, the representations often describe quite crudely the surface fluxes. In this work, particular emphasis is placed in the biophysical processes that take place within the canopy and its impact above. Our approach is to represent the coupling of the flow between the canopy and the atmosphere including the following processes: radiative transfer, photosynthesis, soil evaporation and CO2 respiration, combined with the mostly explicit atmospheric turbulence within and above the canopy. To this end, we implemented in LES a detailed multi-layer canopy model that solves the leaf energy balance for sunlit and shaded leaves independently, regulating the exchange of heat, moisture and carbon between the leaves and the air around. This allows us to connect the mechanistically represented processes occurring at the leaf level and strongly regulated by the transfer of diffuse and direct radiation within the canopy to the turbulent mixing explicitly resolved at the meter scale.

We test and validate this combined photosynthesis-turbulence-canopy model by simulating a representative clear day transitioning to shallow cumulus. We based our evaluation on observations by the GoAmazon2014/5 campaign in Brazil in 2014. More specifically, we systematically validate the in-canopy radiation profiles; sources, sinks and turbulent fluxes of moisture, heat and CO2, and main state variables within the canopy, and also study the effects of these in the air above. Preliminary results show an encouraging satisfactory match to the observed evolution of the profiles. As a first exploration and demonstration of the capabilities of the model, we test the effects of a coarser in-canopy resolution, a different radiation scheme and the use of a more simple 2D canopy representation.
Sustainable management of water environment in anthropopressure area for municipal purposes, water quality improvement and utilization of renewable energy sources
Authors: Wilczynski Artur , Namyslowska-Wilczynska Barbara , Maslankiewicz Pawel
Published: March 2021

The Authors deal with the problems of management of post-industrial areas affected by high unemployment leading to prevailing frustration, increasing migration of the population and other socially and economically adverse phenomena. This is accompanied by the considerable degradation of the natural environment and the deterioration in the quality of life of the local population. The aim of the studies is showing the possibilities to create a model to manage the resources in order to achieve sustainable development, particularly to manage water and energy in the post-industrial areas. The studies have been carried out for a region heavily industrialized in the recent past with present closed down mines. In particular, the work relates to examine the possibility of: improving the quality of the surface and underground waters, using the water as a source of low-temperature heat, storing energy and producing energy in local renewable sources, ensuring proper water retention, developing post-industrial tourism through managing the post-industrial facilities and making them available. Innovation of work is to create an integrated model of resources and the environment management, in particular water resources and non-conventional energy.

The proposals constitute a contribution to the implementation of the principles of sustainable development by focusing on three of its dimensions - economic, environmental and social. At the same time it would be a way for the sustainable management of the water environment in the areas of anthropopressure, in industrial and post-industrial areas, for the purpose of collecting water, improving water quality and the use of local energy sources. The possibility of energy storage, which is extremely important in the area of an intensive development of unconventional sources of energy (wind farms, solar sources, hydroelectric, etc.), the characteristics of which are irregular, referred to simply as chimeric sources, also exists.
Cost-effective implementation of the Paris Agreement using flexible greenhouse gas metrics
Authors: Tanaka Katsumasa , Boucher Olivier , Ciais Philippe , Johansson Daniel , Morfeldt Johannes
Published: March 2021

Greenhouse gas (GHG) metrics, that is, conversion factors to evaluate the emissions of non-CO2 climate forcers on a common scale with CO2, serve crucial functions upon the implementation of the Paris Agreement. While different metrics have been proposed, their economic cost-effectiveness has not been investigated under a range of pathways, including those temporarily missing or significantly overshooting the temperature targets of the Paris Agreement. Here we show that cost-effective metrics for methane that minimize the overall cost of climate mitigation are time-dependent, primarily determined by the pathway, and strongly influenced by temperature overshoot. The Paris Agreement will implement the conventional 100-year Global Warming Potential (GWP100), a good approximation of cost-effective metrics for the coming decades. In the longer term, however, we suggest that parties consider adapting the choice of common metrics to the future pathway as it unfolds, as part of the global stocktake, if cost-effectiveness is a key consideration.
Assess 21st century Flash Drought in the United States using high resolution regional climate models
Authors: Gamelin Brandi , Wang Jiali , Kotamarthi V. Rao
Published: March 2021

Flash droughts are the rapid intensification of drought conditions generally associated with increased temperatures and decreased precipitation on short time scales.  Consequently, flash droughts are responsible for reduced soil moisture which contributes to diminished agricultural yields and lower groundwater levels. Drought management, especially flash drought in the United States is vital to address the human and economic impact of crop loss, diminished water resources and increased wildfire risk. In previous research, climate change scenarios show increased growing season (i.e. frost-free days) and drying in soil moisture over most of the United States by 2100. Understanding projected flash drought is important to assess regional variability, frequency and intensity of flash droughts under future climate change scenarios. Data for this work was produced with the Weather Research and Forecasting (WRF) model. Initial and boundary conditions for the model were supplied by CCSM4, GFDL-ESM2G, and HadGEM2-ES and based on the 8.5 Representative Concentration Pathway (RCP8.5). The WRF model was downscaled to a 12 km spatial resolution for three climate time frames: 1995-2004 (Historical), 2045-2054 (Mid), and 2085-2094 (Late).  A key characteristic of flash drought is the rapid onset and intensification of dry conditions. For this, we identify onset with vapor pressure deficit during each time frame. Known flash drought cases during the Historical run are identified and compared to flash droughts in the Mid and Late 21st century.
A case study on the impact of severe convective storms on the water vapor mixing ratio in the lower mid-latitude stratosphere
Authors: Khordakova Dina , Rolf Christian , Grooß Jens-Uwe , Konopka Paul , Müller Rolf , Krämer Martina , Riese Martin
Published: March 2021

Extreme convective events in the troposphere have not only immediate destructive impact on the surface, but can also influence the dynamic and composition of the lower stratosphere (LS). One of the impacts is the moistening of the LS. This effect plays a crucial role in climate feedback as water vapor in the UTLS (Upper Troposphere/Lower Stratosphere) has a major impact on the radiation budget of the atmosphere. 
In this case study we investigate water vapor injection into the LS by convective events in mid-latitudes. In the framework of the MOSES (Modular Observation Solutions for Earth Systems) measurement campaign during the early summer of 2019, balloon borne measurements were performed to capture the water vapor injected into the stratosphere by convective events. On two consecutive days the balloon profiles showed clear evidence of water vapor transported above the tropopause by convection. The magnitude of the water vapor enhancement is comparable to other studies which show measurements above North America. At the altitude of the measured injection a sharp cut-off in a local ozone enhancement peak verifies the tropospheric origin of the water vapor injection. Back trajectories of the measured air masses reveal that the moistening took place multiple hours before the balloon launch and correlate well with ERA5 data showing a strong change in the structure of isotherms and a sudden and short lived increase in potential vorticity at the altitude of the trajectory. A comparison with MLS data shows that this process can barely be recognized by satellite measurements due to the low vertical and horizontal resolution. It is hence desirable to increase the number of in-situ measurements focusing on the impacts of convective events on the lower stratosphere over Europe and to assess its impact on UTLS water vapor.
Post‑collisional mantle delamination in the Dinarides implied from staircases of Oligo‑Miocene uplifted marine terraces
Authors: Balling Philipp , Grützner Christoph , Tomljenović Bruno , Spakman Wim , Ustaszewski Kamil
Published: March 2021

The Dinarides fold and thrust belt on the Balkan Peninsula is the result of the long-lasting convergence between the Adriatic and Eurasian plates since the Mid-Jurassic. Late Jurassic obduction of ophiolites, Early Cretaceous composite nappe stacking, and subsequent continent-continent collision in the latest Cretaceous resulted in folding and thrusting that in the most external part of the Dinarides took place during the Middle Eocene – Oligocene. This extensive last phase of substantial crustal shortening and thickening was associated with flexural foreland basin deposition, resulting in Eo- to early Oligocene syntectonic units. These rocks and older Mesozoic carbonate platform units now form the mountain chain of the external Dinarides. So far, the driving mechanism behind the rock uplift was unknown and it was not clear when the present-day topography formed. Here we show that horizontal marine terraces preserved at elevations of up to 600 m in the external Dinarides are crucial to answer these questions.

We extracted horizontal surfaces, river incision profiles, and the Adriatic and Black Sea catchments from a digital elevation model (DEM). The extracted horizontal surfaces are interpreted as marine terraces because they are degradational, locally preserved in a staircase morphology, neither bedding- nor fault-related, and located close to the present-day Adriatic shoreline. The marine terraces stretch c. 600 km along-strike the entire Dinaric coastal region. Their spatial correlation agrees with the position of a reported positive P-wave tomography anomaly beneath the Dinarides. This up to 180 km deep anomaly correlates also with the thinnest part of the Adriatic lithosphere and the Adriatic-Black Sea drainage divide. The orogen-perpendicular river incisions profiles reveal a symmetric river incision pattern on both sides of the drainage divide. The mean amount of the river incision is equivalent to the mean elevation of the documented marine terraces. All results point to an orogen-wide surface uplift of the Dinarides.

Based on the geological record this post-collisional uplift event can be relatively dated to Oligocene-Miocene (28-17 Ma) and seems to be broadly contemporaneous with the emplacement of igneous rocks with mantle affinity (33-22 Ma) in the internal Dinarides. Previously published geophysical and petrological, as well as the new geomorphological data presented here suggest that the post-collisional reorganization of the Dinarides is attributed to an Oligocene-Miocene mantle delamination event, which results in uplift event affecting the entire Dinarides. We also show that no significant, orogen-scale deformation affected the uplifted Dinarides after the Early Miocene.
The recent upgrade of CMEMS MEDWAVES wave system: description and evaluation.
Authors: Ravdas Michalis , Zacharioudaki Anna , Korres Gerasimos
Published: March 2021

The Med-waves system has been implemented in the framework of the Mediterranean component (MED MFC) of the Copernicus Marine Environment Service (CMEMS) and generates high-resolution analysis, forecast, and reanalysis wave products for the Mediterranean Sea area. The system which is based on the WAM wave model is operational since 2017 and is continuously upgraded in order to represent better the Mediterranean wave dynamics with a high forecast skill. The purpose of this work is to present a description of the various improvements introduced to the system and their impact on the wave product quality. The validation of the system which is done by comparing the model output against buoys and satellite altimeters measurements shows the product quality changes (improvements) due to the different upgrades of the Med-waves system. Based on this upgraded system, we will also give the detailed characteristics of the new reanalysis wave product which is driven by atmospheric forcing from ECMWF ERA5 and provides hourly wave parameters from 1993.
27-day variations of the galactic cosmic rays intensity and anisotropy in solar minima 23/24 and 24/25 by ACE/CRIS, STEREO, SOHO/EPHIN and neutron monitors
Authors: Modzelewska Renata , Gil Agnieszka
Published: March 2021

We study the 27-day variations of galactic cosmic rays (GCRs) based on neutron monitor (NM), ACE/CRIS, STEREO and SOHO/EPHIN measurements, in solar minima 23/24 and 24/25 characterized by the opposite polarities of solar magnetic cycle. Now there is an opportunity to re-analyze the polarity dependence of the amplitudes of the recurrent GCR variations in 2007-2009 for negative A < 0 solar magnetic polarity and to compare it with the clear periodic variations related to solar rotation in 2017-2019 for positive A > 0. We use the Fourier analysis method to study the periodicity in the GCR fluxes. Since the GCR recurrence is a consequence of solar rotation, we analyze not only GCR fluxes, but also solar and heliospheric parameters examining the relationships between the 27-day GCR variations and heliospheric, as well as, solar wind parameters. We find that the polarity dependence of the amplitudes of the 27-day variations of the GCR intensity and anisotropy for NMs data is kept for the last two solar minima: 23/24 (2007-2009) and 24/25 (2017-2019) with greater amplitudes in positive A > 0 solar magnetic polarity. ACE/CRIS, SOHO/EPHIN and STEREO measurements are not governed by this principle of greater amplitudes in positive A > 0 polarity. GCR recurrence caused by the solar rotation for low energy (< 1GeV) cosmic rays is more sensitive to the enhanced diffusion effects, resulting in the same level of the 27-day amplitudes for positive and negative polarities. While high energy (> 1GeV) cosmic rays registered by NMs, are more sensitive to the large-scale drift effect leading to the 22-year Hale cycle in the 27-day GCR variation, with the larger amplitudes in the A > 0 polarity than in the A < 0.
The role of subpolar North Atlantic as a source of predictability
Authors: Yang Shuting , Tian Tian , Wang Yiguo , Schmith Torben , Olsen Steffen M. , Keenlyside Noel
Published: March 2021

The subpolar North Atlantic (SPNA) is a region experiencing substantial decadal variability, which has been linked to extreme weather impacts over continents. Recent studies have suggested that the connectivity with the SPNA may be a key to predictions in high latitudes. To understand the impact of the SPNA on predictability of North Atlantic-European sectors and the Arctic, we use two climate prediction systems, EC-Earth3-CPSAI and NorCPM1, to perform ensemble pacemaker experiments with a focus on the subpolar extreme cold anomaly event in 2015. This 2015 cold anomaly event is generally underestimated by the decadal prediction systems. In order to force the model to better represent the observed anomaly in SPNA, we apply nudging in a region of the SPNA (i.e., 51.5°W - 13.0°W, 30.4°N - 57.5°N, and from surface to 1000 m depth in the ocean). Here ocean temperature and salinity is restored to observed conditions from reanalysis in both model systems. All other aspects of the setup of this pacemaker experiment follow the protocol for the CMIP6 DCPP-A hindcasts and initialized on November 1, 2014. The restoration is applied during the hindcasts from November 2014 to December 2019. Multi-member ensembles of 10-year hindcasts are performed with 10 members for the EC-Earth3-CPSAI and 30 members for the NorCPM1.

The time evolution of ensembles of the initialized nudging hindcasts (EXP1) is compared with the initialized DCPP-A hindcast ensembles (EXP2) and the uninitialized ensembles (EXP3). The prediction skills of the three sets of experiments are also assessed. It can be seen that restoring the ocean temperature and salinity in the SPNA region to the reanalysis improves the prediction in the region quickly after the simulation starts, as expected. On the interannual to decadal time scales, the areas with improved prediction skills extend to over almost the entire North Atlantic for both models. The improved skill over Nordic Seas is particularly significant, especially for EC-Earth3-CPSAI. For NorCPM, the regions with improved skills extend to the entire Arctic. Our results suggest the possible role of the SPNA as a source of skillful predictions on interannual to decadal time scale, especially for high latitudes. The ocean pathways are the critical source of skill whereas our results imply a limited role of coupled feedbacks through the atmosphere.  
Detecting tectonic tremor during slow slip events in Costa-Rica using templates of ordinary earthquakes
Authors: Renou Julien , Hawthorne Jessica
Published: March 2021

Slow slip events (SSEs) have been observed beneath the Nicoya peninsula in Costa-Rica for more than 10 years, and are accompanied by tremor activity both updip and downdip of the seismogenic region. However, tremor detection in this region can be challenging and time-consuming, as many local earthquakes occur amidst the tremor, so envelope-based techniques do not perform as well as they do in other regions. Matched-filter techniques are more appropriate to detect many of the individual low-frequency earthquakes (LFEs) that constitute tremor, but these techniques can also be time-consuming and restricted to small areas because they require a set of template seismograms for each LFE family.

In this study, we attempt to take advantage of the many local earthquakes to use the ordinary earthquakes' waveforms as templates to detect tremor all along the subduction interface. We use an extension of matched-filter techniques, a phase coherence (or matched field) method which can identify signals from locations near the template event even if the template and target signals have different source time functions. Because of this specificity of the coherence method, we should be able to detect tremor co-located with an ordinary earthquake, as long as they share similar Green's functions.

We create template waveforms from a catalog created by the Nicoya Seismic Cycle Observatory, whose events are located using local 3-D velocity model (DeShon et al. 2006). We first apply the method during a SSE event in June 2009, and initial investigations suggest that the tremor and earthquakes are similar enough: high coherence values are found at time of known tremor. Bursts of activity with various duration close to the trench are successfully detected, and their location is consistent with slip distribution of the SSE. Our final goal is to identify potential migration of these bursts related to the propagation of the main front of the SSE, as well as investigate the relation between their released seismic energy and duration. These findings will be finally discussed in comparison with tremor characteristics in other subduction areas.
Seismic classification of rainfall-induced lahars at Volcán de Colima, México
Authors: Martínez Valdés Ivonne , Márquez Ramírez Víctor Hugo , Capra Lucia , Coviello Velio , Arámbula Mendoza Raúl
Published: March 2021

 Rainfall-induced lahars are one of the most common phenomena in tropical volcanoes. Volcán de Colima (VdC) is the most active volcano in Mexico regarding intra-eruptive lahar generation. Lahars represent one of the main hazards for local communities located within a radius of 15 km from the summit. During the rainy season, from May to October dozens of lahars occur in the different ravines draining the VdC. Since 2007, lahar monitoring is performed for both research and civil purposes. Rain gauges, seismic sensors, cameras, and infrasound sensors are part of the current monitoring system deployed at Montegrande ravine (MR) which is located in the southern flank of the volcano. Here we present the data collected during the 2018 monitoring season that are composed of seventeen flow events, six of which feature the most complete dataset ever collected at MR. Data are recorded with multiple stations including broad-band seismic sensors (120 s), geophones (4.5 Hz), short-period seismometers (1 Hz) and a video camera installed along a 1.5 km channel reach. Three types of lahars have been classified based on the join-analysis of seismic signals and video images of these latter six events: dry front, diluted and multi-front. These classes are related to the solid-liquid composition and dynamics of the flows, and to the rainfall amount possibly triggering the processes. A linear discriminant analysis (LDA) is proposed to classify the rest of the events using seismic and rainfall records. Preliminary results show how the flow velocity and the presence of coarse fronts, inferred by means of cross-correlation method and inspection of the video images respectively, are the first factors controlling the characteristics of the seismic signals. This work also demonstrate how seismic techniques represent a valuable tool to describe the remarkable variability of flow dynamics along the travel path.

 
Sea ice controls on Arctic water vapor content and transport: Discoveries from MOSAiC’s pan Arctic Water Isotope Network (AWIN)
Authors: Kopec Ben , Werner Martin , Mattingly Kyle , Klein Eric , Noone David , Akers Pete , Bailey Hannah , Bonne Jean-Louis , Brunello Camilla , Mustonen Kaisa-Riikka , Hubbard Alun , Kløve Bjørn , Welker Jeffrey
Published: March 2021

One of the key changes of the global climate system is the loss of Arctic sea ice, particularly through its impact on ocean-atmosphere interactions. Enhanced evaporation under open-water conditions is widespread from places and periods previously precluded by perennial sea ice cover, leading to an increase in vapor uptake across the Arctic. However, the response of ocean-atmosphere system to sea ice loss varies significantly over time and space. To quantify these variations, the Arctic Water Isotope Network (AWIN) has been established to make continuous water vapor isotope measurements (δD, δ18O, and d-excess) at seven land-based stations from Barrow, Alaska to Ny Alesund, Svalbard. This network has been supplemented by continuous mobile isotope data from the CiASOM project on the Polarstern ice-breaker throughout the MOSAiC “Arctic-drift” expedition. With this network, we comprehensively track water vapor from its source to sink, thereby demonstrating how it varies simultaneously across the entire Arctic Basin.

Here, we utilize AWIN measurements to specifically quantify how variations in sea ice extent and distribution affect moisture content, water vapor isotope traits, and transport along several critical storm tracks. By monitoring vapor isotopic changes in air masses advected from one site to another, we are able to track how much moisture is added along a given trajectory. We investigate several primary vapor transport pathways into the Arctic, including the North Atlantic/Greenland Sea, Baffin Bay, and the Bering Strait, and track the geochemical signature of this vapor as it transits along these well-established storm pathways into and within the Arctic. By quantifying isotopic changes between our sites we: 1) identify the distinct isotopic fingerprint of moisture sourced by evaporation from Arctic seas that is critically dependent on variable sea ice conditions, 2) detect moisture addition into critical storm tracks as they transit across the Arctic, and 3) determine the spatial variability of this enhanced Arctic-sourced evaporation and moisture. We find that for every major storm track observed, the Arctic Ocean and surrounding seas are significant sources of enhanced moisture uptake, acting within an amplified water cycle.
Determination of hygroscopic aerosol growth based on the OPC-N3 counter
Authors: Nurowska Katarzyna , Florczyk Grzegorz , Han Agata , Chiliński Michał , Markowicz Krzysztof
Published: March 2021

In this study the OPC-N3 low-cost particle matter counter was used to determine the hygroscopic properties of the aerosol. The work shows the first results of aerosol hygroscopicity conducted in Poland. The study was performed during Spring 2020 (lock-down period) and Winter 2020/2021. The research was conducted in the Geophysics Institute at the University of Warsaw, close to the city center. 

Two OPC-N3 sensors were connected to the outlet from two legs of the Aerosol Conditioning System ACS1000. In one of them, low relative humidity was kept at the level of 20%, and in the other, the relative humidity was changed in the range of 50-90% in cycles.

The calculation of growth factor was done by dividing the PM1 measured from wet pipe by PM1 measured in the dry channel. The hygroscopicity parameter κ was calculated from κ-Köhler theory, showing a fluctuation of the κ parameter which depends on aerosol type.

The variability of κ during Spring was ranging from values of 0.075 up to 0.437 (growth factor range 1.294 – 2.625).  The observed κ for Winter oscillates between 0.018 - 0.077 (growth factor range 1.057 – 1.246). The values of hygroscopicity of aerosol in winter are smaller than the ones corresponding to Spring, in line with respect to previous literature reports.

The study shows possibility to use OPC-N3 for calculation of the hygroscopic properties of the aerosol, however it means that the measurements of PM done by OPC-N3 can be biased by high relative humidity.
Is 1.5 °C of global warming inevitable and if so, when?
Authors: Milinski Sebastian , Fischer Erich , Forster Piers , Fyfe John C. , Lee June-Yi , Smith Christopher J. , Thorne Peter , Trewin Blair , Marotzke Jochem
Published: March 2021

The likelihood of exceeding 1.5 °C of global warming relative to preindustrial depends on the warming observed so far, anthropogenic warming that may occur in the future, and the degree to which internal variability will either temporarily amplify or attenuate future anthropogenic warming.  Here, we introduce a new framework that estimates the likelihood of exceeding 1.5 °C of global warming wherein uncertainties in each one of these factors is explicitly accounted for.

In this new framework, we estimate the historical warming, and its uncertainty, from preindustrial to present using the recently-minted HadCRUT5 dataset. Future anthropogenic warming is estimated using an energy balance model tuned to an assessed range of climate sensitivity and applied to each of the core emissions scenarios (i.e. SSPs) underlying the Sixth Phase of the Coupled Model Intercomparison Project (CMIP6). Finally, we estimate the influence of internal variability using a large ensemble of initial condition simulations. On this basis, we find that the largest uncertainty in estimates of the likelihood of exceeding 1.5°C of global warming is due to model-to-model differences in estimates of future anthropogenic warming, followed by historical warming uncertainty, and then uncertainty due to internal variability.

Based on our analysis, we find that the earliest time for crossing 1.5 °C of global warming, here defined as the 5% likelihood, is approximately emissions-scenario independent. We define the 1.5 °C threshold without any overshoot: if a time series warms by more than 1.5 °C during any 20-year period before 2100, it is counted as having crossed 1.5 °C. In each considered scenario except SSP5-8.5, the 20-year average period that crosses the 1.5 °C threshold with a 5% likelihood is 2013 to 2032. On the other hand, the 50% likelihood does depend on the scenario, with the SSP5-8.5 crossing occurring in 2018 to 2037 and SSP1-1.9 crossing in 2022 to 2041. All scenarios except SSP1-1.9 have a likelihood close to 100% to cross 1.5 °C global warming before 2100. Even in SSP1-1.9, the scenario with the strongest emission reductions, there is a 71% likelihood to cross 1.5 °C by the end of this century. This implies that even in SSP1-1.9, the world may stay below 1.5 °C only if both climate sensitivity and historical warming are near the lower end of their respective distributions.

These estimates, with their associated uncertainties, may have major implications for policy decisions.
3D glacial-isostatic adjustment models using geodynamically constrained Earth structures
Authors: Bagge Meike , Klemann Volker , Steinberger Bernhard , Latinović Milena , Thomas Maik
Published: March 2021

The interaction between ice sheets and the solid Earth plays an important role for ice-sheet stability and sea-level change and hence for global climate models. Glacial-isostatic adjustment (GIA) models enable simulation of the solid Earth response due to variations in ice-sheet and ocean loading and prediction of the relative sea-level change. Because the viscoelastic response of the solid Earth depends on both ice-sheet distribution and the Earth’s rheology, independent constraints for the Earth structure in GIA models are beneficial. Seismic tomography models facilitate insights into the Earth’s interior, revealing lateral variability of the mantle viscosity that allows studying its relevance in GIA modeling. Especially, in regions of low mantle viscosity, the predicted surface deformations generated with such 3D GIA models differ considerably from those generated by traditional GIA models with radially symmetric structures. But also, the conversion from seismic velocity variations to viscosity is affected by a set of uncertainties. Here, we apply geodynamically constrained 3D Earth structures. We analyze the impact of conversion parameters (reduction factor in Arrhenius law and radial viscosity profile) on relative sea-level predictions. Furthermore, we focus on exemplary low-viscosity regions like the Cascadian subduction zone and southern Patagonia, which coincide with significant ice-mass changes.
Assessment of the climate change-induced impact on forest vegetation in the Mediterranean Basin using an integrated approach
Authors: Castellaneta Maria , Rita Angelo , Camarero Jesus Julio , Colangelo Michele , Ripullone Francesco
Published: March 2021

The recent increase in the frequency and severity of heat weaves and droughts has intensified efforts to understand their impact on forest productivity and tree vigor. These climate extreme events are expected to reduce productivity and increase the tree mortality rate, particularly in drought-prone Mediterranean forests. Thus, our goal is to quantify the impacts of hotter droughts on forests vulnerable to drought in the Italian and Iberian peninsulas by using remotely sensed data (NDVI, Normalized Difference Vegetation Index) to track vegetation changes and tree-ring data from forest sites showing dieback to assess tree’s growth trends. The survey involved the comparison of stands showing dieback where trees showed growth decline and high defoliation rates (decay) versus stands where trees showed low or no defoliation. Our outcomes will be discussed i) to describe the effects of climate anomalies on forest vulnerability in terms of resistance and resilience, and ii) to evaluate the existence of a correlation between vegetation response and “post-disturbance” recovery.
ET of a mosaic landscape – measurements and modelling
Authors: Moderow Uta , Fischer Stefanie , Grünwald Thomas , Körner Philipp , Spank Uwe , Queck Ronald , Bernhofer Christian
Published: March 2021

Evapotranspiration changes with landuse, soil conditions and meteorological conditions. Landscapes in middle Europe are typically of mosaic pattern at micro to local scale with different landuses adjacent to one another and we therefore have areas of different ET. This work shall address how ET changes with landuse based on 10 years of Eddy-Covariance data for different landuses. In a first step, it will be focussed on two landuses (coniferous forest and grassland). ET obtained via measurements will be compared to ET obtained via modelling by a using a one dimensional soil-vegetation transfer scheme and a machine learning approach using gradient boosting. Results will be analysed whether typical characteristic properties of the respective landscape are preserved (e.g. Bowen ratio) as well as differences between land uses (e.g. differences in yearly ET estimates).
Satellite-Based Emission Estimates of Tropospheric Bromine During Arctic Spring and Impact on Surface Ozone 
Authors: Wales Pamela , Keller Christoph , Knowland Emma , Pawson Steven , Choi Sungyeon
Published: March 2021

The OMI satellite instrument provides total column measurements of bromine monoxide (BrO) with daily global coverage. Reactive bromine compounds (Br and BrO) catalytically destroy ozone in both the stratosphere and troposphere. Periods of elevated tropospheric BrO during polar spring are observable by OMI. Past studies have connected these elevated bromine events to near complete removal of surface ozone as well as significant perturbations to polar NOx (NO + NO2) and HOx (OH + HO2) chemistry.

In this study, we use OMI observations of BrO in combination with the GEOS-Chem global model to develop a method for estimating tropospheric emissions of bromine during Arctic spring. Total column BrO is modeled in GEOS-Chem using a combined stratospheric and tropospheric chemical mechanism. We find that globally total column BrO in GEOS-Chem is low with respect to the OMI retrievals. Because the stratospheric burden of bromine is well represented in GEOS-Chem, a portion of this bias likely originates from uncertainties in the chemical partitioning of inorganic bromine in the lower stratosphere and free troposphere. We specify a bias threshold to define elevated tropospheric BrO events and estimate lower limits for the missing tropospheric bromine during Arctic spring. Additionally, we evaluate the ability of our emission scheme to capture surface observations of ozone and explore the impact of bromine explosion events on the Arctic oxidative capacity.
Effects of warming, elevated CO2, and drought on root water uptake and its relation to root traits
Authors: Tissink Maud , Radolinski Jesse , Reinthaler David , Pötsch Erich , Bahn Michael
Published: March 2021

Plants can modulate the source and magnitude of water uptake under environmental stresses, ultimately constraining water and energy fluxes across Earth’s surface. These alterations are scarcely quantified for future climatic scenarios such as warming, elevated atmospheric CO2 (eCO2), and droughts—all projected by the end of this century. Here we use diurnal soil moisture dynamics throughout the 2019 growing season to quantify the impacts of these three global change factors on root water uptake in a managed C3 mountain grassland in Austria; a key agricultural landscape within central Europe. To determine whether plants alter water uptake via root trait adjustments, we then compared water uptake to root morphological traits. We expected that 1) drought and eCO2 (+300 ppm) would reduce root water uptake relative to ambient conditions due to supply limitation and a lower stomatal conductance, whereas 2) greater vapor pressure gradients in warmed systems would elevate transpiration rates, increasing root water uptake. Plants reduced water uptake in droughted plots by ~35% regardless of other factors applied, due to decreased water extraction from the soil surface during the peak drought. Warmed plots had unexpectedly lower water uptake by 17-25% relative to control plots. Finally, vegetation in eCO2 plots displayed similar water uptake to plots under ambient conditions; however, eCO2 effects did buffer warming effects, such that plots with eCO2 and warming extracted less water than those subjected to warming alone. Root morphological traits showed strong linear correlations (R > 0.7, or R < -0.7) to root water uptake in ambient, drought, and eCO2 plots, yet no significant relationship was found for plots under warming or multifactor treatments. Relationships were strongest and most abundant following a drought. This suggests that—though plants may optimize root structure for drought recovery—plants may alter their root systems to account for resource limitations other than water in a warming climate. Altogether, we show that warming, eCO2, and droughts may significantly alter the root water extraction in managed C3 mountain grasslands, but changes in water availability alone may not fully explain plant water uptake responses.
Reconstruction of the sudden drainage of a moraine-dammed lake in the Cordillera Vilcabamba (Peru): the 2020 Salkantay event
Authors: Vilca Oscar , Mergili Martin , Emmer Adam , Frey Holger , Huggel Christian
Published: March 2021

On 23rd February 2020, a landslide-triggered GLOF process chain was initiated from the SW slope of Nevado Salkantay, Cordillera Vilcabamba, Peru. An initial slide evolved into a rock/ice avalanche and part of the released material fell into the moraine-dammed Lake Salkantaycocha, triggering a displacement wave which overtopped and eroded the distal face of the dam. Dam overtopping resulted in a far-reaching GLOF causing fatalities and people missing in the valley downstream. In this contribution, we analyse the situation before and after the event as well as the dynamics of the GLOF process chain, based on field investigations, remotely sensed data, meteorological data, and a computer simulation with a two-phase flow model. Comparing pre- and post-event field photographs helped us to estimate the initial landslide volume of 1–2 million m³. Meteorological data suggest rainfall and/or melting/thawing processes as possible causes of the landslide. The simulation reveals that the landslide into the lake created a displacement wave height of up to 27 m. We reconstructed a released volume 57,000 m3 (less than 10% of lake volume) and estimated a total GLOF peak discharge almost 10,000 m³/s at the dam. The lake had 40 m dam freeboard at the time of a GLOF, and the lake level increased by 10–15 m directly after the event, since most of the volume of landslide material deposited in the lake (roughly 1.3 million m³). The model results show a good fit with the observations, including the travel time to the uppermost village. The findings of this study serve as a contribution to the understanding of landslide-triggered GLOFs in changing high-mountain regions.
Ocean carbon storage uniquely linked to ocean heat 
Authors: Bronselaer Ben , Zanna Laure
Published: March 2021

As the climate warms due to greenhouse gas emissions, the ocean absorbs excess heat and carbon. The patterns of ocean excess heat and carbon storage appear tightly linked when the large-scale circulation is fixed. This unique link is not shared with any other ocean tracer, such as Chlorofluorocarbons (CFCs). At the same time, ocean excess carbon storage patterns are mostly unchanged whether the large-scale circulation is free to evolve, or fixed to the pre-industrial circulation pattern, as the climate warms. Here, we interpret the reason for this behavior by breaking ocean carbon storage into two parts: uptake of atmospheric anomalies by the surface ocean, and subsequent internal storage by the ocean’s circulation. We show that the patterns of surface ocean carbon anomalies are dictated by mean state biogeochemical properties and therefore mostly unchanged by circulation changes. Furthermore, surface biogeochemical properties are strongly shaped by the ocean temperature, providing a link between ocean heat and carbon uptake. CFCs on the hand, lack chemical buffering and therefore the patterns of CFC storage do not correlate with heat as much as carbon patterns do. The patterns of surface anomalies ultimately explain most of the differences in how temperature, carbon and CFCs are stored by the ocean, while changes in internal pathways are of secondary importance. Furthermore, the ratio of total ocean carbon and heat storage is roughly constant across warming scenarios and climate models, which might have further implications for relating ocean carbon storage to important climate metrics, such as the transient response to cumulative emissions.