bluuebunny/crossref_metadata_2025 huggingface dataset:
Utility of hyperspectral remote sensing data in estimating biomass and structure variables in boreal forest of Finland
Authors: Halme Eelis , Pellikka Petri , Mõttus Matti
Published: March 2020

Three-quarters of Finland’s land surface area (22.8 million hectares) is filled with forests. The role of remote sensing in large area inventories is crucial. The forests of Finland serve as an important resource for the nation’s nature conservation as well as for the forestry industry. Furthermore, forests are significant carbon sinks and play a great role in climate change mitigation. Research on vegetation parameter retrieval is of special relevance in order to extend our knowledge about the vegetation dynamics and terrestrial carbon stocks at regional and global scales.

In future in addition to multispectral satellites, hyperspectral satellite missions will start to provide remote sensing data to support the needs of forestry and other natural resource management practices. We investigated the influence of spectral and spatial resolution of remote sensing data on retrieval of biomass and other forest properties. The study contributed to better information productivity on forest variables in boreal forest ecosystem.

We used the remote sensing data by Sentinel-2 (10 bands, resolution 10 m) and hyperspectral AISA imager (128 bands, 400–1000 nm, resolution 0.7 m). As reference data, we used new forest resource dataset provided by the Finnish Forest Centre and additional independent in situ measurements. We applied kernel-based regression methods to relate the forest variables of interest with the remotely sensed data. Based on recent studies, we selected Gaussian process regression (GPR) and support vector regression (SVR), which have proven to work well with hyperspectral and multispectral remote sensing data. Regression estimations were performed for stem biomass, basal area, mean height, leaf area index (LAI) and main tree species. The estimation accuracies were examined with absolute and relative root-mean-square errors.

Successful forest variable estimations showed that kernel-based regression algorithms are suitable tools for quantification of forest structure and assessment of its change. The estimation accuracies between the two algorithms were similar. However, the faster SVR algorithm was found to be more practical, especially considering large scale mapping and future near real-time applications. Based on the study results, the additional value of hyperspectral remote sensing data in forest variable estimation in Finnish boreal forest is mainly related to variables with species-specific information, such as main tree species and LAI. The more interesting variables for forestry industry, such as basal area or stem biomass, can also be estimated accurately with more traditional multispectral remote sensing data.
Design of a neural network aimed at predicting meteotsunamis in Ciutadella harbour (Balearic Islands, Spain)
Authors: Vich Maria-del-Mar , Romero Romualdo
Published: March 2020

This work explores the applicability of neural networks (NN) for forecasting atmospherically-driven tsunamis affecting Ciutadella harbor in Menorca (Balearic Islands). These meteotsunamis can lead to wave heights around 1 m, and several episodes in the modern history have reached 2-4 m with catastrophic consequences. A timely and skilled prediction of these phenomena could significantly help to mitigate the damages inflicted to the port facilities and moored vessels. We examine the relevant physical mechanisms that promote meteotsunamis in Ciutadella harbour and choose the input variables of the NN accordingly. Two different NNs are devised and tested: a dry and wet scheme. The difference between schemes resides on the input layer; while the first scheme is exclusively focused on the triggering role of atmospheric gravity waves (governed by temperature and wind profiles across the tropospheric column), the second scheme also incorporates humidity as input information with the purpose of accounting for the occasional influence of moist convection. We train both NNs using resilient backpropagation with weight backtracking method. Their performance is tested by means of classical deterministic verification indexes. We also compare both NN results against the performance of a substantially different prognostic method that relies on a sequence of atmospheric and oceanic numerical simulations. Both NN schemes show a skill comparable to that of computationally expensive approaches based on direct numerical simulation of the physical mechanisms. The expected greater versatility of the wet scheme over the dry scheme cannot be clearly proved owing to the limited size of the training database. The results emphasize the potential of a NN approach and open a clear path to an operational implementation, including probabilistic forecasting strategies.
Controls of Li incorporation in aragonite
Authors: Mavromatis Vasileios , Brazier Jean-Michel , Goetschl Katja
Published: March 2020

The cation-to-Ca ratio in natural carbonate minerals is routinely used by the geoscientific community in order to reveal information about the conditions occurred during mineral formation in the geological past. Environmental reconstruction, however, relies on our understanding on the mechanisms controlling mineral growth but also on the physico-chemical properties of cations. In this respect experimental studies and laboratory calibrations of elemental ratios in synthetic carbonates provide important insights on the interpretation of the chemical signatures in natural samples. This holds especially truth for the chemical and isotopic signals of carbonates forming in continental environments that are characterized by the absence of bio-induced precipitation, low concentration of solutes in the forming fluid and slow growth rates (e.g. speleothems). In this study, we examine the incorporation of Li in aragonite, owing to its use as a temperature proxy and its importance in paleo-weathering reconstruction. Our preliminary results suggest that aragonite growth rate is likely the most important parameter controlling Li content in the forming phase. This finding comes in excellent agreement with the recent study by Füger et al. (2019). In addition, the experimental work suggest that temperature is also affecting the distribution of Li in aragonite but to a lesser extent than growth rate. It is anticipated that once completed this work will provide the fundamental knowledge needed for adequate interpretation of Li partitioning in aragonite and significantly improve our ability to interpret Li signatures in natural carbonates.

 

References: Füger et al. 2019. Effect of growth rate and pH on lithium incorporation in calcite, Geochim. Cosmochim. Acta., 248, 14-24.
EarthCARE Mission Preparation Status: Performance and Science Processing
Authors: Wehr Tobias , Eisinger Michael , Koopman Rob , Lefebvre Alain , Maeusli Damien , Wallace Kotska , Pereira Do Carmo João , Livschitz Jakob , Maksym Sebastian
Published: March 2020

The influence of clouds on the incoming solar and reflected thermal radiation remains one of the most important climate uncertainties. The global observation of vertical profiles of cloud ice and liquid water with simultaneous and collocated solar and thermal flux observation will provide crucial data to address this uncertainty. Furthermore, collocated global observation of vertical profiles of aerosol types are required to address the direct and indirect effects of aerosol.

In response to these needs, the European Space Agency (ESA), in cooperation with the Japan Aerospace Exploration Agency (JAXA), is implementing the Earth Cloud, Aerosol and Radiation Explorer Mission, EarthCARE.

Vertical profiles of cloud ice and liquid water, aerosol type, precipitation, heating rates, solar and thermal top-of-atmosphere radiances and flux profiles will be synergistically derived from the observations of the satellite’s four instruments.

Two active instruments are embarked, a cloud-aerosol lidar and a cloud Doppler radar. The Atmospheric Lidar (ATLID) operates at 355nm and is equipped with a high-spectral resolution receiver and depolarisation channel that separates molecular from particulate backscatter and distinguishes cloud and aerosol types. The Cloud Profiling Radar (CPR), provided by JAXA, is a highly sensitive W-band Doppler radar (94GHz) that measures cloud profiles, precipitation and vertical motion within clouds. The Doppler observation will measure vertical motion in clouds providing novel information on convection, precipitating ice particles and raindrop fall speed. Two passive instruments provide cloud and aerosol swath information and solar and thermal radiances and top-of-atmosphere fluxes. The Multi-Spectral Imager (MSI) has a 150km wide swath and seven channels in the visible, near-IR, short-wave IR, and thermal IR. The Broad-Band Radiometer (BBR) observes broad-band solar and thermal radiation reflected and emitted from the Earth, with three fixed fields of view: forward, nadir and backward.

In preparation for the science exploitation of the mission, complex data retrieval algorithms in the Ground Segment will exploit the synergy of the four instruments and deliver a range of cloud, aerosol and radiation related data products, including three-dimensional cloud-aerosol-precipitation scenes, with collocated broad-band heating rate and radiation data, over a mission lifetime of three years.

The presentation will provide an overview of the mission, main performances of the three ESA instruments and expected science data products.

 
Remote predictive geological mapping as a tool for the reconstruction of the complex geodynamic evolution of Melanesia
Authors: Brandl Philipp , Kraetschell Anna , Emberley Justin , Hannington Mark , Stewart Margaret , Petersen Sven , Baxter Alan
Published: March 2020

The offshore regions of Eastern Papua New Guinea and the Solomon Islands include several active and remnant arc and backarc systems that formed in response to complex plate tectonic adjustments following subduction initiation in the Eocene. Although there has been extensive exploration for offshore petroleum resources, and more than 54 research cruises have investigated or transited the region since 1993, a comprehensive regional geological map, including the deep marine areas, has not been available at a scale that permits quantitative analysis of the basin history. We present the first map that depicts interpreted assemblage- and formation-level lithostratigraphic units correlated across the marine basins and adjacent land masses. The mapped assemblages and large-scale formations are based on a compilation of land-based geological maps, marine geophysical data (hydroacoustics, magnetics, and gravity) integrated with the results of geological sampling, ocean drilling, seismic surveys, and seabed observations.

More than 400,000 km2 of the map area covered by ship-based multibeam and other geophysical data were inspected to derive the offshore geological units. In areas with limited data, the units were extrapolated from well-documented formations in adjacent regions with more complete information, including on land. This approach follows closely the techniques used for remote predictive mapping in other regions of the Earth where geological information is sparse. Geological boundaries were constrained by ship-based multibeam data reprocessed at 35-m to 50-m resolution and integrated with the Global Multi-Resolution Topography (GMRT) gridded at 100 m. Lithotectonic assemblages were assigned on the basis of plate structure, crustal type and thickness, age, composition, and sedimentary cover and further refined by bathymetric and geophysical data from the literature and cruise reports. The final compilation is generalized and presented here at 1:1 М. Our new approach integrates conventional mapping on land with remote predictive mapping of the ocean floor.

The newly compiled geological map illustrates the diversity of assemblages in the region and its complex geodynamic evolution. The resolution of our map allows to perform quantitative analyses of area-age relationships and thus crustal growth. Further geoscientific analyses may allow to estimate the regional mineral potential and to delineate permissive areas as future exploration targets.
Validating snow surface radiative transfer models between 89 and 243GHz using airborne observations over Arctic tundra
Authors: Wivell Kirsty , Sandells Melody , Rutter Nick , Fox Stuart , Harlow Chawn , Essery Richard
Published: March 2020

Satellite microwave radiances in atmospheric sounding bands, such as the 183GHz water vapour band, are an important source of data for Numerical Weather Prediction. However, these observations are frequently discarded in polar regions as they are also sensitive to the surface, and there is large uncertainty in the background surface emissivity which depends on the microphysical properties of the snowpack. We evaluate simulations of brightness temperature and emissivity from the Snow Microwave Radiative Transfer (SMRT) model for Arctic tundra snow at frequencies between 89 and 243GHz to assess the potential of being able to assimilate observations at key sounding frequencies, such as 183GHz. In-situ measurements of the surface snowpack were collected for 36 snow pits in Trail Valley Creek, near Inuvik, Canada during the March 2018 Measurements of Arctic Cloud, Snow, and Sea Ice nearby the Marginal Ice Zone (MACSSIMIZE) campaign, a collaboration between the Met Office, Northumbria University, Edinburgh University and the Universite de Sherbrooke. These snowpack measurements provide realistic microphysical snow properties as input to SMRT. We present the evaluation of SMRT simulations against surface-based radiometer observations and airborne observations taken with the Microwave Airborne Radiometer Scanning System (MARSS) and International Submillimetre Airborne Radiometer (ISMAR) on the Facility for Airborne Atmospheric Measurements (FAAM) BAe 146 research aircraft.
Robust Mahalanobis-distance based spatial outlier detection on discrete GNSS velocity fields
Authors: Magyar Balint , Kenyeres Ambrus , Toth Sandor , Hajdu Istvan
Published: March 2020

The GNSS velocity field filtering topic can be identified as a multi-dimensional unsupervised spatial outlier detection problem. In the discussed case, we jointly interpreted the horizontal and vertical velocity fields and its uncertainties as a six dimensional space. To detect and classify the spatial outliers, we performed an orthogonal linear transformation technique called Principal Component Analysis (PCA) to dynamically project the data to a lower dimensional subspace, while redacting the most (~99%) of the explained variance of the input data.

Therefore, the resulting component space can be seen as an attribute function, which describes the investigated deformation patterns. Then we constructed two subspace mapping functions, respectively the k-nearest neighbor (k-NN) and median based neighbor function with Haversine metric, and the samplewise comparison function which compares the samples with the properties of its k-NN environment. Consequently, the resulting comparison function scores highlights the significantly different observations as outliers. Assuming that the data comes from Multivariate Gaussian Distribution (MVD), we evaluated the corresponding Mahalanobis-distance with the estimation of the robust covariance matrix of the investigated area. Then, as the main result of the Robust Mahalanobis-distance (RMD) based approach, we implemented the binary classification via the p-value and critical Mahalanobis-distance thresholding.

Compared to the formerly investigated and applied One-Class Support Vector machine (OCSVM) approach, the RMD based solution gives ~ 17% more accurate results of the European scaled velocity field filtering (like EPN D1933), as well as it corrects the ambiguities and non-desired features (like overfitting) of the former OCSVM approach.

The results will be also presented as an interactive web page of the velocity fields of the latest version of EPN D2050 filtered with the introduced RMD approach.
A model approach to estimate the potential for mussel beds in a Wadden Sea area of the German North Sea coast
Authors: Rubel Malte , Ricklefs Klaus , Milbradt Peter , Sievers Julian
Published: March 2020

In the awareness of the increasing conciousness regarding the sensitivity, vulnerability, and
complexity of near coastal marine ecosystems, including tidal flats, it is imperative to improve the
understanding of its individual elements. One of these elements are organisms habitating the
seabed, such as mussels.
Bivalves - specifically blue mussels (Mytilus edulis) and pacific oysters (Magallana gigas) - besides
other smaller organisms are an integral part of the seabed fauna. On the one hand they serve as a
basic food resource for a large number of higher trophic level predator. On the other hand they
affect the surface structure, stability and composition of the seabed.
To better understand the large fluctuations the mussel stocks underwent during the last decades, it is
of great benefit to know the environmental conditions of their habitats. Based on the analysis of
different physical parameters at known mussel beds, prototypical automated algorithms were
developed and used to identify other tidal flat regions with favorable conditions for epibenthic
mussels. The input parameters originate from different morphological, hydrodynamical,
sedimentological and hydrochemical numerical models. Morphological factors include
morphological activity and gradient conditions of the ground surface, hydrodynamical factors
include stream velocities, bottom shear stress, wave orbital velocities, energy of wave breaking and
duration of tidal flats falling dry during low tide, sedimentological factors include sediment
composition and hydrochemical factors include salinity. These parameters were available as
products of the mFUND project EasyGSH-DB and were supplemented with additional evaluations.
It is expected that the approach of habitat modeling will allow to determine the possibility of initial
and long-term settlements of epibenthic mussels by ruling out intertidal or subtidal seabed areas
where environmental parameter combinations do not fulfill the necessary requirements.
Can we deduce irrigation trends at global scale from the ones of essential climate variables?
Authors: Ducharne Agnes , Al-Yaari Amen , Cheruy Frédérique , Wigneron Jean-Pierre
Published: March 2020

Irrigation is the most important water use sector that can impact land-atmosphere feedback and climate. The use of irrigation is increasing but its effects on climate are still ignored in most of the climate models due to the lack of accurate information on its sources or its extent over the whole globe. The only map that presented a global inventory on the extent of areas irrigated with groundwater and surface water was published in 2013 (Siebert et al., 2013). Here, we take advantage of the abundance of global satellite observations to investigate the effects of irrigation on long-term trends in essential climate variables: (i) temperature obtained from the Climate Research Unit (CRU data), (ii) precipitation obtained from CRU, Global Precipitation Climatology Project (GPCP), and Global Precipitation Climatology Centre (GPCC), (iii) soil moisture obtained from Soil moisture and ocean salinity (SMOS) satellite, (iv) evapotranspiration obtained from CRU and the Global Land Evaporation Amsterdam Model (GLEAM), and (v) land cover based on the multi-epoch ESA LC dataset. Based on the potential links between the existing information of irrigation and these five climate and land-surface variables, possible tracking of the irrigation extent over other regions, where no information exist, will be investigated. This study is ongoing and preliminary results will be presented.

References

Siebert, S., Henrich, V., Frenken, K., Burke, J., 2013. Update of the Global Map of Irrigation Areas to version 5. Proj. Rep.
The role of hyporheic fluxes in regional groundwater modelling
Authors: Mojarrad Brian Babak , Wörman Anders , Riml Joakim , Xu Shulan
Published: March 2020

The effect of hyporheic fluxes on deep groundwater flow field was investigated in a numerical modelling framework over a spectrum of spatial scales ranging from local bed forms to landscape structures in a Swedish boreal catchment. The groundwater modelling was conducted for the whole catchment in which the site-specific landscape morphology and geological heterogeneity were accounted for. Deep groundwater discharge was quantified through conducting particle tracing analysis for 10,000 inert particles (grid of 100 × 100) released from a flat horizontal surface located 500 meter below the minimum topographical elevation. Further, the streambed scale modelling was performed independently by applying an exact spectral solution to the hyporheic fluxes in streambeds based on fluctuations of the streambed topography. Monte Carlo simulations were used in the streambed scale modelling to cover uncertainties in hydrostatic and dynamic head contributions, as well as topographic fluctuations. Through superpositioning of the two model results, we found that the magnitude of deep groundwater vertical velocity at the stream-water interface was generally lower than the hyporheic exchange velocity at the streambed interface. Finally, the deep groundwater particles’ travel time and the fragmentation of groundwater upwelling zones used as the main metrics to evaluate the impact of hyporheic fluxes on deep groundwater flow field. The results showed that the regional groundwater travel time distribution near the streambed surface was influenced by hyporheic fluxes, an impact that was  substantial for the particles with longer travel times. The size of coherent groundwater upwelling zone at the streambed interface was also affected by hyporheic fluxes. Almost half the superimposed cases were found to be more fragmented due to the presence of hyporheic flow field, which shifted the cumulative distribution function for upwelling regions towards smaller areas. This study, highlights the role of hyporheic fluxes in groundwater modelling, which controls the streambed sediment ecosystem as well as fate and transport of contaminations between aquifer and streams.
The characteristic of source spectra and stress drop of earthquakes in the Bucaramanga nest
Authors: Gong Wenzheng , Chen Xiaofei
Published: March 2020

Spectra analysis is helpful to understand earthquake rupture processes and estimate source parameters like stress drop. Obtaining real source spectra and source time function isn’t easy, because the station recordings contain path effect and we usually can’t get precise path information. Empirical Green’s function (EGF) method is a popular way to cancel out the path effect, main two of which are the stacking spectra method (Prieto et al, 2006) and the spectral ratio method (Viegas et al, 2010; Imanishi et al, 2006). In our study, we apply the latter with multitaper spectral analysis method (Prieto et al, 2009) to calculate relative source spectra and relative source time function. Target event and EGFs must have similar focal mechanism and be collocated, so we combine correlation coefficient of wave at all stations and focal mechanism similarity to select proper EGFs.

The Bucaramanga nest has very high seismicity, so it’s suitable to calculate source spectra by using EGF method. We calculate the source spectra and source time function of about 1540 earthquakes (3-5.7ml, 135-160km depth) at Bucaramanga nest in Colombia. Simultaneously we also estimate corner frequency by fitting spectral source model (Brune, 1970; Boatwright, 1980) and stress drop using simple model (Eshelby, 1957) of earthquakes with multiple station recordings or EGFs. We obtain about 30000 events data with 12 stations from National Seismological Network of Colombia (RSNC).

The result show that the source spectra of most earthquakes fitted well by omega-square model are smooth, and the source spectra of some have obvious ‘holes’ near corner frequency, and the source time function of a few earthquakes appear two separate peeks. The first kind of earthquakes are style of self-arresting ruptures (Xu et al. 2015), which can be autonomously arrested by itself without any outside interference. Abercrombie (2014) and Wen et al. (2018) both researched the second kind of earthquakes and Wen think that this kind of earthquakes are style of the runaway ruptures including subshear and supershear ruptures. The last kind of earthquakes maybe be caused by simultaneous slip on two close rupture zone. Stress drop appear to slightly increase with depth and are very high (assuming rupture velocity/s wave velocity is 0.9). We also investigate the high-frequency falloff n, usually 2, of Brune model and Boatwright model by fitting all spectra, and find that the best value of n for Boatwright model is 2 and for Brune model is 3.5.
Characterizing seismic scattering in 3D heterogeneous Earth by a single parameter
Authors: Vyas Jagdish Chandra , Galis Martin , Mai Paul Martin
Published: March 2020

We analyze the power spectral density (PSD) of von Karman autocorrelation function (ACF) to derive a theoretical parameter which characterizes the scattering of seismic wavefield due to random heterogeneities in 3D Earth structure. We then verify our analytical findings by performing ground-motion simulations. We characterize scattering using root-mean-square (RMS) fluctuations of normalized seismic wave speed, which represents wavefield scattering due to random heterogeneities in 3D Earth under the diffraction condition. The isotropic von Karman ACF is parameterized by correlation length a, standard deviation σ, and Hurst exponent H. To compute the RMS value, we simplify the von Karman PSD for three regimes: k·a ≫ 1 (λ ≪ a), k·a ≈ 1 (λ ≈ a) and k·a ≪ 1 (λ ≫ a), where λ is wavelength and k wavenumber of the seismic waves. The analysis of the RMS values reveals that 1) scattering is proportional to the standard deviation σ of small-scale velocity variations in all three regimes, 2) scattering is inversely proportional to the correlation length in the k·a ≫ 1 regime, but directly proportional to the correlation length in the other two regimes, 3) a small Hurst exponent H for the k·a ≫ 1 regime leads to scattering controlled solely by the standard deviation of small-scale velocity variations (for the other two regimes, it leads to weaker scattering). The seismic scattering effectively vanishes for H approaching zero. Our theoretical findings are purely physics based and are furthermore verified by 3D high resolution numerical simulations. Hence, we developed solid physics-based understanding of 3D seismic scattering due to random heterogeneities in the Earth which will be helpful for future modeling studies.
Centrifugal Instability of a Geostrophic Jet
Authors: Poulin Francis , Harris Matthew , Lamb Kevin
Published: March 2020

Oceanic and Atmospheric jets with sufficiently strong anticyclonic vorticity are subject to centrifugal instabilities. This mechanism is relatively fast in comparison to barotropic and baroclinic instabilities and require non-conservative forces that mix the fluid properties. In this work, we present a novel approach to compute the linear stability characteristics of both barotropic and baroclinic jets. This enables us to compute the growth rates and spatial structures very accurately and efficiently. Subsequently, by integrating the fully nonlinear, non-hydrostatic dynamics using the spectrally accurate numerical model SPINS, we validate the predictions of the linear theory and then investigate the nonlinear equilibration that results. Depending on the Reynolds number of the flows, there are instances where a secondary instability occurs that eventually produces vortical structures, some of which are themselves subject to centrifugal instabilities. This idealized investigation quantifies the effects of centrifugal instabilities as an initial step to determine how to parameterize them.

 
Iron in Soils and Road Dust is Modulated by Coal-Fired Power Plant Sulfur Making Toxic PM2.5
Authors: Weber Rodney J. , Wong Jenny , Wang Yuan , Fang Ting , Mulholland James , Russell Armistead (Ted) , Sarnat Stefanie , Nenes Athanasios (Thanos)
Published: March 2020

Transition metal ions, such as water-soluble iron (WS-Fe), are toxic components of fine particulate matter (PM2.5). In Atlanta, GA, from 1998 to 2013, WS-Fe was the PM2.5 species most associated with adverse cardiovascular outcomes in a previous study. We examined this data set to investigate the sources of WS-Fe and effects of air quality regulations on ambient levels of WS-Fe. Insoluble forms of iron in mineral and traffic dust combined with sulfate from coal-fired electrical generating units (EGU) were converted to soluble forms by sulfate-driven acid-dissolution. Sulfate produced both the highly acidic aerosol (summer pH 1.5-2) and liquid water required for the aqueous phase acid-dissolution, but variability in WS-Fe was mainly driven by particle liquid water. These processes were more pronounced in summer when particles were most acidic, whereas in winter the relative importance of WS-Fe from combustion emissions increased. Although WS-Fe represents a minute mass fraction (0.15%) of PM2.5, the observed high correlation between WS-Fe and PM2.5 mass (r=0.67) may result from these formation routes and account for some association between mass and adverse health seen in past studies. Similar processes are expected in many regions, implying these unexpected benefits from coal-burning reduction may be widespread.
Estimation of the Rates of Particle Aggregation and Disaggregation in the Mesopelagic Zone of the Eastern North Pacific
Authors: Amaral Vinicius , Marchal Olivier , Lam Phoebe , Lee Jong-Mi , Buesseler Ken , Roca Marti Montserrat
Published: March 2020

The processes of particle aggregation and disaggregation are of paramount importance for ocean biogeochemical cycles. Particle aggregation leads to a transfer of particulate material and of their chemical constituents into large size fractions that can settle rapidly through the water column, thereby contributing to the ocean biological pump. In contrast, particle disaggregation redistributes material into smaller size classes and places limits on the size of the largest aggregates. In spite of their preeminent importance for ocean biogeochemistry, rates of particle (dis)aggregation in the ocean cannot be measured directly and are notoriously difficult to constrain. Indeed, current estimates obtained in a variety of oceanographic environments range over several orders of magnitude and suffer from appreciable uncertainties.

The goal of the Export Processes in the Ocean from Remote Sensing (EXPORTS) program is to develop a predictive understanding of the export and fate of global ocean net primary production for present and future climates. As part of this program, an extensive oceanographic campaign took place in summer 2018 in the Gulf of Alaska, during which various measuring and sampling platforms including a large-volume filtration (LVF) system have been deployed at different depths in the euphotic and mesopelagic zones at stations centered around a drifting Lagrangian float. Here we present the status of our ongoing effort to estimate the rates of particle (dis)aggregation in the mesopelagic zone of EXPORTS stations based on concomitant measurements of the concentration of particulate organic carbon (POC), lithogenic elements (Al and Ti), and thorium-234 (a naturally-occurring particle-reactive radionuclide), in different size fractions sampled from LVF and bottles. The rates of particle (dis)aggregation, as well as remineralization and sinking, are estimated from the quantitative combination of this diverse dataset with a simplified model of the cycling of POC, Al, Ti, and Th-234 in the upper water column using a least-squares procedure that accounts for both data and model errors. Rate estimates and their errors obtained at different stations and at different depths in the upper 500 m are presented and discussed in the context of independent measurements bearing on the mesopelagic ecosystem of the eastern North Pacific.
Discrimination of forest species by remote sensing in the national park "Smolenskoe Poozerie"
Authors: Narykova Anna
Published: March 2020

Forests cover about 40 percent of the Earth surface and they are very important for the ecosystems. For instance, forest land highly impacts carbon dynamics, provides habitats for organisms, conserves soil and water resources, and supports human demand for timber and recreation.

This study will discuss the method of determining the deciduous and coniferous tree species in forests by using Unmanned Aerial System (UAS) or drones for distinction of old-growth and second-growth forests. The key area of research is the national park in Smolensk region in the west of Russia, it is called «Smolenskoe Poozerie».The original forests (old-growth) in this area are Pine-Spruce and Oak-Linden forests but the main part were cut down for agriculture and to fuel both industry and farms. The second-growth tree species, such as Poplar-Birch forests, have a tendency to spread to disturbed habitats and replace native tree species.

This theme is relevant because it is one of the modern methods of distinction of old-growth and second-growth forests. Drones are able to cover a relatively large area in a single flight. They operate on user demand and deliver very high resolution images. They have a huge advantage of mapping in order to analyze and monitor forest ecosystems on a tree-level, instead of on a stand-level.
Ensuring Scientific Reproducibility within the Earth Observation Community: Standardized Algorithm Documentation for Improved Scientific Data Understanding
Authors: Kaulfus Aaron , Bugbee Kaylin , Harris Alyssa , Ramachandran Rahul , Harkins Sean , Barciauskas Aimee , Smith Deborah
Published: March 2020

Algorithm Theoretical Basis Documents (ATBDs) accompany Earth observation data generated from algorithms. ATBDs describe the physical theory, mathematical procedures and assumptions made for the algorithms that convert radiances received by remote sensing instruments into geophysical quantities. While ATBDs are critical to scientific reproducibility and data reuse, there have been technical, social and informational issues surrounding the creation and maintenance of these key documents. A standard ATBD structure has been lacking, resulting in inconsistent documents of varying levels of detail. Due to the lack of a minimum set of requirements, there has been very little formal guidance on the ATBD publication process.  Additionally, ATBDs have typically been provided as static documents that are not machine readable, making search and discovery of the documents and the content within the documents difficult for users. To address the challenges surrounding ATBDs, NASA has prototyped the Algorithm Publication Tool (APT), a centralized cloud-based publication tool that standardizes the ATBD content model and streamlines the ATBD authoring process. This presentation will describe our approach in developing a common information model for ATBDs and our efforts to provide ATBDs as dynamic documents that are available for both human and machine utilization. We will also include our vision for APT within the broader NASA Earth science data system and how this tool may assist in standardizes and easing the ATBD creation and maintenance process.
Mineralogy and environmental stability of vanadium-rich slags from the historical processing of Zn-Pb-V ores at Berg Aukas (Namibia)
Authors: Ettler Vojtech , Mihaljevic Martin , Jarosikova Alice , Culka Adam , Kribek Bohdan , Vanek Ales , Penizek Vit , Sracek Ondra , Mapani Ben , Kamona Fred
Published: March 2020

Vanadium (V) is one of the key technologically critical elements. The slags produced by the historical mining and processing of Zn–Pb–V ores in the Waelz kiln at Berg Aukas (northern Namibia) can be potentially used as a secondary resource of V. A combination of mineralogical methods, bulk chemistry, leaching tests and speciation-solubility modeling was used to understand the binding of the major contaminants (Zn, Pb, V) in the solid phase and their potential release under the changing environmental conditions. The average concentrations of the metal(loid) contaminants in the slags are 3.78 wt% Zn, 3370 mg/kg Pb, 5880 mg/kg V, 767 mg/kg Cu, 578 mg/kg As and 92 mg/kg Sb. The mineralogy is dominated by high-temperature silicates (clinopyroxene, melilite, olivine-family phases) and Zn-bearing phases (willemite, zincite). All the primary silicates and oxides are Zn-rich, but vanadium is mainly concentrated in clinopyroxene (up to 5 wt% V2O3). Metallic Fe inclusions, formed under highly reducing conditions in the kiln, are highly weathered. Secondary Fe(III) (hydr)oxides, corresponding to the main weathering products in the slag, efficiently sequester the metal(loid)s (mainly As and Sb). The EU regulatory leaching tests indicated that the release of the metal(loid) contaminants is quite low at the natural pH (deionized water extract: 8.5–10.4) obtained by extraction in the deionized water and only Sb in all the slag samples exceeds the EU limits for the landfilling of inert waste. The pH-static leaching tests revealed up to 5 orders of magnitude higher release of Pb and Zn under acidic conditions (up to 38% and 63% of their total concentration, respectively), compared to the natural pH. In contrast, V exhibits relatively flat pH-dependent leaching patterns with only <1.6% of the total V leached. Using the slag re-processing costs by acidic (bio)leaching and the current metal prices, the recovery of V, being the most important critical metal in the Berg Aukas slags, seems to be non-economical (Ettler et al., 2020, Applied Geochemistry, DOI: 10.1016/j.apgeochem.2019.104473). This study was supported by the Czech Science Foundation project (GAČR 19-18513S).
Investigating the climate predictability in the Southern Ocean using global and regional coupled models
Authors: Moreno-Chamarro Eduardo , Verfaillie Deborah , Goosse Hugues , Ortega Pablo , Fichefet Thierry , Massonnet François , Klein François , Pelletier Charles , Van Achter Guillian
Published: March 2020

The PARAMOUR project (Decadal Predictability and vAriability of polar climate: the Role of AtMosphere-Ocean-cryosphere mUltiscale inteRactions) is a new project funded in the framework of the Belgian program EOS - The excellence of Science. It aims at revealing fundamental drivers of climate variability and assessing the predictability in high-latitudes by using coupled regional climate models in both hemispheres. In this communication, we will present the ongoing contribution of the Earth and Life Institute in Louvain-la-Neuve (ELI, Belgium) and the Barcelona Supercomputing Center (BSC, Spain) to the PARAMOUR project, specifically in the Austral regions. The ELI and BSC efforts centre around two main objectives. The first one is improving our understanding of key processes that control the variability of the ice-ocean-atmosphere system at decadal timescales. The focus will initially be on the interactions between the components at regional scale and, later on, on the links with larger spatial scales. The second one is to determine how those interactions will lead to some predictability of the full ice-ocean-atmosphere system at decadal timescales or of some specific components only. Achieving our goals will require the development of coupled regional models including the atmosphere, ocean, sea ice and ice sheets, driven at their boundaries by the results of global models. Three configurations are proposed in the PARAMOUR project, covering 1/ Greenland, the Arctic and the North Atlantic sector, 2/ Antarctica and the Southern Ocean, 3/ The Totten glacier region. We will focus here on the latter two configurations, for the Austral regions. Retrospective (1980-2015) and prospective (2015-2045) climate simulations at high resolution will be conducted to evaluate the respective roles of initial conditions, some specific physical processes, teleconnections and couplings in the recent trends and to appreciate the potential fluctuations of key climate indicators within the next decades. A specific aspect will also be to determine the added-value of the regional models compared to the global ones.
Stable Isotopes in Tree Rings: Inferring Physiological, Climatic and Environmental Responses
Authors: Siegwolf Rolf , Brooks Renée , Roden John , Saurer Matthias
Published: March 2020

We are editing a new book in the Springer Tree Physiology Series entitled “Stable Isotopes in Tree Rings: Inferring Physiological, Climatic and Environmental Responses” due out in 2020. Because trees produce annual growth increments that can be precisely dated, annual and interannual variations in tree ring width and stable carbon, oxygen and hydrogen isotopes provide detailed records of past physiological responses to biotic and abiotic impacts over many decades and centuries. In contrast to non-living chronologies (ice cores, stalagmites etc.), trees modify base physical inputs in response to local microclimates through their physiological response to light, temperature, humidity, water availability, CO2 and nutrients. Although this can make interpretation of isotopic variation in organic matter more complicated, it also means that these proxies can provide a wealth of additional information. Thus, an understanding of the combined physical and biological drivers of isotope fractionation in tree rings is crucial for paleoclimate interpretation. In addition, tree rings and stable isotopes contained therein integrate dynamic environmental, phenological and developmental variation that can be used to study present organism function and recent anthropogenic influences apart from their use as proxies for conditions in the distant past. The last few decades have seen tremendous progress in understanding the mechanisms by which tree physiology modifies stable isotope fractionation in organic matter.

This book will be the first to comprehensively cover the field of tree ring stable isotopes. This volume highlights how tree ring stable isotopes have been used to address a range of environmental issues from paleoclimatology to forest management, and anthropogenic impacts on forest growth. It evaluates strengths and weaknesses of isotope applications in tree rings. This book focuses on physiological mechanisms that influence isotopic signals and reflect environmental impacts. Each of the 25 chapters has been authored by leading experts providing the most recent developments in the area.
Local kinetic processes determining macroscopic properties of interlinked magnetic flux tubes
Authors: Hwang Kyoung-joo , Burch Jim , Russell Christopher , Choi Eunjin , Dokgo Kyunghwan , Fear Robert , Fuselier Stephen , Petrinec Steve , Sibeck David , Hasegawa Hiroshi , Fu Huishan , Øieroset Marit , Escoubet Philippe , Giles Barbara , Strangeway Robert , Khotyaintsev Yuri , Graham Daniel , Gershman Daniel , Pollock Craig , Ergun Robert ,   MMS science working group
Published: March 2020

One of the most important transient phenomena affecting the solar wind-Earth’s magnetosphere coupling is non-steady dayside magnetic reconnection, observationally evidenced by a transient structure consisting of a bipolar magnetic-field component normal to the magnetopause. This signature, termed a flux-transfer-event (FTE), has been recently found to often consist of two interlinked flux tubes. The recent observations, particularly from the MMS spacecraft, showed a reconnecting current sheet between the interlaced flux tubes. However, local kinetic processes between the flux tubes have not been understood in the context of the broader FTE structure and evolution. An FTE observed by MMS on 18 December, 2017 comprised two flux tubes of different topology. One includes field lines with their ends connected to the northern and southern hemispheres while the other includes field lines that are connected to the magnetosheath (and ultimately the Sun). Evidence for reconnection occurring at the interface of the two flux tubes indicates how interacting flux tubes evolve into a flux rope having helical magnetic topology connecting either both to the Earth or being completely open. This study proposes a new aspect of how micro-to-meso-scale dynamics occurring within FTEs determines the macroscale characteristics and evolution of the structures.
Improving the representation of the prairie pothole dynamics in land surface models
Authors: Ahmed Mohamed I. , Elshorbagy Amin , Pietroniro Alain
Published: March 2020

The hydrography of the prairie basins is complicated by the existence of numerous land depressions, known as prairie potholes, which can retain a substantial amount of surface runoff. Consequently, the runoff production in the prairies follows a fill, spill, and merging mechanism, which results in a dynamic contributing area that makes the streamflow simulation challenging. Existing approaches to represent the potholes’ dynamics, in different hydrological models, use either a lumped or a series of reservoirs that contribute flow after exceeding a certain storage threshold. These approaches are simplified and do not represent the actual dynamics of the potholes nor their spatial water extents. Consequently, these approaches may not be useful in capturing the potholes’ complexities and may not be able to accurately simulate the complex prairie streamflow. This study advances towards more accurate and physically-based streamflow simulation in the prairies by implanting a physically-based runoff generation algorithm (Prairie Region Inundation MApping, PRIMA model) within the MESH land surface model, and is referred to as MESH-PRIMA. PRIMA is a recently developed hydrological routing model that can simulate the lateral movement of water over prairie landscape using topographic data provided via DEMs. In MESH-PRIMA, MESH handles the vertical water balance calculations, whereas PRIMA routes the water and determines the amount of water storage and surface runoff. The streamflow simulations of MESH-PRIMA (using different DEM resolution as a topographic input) and MESH with its existing conceptual pothole dynamics algorithm are tested on a number of pothole-dominated watersheds within Saskatchewan, Canada, and compared against observed flows. MESH-PRIMA provides improved streamflow and peak flow simulation, compared to that of MESH with its conceptual pothole algorithm, based on the metrics evaluated for the simulations. MESH-PRIMA shows potential for simulating the actual pothole water extents when compared against water areas obtained from remote sensing data. The use of different DEM resolution changes the resulting pothole water extent, especially for the small potholes as they are not detected in the coarse DEM. MESH-PRIMA can be considered as a hydraulic-hydrologic model that can be used for better understanding and accurate representation of the complex prairie hydrology.
Probability Assessments of an Ice-Free Arctic: Comparing Statistical and Climate Model Projections
Authors: Rudebusch Glenn , Diebold Francis
Published: March 2020

The downward trend in the amount of Arctic sea ice is a key factor determining the pace and intensity of future global climate change. Diminished sea ice also has a wide range of other environmental and economic consequences. Based on several decades of satellite data, we provide statistical forecasts of Arctic sea ice extent during the rest of this century. The best fitting statistical model indicates that overall sea ice coverage is declining at an increasing rate. By contrast, average projections from the CMIP5 global climate models foresee a gradual slowing of Arctic sea ice loss even in scenarios with high carbon emissions. Our long-range statistical projections also deliver probability assessments of the timing of an ice-free Arctic. These results indicate almost a 60 percent chance of an effectively ice-free Arctic Ocean during some summer in the 2030s -- much earlier than the average projection from global climate models.