bluuebunny/crossref_metadata_2025 huggingface dataset:
Extreme rainfall event in Crimea: Cloud-resolving modeling and radar observations
Authors: Anisimov Anatolii , Efimov Vladimir , Lvova Margarita , Popov Viktor , Mostamandi Suleiman
Published: March 2020

We present a case study on extreme rainfall event in Crimea in September 2018. The event was caused by extratropical cyclone forming above the Black Sea. The cyclone approached the Crimean Mountains from the south, producing over 100 mm of rainfall in Yalta on September 6 and causing a flash flood. In the mountains, about 140 mm of rainfall was reported. 

To study this extreme event, we use the WRF model v.4.0.1 forced by the boundary conditions from ECMWF operational analysis with the spatial resolution of approximately 10 × 10 km. The model was run for 8 days of September 1 – 8, and 5 microphysical schemes were tested (WDM6, Morrison, Milbrandt, NSSL, and Thompson). Other model parameters were set identical to CONUS configuration suite. The simulations were done for two one-way nested convective-resolving domains with spatial resolution of 2.7× 2.7 km and 0.9 × 0.9 km. The simulations were verified using the meteorological radar observations in Simferopol airport and GPM measurements.

All of the microphysical schemes substantially underestimate the amount of rainfall reaching the ground compared to observations. However, several schemes (Milbrandt, Morrison, and WDM6) do add value to the forecasts, producing significantly larger amount of rainfall compared to the driving model that almost completely missed it on the local scale. WDM6 performs best to capture the proper location of the squall line and to reproduce the rainfall orographic enhancement in the mountains. The amount of rainfall in the child domain was also slightly larger compared to the parent one. Despite the rainfall underestimation, we also show that the simulated reflectivity patterns are in good agreement with observations, although the convective cores are wider and less intense compared to the observed by the radar.
Toward a regional-scale seasonal climate prediction system over the Mediterranean basin: evaluation and comparison of RegCM- and WRF-based dynamical downscaling approaches
Authors: Sangelantoni Lorenzo , Mazzarella Vincenzo , Ricchi Antonio , Ferretti Rossella , Redaelli Gianluca
Published: March 2020

Seasonal Climate Predictions (SCPs) represent a challenging intermediate field where aspects typical of the short-term weather forecasts and long-term climate projections interact. Skillful SCPs represent an essential tool to reduce societal vulnerabilities to the inter-annual climate fluctuation through short-term (i.e., next season) climate impact mitigation measures. This is especially true over areas characterized by large climate inter-annual variability as the Mediterranean basin, which is also traditionally characterized by a poor seasonal predictability.

The primary research question of present study is to assess the capability of two dynamical downscaling approaches to improve the seasonal inter-annual variability signal coming from the global-scale driving SCP system on the Mediterranean basin.

In this work the Weather Research and Forecasting model (WRF3.9.1.1) and the Regional Climatic Model (RegCM4.1) were nested into NCEP’s operational seasonal forecast model Climate Forecast System version 2 (CFSv2) to dynamically downscale seasonal predictions over Mediterranean basin.

Using the initial and boundary conditions of an ensemble of the CFSv2 we compare the capability of the two downscaling approaches on improving the large scale CFSv2 prediction of a climatological period of 22-cold seasons (December–February) during 1982–2002.

The SCP systems (WRF- and RegCM-based) consist on a double dynamical downscaling where a height-member lagged ensemble of 3-month CFSv2 climate predictions represent the common driving fields. Both the nested models dynamically downscales CFSv2 climate prediction from the original 100 km resolution to 60 km over a domain covering the Mediterranean basin and Central Europe. The first downscaling feeds a second downscaling performed over a domain centered over Central Italy with a resolution of 12 km.

Climate variables considered are: 2 m temperature, precipitation, geopotential height at different pressure levels and mean sea level pressure. Results will be discussed by means of mean bias spatial distribution, inter-annual anomaly variability reproduction and probabilistic hit-rate of anomalous seasons, through tercile plots and reliability diagrams of the above mentioned variables.

Preliminary results, considering the RegCM, identify temperature variability reproduction benefiting from the downscaling. At the same time, precipitation shows an improved spatial distribution patterns but not improved inter-annual variability representation if compared to the driving CFSv2 reference period climate predictions.
Anthropogenic CO2 emission uncertainties
Authors: Choulga Margarita , Janssens-Maenhout Greet , Balsamo Gianpaolo , McNorton Joe , Solazzo Efisio , Bousserez Nicolas , Agusti-Panareda Anna
Published: March 2020

The CO2 Human Emissions (CHE) project has been tasked by the European Commission to prepare the development of a European capacity to monitor anthropogenic CO2 emissions. The monitoring of fossil fuel CO2 emissions has to come with a sufficiently low uncertainty in order to be useful for policymakers. In this context, the main approaches to estimate fossil fuel emissions, apart from bottom-up inventories, are based on inverse transport
modeling either on its own or within a coupled carbon cycle fossil fuel data assimilation system. Both approaches make use of atmospheric CO2 and other tracers (e.g., CO and NOx) and rely on the availability of prior fossil fuel CO2 emission estimates and uncertainties (as well as biogenic fluxes for the transport inverse modeling). For a robust estimate of the uncertainty, information from different sources needs to be brought together.
A methodology to calculate yearly and monthly anthropogenic CO2 emission uncertainties based on IPCC guidelines (2006 IPCC Guidelines for National Greenhouse Gas Inventories + its 2019 Refinements) has been developed. Emission uncertainties are calculated for all world countries, under the assumption of two categories of world countries, depending on whether the country’s statistical infrastructure is well or less developed. For well-developed statistical infrastructure, emission uncertainties are lower, while less developed statistical infrastructure countries have higher emission uncertainties. A sensitivity analysis is investigating the impact of the well or less developed infrastructure assumption for several countries on the global emission uncertainty. Sensitivity experiments with different anthropogenic CO2 sources distributions, as well as the first results on using these prior anthropogenic CO2 uncertainties in ensemble perturbation runs will be presented.
Dynamics and source identification of colloids in surface and subsurface waters
Authors: Tang Xiangyu , Zhang Wei , Xian Qingsong
Published: March 2020

Natural colloids may act as carriers of contaminants and enhance the transport of strongly-sorbing pollutants toward surface waters and groundwater. Field investigations on colloid transport remain rare. This is of high importance for the hilly central Sichuan in the upper reaches of the Yangtze River, which is characterized by thin (mostly <60 cm) purple soil cover and underlying finely fractured mudrock and impermeable sandstone. In Jieliu catchment of Yanting, colloid dynamics in surface and subsurface flows for two sloping (6°) farmland plots (24 m2 and 1500 m2) as well as in stream flows at two weirs (3 ha and 35 ha) were monitored based on individual rain events to identify the major factors governing colloid transport. Daily monitoring of fracture flow from the 1500 m2 plot and biweekly monitoring of three lowland shallow wells was also conducted simultaneously throughout a whole year to identify the source of colloids in groundwater.

Results show that colloid concentration in the surface runoff was 1-2 orders of magnitude higher than that in the subsurface flows (i.e., the interflow from the soil-mudrock interface and fracture flow from the mudrock-sandstone interface). The lowest colloid concentration was observed in the interflow, probably as a result of pore-scale colloid straining. The rainfall intensity and its temporal variation govern colloid dynamics in both surface runoff and subsurface flows. Analyses of δ13C and mineral composition, organic matter and carbonate content in groundwater colloids and the upper geological samples can be used combinedly to identify the sources of groundwater colloids. By using the δ13C tracking technique, it was found that the suspended fine sediment export via stream flow during rain events at the catchment outlet came mainly from the sloping farmland, while the deposited fine sediment on stream bed derived from multiple sources including paddy field (55.3%), woodland (29.7%) and sloping farmland (15.0%).
SP4GATEWAY: a Space Plasma Physics Payload Package conceptual design for the Deep Space Gateway Lunar Orbital Platform
Authors: Dandouras Iannis , Devoto Pierre , De Keyser Johan , Futaana Yoshifumi , Bamford Ruth , Branduardi-Raymont Graziella , Constantinescu Dragos , Chaufray Jean-Yves , Eastwood Jonathan , Echim Marius , Grison Benjamin , Hercik David , Milillo Anna , Nakamura Rumi , Přech Lubomír , Roussos Elias , Štverák Štěpán , Laurens André , Winter Josef , Taylor Matt G. G. T. ,   SP4GATEWAY Team
Published: March 2020

The Deep Space Gateway is a crewed platform that will be assembled and operated in the vicinity of the Moon by ESA and its international partners in the early 2020s and will offer new opportunities for fundamental and applied scientific research. The Moon is a unique location to study the deep space plasma environment, due to the absence of a substantial intrinsic magnetic field and the direct exposure to the solar wind, galactic cosmic rays (GCRs) and solar energetic particles (SEPs). However, 5-6 days each orbit, the Moon crosses the tail of the terrestrial magnetosphere facilitating the in-situ study of the terrestrial magnetotail plasma environment as well as atmospheric escape from the ionosphere. When back outside of the magnetosphere, a variety of these and other phenomena, e.g. those driving solar-terrestrial relationships, can be investigated through remote sensing using a variety of imaging techniques. Most importantly, the lunar environment offers a unique opportunity to study the interaction of the solar wind and the magnetosphere with the lunar surface and the lunar surface-bounded exosphere. In preparation of the scientific payload of the Deep Space Gateway, we have undertaken a conceptual design study for a Space Plasma Physics Payload Package onboard the Gateway (SP4GATEWAY). The main goal is first to provide a science rationale for hosting space plasma physics instrumentation on the Gateway and to translate that into a set of technical requirements. A conceptual payload design, that identifies a strawman payload and is compatible with the technical requirements, is then put forward. The final outcome of this project, which is undertaken following an ESA AO, is an implementation plan for this space plasma physics payload package.
Photophoresis used for measurements of light absorption by a single particle
Authors: Bluvshtein Nir , Krieger Ulrich
Published: March 2020

The contribution of light absorption by brown carbon aerosols to the Earth’s energy balance still poses a significant uncertainty in our understanding of climate forcing. As a result, one of the main open questions regarding organic aerosols in atmospheric chemistry is related to the formation and degradation of light-absorbing compounds during aging processes. Towards this goal, we explore the use of photophoresis for high sensitivity measurements of light absorption by a single levitated particle in an experimental setup that facilitates realistic atmospheric gas concentrations and aging time.

Photophoresis occurs when the surface of an illuminated, light-absorbing particle is unevenly heated relative to its surroundings. The temperature difference between the illuminated and the ‘dark’ side of the particle results in an uneven momentum transfer from colliding gas-phase molecules. This leads to a net photophoretic force, acting on the particle in the direction of the momentum transfer gradient. The photophoretic force is related to the complex refractive index of the particle and to its size parameter through the distribution of internal electric fields. As such, it may lead to a net force away from (positive) or towards (negative) the light source.

Using this phenomenon, we were able to retrieve the imaginary part of the complex refractive index (k) of a single particle levitated in an electrodynamic balance (EDB) at 473 nm wavelength. Extremely low values of k from 10-4 to 10-5 were successfully retrieved with uncertainty of less than 35% during a photo-bleaching experiment of a slightly absorbing organic particle used as a model for atmospheric brown carbon.    

An advantage of the EDB is that heterogeneous chemistry and photochemistry experiments are performed on a single particle that is levitated for days and weeks allowing for realistic atmospheric gas concentrations and aging times. In such experiments, measurements of the particle’s light absorption properties using photophoresis would add valuable information on the evolution of light absorption by the aging of organic aerosols.

A future study will implement this approach in an EDB-MS system where the EDB will be coupled with a soft ionization mass spectrometer. This will allow the identification of the molecular species responsible for light absorption as it evolves.  
The effects of waterlogging on the solubility of arsenic and ecotoxicity of soil pore water in non-fertilized and fertilized soils in historical mining sites.
Authors: Szopka Katarzyna , Karczewska Anna , Dradrach Agnieszka , Gałka Bernard
Published: March 2020

Soil contamination with arsenic in historical mining sites is a matter of considerable environmental concern, as the concentrations of As in those soils are locally as high as thousands mg/kg. Some of soils, particularly those affected in the past by tailings that were released from impoundments, are located in floodplains and used as grasslands. Those lands are periodically flooded, and the frequency and duration of flooding will probably increase in the future with changing climatic conditions. Reducing environment that develops upon soil flooding can cause a release of As from soil solid phase. This is an inherent effect of reductive dissolution of amorphous and crystalline iron hydroxides that are the main hosting components for metalloids. Changing redox conditions affect also the speciation of As in pore water, influencing its toxicity to soil biota. Moreover, soil fertilization with inorganic fertilizers that contain phosphates, or with organic fertilizers such as cattle manure, can accelerate As release from iron hydroxides, mainly via competitive desorption. The effects of all those processes are highly dependent on soil properties and still require a close examination.

Three kinds of soil material, containing up to 8000 mg/kg As, were collected from the tailings-affected floodplain of the Tująca river in Złoty Stok, a historical As mining centre. A laboratory incubation experiment with fertilized and non-fertilized soils was carried out to examine the changes in As concentrations in soil pore water, as well as to assess pore water ecotoxicity, determined in standard bioassays, including Microtox and Phytotox. Soil flooding resulted in a rapid release of As from soil solid phase. As concentrations in soil pore water in all samples exceeded 10 mg/L after a 2-day incubation, and tended to increase slowly with time. In some cases, after the 270-day incubation, As concentrations in pore water reached several hundred mg/L. Those effects resulted in a very high ecotoxicity of pore water, caused lethal effects to bacteria and springtails, and impeded plant germination. Soil amendment with manure was a factor that significantly enhanced those effects. The factors responsible for various effects that were reported from three soils were discussed.
Soil organic matter in soils of the Russian Arctic: insights from 13C-NMR spectroscopy
Authors: Alekseev Ivan , Abakumov Evgeny
Published: March 2020

Polar soils play a key role in global carbon circulation and stabilization as they contain maximum stocks of soil organic matter (SOM) within the whole pedosphere. Cold climate and active layer dynamics result in the stabilization of essential amounts of organic matter in soils, biosediments, and grounds of the polar biome. Chemical composition of soil organic carbon (SOC) determines its decomposability and may affect soil organic matter stabilization (SOM) rate (Beyer, 1995). This is quite important for understanding variability in SOC pools and stabilization rate in context of changes in plant cover or climate (Rossi et al. 2016). 13C nuclear magnetic resonance spectroscopy, which provides detailed information on diversity of structural composition of humic acids and SOM, may also be used to study the SOM dynamics under decomposition and humification proceses (Kogel-Knabner, 1997; Zech et al., 1997). This study aims to characterize molecular organization of the humic acids, isolated from various permafrost-affected soils of Yamal region and to assess the potential vulnerability of soils organic matter in context of possible mineralization processes. Organic carbon stocks for studied area were 7.85 ± 2.24 kg m-2 (for 0-10 cm layer), 14.97 ± 5.53 kg m-2 (for 0-30 cm), 23.99 ± 8.00 kg m-2 (for 0-100 cm). Results of solid-state 13C-NMR spectrometry showed low amounts of aromatic components in studied soils. All studied humic powders are characterized by predominance of aliphatic structures, and also carbohydrates, polysaccharides, ethers and amino acids. High content of aliphatic fragments in studied humic acids shows their similarity fulvic acids. Low level of aromaticity reflects the accumulation in soil of lowly decomposed organic matter due to cold temperatures. Our results provide further evidence of high vulnerability and sensitivity of permafrost-affected soils organic matter to Arctic warming. Consequently, these soils may play a crucial role in global carbon balance under effects of climate warming.
Mycobiota in urban soils of Russian North
Authors: Vaseneva Inna , Kuznetsova Elena , Khabibullina Fluza
Published: March 2020

Microbilogical properties of urban soils were studied in Syktyvkar town (Komi Republic), in the taiga zone of Russia. Within the settlement, two different types of functional zones were compared: transport (roadside areas with limited influence of traffic and highway area) and recreation areas (parks). The soils of parks are man-changed urban soils, whereas the soils of roadside areas were mainly man-made or considerably disturbed. The investigated soils were formed on the cultural layer or buried soils and sediments of various genesis. The soil profiles included a humus-accumulative horizon in the top part, followed by an anthropogenically transformed part, underlain by a slightly modified parent rock.

The highest number of species was determined in the soils of recreational areas, including 33 species of microscopic fungi. Soils of the transport area contained 22 species. The higher number of species is associated with the development of specific for urban zone fungal complex and partial preservation of natural zonal species of fungi, mainly representatives of Penicilliumgenus. Non-typical for the taiga zone species from Aspergillus and Fusariumgenera were frequently noted. Highway areas with intensive traffic were characterized by the dominance of dark-colored melanin-containing fungi, which are conditional pathogens for humans, and increasing presence of sterile mycelium – indicator of soil disturbance. Stenotopic species which are typical for undisturbed zonal conditions were rarely isolated.

Acknowledgements The experimental research was partly supported by Russian Science Foundation project № 19-77-30012.
Assessment of the quality of TROPOMI high-spatial-resolution NO2 data products
Authors: Zhao Xiaoyi , Griffin Debora , Fioletov Vitali , McLinden Chris , Cede Alexander , Tiefengraber Martin , Müeller Moritz , Bognar Kristof , Strong Kimberly , Boersma Folkert , Eskes Henk , Davies Jonathan , Ogyu Akira , Lee Sum Chi
Published: March 2020

The TROPOspheric Monitoring Instrument (TROPOMI) on-board the Sentinel-5 Precursor satellite (launched on 13 October 2017) is a nadir-viewing spectrometer measuring reflected sunlight in the ultraviolet, visible, near-infrared, and shortwave infrared spectral ranges. The measured spectra are used to retrieve total columns of trace gases, including nitrogen dioxide (NO2). In this study, Pandora NO2 measurements made at three sites located in or north of the Greater Toronto Area (GTA) are used to evaluate the TROPOMI NO2 data products, including the standard Royal Netherlands Meteorological Institute (KNMI) NO2 data product and a research data product developed by Environment and Climate Change Canada (ECCC) using a high-resolution regional air quality forecast model (used in the airmass factor calculation).

TROPOMI pixels located upwind and downwind from the Pandora sites were analyzed using a new wind-based validation method that increases the number of coincident measurements by about a factor of five compared to standard techniques. Using this larger number of coincident measurements, this work shows that both TROPOMI and Pandora instruments can reveal detailed spatial patterns (i.e., horizontal distributions) of local and transported NO2 emissions, which can be used to evaluate regional air quality changes. The TROPOMI ECCC NO2 research data product shows improved agreement with Pandora measurements compared to the TROPOMI standard tropospheric NO2 data product, demonstrating the benefit of using the high-resolution regional air quality forecast model to derive NO2 airmass factors.
Improved characterisation of the impact of chlorinated VSLSs on atmospheric chemistry and climate: past, present and future
Authors: Bednarz Ewa , Hossaini Ryan , Abraham Luke , Chipperfield Martyn
Published: March 2020

The emissions of most long-lived halogenated ozone-depleting substances (ODSs) are now decreasing, owing to controls on their production introduced by Montreal Protocol and its amendments. However, short-lived halogenated compounds can also have substantial impact on atmospheric chemistry, including stratospheric ozone, particularly if emitted near climatological uplift regions. It has recently become evident that emissions of some chlorinated very short-lived species (VSLSs), such as chloroform (CHCl3) and dichloromethane (CH2Cl2), could be larger than previously believed and increasing, particularly in Asia. While these may exert a significant influence on atmospheric chemistry and climate, their impacts remain poorly characterised.

 

We address this issue using the UM-UKCA chemistry-climate model. We use a newly developed Double-Extended Stratospheric-Tropospheric (DEST) chemistry scheme, which includes emissions of all major chlorinated and brominated VSLSs alongside an extended treatment of long-lived ODSs. Employing novel estimates of Cl-VSLS emissions we show model results regarding the atmospheric impacts of chlorinated VSLSs over the recent past (2000-present), with a focus on stratospheric ozone and HCl trends. Finally, we introduce our plans regarding examining the impacts of chlorinated VSLSs under a range of potential future emissions scenarios; the results of which will be directly relevant for the next WMO/UNEP assessment.
Dynamics of sediment delivery to mangrove forests of the Ganges-Brahmaputra-Meghna Delta
Authors: Hale Richard , Garnand Alexandra , Wilson Carol
Published: March 2020

The Ganges-Brahmaputra-Meghna Delta (GBMD) is among the largest in the world, nourished by the ~1 Gt/yr sediment load of its titular rivers. Approximately 75% of this sediment load is debouched to the Bay of Bengal, with ~180 Mt subsequently reworked by tidal processes across the southwestern portion of the delta. This region includes this Sundarbans National Reserve Forest (SNRF), which is the words’ largest continuous mangrove stand. In addition to global sea level rise and the enhanced subsidence intrinsic to deltas, ongoing and proposed alterations to the upstream fluvial sediment supply threaten the future viability of this important ecological and cultural resource.

 

In this study, we use data collected in situ by acoustic and optical instrumentation to examine the physical processes controlling sedimentation in the mangrove forest along the southern coast during both the monsoon (October 2019) and dry seasons (March 2020).  These data are then compared with sedimentation rates measured using sediment elevation tables and marker horizons, as well as observations made 100 km further inland near the northern extent of the SNRF. At this inland site, sediment supply, inundation depth, and salinity have been identified as important factors controlling sediment deposition to the mangrove platform, which ranges from ~1 cm during the dry season (November – June), to > 2 cm during the monsoon (July-October). Data from the second location along the coast are vital for understanding the regional nature of the various threats to delta viability.

 

Preliminary analysis of the 2019 monsoon season data from the southern coast reveals the relative importance of water depth, water velocity, and mangrove pneumatophore density on modulating both water velocity and suspended sediment concentration. Previous studies have identified that while the inland location features a larger tidal range (~5 m vs. ~3 m), frequent cyclone activity likely impacts sedimentation at the coastal site. Data collected in March 2020 will address how these variables impact controls on sedimentation both seasonally and regionally. Results from this study demonstrate the importance of providing regional context to sedimentation studies, as delta communities adapt to dynamic forcing conditions.   
Soil microbial biomass, community level physiological profiles relate to tree species and its state in urban environment
Authors: Seleznyova Alexandra , Yaroslavtcev Alexey , Gavrichkova Olga , Ryazanov Alexey , Kovaleva Julia , Ananyeva Nadezhda , Valentini Riccardo
Published: March 2020

Urban trees and soil microbial communities are the key ecosystem components to provide the supporting, provisioning and regulating services that define citizen’s well-being. Understanding the relationships between physiological states, age, species of trees and microbial functional properties are needed for a management of urban areas and landscapes' engineering. The research focuses on finding linkages between a wide range of trees’ properties monitored by smart TreeTalker technology and soil functional microbial indexes in Moscow megapolis.

The study was carried out on the RUDN University campus area (Moscow, Russia), where six tree species were selected (Pinus sylvestris, Populus tremula, Acer platanoides, Tilia cordata, Picea abies, Betula pendula). TreeTalker device was installed on the preselected five trees of each species for monitoring the sap flux, vertical stability (according to digital accelerometer), spectrums of canopy reflectance, trunk and canopy air temperature and humidity. Monitoring started in May 2019. The composite soil samples (0-10) were taken under each tree at the 0.5 m distance from its stand by augering in October 2019. In the samples, the microbial biomass carbon (MBC, SIR-method), basal respiration (BR), community level physiological profile (CLPP, MicroResp) and Shannon microbial diversity index (H’) based on CLPP were determined.

Soil MBC content was significantly depended on tree species, increasing from A.platanoides to T.cordata (from 538 to 1445 µg C g-1). The microbial diversity index was lowest in soil under A.platanoides (H’=2.1) and the highest for B.pendula (H’=2.4). The soil CLPP for A.platanoides was mainly shifted to microbial response on carboxylic acids with the low reaction on amino and phenolic acids compared to other trees species (e.g. B.pendula). Soil qCO2 (BR/MBC ratio) was positively related to trees’ age (r=0.8). Response to carboxylic acids (especially oxalic) had the highest correlation with physiological properties of the trees: trunk moisture, photochemical reflectance index and vertical stability (r > -0.5).

Current research was financially supported by Russian Science Foundation [No 19-77-30012].
Underestimated Role of Fires in Providing Nutrients for Biogeochemical Cycles
Authors: Hamilton Douglas , Barkley Anne , Moore J. Keith , Arneth Almut , Bond Tami , Carslaw Kenneth , Gaston Cassandra , Hantson Stijn , Ito Akinori , Kaplan Jed , Lindsay Keith , Nieradzik Lars , Prospero Joseph , Rathod Sagar , Scanza Rachel , Mahowald Natalie
Published: March 2020

Fire regimes respond to both climate and human land management practice changes, in turn modifying land cover distributions, surface albedo, carbon storage, and emissions. Much attention has recently been given to the health and climate impacts of fires, but fires are also an important source of nutrients, such as iron and phosphorus, to both land and ocean biospheres. Fires therefore create important feedbacks within the Earth system. Here we discuss recent developments showing how fires are a previously underestimated source of limiting nutrients, providing up to half the annual deposited amount of soluble iron and soluble phosphorus to southern oceans and the Amazon, respectively. Fire can therefore stimulate ocean productivity by providing long range transport of essential nutrients, released from the vegetation burned and entrained with dust from the surrounding environment, to remote regions. We considered the impact of human activity on soluble iron deposition for the past (c.1750 CE), present (c.2010 CE), and future (c.2100 CE). We find that the global carbon cycle and climate response is dominated by changes to primary productivity within the Southern Ocean (>30ºS) and that the carbon export efficiency (gram of carbon sequestered per gram of soluble iron added) for this region is 43% larger when altering fire emissions compared to altering dust emissions. Results suggest that modelling past and future changes in biogeochemical cycles should incorporate information on how fires, and the nutrients carried within their plumes, respond to changes in climate.
Passive neutron sensing of martian subsurface from onboard rovers: results from MSL/DAN and expectations from ExoMars/Adron-RM
Authors: Nikiforov Sergey , Mitrofanov Igor , Litvak Maxim , Djachkova Maya , Golovin Dmitriy , Lisov Denis , Malakhov Alexey , Mokrousov Maxim , Sanin Anton , Tretyakov Vladislav
Published: March 2020

During more than 7 years, the NASA MSL Curiosity rover is successfully traversing across the Mars surface exploring Gale crater with the Dynamic Albedo of Neutron (DAN) instrument installed onboard. This year, next generation neutron spectrometer Adron-RM is ready to be launched to Mars as a payload of the ExoMars 2020 rover. The main objectives of these instruments are analogous  and consist in the assessment of Water Equivalent Hydrogen (WEH) in the shallow martian subsurface.

The hydrogen presence significantly influences the neutron leakage spectrum because of  neutron moderation and thermalization through collisions with hydrogen nuclei. As a result, the variations of neutron flux detected onboard in different energy bands correlate with subsurface hydrogen/water abundance.

In our study, we will demonstrate scientific potential and latest results of natural neutron background measurements (called as passive measurements) by DAN. We will provide assessment on average WEH content in the area of the ExoMars 2020 landing site, which could be expected from first measurements of Adron-RM.
Analyzing Near Surface Temperature Inversions Across the Greenland Ice Sheet Using In-situ, Remote Sensing, and Reanalysis Data
Authors: Adolph Alden , Brown Wesley , Zikan Karina , Fausto Robert
Published: March 2020

As Arctic temperatures have increased, the Greenland Ice Sheet has exhibited a negative mass balance, with a substantial and increasing fraction of mass loss due to surface melt. Understanding surface energy exchange processes in Greenland is critical for our ability to predict changes in mass balance. In-situ and remotely sensed surface temperatures are useful for monitoring trends, melt events, and surface energy balance processes, but these observations are complicated by the fact that surface temperatures and near surface air temperatures can significantly differ due to the presence of inversions that exist across the Arctic. Our previous work shows that even in the summer, very near surface inversions are present between the 2m air and surface temperatures a majority of the time at Summit, Greenland. In this study, we expand upon these results and combine a variety of data sources to quantify differences between surface snow/ice temperatures and 2m air temperatures across the Greenland Ice Sheet and investigate controls on the magnitude of these near surface temperature inversions. In-situ temperatures, wind speed, specific humidity, and albedo data are provided from automatic weather stations operated by the Programme for Monitoring of the Greenland Ice Sheet (PROMICE). We use the Clouds and the Earth's Radiant Energy System (CERES) cloud area fraction data to analyze effects of cloud presence on near surface temperature gradients. The in-situ temperatures are compared to Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) and Moderate Resolution Imaging Spectrometer (MODIS) ice surface temperature data to extend findings across the ice sheet. Using PROMICE in-situ data from 2015, we find that these 2m temperature inversions are present 77% of the time, with a median strength of 1.7°C. The data confirm that the presence of clouds weakens inversions. Initial results indicate a RMSE of 3.9°C between MERRA-2 and PROMICE 2m air temperature, and a RMSE of 5.6°C between the two datasets for surface temperature. Improved understanding of controls on near surface inversions is important for use of remotely sensed snow surface temperatures and for modeling of surface mass and energy exchange processes.
Impacts on soil organic matter quantity and composition of a prescribed fire in a eucalypt forest (Sydney, Australia)
Authors: Santin Cristina , Merino Agustin , Sayyad-Amin Parvaneh , Doerr Stefan H.
Published: March 2020

In this presentation, we will assess the direct impacts of a prescribed fire on the quantity and composition of organic matter in oligotrophic soils of a dry eucalypt forest (Warragamba, Sydney, Australia). Samples of the litter layer and surface soils horizons (Oa and Ah) were collected immediately before and after the fire. The prescribed fire was carried out September 2014 and was classified of moderate to high severity. In addition to litter and soil, samples of ash (burnt litter) were also collected after the fire.  In order to monitor the temperatures reached by the different soil organic matter pools during the fire, we installed thermologgers at the litter layer (n=30), the surface of the Oa soil horizon (n = 9), and at 1 cm depth within the Ah soil horizon (n =4). All samples were characterized by elemental analysis (total carbon, nitrogen, oxygen and hydrogen), thermogravimetry-differential scanning calorimetry and, a selected subset by solid-state 13C nuclear magnetic resonance. The observed changes in quantity and characteristics of the different organic matter pools will be discussed and the relationships between these changes and the temperatures recorded during the burn explored.
Is more data better? A comparison of multi- and hyperspectral imaging in phenotyping.
Authors: Haagsma Marja , Page Gerald , Johnson Jeremy , Still Christopher , Waring Kristen , Sniezko Richard , Selker John
Published: March 2020

Spectral imaging of vegetation for phenotyping is a fast-developing field that enables fast, objective and automated assessment of plant traits. Advances in instrumentation allow collection of ever more detailed observations using hyperspectral imaging. This technique captures the reflected light in 100+ wavelengths, compared to multispectral sensors which typically obtain 3 to 5 wavelengths. With machine learning and careful statistical analysis these data can be efficiently transformed into predictions of crop health, yield, etc. However, these instruments are costly to acquire and produce volumes of data which are expensive to handle and archive, and therefore we must ask the question whether/when the investment is worth it. In this case study, we assess the implications of using hyperspectral vs multispectral imaging when monitoring the effects of an invasive fungal pathogen on seedlings of southwestern white pine. We discuss the impacts in terms of the complexity level of the research goals. Firstly, we discuss the impact on the accuracy and timing of infection detection. Pre-symptomatic detection of infection is possible using hyperspectral. To what extent is this possible using multispectral? Next, what is the trade-off between the two spectral methods when predicting for symptom severity? And lastly, the study contains a third level of complexity, a variety in genotypes. Using hyperspectral we can successfully separate the genotypes. However, is there still a significant difference in reflectance between genotypes when using multispectral data? This study shows that the need for hyperspectral depends on the complexity of the research goal, and therefore collecting more data might not always be useful.
The Barents Sea Benthic Silica Cycle and its Sensitivity to Change: a Stable Isotopic and Reaction-Transport Model Study
Authors: Ward James , Sales de Freitas Felipe , Chin Ng Hong , Hendry Katharine , Arndt Sandra , Pickering Rebecca , Henley Sian , Ward Rachael , März Christian , Faust Johan
Published: March 2020

Biogeochemical cycling of silicon (Si) in the high latitudes has an important influence on the marine Si budget. The Barents Sea is divided aproximately equally into Arctic and Atlantic water (ArW and AW respectively) domains.  However, increases in the temperature and inflow of AW across the Barents Sea opening is driving an expansion of the AW realm. While the sensitivity of pelagic processes pertaining to primary production is receiving increasingly more attention, less is known of the effect on the benthic Si cycle. This knowledge gap could prove integral, as the flux of Si across the sediment-water interface (SWI) from Arctic shelf sediments could be up to 20% higher than that of riverine sources. This benthic flux is largely controlled by early diagenetic processes in sediment pore waters, including biogenic silica (bSi) dissolution and authigenic precipitation.

To improve our understanding of benthic Si dynamics in the Barents Sea and examine its sensitivity to future change, we analysed pore water and sediment samples from both the AW and ArW realms between 2017-2019 for dissolved silica (dSi) concentrations and stable silicon isotopic compositions. Moreover, to determine the composition and content of bSi, as well as Si sorbed onto metal oxides, we conducted a sequential digestion of surface sediment. Following this we coupled our analyses with reaction transport modelling to further improve our mechanistic understanding of the system and to quantitatively disentangle the relative importance of these diagenetic processes to pore water Si chemistry and benthic fluxes.

Our work suggests that both interannual and spatial variability of dSi are increased in the southern, AW region of the Barents Sea. Benthic flux estimates for the southern sites have been found to more than double (~30 to 100 mmol m-2 yr-2) between cruise years, compared to a more consistent flux in the north (~80 mmol m-2 yr-2). Therefore, future Atlantification of the northern region may enance the variability of dSi supply from the benthos to bottom waters, with potential consequences for diatom productivity in the region.
Investigating Spatio-temporal Changes in Subglacial Hydrology from Dense Array Seismology.
Authors: Nanni Ugo , Gimbert Florent , Roux Philippe , Lecointre Albanne
Published: March 2020

Subglacial hydrology strongly modulates glacier basal sliding, and thus likely exerts a major control on ice loss and sea-level rise. However, the limited direct and spatialized observations of the subglacial drainage system make difficult to assess the physical processes involved in its development. Recent work shows that detectable seismic noise is generated by subglacial water flow, such that seismic noise analysis may be used to retrieve the physical properties of subglacial channelized water flow. Yet, investigating the spatial organisation of the drainage system (e.g. channels numbers and positions) together with its evolving properties (e.g. pressure conditions) through seismic observations remains to be done. The objective of this study is to bring new insights on the subglacial hydrology spatio-temporal dynamics using dense array seismic observations.

We use 1-month long ground motion records at a hundred of sensors deployed on the Argentière Glacier (French Alps) during the onset of the melt season, when the subglacial drainage system is expected to strongly evolve in response to the rapidly increasing water input. We conduct a multi-method approach based on the analysis of both amplitude and phase maps of seismic signals. We observe characteristic spatial patterns, consistent across those independent approaches, which we attribute to the underlying subglacial drainage system.

The phase-driven approach shows seismic noise sources that focuses in the along-flow direction as the water input increases. We identify this evolution as the development of the main subglacial channel whose position is coherent with the one expected from hydraulic potential calculations. During periods of rapid changes in water input (5 days over 31) and concomitant glacier acceleration the amplitude-driven approach shows spatial pattern highly consistent with the seismic noise sources location. At this time, we suggest that the spatial variations in the amplitude are representative of the water pressure conditions in subglacial channels and surrounding areas. Our spatialized observations therefore reveal the spatio-temporal evolution of the subglacial drainage system together with its changing pressure conditions. We observe, for instance, that channels develop at the very onset of the melt-season and rapidly capture the water from surrounding areas. Such unique observations may allow to better constrain the physics of subglacial water flow and therefore strengthen our knowledge on the dynamics of subglacial environments.
Water, Weather and Climate Services for Africa: the case of Ghana and Kenya
Authors: Annor Frank Ohene , van de Giesen Nick , ten Veldhuis Marie-Claire
Published: March 2020

Close to 80% of Sub-Saharan African farmers rely on rainfed agriculture.  This makes it important that the weather and climate in this region is well understood, since it accounts for more than 15% of the GDP for instance in Ghana and Kenya. However, uncertainties in weather forecast and climate projections are very high in particular for this region, which leads to poor weather and climate services for agriculture production. One of the underlying factors among many is the poor conditions of weather and climate infrastructure in Sub-Saharan Africa.  The Trans-African Hydro-Meteorological Observatory (TAHMO) together with some National Meteorological and Hydrological Services (NMHSs) in Africa and other partners through the TWIGA project (http://twiga-h2020.eu/) are building a network of weather and hydrological stations to address this need. This network builds on the over 500 TAHMO stations in countries of interest like Ghana, Kenya, Uganda, South Africa, and Mozambique.

The observation network includes automatic weather stations, soil moisture sensors, Global Navigation Satellite System (GNSS) receivers, distributed temperature sensing (DTS), lightning sensors, neutron counters, evaporometers, laser speckle scintillometers, accelerometers for tree weighing, intervalometer rain gauges, flood mapper using citizen science mobile applications (Apps) and crop doctor using drones and Apps. The project has accelerated the Technology Readiness Levels (TRLs) of these innovations with some already set up for operational purposes delivering the first set of TWIGA services such as “How humid is my environment?; Crop detection and condition monitoring; Weather-based alerts for citizens/farmers; Area-specific near real-time weather forecast for farmers; Crop insurance based on soil index; Plastic accumulation monitor; Short-term prediction for solar energy; and Precipitable water vapour monitoring with TWIGA GNSS stations. These new innovations and the services developed using the value chain approach is a game changer for Sub-Saharan Africa.
Geomagnetic Response to a Chain of Interplanetary Coronal Mass Ejections
Authors: Akhavan-Tafti Mojtaba , Fontaine Dominique , Le Contel Olivier , Slavin James
Published: March 2020

The most geoeffective storms in the Space Age have been driven solely by the sheath preceding an interplanetary coronal mass ejection (ICME) or by a combination of the sheath and an ICME magnetic cloud. In the present study, the magnetospheric response to a chain of three independent and well-spaced ICMEs (Pdyn > 15 nPa and Sym-H < -50 nT) spanning one month (December 12, 2015 – January 12, 2016) is investigated using WIND, Cluster, and MMS fields and plasma measurements. The first of the three ICMEs consists of a sheath preceding an ICME (ICME-SH). The latter two ICMEs are preceded by a combination of the sheath and an ICME magnetic cloud (ICME-SH-MC).

Following the passage of the first ICMEs (ICME-SH) the interplanetary environment was made up of moderate Alfvenic Mach number (MA ~ 10) and average magnetopause standoff distance (RMP ~ 11 RE). The arrival of the ICME-SH-MC then initiated a sudden storm commencement (SSC) phase. During the SSC, the storm index (Sym-H ~ +50 nT) remained positive through the ICME shock and sheath regions. The storm index and the Alfvenic Mach number sharply declined (Sym-H~ -200 nT and MA ~ 1.0, respectively) with the arrival of the leading edge of the magnetic cloud (BIMF, core ~ 20 nT) and the associated sharp IMF Bz reversal (Bz<0). The Alfvenic Mach number and IMF Bz are found to directly correlate with the Sym-H index. ICME-SH-MC compressed the magnetopause standoff distance (∂RMP/∂t ~ -1 RE/min), resulting in a sudden reduction in the total magnetospheric volume (∂VMP/∂t ~ -3×102 RE3/min), as determined by cross-scale observations. In particular, the sharp drops in the magnetospheric volume (relative change in volume >30%) with the arrival of each of the three independent ICMEs are shown to start with the SSC and remain low through the main phase, before slowly recovering (∂VMP/∂t ~ +1 RE3/min) to the pre-ICME conditions during the recovery phase.