bluuebunny/crossref_metadata_2025 huggingface dataset:
A consistent and uniform research earthquake catalog for the AlpArray region
Authors: Molinari Irene , Bagagli Matteo , Diehl Tobias , Kissling Edi , Clinton John , Scarabello Luca , Giardini Domenico , Wiemer Stefan , Working Group the AlpArray
Published: March 2020

We take advantage of the new large seismic data set provided by the AlpArray Seismic Network (AASN) as part of the AlpArray research initiative (www.alparray.ethz.ch), to provide consistent and precise hypocenter locations and uniform magnitude calculations across the greater Alpine region. The AASN is composed of more than 650 broadband seismic stations, 300 of which are temporary. The uniform station coverage provides an unique occasion to study the laterally strongly variable seismicity that is presently monitored and reported by a dozen individual observatories. A homogeneous earthquake catalog in terms of location and magnitude is a prerequisite to improve our understanding of seismo-tectonics and the seismic hazard in the greater Alpine region.

Our catalog covers four years of seismicity with a targeted magnitude of completeness of 2.5 from 2016 to 2019 and results from scanning ∼1000 broadband stations (∼60 TB of data). First, we detect and analyse events in the region using the STA/LTA based detector of the SeisComP3 monitoring system in off-line mode. Later, after an initial location has been obtained, we apply a high-quality semi-automated re-picking approach defining the consistent phase arrival times in combination with timing uncertainties and phase identification assessment. This automatic re-picking framework is implemented with the QUAKE library (Bagagli et al., 2019), an object-oriented Python package that exploit different waveform information both frequency- and energy- related by taking advantage of different well-established picking algorithms. The QUAKE picker has been tuned and tested against a consistent phases reference data set (P-, S- and secondary phases) of ∼2500 phases manually picked for 10 events (M≥ 2.5) homogeneously distributed in the region.

Subsequently, the high-quality automatic picks of selected well-locatable earthquakes are used to calculate a minimum 1D P-wave velocity model for the region with appropriate stations corrections. Finally, all events are relocated with the NonLinLoc algorithm in combination with the updated 1D model and a final estimate of the magnitude is given. We compare our locations and magnitudes with existing regional and local earthquake catalogs (ISC, EMSC, national catalogs) to assess and discuss the completeness and quality of the derived AlpArray research catalog.
Lateral redistribution of fire-derived carbon: A rainfall simulation experiment
Authors: Bellè Severin-Luca , Asefaw Berhe Asmeret , Hagedorn Frank , Schiedung Marcus , Abiven Samuel
Published: March 2020

Wildfires are a key component in the global carbon (C) cycle, releasing significant amount of CO2 to the atmosphere, but also producing one of the most persistent terrestrial organic C forms by the incomplete combustion of natural vegetation, namely fire-derived or pyrogenic carbon (PyC). Post-fire, PyC is deposited on the soil surface, but can then be laterally redistributed by wind or water erosion. Due to the lack of vegetation cover after a fire, primary factors that govern rate of PyC distribution post-fire will be changes in soil surface properties and physical characteristics of PyC. However, the drivers and quantities of transported PyC (and non-fire derived organic matter) by water erosion from its site of production remain largely unknown, which limits our understanding of PyC movement in the landscape.

In this study, we tracked PyC erosion (and movement in soil) in a controlled experiment using a gravity-type rainfall simulator (at an intensity of 50mmh-1). We studied the quantity of PyC eroded from the soil surface (runoff and splash sediment) as well as its vertical movement within the soil (soil cores) for two Swiss temperate forest soils (initial soil moisture of 12-16%). We calculated the distribution of PyC using the isotopic 13C signature differences of grass-PyC (Miscanthus grass), wood-PyC (spruce wood grown under FACE conditions) and natural forest soil C in soil flume of 0.25m2. We studied the combination of the following factors: soil texture (sandy silt and clay loam), slope (10° and 25°), PyC particle size (63µm and 63µm-2mm) and PyC feedstock (grass and wood) to identify the major drivers of PyC redistribution.

We hypothesize that: i) higher quantities of PyC can be found in the sediment of the sandy silt soil, with higher slopes and with bigger PyC particles, ii) higher quantities of PyC move vertically in the clay loam soil and with smaller PyC particles and iii) PyC is preferentially eroded compared to bulk SOC.

Results suggest that we find 100 times more runoff sediment on sandy silt soil compared to clay loam soil, and two times more runoff sediment on 25° slope compared to 10°. We also find 1.5 times more splash erosion on sandy silt soil than on the clay loam soil. Regarding PyC erosion, observations suggest that > 50% of initial PyC is eroded on the sandy silt soil, whereas a majority of the PyC particles moves vertically through the soil for the clay loam.
Pervasive influence of fine silt sediments on the radiocarbon age of bulk sedimentary OC, alkenones and GDGTs via hydrodynamic mineral sorting processes in continental margins.
Authors: Ausin Blanca , Bruni Elena , Haghipour Negar , Welte Caroline , Gies Hannah , Bernasconi Stefano M. , Eglinton Timothy I.
Published: March 2020

Since Ohkouchi et al. (2002) pioneering work, compound specific radiocarbon (14C) dating has been largely used to explore 14C age discrepancies between co-deposited sedimentary components in a wide range of depositional settings. Older 14C ages of bulk organic carbon (OC) and alkenones relative to co-deposited planktonic foraminifera have been mainly attributed to lateral sediment transport processes by means of organic matter (OM)-mineral associations.

Definitive evidence for this hypothesis requires in-depth investigations at the mineral grain-size level. Here, we examine the radiocarbon signatures of OC and two molecular biomarkers widely used as paleothermometers (i.e., alkenones and glycerol diakyl glycerol tetraether (GDGTs)) associated to discrete sediment grain-size fractions collected from a range of continental margin settings. Our results evidence the pervasive influence of hydrodynamically-driven sorting processes on the OM content and composition of continental margin sediments, manifested in the 14C age variability of OC, alkenones and GDGTs residing in bulk sediments corresponding grain-size fractions. We find that OC and both, alkenones and GDGTs, preferentially reside within the fine silt fraction, which accounts for a substantial fraction of the bulk sediment mass. Therefore, fine silt exerts a strong influence on the 14C ages of these three components in bulk sediments. Given the propensity to resuspension and advection of fine silt under strong currents, the extent of its impact on the paleotemperature signal recorded by alkenones and GDGTs is also assessed. 

 

Ohkouchi, N., Eglinton, T.I., Keigwin, L.D., Hayes, J.M., 2002. Spatial and Temporal Offsets Between Proxy Records in a Sediment Drift. Science 298, 1224-1227.
The water cycle in nature is disturbed
Authors: Bakou Alexandra
Published: March 2020

Experimental Junior High School of Heraklion, Crete, Greece (alekabk5@gmail.com)

Teaching Geography in the first grade of Junior High School – Secondary education, we will focus on the meaning of the water on Earth.

The water cycle in nature is one of the most important systems in our planet on which life depends. The technological interventions of human cause severe disturbances in this cycle. Thus, there are large periods of drought alternating with periods of heavy rainfall.

Some of the causes of the water cycle disorder are:

- The destruction of the forests.

- The drainage of wetlands.

- The diversion of rivers.

- The construction of dams.

- The greenhouse effect.

Man is largely responsible for the disruption of the water cycle, since he pollutes both the ground and surface water supplies. In developed countries people use water more than people in underdeveloped countries. Half of the earth’s population is not provided with basic standards of hygiene. Lack of water means thirst and hunger, since land cultivation is impossible without water.

Questions that students will answer:

- What is the water cycle?

- What problems are associated with water cycle disorder?

- The water cycle in nature is characterized as a system. What are the parts of the system in this cycle?

- How human interventions in the environment need to be done so as to maintain the balance of the water system?

 

Students will find information on topics:

- Province in drinking water in Africa.

- The problem of water shortage in the Middle East and its treatment.

- Areas of land with disputes over rivers.

- Areas of Greece with water shortage problem.
Comparative analysis of watershed basins landscape structure in Southwest Asia region based on remote sensing data.
Authors: Milichenkova Victoria , Trifonova Tatiana , Lebedev Artem
Published: March 2020
Summer schools of the HOSST-TOSST graduate programme: a multi-sector approach towards scientific communication and outreach
Authors: Meulenbroek Kirsten , Yao WanXuan , Herrero Tatum Miko
Published: March 2020

The goal of the HOSST-TOSST programme is to cultivate the next generation of advocates of the ocean. As we enter a time where all kinds of opinions are formed through the rapid exchange of unfounded information, the importance of science stays ever crucial as it could and should serve as a common ground based on factual evidence and analytical reasoning. The programme directly embedded training for scientific communication and outreach methods at the very beginning of the careers of the next generation of ocean scientists. One of the ways was through various mandatory summer schools located in marine institutes across the North Atlantic. The summer schools challenged our doctoral candidates from diverse disciplines to collaborate in teams. Each team was assigned with a mini-project, where communication and outreach were essential for their success. 

In Halifax, Canada, the project aim was to create business proposals or products that would be financially viable whilst not encumbering the already struggling ocean.
In Kiel, Germany, the end goal was to come up with proposals for Marine Protected Areas in the busiest regions of the Atlantic, all the while navigating between various stakeholders and other ocean users to come up with the best compromise.
In Mindelo, Cabo Verde, the participants, including local students, did field research and presented findings on geological processes and marine ecosystems which directly influence the lives of the residents.

The summer schools aimed to instill an awareness of how to conduct scientific communication and outreach to the general public from a multi-spectrum approach. The variety within the three projects, places and the diverse communities involved have all contributed to discussions leading to a broader view on the issues, possible solutions and scientific questions that remain open surrounding the Atlantic Ocean in all its facets.
Tree-ring dating of snow avalanche history in Parâng Mountains (Southern Carpathians, Romania)
Authors: Todea Corina , Pop Olimpiu
Published: March 2020

In high mountainous areas worldwide, snow avalanches represent one of the main morphodynamic processes which influence the morphology of steep slopes. They usually disturb the forests, and represent a significant natural hazard that may endanger the safety of tourists exposed along the hiking trails crossing the avalanche-prone slopes. In the context of the growing tourism activities in the area where tourist become exposed to snow avalanche hazard, there is need for detailed analysis for documenting the past activity of this geomorphic process, especially in remote areas where historical data is lacking. Such mountainous area without snow avalanche monitoring and archival records is in Parâng Mountains (Southern Carpathians, Romania). On forested slopes, trees disturbed by snow-avalanches may record in their growth rings information about the past event occurrence. The main aim of this study is to improve the knowledge about the past snow avalanche history using tree-rings approach. To this end, 57 disturbed spruce (Picea abies (L.) Karst.) trees growing along an avalanche path located on the western slopes of the Parâng Mountains were sampled and their growth disturbances (scars, traumatic resin ducts, compression wood and growth suppression sequences) served to reconstruct the snow-avalanche history back to 1950. Tree-ring analyses allowed reconstructing a minimum of 14 snow avalanche events which occurred in the past along the investigated path. The tree-ring approach presented in this study proved to be a valuable tool in reconstructing snow avalanche history and compliting the snow avalanche database in Parâng Mountains. The number and spatial extent of documented snow avalanches evidence the potential snow avalanche hazards in the study area. The tree-ring data from the present study, together with those presented by the previous studies in the study area may further contribute to the snow avalanche hazard assessment. 
Simulation of sub-basin sediment yields and river runoffs into Davao Gulf, Philippines
Authors: Gallentes Adonis , Maloles Peter Jeffrey , Villanoy Cesar
Published: March 2020

The Philippines is a country within the Coral Triangle which is known to be the center of the most biologically diverse marine ecosystem in the world. Despite being a crucial area for marine biodiversity, discharge measurements of many rivers in the country are either sparse or non-existent. Such data are important in assessing aspects such as sedimentation which is highly related to the health of the reef community.

Here, we applied SWAT hydrological model in order to simulate the sediment yield of sub-basins and river discharge surrounding Davao Gulf, one of the country’s richest zones in terms of fish production. Monthly-averaged results of the model from 2001 to 2018 indicate that the relative maxima of sediment yield coincide with precipitation maxima, and that consecutive rainfall events which start around midyear results to higher erodibility and thus, higher peaks in sediment yield during the second half of each year until the early part of the following year. Dependence of sediment yield on slope class/angle and land use was also observed, identifying the northwestern catchments as critical sources of land surface erosion. Good agreement was obtained between simulations of river discharge and the sparse observed streamflow values during model validation (Davao River: NSE=0.61, R2=0.61, PBIAS = 2.87, r= 0.78; Hijo River: NSE=0.62, R2=0.90, PBIAS = -2.1630, r= 0.95).

Overall, this modeling study helped fill in the temporal gaps of observed streamflow data from river gauges, and provided estimates of the historical streamflow pattern of those rivers with no river gauges. Outputs of this study can also be used as science-based reference in crafting laws and ordinances for proper land use and Marine Protected Area (MPA) management plans, with emphasized consideration of the likely effects of climate change such as the latitudinal shift of typhoon tracks, increasing temperature, and more pronounced precipitation events which have already been observed in the area during the past two decades. 
Enhancing the Science Return of Landed X-ray Spectrometers on the Mars Rovers
Authors: VanBommel Scott , Gellert Ralf
Published: March 2020

Alpha Particle X-ray Spectrometers (APXS) have flown on the Mars Exploration Rovers (MER) Spirit and Opportunity as well as the Mars Science Laboratory (MSL) rover Curiosity. The APXS was designed and calibrated for in situ interrogation of solid martian samples through the use of complementary particle-induced X-ray emission and X-ray fluorescence analysis techniques. Its compact and robust design, combined with low power and data demand, further suit the APXS instrument and method for lengthy missions to the surface of rocky bodies in our solar system. Since their three respective landings, the science derived from the latest APXS instruments has been expanded beyond its original scope through the integration of computational techniques and modest changes to how the instrument is utilized on Mars. We will discuss these new methods, operational considerations, as well as the enhanced science achieved, with a particular focus on the relevance and future application on the surface of Mars.
Working with light and shadows
Authors: giordano donatella
Published: March 2020

The observation of the behavior of sunlight when it encounters an opaque body and, consequently, the shadow it produces allows several considerations to be made.

First activity: In the school garden, pupils studied the apparent motion of the Sun by observing the movement of the shadow produced by a stick perpendicular to the ground. They drew on the ground the position of the shadow of the stick and measured every hour the angular distance between the different tracts. They verified that between one tract and the next there were always 15 degrees, which is the same angular distance between the meridians that make a time zone. Starting from this observation, the kids built a Sundial to determine the local time.

Second activity: Working with the Homothetic Globe, that is a globe freed from its support and inclined according to the parallel of the place where you are, and placing a toothpick right to the city on the Globe where you want to proceed with the observation, allows you to observe everything that happens regarding the behavior of light and shadows as an exact reproduction, in small, of what happens in reality: the Sun acts on the sphere/ world map, exactly the same way as on the sphere/ Earth. The students were able to observe how the Sun illuminates different regions of the Earth in real time, helping them to understand time zones. The Homothetic globe also allowed them to understand the alternation of seasons in our Planet.
Subtleties in spherical harmonic synthesis of the gravity field
Authors: Goyal Ropesh , Claessens Sten , Featherstone Will , Dikshit Onkar
Published: March 2020

Spherical harmonic synthesis (SHS) can be used to compute various gravity functions (e.g., geoid undulations, height anomalies, deflections of vertical, gravity disturbances, gravity anomalies, etc.) using the 4pi fully normalised Stokes coefficients from the many freely available Global Geopotential Models (GGMs).  This requires a normal ellipsoid and its gravity field, which are defined by four parameters comprising (i) the second-degree even zonal Stokes coefficient (J2) (aka dynamic form factor), (ii) the product of the mass of the Earth and universal gravitational constant (GM) (aka geocentric gravitational constant), (iii) the Earth’s angular rate of rotation (ω), and (iv) the length of the semi-major axis (a). GGMs are also accompanied by numerical values for GM and a, which are not necessarily identical to those of the normal ellipsoid.  In addition, the value of W0, the potential of the geoid from a GGM, needs to be defined for the SHS of many gravity functions. W0 may not be identical to U0, the potential on the surface of the normal ellipsoid, which follows from the four defining parameters of the normal ellipsoid.  If W0 and U0 are equal and if the normal ellipsoid and GGM use the same value for GM, then some terms cancel when computing the disturbing gravity potential.  However, this is not always the case, which results in a zero-degree term (bias) when the masses and potentials are different.  There is also a latitude-dependent term when the geometries of the GGM and normal ellipsoids differ.  We demonstrate these effects for some GGMs, some values of W0, and the GRS80, WGS84 and TOPEX/Poseidon ellipsoids and comment on its omission from some public domain codes and services (isGraflab.m, harmonic_synth.f and ICGEM).  In terms of geoid heights, the effect of neglecting these parameters can reach nearly one metre, which is significant when one goal of modern physical geodesy is to compute the geoid with centimetric accuracy.  It is also important to clarify these effects for all (non-specialist) users of GGMs.
Shipboard Measurements of Aerosol Properties in the Coupled Ocean-Atmosphere System of the Northwest Tropical Atlantic
Authors: Bates Tim , Quinn Patricia
Published: March 2020

The fair-weather cumulus clouds, that cover much of the low-latitude oceans, affect the radiation balance of the planet by reflecting incoming solar radiation and absorbing outgoing longwave radiation.  These clouds also drive atmospheric circulation by mixing the lower atmosphere in a process called shallow convection.  This mixing, in turn, affects sea surface temperature and salinity by moderating the air-sea exchange of energy and moisture.  Marine boundary layer (MBL) atmospheric aerosols play a role in the processes described above by scattering and absorbing solar radiation and by serving as cloud condensation nuclei (CCN) thereby influencing cloud droplet concentrations and size; the extent, lifetime, and albedo of clouds; and the frequency and intensity of precipitation. Quantifying the role of aerosols over the Northwest Tropical Atlantic is critical to advance understanding of shallow convection and air-sea interactions.

MBL aerosol properties were measured aboard the RV Ronald H. Brown during the EUREC4A and ATOMIC field studies in January/February 2020.  Aerosols encountered during the study include background sulfate/sea spray particles and African dust/biomass burning particles.  Aerosol physical, chemical, optical and cloud condensation nuclei properties will be presented and their interaction with local and regional circulation.
Semi-automatic road damage detection in landslide areas using UAV-based 3D models
Authors: Nappo Nicoletta , Mavrouli Olga , van Westen Cees , Gambillara Roberto , Michetti Alessandro Maria
Published: March 2020

The efficiency of linear infrastructure influences heavily the social and economic development of a territory; hence the assessment of pavement damage is of major interest for local authorities when planning road maintenance in landslide affected areas to ensure the safety of its users. Ground movements related to landslides, subsidence and earthquakes are common causes of pavement deterioration, other than usual traffic stress conditions. Major issues for the assessment of landslide impacts on transportation routes remain the quantitative and objective description of the typology and extent of pavement damage, and its classification, with the aim to correlate the damage with the nature and intensity of the causing phenomena. This work investigates the use of three-dimensional models reconstructed from UAV based digital photogrammetry, as a rapid and less laborious alternative to the traditional field surveys, for assessing the damage induced by slow-moving landslides interacting with linear infrastructure. A semi-automatic procedure is proposed to rapidly detect and quantitatively describe the damage on asphalt-paved roads affected by slow-moving landslides. The methodology includes the processing of the 3D points cloud models using edge detection algorithms and roughness estimations to detect pavement anomalies. Damage assessment using the proposed methodology allows to i) automatically extract the geometric features of road damage, ii) measure objectively fractures and/or deformations of the road pavement and iii) create a damage database using geolocation data. The procedure is applied to road tracks located within slow-moving landslides and tested using RGB images taken from a Phantom 4 drone flight at 30m and 10m altitudes from the road surface and field measurements. The proposed methodology for semi-automatic road damage detection can contribute to the improvement of landslide risk analysis and mitigation for road networks affected by ground movements.
Role of horizontal eddy diffusivity within the canopy on fire spread
Authors: Bebieva Yana , Speer Kevin
Published: March 2020

Wind profile observations are used to estimate turbulent properties in the atmospheric boundary layer from 1 m up to 300 m height above north Florida pine woods. Basic turbulence characteristics of the lower boundary layer are presented. Together with theoretical models for the mean horizontal velocity we derive the lateral diffusivity using Taylor's frozen turbulence hypothesis in the surface fuel layer (tens of centimeters). This parameter is used to predict the spread of surface fires in a simple 1D model. Initial assessments of sensitivity of the fire spread rates to the lateral diffusivity are made. Estimated lateral diffusivity with and without fire are made and associated fire spread rates are explored. Our results support the conceptual framework that eddy dynamics in the fuel layer is set by larger eddies developed in the canopy layer aloft. The presence of fire modifies the eddy structure depending on the fire intensity.
Long-term trends in heating and cooling degree days at Mediterranean cities, in the context of climate change
Authors: Kaza Ioanna , Founda Dimitra , Giannakopoulos Christos , Kolokotsa Dionysia
Published: March 2020

Nowadays, the global climate change has important impacts on many aspects of human life such as agriculture, economy, health and energy consumption. The issue of climate change has concerned the scientific community as the solutions have to be direct and effective. Studies on energy demands under a climate change environment are particularly useful as they improve our understanding of the impacts of changing climate on energy sector. This research focuses on a very responsive to climate change area, the Mediterranean, and attempts to analyze the climate and energy demand trends, processing historical temperature records from weather stations at seven Mediterranean cities (Nicosia, Athens, Rome, Palma, Montpellier, Madrid and Seville) for the period of 1970 – 2018. Consecutively, cooling degree days (CDD) and heating degree days (HDD) have been estimated according to the given climatic data. These simple indicators are very useful as they point out the amount of energy demand, according to the deviation of a standard temperature value (threshold).

The research has shown a statistically significant increase in the ambient air temperature at all cities, ranging from 0.37 to 0.50 0C per decade on annual basis, but with notably higher increasing trends in summer compared to winter.  Consequently, the energy demand for cooling interior spaces has increased as well.  On the other hand, there is a significant decrease of heating demand. Annual CDDs have increased at rates reaching up to 65 degrees per decade over the study period (Nicosia), while the rate of decrease in HDDs ranges approximately between 55 and 110 degrees per decade at the selected cities. The analysis has been conducted on different timescales (monthly and annual) in order to approach the optimal accuracy. 

 

Further, our results will be used to validate simulations of CDD and HDD from Regional Climate Models downscaled over the areas of interest for a reference period, while future simulations will be realized to find projected trends in CDDs and HDDs at the Mediterranean cities by the end of the century.
AGU Ethics Diversity and Inclusion: Leveraging Partnerships to Achieve Inclusive Excellence
Authors: Williams Billy , Hanson Brooks , Bell Robin
Published: March 2020

The American Geophysical Union, a scientific society of > 60,000 members worldwide, has undertaken strategic initiatives over the past twenty-four months, to help spotlight and address important issues around ethics, diversity and inclusion.  Most recently, this work has focused on building partnerships and a unique coalition of societies to help extend and promote leading ethics and diversity practices across STEM. These recent advancements build on AGU’s earlier work of establishing an updated AGU Ethics Policy which defines sexual harassment as scientific misconduct and its more recent adoption of an updated AGU Diversity and Inclusion Strategic plan – providing a vision and roadmap for AGU to operate as a model organization for advancing diversity and inclusion in science.

This presentation will review AGU global demographics considerations, highlight key features of the AGU Diversity and Inclusion Strategic plan, and will include an update on key programmatic work and unique resources provided through the AGU Ethics and Equity Center and its partner organizations. AGU’s role in the formation of a consortium of more than 120 scientific societies to help leverage D&I-related leading practices and influence culture change—will also be discussed, including progress to date, preliminary program metrics, and remaining challenges and opportunities.
A new convective model for the Maud Rise Polynya
Authors: Boot Amber , van Westen Rene , Dijkstra Henk
Published: March 2020

The Maud Rise Polynya, a large hole in the Antarctic sea-ice, was first observed in the 1970s and reappeared again in 2017. The general paradigm is that the polynya formed due to deep convection caused by static instability of the water column. There is, however, no consensus on the processes responsible for the initialisation of deep convection. Both atmospheric and oceanic processes have been suggested by observational and model studies. Deep convection is viewed as an irregular event caused by densification of the surface layer. Heat accumulation in the subsurface layer is also considered to be vital for the formation of the polynya. This study investigates the initiation of deep convection using a simple 1D convective model introduced by Martinson et al. (1981) which is further extended with a dynamical subsurface layer. This extended version of the model allows us to study the contribution of both surface- and subsurface forcing on the initiation of deep convection. Two model set-ups with different subsurface characteristics have been used: (1) with a constant subsurface layer; (2) with periodic subsurface accumulation of heat and/or salt. Model set-up 1 results in either one or no polynya events. This does not agree with observations, since multiple polynya events have been observed. Model set-up 2 results in in periodically returning polynyas with the same period as the subsurface accumulation. Therefore, model set-up 2 is able to again multiple events as observed. Adding noise to the simulations does not change the conclusions for both model set-ups. The results suggest that subsurface forcing is a dominant process in Maud Rise Polynya formation. Our results indicate that densification of the surface layer plays a much smaller role than previously assumed by various literature. Based on these results and previous studies, we suggest that subsurface processes govern both the initial formation and reccurrence of the Maud Rise Polynya.
The role of ancestral groundwater techniques as nature based solutions for managing water
Authors: Ribeiro Luis
Published: March 2020

To achieve water sustainability and a more efficient use of water we should base on the ancestral water and territory management knowledge and grained in the culture of the people, 
This article is inspired in Nature Based Solutions (NBS) for managing water availability, particularly groundwater and aquifer-related NBS that hold major un-realized potential for alleviating adverse impacts of progressive climate change, namely to increase water security/drought resilience. In some cases, more ecosystem-friendly forms of water storage, such as natural wetlands, improvements in soil moisture and more efficient recharge of groundwater, could be more sustain-able and cost-effective than traditional grey infrastructure such as dams
The core of this article is centered in the pre-Inca and Inca civilizations and how these communities have developed ingenious NBS solutions to adapt to extreme climate scenarios such as prolonged droughts, managing water resources in a holistic way and how they understand clearly the global water cycle in all the components specially groundwater.
The article is divided in three interlinked parts: 1) to sow water, by implementing ancestral aquifer recharge solutions, 2) to retain water by improve hydraulic efficiency in terms of infiltration and drainage and 3) to collect water by improve the performance of extraction in the subterranean aqueducts in arid regions.
Impact of Atmospheric and Model Physics Perturbations On a High-Resolution Ensemble Data Assimilation System of the Red Sea
Authors: sanikommu siva reddy , Toye Habib , Zhan Peng , Langodan Sabique , Krokos George , Knio Omar , Hoteit Ibrahim
Published: March 2020

The Ensemble Adjustment Kalman Filter of the Data Assimilation Research Testbed is implemented to assimilate observations of satellite sea surface temperature, altimeter sea surface height and in-situocean temperature and salinity profiles into an eddy-resolving 4km-Massachusetts Institute of Technology general circulation model (MITgcm) of the Red Sea. We investigate the impact of three different assimilation strategies (1) Iexp– inflates filter error covariance by 10%, (2) IAexp– adds ensemble of atmospheric forcing to Iexp, and (3) IAPexp– adds perturbed model physics toIAexp. The assimilation experiments are run for one year, starting from the same initial ensemble on 1stJanuary, 2011 and the data are assimilated every three days.

Results demonstrate that the Iexp mainly improved the model outputs with respect to assimilation-free MITgcm run in the first few months, before showing signs of dynamical imbalances in the ocean estimates, particularly in the data-sparse subsurface layers. The IAexp yielded substantial improvements throughout the assimilation period with almost no signs of imbalances, including the subsurface layers. It further well preserved the model mesoscales features resulting in an improved forecasts for eddies, both in terms of intensity and location. Perturbing model physics in IAPexp slightly improved the forecast statistics. It further increased smoothness in the ocean forecasts and improved the placement of basin-scale eddies, but caused loss of some high-resolution features. Increasing hydrographic coverage helps recovering the losses and yields more improvements in IAPexp compared to IAexp. Switching off inflation in IAexp and IAPexp leads to further improvements, especially in the subsurface layers.
AEROCOM/AEROSAT: use of satellite observations in evaluating global aerosol models
Authors: Schutgens Nick ,   AEROCOM & AEROSAT teams
Published: March 2020

In contrast to most aerosol species, black carbon and dust absorb visual light and may heat the atmosphere. However, their overall effect is highly uncertain. In this study we explore the use of novel satellite AAOD (Absorptive Aerosol Optical Depth) measurements in evaluating global (AEROCOM) models.  

Two POLDER retrieval products, and one product each from OMI and a CALIOP/MODIS combination are intercompared and evaluated with AERONET ("truth") data. While all products have skill in measuring AAOD, there are substantial biases amongst the products. In particular, we note a bias between the two POLDER products of 0.04 in SSA (Single Scattering Albedo), independent of AOD (Aerosol Optical Depth). Identification of the cause of this bias would allow a substantial improvement in AAOD observations. However, we show that even with such biases, consistent evaluation of global models with satellite products is possible.

In particular we show that there can be substantial under- and over-estimates of AAOD, depending on model. Furthermore, in recent years, models have diverged amongst themselves. This can be traced to different emission inventories, and we show that satellite AAOD may be used to provide constraints on these emissions. At the same time, models still differ in their particle properties, and we show that this can, to some extent, be evaluated with observations as well.

In addition, we will introduce a similar study for an ensemble of 14 satellite products of AOD. This larger ensemble allows us to study AOD diversity between the products in detail. In particular, we show that this diversity is a pretty good predictor of AOD uncertainty (versus "truth" data) in multi-year averages. This provides us with uncertainty estimates even in the absence of truth data, which allows many exciting applications (to be discussed).

These studies are the fruit of collaboration between the AEROCOM (AEROsol Comparisons between Observations and Models, https:// aerocom.met.no) and AEROSAT (International Satellite Aerosol Science Network, https://aero-sat.org) communities.
Microstructure and solutal boundary layer at the sea ice - ocean interface
Authors: Maus Sönke
Published: March 2020

Sea ice growth into seawater proceeds by congelation of almost pure ice crystals, with most sea salts being rejected into a solute-enriched boundary layer. This solute enrichment does locally change the freezing point and thereby alter crystal growth due to a process termed "Constitutional Supercooling" (heat diffusing much faster than solute). It also sets up solute gradients that drive convection in a boundary layer of thickness D/V, where D is the coefficient of solute diffusion and V the ice growth velocity. The crystal pattern arising from such interaction of solute and temperature gradients, and respective solute and heat fluxes at the freezing interface, has been observed for other systems. It may be described by the theory of "Morphological Instability" formulated half a century ago by Mullins and Sekerka (1964). In principal this theory predicts the cell or dendrite spacing at a freezing interface of a saline solution. However, application of the theory to the case of sea ice growing from seawater has been incomplete so far due to three aspects: (i) detailed observations of the sea ice - ocean interface are difficult to obtain, as this high-porosity regime is rather fragile and often lost during sampling, and/or altered during cooling when the sample is removed from the water. However, from thin sections further up in the ice the interface is known to be lamellar, consisting of vertical oriented plates with a distance of 0.3 to 1 mm found for natural growth conditions; (ii) observations of the solutal boundary layer are even sparser and limited to a few laboratory studies, where this layer was heavily convecting; (iii) from a theoretical point it turns out that the classical Mullins-Sekerka theory needs to be modified due to such a convecting boundary layer. In the present talk I review the existing observations, and present novel 3-d observations of the microstructure near the interface of growing sea-ice. I propose an application of morphological stability theory to predict the plate spacing of sea ice and the salt fluxes through a convectively unstable solutal boundary layer. The predictions are consistent with observed plate spacings over a wide range of ice growth velocities, ranging from fast (100 cm/day) laboratory ice growth to slow (0.01 cm/day) accretion at the bottom of marine ice shelves. These predictions are not only of importance to predict ice properties near the interface, yet indicate the potential to trace sea ice and ice shelf growth rates through microstructure observations. Regarding the solutal boundary layer, the theory is found to be consistent with published observations of salt fluxes from growing sea ice.

W. W. Mullins and R. F. Sekerka, J. Appl. Phys., 1964, 35, 444.
Causality and Evolution of Summer Polynyas off the Coast of Northern Greenland
Authors: Lee Younjoo , Maslowski Wieslaw , Osinski Robert , Clement Kinney Jaclyn , Craig Anthony , Cassano John , Nijssen Bart , Seefeldt Mark
Published: March 2020

The summer polynya along the northern coast of Greenland has been observed only six months later after the winter polynya in 2018, which has prompted concerns about the stability of some of the thickest sea-ice in the Arctic region. This study combines retrospective remotely sensed sea-ice measurements with results from the Regional Arctic System Model (RASM) to examine the causes, effect, and evolution of open-water areas/polynyas in the region.

RASM is a limited-domain, fully-coupled climate model, consisting of the atmosphere (Weather Research and Forecasting, WRF3.7), ocean (Los Alamos National Laboratory Parallel Ocean Program, POP2), sea-ice (Community Sea Ice Model, CICE5), land hydrology (Variable Infiltration Capacity, VIC4) and streamflow routing (RVIC) components. The ocean and sea-ice models are configured with the horizontal resolution of 1/12-degree with 45 vertical levels and 5 sea-ice thickness categories, respectively. The atmosphere and land hydrology components are set up on a 50-km grid with 40-vertical levels and 3-soil layers, respectively. The Climate Forecast System Reanalysis (CFSR) and version 2 (CFSv2) output are used as boundary conditions for dynamic downscaling.

Analysis of the sea-ice conditions off the coast of northern Greenland revealed that RASM, in agreement with satellite measurements, has simulated five summer polynya events, i.e. in August of 1984, 1985, 2002, 2004 and 2018, over the 39-year period (1980-2018). All these events were primarily dynamically forced, with the thermodynamic forcing playing the secondary, yet still important role. While the thermodynamically driven sea-ice melting exhibited a relatively little year-to-year variability, between 87 km3 and 115 km3, its relative contribution to the total sea-ice loss increased by 2.5 times, from 16% in 1984 to 40% in 2018. This implies that with continuing thinning of sea-ice, increasingly less mechanical forcing may be required to generate and maintain a polynya or open water north of Greenland in summers to come.  
Investigation of juxtaposed high- and low-pressure metamorphic field gradients rocks and its tectonic implications, a case study of Turvo-Cajati Formation, Ribeira Belt, Brazil
Authors: Ricardo Bruna , Moraes Renato , Faleiros Frederico , Siga Júnior Oswaldo , Campanha Ginaldo , Mottram Catherine
Published: March 2020

The Turvo-Cajati Formation (TCF) is a metasedimentary unit composing the Curitiba Terrane, a major segment of the southern Ribeira Belt, SE Brazil. It is composed of rocks of greenschist (Low-TCF), amphibolite (Medium-TCF) and granulite (High-TCF) facies conditions. Previous studies in High-TCF indicates that the unit underwent extensive partial melting under high-pressure conditions (670-810 °C and 9.5-12 kbar), within the kyanite stability field. New data on the metamorphic zoning within Low and Medium-TCF were collected using petrography and thermodynamic modeling in the MnNCKFMASHTO system. Four metamorphic zones were recognized for Low-TCF and Medium-TCF: biotite, garnet, staurolite and sillimanite zones where sillimanite zone prevails. The pressure regime is estimated to be below 8 kbar, as staurolite breaks down straight to sillimanite. Thermodynamic modeling yielded metamorphic peak conditions of ~530-560 °C ,~6-7 kbar (garnet zone) and ~660-690 °C ,~6-7 kbar (sillimanite zone). The metamorphic field gradient is flat and of low to medium pressure, below the typical barrovian-type baric regime. It is inferred that Low and Medium-TCF were metamorphosed in a tectonic setting different from the High-TCF. Probability density plots(pdp) from detrital zircon indicate late-Cryogenian-Ediacaran arc-related and Rhyacian sources for all TCF sub-units, where High-TCF presents forearc depositional setting and Low-Medium-TCF back arc depositional setting. This scenario suggests that the TCF is made up of a collisional juxtaposition of an accretionary wedge (High-TCF) and a back-arc basin (Medium-TCF and Low-TCF) on the border of a microplate that includes a Rhyacian basement microcontinent (Atuba Complex). Available petrological and geochronological data suggest that the TCF comprises a paired low-P and high-P belt, associated with a major Ediacaran suture zone in the southern Ribeira Belt. The high metamorphic gradient recorded in the Medium-TCF and Low-TCF was related to asthenospheric upwelling in the back-arc region, which also produced extensive partial melting in the Atuba Complex basement. Metamorphic ages where previously obtained in High-TCF with ages around 589 ± 12 Ma and 584 ± 4 Ma. Petrochronology will be used to obtain the age of metamorphic events, using monazite and apatite grains from Low and Medium-TCF and compare them to available High-TCF data to understand and adjust the proposed model.
Hydrodynamic characterization of a meso-tidal estuary: Inhambane Bay (Mozambique)
Authors: Grifoll Manel , Solana Gorka , Espino Manuel
Published: March 2020

This contribution analyze “in-situ” data obtained in the unexplored estuary of Inhambane Bay (Mozambique). Inhambane Bay is a bar-built estuary with a length of 30.5 km and an extension of 288 km2. Synchronous measurements of sea-level, temperature/salinity and water current velocity were obtained during two intensive field campaigns covering dry and wet climatological seasons. Additional Sea Surface Temperature (SST) obtained from GHRSST project were used to charcterize the estuary. The first results reveal a meso-tidal estuary with water currents of 1.0 m/s. The water velocity profiles show an homogeneous profile in the ADCP measurements. The hydrographic surveys and GHRSST product confirms a remarkable seasonal variability. The largest SST are observed from November to May, coinciding with the warm and rainy season. Salinity profiles are almost vertical and the variability follows the direction of the tidal phase (lower salinity values are observed during low tide). In consequence, the estuary is well-mixed with salinity increasing values downward the estuary. The flushing time is estimated between 1 -3 days in function of the neap/spring tide using the Tidal Prism method.

Acknowledgments:

 ECOSISTEMA project (CTM2017-84275-R)
Run-up of narrow and wide-banded irregular waves on a beach
Authors: Abdalazeez Ahmed , Dutykh Denys , Didenkulova Ira , Labart Céline
Published: March 2020

The runup of initial Gaussian narrow-banded and wide-banded wave fields and its statistical characteristics are investigated using direct numerical simulations, based on the nonlinear shallow water equations. The bathymetry consists of the section of a constant depth, which is matched with the beach of constant slope. To address different levels of nonlinearity, the time series with five different significant wave heights are considered. The total time of each such calculated time-series is 1000 hours.

It is shown for narrow-banded wave signal that runup oscillations are no more distributed by the Gaussian distribution. The distribution is shifted to the right towards larger positive values of wave runup. Its mean value increases with an increase in nonlinearity, which reflects the known phenomenon of wave set-up. The higher moments of runup oscillations, skewness and kurtosis are negative. The skewness is decreasing with an increase in wave nonlinearity, while kurtosis is negative and varies non-monotonically with an increase in wave nonlinearity. For Gaussian wide-banded signal, the runup oscillations also deviate from Gaussian distribution. The distribution is also shifted to the right towards larger positive values of wave runup. Its mean values increase with an increase in nonlinearity, while all other higher moments change non-monotonically.     

For the extreme wave runup heights, we conclude that the tail of the probability density function behaves like a conditional Weibull distribution if the incident random waves are represented by Gaussian narrow-banded or wide-banded spectrum. This distribution can be used for evaluation of wave inundation during extreme floods (rogue runups). 