bluuebunny/crossref_metadata_2025 huggingface dataset:
Aerosol Pollution in Asia and Its Interactions with Climate
Authors: Gao Meng
Published: March 2020

With rapidly expanding economic and industrial developments and tremendous increases in energy consumption, China and India are facing serious aerosol pollution, posing great threat to human health. Aerosols also modulate the climate and ecosystems via aerosol-cloud-radiation interactions. Yet, the poor understanding of aerosol pollution in Asia and its interactions with climate impedes the design and implementation of effective pollution control measures. Combining atmospheric modeling and observations, we demonstrated that the aerosol interactions with radiation and clouds contributed in important ways to intensification of the aerosol enhancements in North China. We manifested also how assimilation of PM2.5 in winter haze periods can improve model predictions and that these improved predictions can reduce significantly the uncertainties in health impacts and estimates of aerosol radiative forcing. It was also demonstrated that the conditions of the ocean temperature in fall can be effectively used to predict the severity of Indian winter haze, which provides useful implications for pollution control at least a season in advance.
Predicting forest fire in Indonesia using remote sensing data
Authors: Yang Suwei , Meel Kuldeep S , Lupascu Massimo
Published: March 2020

Over the last decades we are seeing an increase in forest fires due to deforestation and climate change. In Southeast Asia, tropical peatland forest fires are a major environmental issue having a significant effect on the climate and causing extensive social, health and economical impacts. As a result, forest fire prediction has emerged as a key challenge in computational sustainability. Existing forest fire prediction systems, such as the Canadian Forest Fire Danger Rating System (Natural Resources Canada), are based on handcrafted features and use data from instruments on the ground. However, data from instruments on the ground may not always be available. In this work, we propose a novel machine learning approach that uses historical satellite images to predict forest fires in Indonesia. Our prediction model achieves more than 0.86 area under the receiver operator characteristic(ROC) curve. Further evaluations show that the model's prediction performance remains above 0.81 area under ROC curve even with reduced data. The results support our claim that machine learning based approaches can lead to reliable and cost-effective forest fire prediction systems.
Residence time of nitrogen deposit in a nival subalpine catchment using the hyper-resolution ParFlow-CLM-EcoSLIM critical zone model.
Authors: Cohard Jean-Martial , Reverdy Alix , Voisin Didier , Hector Basile , Gupta Aniket , Biron Romain
Published: March 2020

Mountain regions represent a particular challenge for critical zone modelling as snowpack interacts with soils, vegetation, surface water and atmosphere and plays a primary role on the water transfers but also on the carbon and nitrogen cycles. Indeed, in these environments ecosystems are adapted to a snow regime under change due to the rise in the 0°C isotherm. In addition, atmospheric nitrogen deposition, a product of industrial activity carried by valley winds and mesoscale atmospheric circulation, already impacts some high-altitude ecosystems by modifying nutrient flows (nitrogen and carbon in particular). These combined forcings could lead to major ecosystem changes (distribution of water, carbon and nitrogen flows, growth rates, species, etc.). Anticipating this evolution, and the associated flows (CO2, nitrogen, water) under this double constraint, remains problematic due to the lack of adapted models.

In this study, we use the Parflow/CLM/Ecoslim model on a small (17ha) nival subalpine catchment close to Lautaret Pass (French Alps) where meteorological and hydrological parameters are measured together with snowpack survey and chemical concentrations measurements in the air, the rivers, the snowpack the vegetation and the ground. Simulations are constrained by a spatially distributed forcing and evaluated from snow pack dynamic and ET measurements. The simulations allow us to estimate the Nitrogen quantities that can be processed by vegetation and those drained in river flows. The estimation of the residence times is then calculated from the velocity field in the catchment. The wide snow cover time distribution leads to wide distribution resident time for any particle deposit. This can impact nitrogen chemical history and any other chemical compounds in the snow pack and the ground even for such small scales.
Exploring the performance of bias correction applied outside the calibration period’s climate regime
Authors: Klehmet Katharina , Berg Peter , Herrera Pascual , Leidinger David , Lemoine Anthony , Pasten-Zapata Ernesto , Pimentel Rafael
Published: March 2020

It is common practice to apply some form of bias correction to climate models before use in impact modelling, such as hydrology. The standard method is to evaluate the correction method based on a cross validation procedure with two or more sub-periods. This allows the method to be assessed on data not previously seen in the calibration step. However, with standard split-sample setups, the data is most likely in a similar climate regime as the calibration data. In effect, the method is evaluated in the same climate regime as it is calibrated, and informs little about the performance outside the current climate regime.

To address this issue, a discrete split sample test (DSST) was set up so that as diverse climate regimes as possible were sampled. The simplest climate analogue would be to perform the DSST on the coldest years and evaluate on the warmest, to mimic a changing temperature. Here, the tests are extended to more exotic indicators, such as snow pack, the joint probability of wet and cold seasons, the number of hot days in a year, the convective activity during summer; all related to a specific case study issue. Six different bias correction methods of both standard quantile mapping and other approaches to scale the reference time series are included. The methods are applied in a pseudo-reality framework to six climate model projections from Euro-CORDEX 12.5 km simulations. The analysis is focused on comparing the DSST performance with the impact on the climate change signals, and to the reliability of each method when applied to different climate regimes.
Tracking bits of information through forecasting systems: from source to decision
Authors: Weijs Steven , Foroozand Hossein
Published: March 2020

Probabilistic forecasts are essential for good decision making, because they communicate the forecaster's best attempt at representation of both information available and the remaining uncertainty of a variable of interest. The amount of information provided, which can be measured in bits using information theory, would then be a natural measure of success for the forecast in a verification exercise. On the other hand, it may seem rational to tune the forecasting system to provide maximum value to users. Somewhat counter-intuitively, there are arguments against tuning for maximum value. When the design of the forecasting system also includes the choice of the sources of information, monitoring network optimization becomes part of the problem to solve.  
In this presentation, we give a brief overview of the different roles information theory can have in these different aspects of probabilistic forecasting. These roles range from analysis of predictability, model selection, forecast verification, monitoring network design, and data assimilation by ensemble weighting. Using the same theoretical framework for all these aspects has the advantage that some connections can be made that may eventually lead to a more unified perspective on forecasting. 
Assessing sliding relations for glacier slip over realistic bed topography
Authors: Helanow Christian , Iverson Neal , Woodard Jacob , Zoet Lucas
Published: March 2020

Accuracy of prognostic ice-sheet models sensitively depend on the degree to which processes related to boundary conditions can be represented. In particular, the extent to which ice slides against and interacts with its substrate highly affects large-scale dynamics of ice sheets and glaciers. A process-based understanding of how basal drag and slip are related to conditions at the ice-bed interface, such as local bed topography, debris and subglacial hydrology, is therefore necessary to constrain ice-sheet response to a changing climate and associated sea-level rise.

We use a numerical model to simulate ice flow over a set of bed topographies of diverse morphological character; each model topography is the result of statistical analysis of a high-resolution digital elevation model of a glacier forefield, surveyed using ground-based LiDAR or drone-based photogrammetry. Allowing for ice-bed separation and water-filled cavities to form, we investigate the range of slip behavior by for each topography relating basal drag to slip velocity and water pressure and how this relation is affected by debris at the ice-bed interface.

Our results for realistic hard beds illustrate that there is an upper bound on the drag supported locally; this is in accordance with previous studies of hard-bedded slip over idealized two-dimensional topographies. The magnitude of this bound depends on the character of the bed, but is for the cases investigated only a fraction of the theoretical maximum and lower than values used in numerical ice-sheet models. However, the range of sliding velocities over which basal drag increases is for the considered topographies comparable to physically reasonable slip velocities, implying that substantial cavitation at the bed does not necessarily preclude a locally rate-strengthening slip relation. The presence of debris at the ice-bed interface influences the magnitude of the upper bound on the basal drag, broadening the range over which heuristic, rate-strengthening sliding relations commonly used in glacier-flow models can apply.
Estimation of subsurface formation temperature in the Upper Yangtze Area, Southwest China
Authors: Li Xianglan , Liu Shaowen , Xu Ming
Published: March 2020

Subsurface formation temperature in the upper Yangtze area, southwest China, is significant for assessment of hydrocarbon generation and preservation, especially that of shale gas. The upper Yangtze area, with well-developed marine carbonate rocks, is one of the important preferred areas of shale gas exploration and development in China. Previous studies have analyzed the accumulation mechanism, development characteristics, hydrocarbon generation potential and occurrence modes of shale gas. However, the analysis of subsurface formation temperature is rare due to a lack of highly accurate temperature data. Here we combined new steady-state temperature logging data, drill-stem test temperature data and measured rock thermal properties, to investigate the geothermal regime and to estimate the formation temperature at specific depths in the range 1000~6000 m in this area.

Our results show that the present-day geothermal gradient for this area ranges from 10 to 74℃/km, with a mean of 24℃/km; While the heat flow varies from 27 to 118mW/m2, with a mean of 64mW/m2, indicating a moderate-high geothermal regime. Formation temperature at the depth of 1000 m is estimated to be between 26 °C and 71°C, with a mean of 40°C; the temperature at 2000 m ranges from 36~125°C with an average of 64°C; 45~180°C is for that at the depth of 3000 m, and the mean is 88°C; the temperature at 4000 m varies from 88 to 235°C, with a mean of 112°C; 65~290°C is for that at 5000 m depth, with a mean of 136°C; 75~344°C is for that at the depth of 6000 and the mean is 160°C. Generally, the pattern of the estimated subsurface temperatures in different depths is similar and has an obvious sub-area characterization, showing a trend of gradually increasing of temperature from northeast to southwest area. Most areas in the south and southeast of Sichuan Basin are with moderate temperature area, which maybe is the “sweet spot area” for shale gas exploration.
PMIP-carbon: towards a multi-models comparison of climate-carbon interactions at the Last Glacial Maximum
Authors: Bouttes Nathaelle , Ivanovic Ruza , Abe-Ouchi Ayako , Kobayashi Hidetaka , Menviel Laurie , Oka Akira , Yamamoto Akitomo ,   PMIP-carbon members
Published: March 2020

More and more climate models now include the carbon cycle, but multi-models studies of climate-carbon simulations within the Climate Model Intercomparison Project (CMIP) are limited to present and future time periods. In addition, the carbon cycle is not considered in the simulations of past periods analysed within the Paleoclimate Modelling Intercomparison Project (PMIP). Yet, climate-carbon interactions are crucial to anticipate future atmospheric CO2 concentrations and their impact on climate. Such interactions can change depending on the background climate, it is thus necessary to compare model results among themselves and to data for past periods with different climates such as the Last Glacial Maximum (LGM).

The Last Glacial Maximum, around 21,000 years ago, was about 4°C colder than the pre-industrial, and associated with large ice sheets on the American and Eurasian continents. It is one of the best documented periods thanks to numerous paleoclimate archives such as marine sediment cores and ice cores. Despite this period having been studied for years, no consensus on the causes of the lower atmospheric CO2 concentration at the time (around 180 ppm) has been reached and models still struggle to simulate these low CO2 values. The ocean, which contains around 40 times more carbon than the atmosphere, likely plays a key role, but models tend to simulate ocean circulation changes in disagreement with proxy data, such as carbon isotopes.

This new project aims at comparing, for the first time, the carbon cycle representation at the Last Glacial Maximum from general circulation models and intermediate complexity models. We will explain the protocol and present first results in terms of carbon storage in the main reservoirs (atmosphere, land and ocean) and their link to key climate variables such as temperature, sea ice and ocean circulation. The use of coupled climate-carbon models will not only allow to compare changes in the carbon cycle in models and analyse their causes, but it will also enable us to better compare to indirect data related to the carbon cycle such as carbon isotopes.
Two Paleoproterozoic metamorphic events in the Zhujiafang ductile shear zone of the Hengshan Complex: Insights into the tectonic evolution of the North China Craton
Authors: Qian Jiahui
Published: March 2020

Ductile shear zones usually record mineralogical and isotopic changes that are not apparent in the surrounding host rocks and thus may preserve a complete evolutionary record in a single locale from relatively undeformed to highly deformed rocks. The Zhujiafang ductile shear zone is situated in the central Hengshan Complex, a key area for understanding the Paleoproterozoic tectonic evolution of the Trans-North China Orogen, North China Craton. Detailed metamorphic and geochronological analyses were carried out on metapelite and garnet amphibolite from the Zhujiafang ductile shear zone. The metapelite preserves two phases of mineral assemblages: early kyanite-rutile-bearing assemblage and late chlorite-staurolite-bearing assemblage in garnet–mica schist, and inclusion-type muscovite (high-Si) + kyanite assemblage and late sillimanite-bearing assemblage in sillimanite–mica gneiss. Garnet in the metapelite occasionally exhibits pronounced two-stage zoning characteristic of a diffusion core with irregular pyrope (Xpy) and grossular (Xgr) contents and a growth rim with Xpy and Xgr increasing outwards. The isopleths of the maximum Xgr in garnet core and Si content in inclusion-type muscovite in the P–T pseudosections suggest that the early mineral assemblages underwent medium-high-pressure type metamorphism with pressures up to 12–14 kbar at 700–750 °C. The late assemblages and the growth zoning of garnet rim predict a late separated clockwise P–T path with peak conditions of 6.5 ± 0.2 kbar/620 ± 10 °C (medium-low-pressure type). The garnet amphibolite is mainly composed of garnet, hornblende, plagioclase, ilmenite and quartz, without overprinting of late mineral assemblages except for localized corona textures. Phase modeling suggests that the rock has experienced high-amphibolite facies metamorphism with peak conditions of 10.5 ± 0.8 kbar/770 ± 50 °C, which is broadly consistent with the early-phase metamorphism of metapelite. Zircon U–Pb dating on metapelite yields two metamorphic age groups of 1.96–1.92 Ga and 1.87–1.86 Ga which are interpreted to represent the timing of the two separated phases of metamorphism. Two separated orogenic events may have occurred respectively at ~1.95 Ga and ~1.85 Ga in the Hengshan–Wutai area. The older orogeny was resulted from continental collision and the younger one may be caused by within-plate deformation. The final exhumation of the high-grade rocks formed in the older (i.e. 1.95 Ga) orogeny should be related with the younger deformation/metamorphic event. For more details, please refer to https://doi.org/10.1016/j.lithos.2019.02.001.
A Multi-Objective Framework for Agricultural Production and Water Use in California’s Greater Kern Region under Groundwater Sustainability Regulations
Authors: Medellin-Azuara Josue , Escriva-Bou Alvar , Rodriguez-Flores Jose , Valero-Fandino Jorge , Cole Spencer
Published: March 2020

Groundwater is a major source for irrigated agriculture yet often managed unsustainably. Groundater overdraft compromises future viability of irrigated agriculture, water for cities, streams baseflows and groundwater dependent ecosystems. The recent 2012-2016 California drought heightened the role of groundwater as a buffer resource and catalyzed the 2014 Sustainable Groundwater Management Act (SGMA). Under this regulation, by 2040 all groundwater basins need to achieve balance in recharge and extractions. Groundwater overdraft in California’s Central Valley accounts for roughly 15 percent of the total agricultural use. The greater Kern region within California’s Central Valley, the most productive region for fruits, nuts and vegetables in the USA, suffers from chronic overdraft and demand hardening due to a rapid increase in perennial crops. This paper presents an integrated multi-objective framework to analyze agricultural production in the greater Kern region as it achieves groundwater sustainability at the irrigation district level by 2040. The model employs a programing model approach with a selection of open access components to predict cropping decisions that maximize net economic returns, using a 1997-2015 calibration period. The agricultural production model bundles with a groundwater module based on the Integrated Water Model Flow model (IWFM) from the California Department of Water Resources to meet sustainability objectives.  Modeling scenarios include SGMA groundwater restrictions, water shortages under climate change and environmental regulations, with and without markets, managed aquifer recharge and infrastructure enhancements. Results show that more flexible water allocations using markets and managed recharge can help mitigate the economic impacts from SGMA and also improve prospects for managing financial risk under economic uncertainty at the irrigation district level.
The First Observation of HOx radicals in the Chengyu Urban Agglomeration
Authors: Yang Xinping , Lu Keding , Ma Xuefei , Zhang Yuanhang
Published: March 2020

A comprehensive field campaign was carried out in summer 2019 in Chengdu, which obtained the first complete radical dataset of Chengyu Urban Agglomeration. Observed daily concentration maxima of radicals by the laser-induced-fluorescence (LIF) technique were in the range of (2-10)×106 cm-3 for OH and (4-15)×108 cm-3 for HO2. During daytime, OH reactivities were generally high (5-32 s-1). The missing reactivity was not be observed within uncertainty, and inorganics, observed VOCs and the calculated oxidation products contributed about one-third in total reactivity, respectively.

The chemical box model RACM 2 was used to interpret the observed radical concentrations. The model over-predicted OH and HO2 at noon during the O3 polluted episode. Constraining the model by the observed HO2 concentration, the overestimation of OH can be explained almost by the overestimation of HO2. Besides, as in the previous field campaigns (e.g. Pennsylvania, Mexico City, New York and so on), the underestimation of the net conversion of OH into HO2 enlarged with the increasing NO concentration, indicating the conversion of HO2 into OH still need to be studied based on the discussion above. Different schemes to improve the agreement between observed and modelled HO2 were explored in this work. The sensitivity tests indicated observed and modelled HO2 can be agreed well by reducing the HO2 yield in the reaction of OH and HCHO a half.

The oxidation rate of primary pollutants dominated by OH radicals was significantly higher than that in winter Beijing, which contributes significantly to secondary pollution, especially O3. Besides, the atmospheric self-cleaning ability and recycling efficiency both peaked for about 600 pptv of NO, indicating small amounts of NO can help to maintain the atmospheric oxidation. The campaign emphasizes the important role of HO2 yield in the reaction channels of OH and VOCs especially, and the need for further laboratory experiments of the HO2 yield measurement in order to understand radical chemistry in VOC-rich air.
Post-disintegration evolution of the largest Larsen B tributary glaciers
Authors: Scambos Ted , Bohlander Jennifer , Alley Karen
Published: March 2020

Crane and Hektoria glaciers, the major tributaries of the former Larsen B Ice Shelf, underwent major structural and ice flow changes in the aftermath of the ice shelf’s disintegration in March, 2002. In addition to the widely reported initial acceleration (leading to speeds 3 to 6 times the pre-disintegration rate), the continued retreat led to the formation of significant ice cliffs. For Hektoria, this occurred as a seamless transition from ice shelf disintegration. Crane Glacier had a two-stage acceleration, first increasing in speed by 3x in the first few months after disintegration, then slowing through September 2004, and then a rapid additional acceleration in 2005-2006. Both glaciers developed significant ice cliffs during retreat, with peak ice-front heights of 105 m for Crane and 85 m for Hektoria.
The codependence of contributors to regional sea-level rise
Authors: Lambert Erwin , Le Bars Dewi , van de Wal Roderik
Published: March 2020

Science-based policy for coastal protection requires accurate estimates of the uncertainty in regional sea-level rise. These estimates are strongly influenced by the codependence of individual contributors: thermosteric expansion, ocean dynamics, and mass loss from glaciers and ice sheets. In this study, we use model output and parameterisations to quantify the projected total sea-level rise from a set of 15 Earth System Models from the Coupled Model Intercomparison Project (CMIP) 5. We use these model-based estimates of total sea-level rise to quantify the codependence of individual contributors, determined by the full climate response. We find that assumptions on codependence made in recent reports of the Intergovernmental Panel on Climate Change (IPCC) lead to an overestimation in the uncertainty in regional sea-level rise by 20 to 60%. We further conclude that global mean surface temperature rise is a poor indicator for the inter-model difference in regional sea-level rise as it does not account for inter-model differences in atmospheric and oceanic heat distribution and precipitation patterns. The codependencies derived in this study are suitable for application to new projections, allowing for accurate and consistent estimates of the uncertainty in global and regional sea-level rise.
Space education through classroom projects – Mission Mars
Authors: Suresh Indukumari
Published: March 2020

I teach Physics and Mathematics to the students of age group 14 to 16.

Space education projects by students are an important activity of science education in our school. We have around thirty Teacher liaisons with Space foundation and eight Honeywell Space educators.  In 2018 Space foundation invited our school to join a project on Mars. Below are some of the activities accomplished under this project.

Students were divided into four groups: Engineering, Geology, Water and Life. Each group had a mission to accomplish. I was in charge of the engineering group.

Engineering group had to design one simple and one complex rover. They built balloon rovers with simple materials like balloon, straw, bottle caps etc. The speed and distance covered by the rover could be measured.

The complex rover was a marvel. The rover had sensors and was programmed to video record and capture images. It could drill and collect surface material in containers. It could also move over rough terrain and climb small obstacles.

Geology group compared the composition of rocks collected from Ladakh in India with those on Mars. Interestingly, a lot of similarities were detected. Both on Mars and in Ladakh the rocks were found igneous in nature. This could be a result of volcanic activity in these areas. Rocks contain abundance of sulphur and phosphorus. They are slightly acidic in nature. The physical features are also similar. Not only the rocks but also the soil is rich in iron. The rocks are regolith. This means they are heterogeneous; deposits of loose material cover the rocks. This is also similar to that of moon as well as several other asteroids

Water group explored methods to locate water in planets and worked on ways to purify water.The students researched the simple technique of water purification and built prototype of a water filter.

Life group were tasked with searching for bio-signatures in the soil, in the water, and in the atmosphere of Mars. They learned to identify simple and complex cellular organisms using a foldscope. After carrying out studies they concluded that the life can exist only in lava tubes in Mars. They constructed model of a habitat shelter for Mars surface. They followed the preparation of an astronaut for space mission.  

Through these projects, all have gained a lot of information about space science.
Coupling between Thermo-Hydro-Chemical reactive transport and Gibbs minimisation: magma evolution in evolving multiphase porous media
Authors: Bessat Annelore , Pilet Sébastien , Schmalholz Stefan M. , Podladchikov Yuri
Published: March 2020

The formation of alkaline magmas observed worldwide requires that low degree-melts, potentially formed in the asthenosphere, were able to cross the overlying lithosphere. Fracturing in the upper, brittle part of the lithosphere may help to extract this melt to the surface. However, the mechanism of extraction in the lower, ductile part of the lithosphere is still contentious. Metasomatic enrichment of the lithospheric mantle demonstrates that such low-degree melts interact with the lithosphere, but the physical aspect of this process remains unclear. The aim of this study is to better understand the percolation of magma in a porous viscous medium at pressure (P) and temperature (T) conditions relevant for the base of the lithosphere. We study such melt percolation numerically with a Thermo-Hydro-Chemical model of reactive transport coupled with thermodynamic data obtained via Gibbs energy minimisation. We perform Gibbs energy minimisation with Matlab using the linprog algorithm. We start with a simple ternary system of Forsterite/Fayalite/Enstatite solids and melts. All variables are a function of T, P and composition of the system (C), and are computed in both the Gibbs energy minimisation and in the reactive transport code, and can therefore vary freely.
Footprints of Tropical Cyclones in WNP Summer Monsoon Variability
Authors: Hsu Huang-Hsiung
Published: March 2020

Tropical cyclones (TCs) in the western North Pacific (WNP) are modulated by large-scale circulation systems such monsoon trough, intraseasonal oscillation, teleconnection pattern, El Niño and Southern Oscillation, and some interdecadal oscillations. While the low-frequency, large-scale circulation produces a clustering effect on TCs, the latter in return leave marked footprints in climate mean state and variability because of large amplitudes in circulation and strong heating. In this study, we applied PV inversion technique to remove TCs from reanalysis and evaluate their contribution to mean circulation and climate variability. It is found that the mean climatological circulation (e.g., low-level monsoon trough and upper-tropospheric anticyclone) would be much weaker with TCs removed. Intraseasonal and interannual variance of certain variables could decrease by as much as 40–50 percent. An accompanied study indicated that TCs had slowed down the sea surface warming in the WNP for the past few decades because of TC-induced cooling. Our results suggest that TC effect has to be considered to understand the climate variability in the tropical atmosphere and ocean. The ensemble effect of TCs, at least in the statistical sense, has to be resolved in climate models to better simulate climate variability and produce more reliable climate projection in the TC-prone regions.
Global cooling linked to increased glacial carbon storage via changes in Antarctic sea ice
Authors: Marzocchi Alice , Jansen Malte
Published: March 2020

Palaeo-oceanographic reconstructions indicate that the distribution of global ocean water masses has undergone major glacial–interglacial rearrangements over the past ~2.5 million years. Given that the ocean is the largest carbon reservoir, such circulation changes were probably key in driving the variations in atmospheric CO2 concentrations observed in the ice-core record. However, we still lack a mechanistic understanding of the ocean’s role in regulating CO2 on these timescales. Here, we show that glacial ocean–sea ice numerical simulations with a single-basin general circulation model, forced solely by atmospheric cooling, can predict ocean circulation patterns associated with increased atmospheric carbon sequestration in the deep ocean. Under such conditions, Antarctic bottom water becomes more isolated from the sea surface as a result of two connected factors: reduced air–sea gas exchange under sea ice around Antarctica and weaker mixing with North Atlantic Deep Water due to a shallower interface between southern- and northern-sourced water masses. These physical changes alone are sufficient to explain ~40 ppm atmospheric CO2 drawdown—about half of the glacial–interglacial variation. Our results highlight that atmospheric cooling could have directly caused the reorganization of deep ocean water masses and, thus, glacial CO2 drawdown. This provides an important step towards a consistent picture of glacial climates.
Evolutionary cooperation in transboundary river basins
Authors: Yu Yang , Tang Pngzhong , Zhao Jianshi , Liu Bo , Mclaughlin Dennis
Published: March 2020

Cooperation in transboundary river basins can make water resources systems more efficient and benefit riparian stakeholders. However, in a basin with upstream and downstream stakeholders that have different interests, non-cooperative outcomes have often been observed. These can be described by a one shot prisoners’ dilemma game where non-cooperation (defection) is a dominant equilibrium strategy. However, cooperative outcomes have also been observed in several transboundary settings, such as the Lancang-Mekong River Basin (LMRB) in Asia. Such cooperation motivates our research effort to refine relevant game theoretic descriptions to account for the evolution of players’ behaviors, from conflict to cooperation. In this study, a repeated game model is proposed to analyze evolutionary transboundary cooperation. A generalized evolutionary cooperation pattern with four stages is summarized, starting with non-cooperation and ending with in-depth cooperation. The LMRB and three other typical transboundary river management case studies are chosen to validate our theoretical findings. Upstream and downstream stakeholder behaviors are analyzed for these case studies, in accordance with a game payoff matrix that accounts for incentives to cooperate. The results indicate that patience and incremental benefits can lead stakeholders to adopt a cooperative equilibrium strategy if appropriate institutional mechanisms are in place. Such mechanisms can be developed through negotiations that recognize the wide range of stakeholder interests that may influence the decision to cooperate. Our analysis suggests that game theory can provide useful insights into the conditions and institutional mechanisms that foster cooperative strategies for managing transboundary water resources.
A public-private collaboration initiative for innovative Earth Observation (EO) technologies and methodologies for investigating climate change impacts by means of an inter-disciplinary approach: the OT4CLIMA project
Authors: Pergola Nicola , Serio Carmine , Ripullone Francesco , Marchese Francesco , Naviglio Giuseppe , Tizzani Pietro , Donvito Angelo ,   OT4CLIMA Team
Published: March 2020

The OT4CLIMA project, funded by the Italian Ministry of Education, University and Research, within the PON 2014-2020 Industrial Research program, “Aerospace” thematic domain, aims at developing advanced Earth Observation (EO) technologies and methodologies for improving our capability to better understand the effects of Climate Change (CC) and our capability to mitigate them at the regional and sub-regional scale. Both medium-to-long term impacts (e.g. vegetation stress, drought) and extreme events with rapid dynamics (e.g. intense meteorological phenomena, fires) will be investigated, trying a twofold (i.e. interesting both “products” and “processes”) technological innovation: a) through the design and the implementation of advanced sensors to be mounted on multiplatform EO systems; b) through the development of advanced methodologies for EO data analysis, interpretation, integration and fusion.

Activities will focus on two of the major natural processes strictly related to Climate Change, namely the Carbon and Water Cycles by using an inter-disciplinary approach.

As an example, the project will make it possible the measurements, with an unprecedented accuracy of atmospheric (e.g. OCS, carbon-sulphide) and surface (e.g. soil moisture) parameters that are crucial in determining the vegetation contribution to the CO2 balance, suggesting at the same time solutions based on the analysis and integration of satellite, airborne and unmanned data, in order to significantly improve the capability of local communities to face the short- and long-term CC-related effects.

OT4CLIMA benefits from a strong scientific expertise (14 CNR institutes, ASI, INGV, CIRA, 3 Universities), considerable research infrastructures and a wide industrial partnership (including both big national players, i.e. E-Geos and IDS companies and well-established italian SMEs consortia, i.e. CREATEC, CORISTA and SIIT, and a spin-off company, Survey Lab) specifically focused on the technological innovation frontier.

This contribution would summarize the project main objectives and show some activities so far carried out.
Anthropogenic lithium in river and tap water
Authors: Ryu Jong-Sik , Choi Hye-Bin , Shin Woo-Jin , Vigier Nathalie
Published: March 2020

During the last two decades, the use of lithium (Li) has dramatically increased due to the proliferation of mobile electronic devices and the diversification of electric-powered vehicles. While Li can exert a toxic effect on living organisms and human beings, few studies have investigated the impact of anthropogenic inputs on Li content in the environment. Here we report Li concentrations and Li isotope compositions of river, waste and tap water, and industrial products from the metropolitan city of Seoul. Results show that the large increase in population density in Seoul is accompanied by a large enrichment in riverine Li content and that Li isotopes evidence a major release from Li-rich industrial products. Water treatment protocols are also shown to be inefficient for Li. Our study therefore highlights the need for a global Li survey and adequate solutions for minimizing their impact on ecosystems and city dwellers.
Global Snow Cover Extent Mapping Using Sentinel-1
Authors: Tsai Ya-Lun , Uereyen Soner , Dietz Andreas , Kuenzer Claudia , Oppelt Natascha
Published: March 2020

Seasonal snow cover extent (SCE) is a critical component not only for the global radiation balance and climatic behavior but also for water availability of mountainous and arid regions, vegetation growth, permafrost, and winter tourism. However, due to the effects of the global warming, SCE has been observed to behave in much more irregular and extreme patterns in both temporal and spatial aspects. Therefore, a continuous SCE monitoring strategy is necessary to understand the effect of climate change on the cryosphere and to assess the corresponding impacts on human society and the environment. Nevertheless, although conventional optical sensor-based sensing approaches are mature, they suffer from cloud coverage and illumination dependency. Consequently, spaceborne Synthetic Aperture Radar (SAR) provides a pragmatic solution for achieving all-weather and day-and-night monitoring at low cost, especially after the launch of the Sentinel-1 constellation. 

In the present study, we propose a new global SCE mapping approach, which utilizes dual-polarization intensity-composed bands, polarimetric H/A/α decomposition information, topographical factors, and a land cover layer to detect the SCE. By including not only amplitude but also phase information, we overcome the limitations of previous studies, which can only map wet SCE. Additionally, a layer containing the misclassification probability is provided as well for measuring the uncertainty. Based on the validation with in-situ stations and optical imagery, around 85% accuracy of the classification is ensured. Consequently, by implementing the proposed method globally, we can provide a novel way to map high resolution (20 m) and cloud-free SCE even under cloud covered/night conditions. Preparations to combine this product with the optical-based DLR Global SnowPack are already ongoing, offering the opportunity to provide a daily snow mapping service in the near future which is totally independent from clouds or polar darkness.
Plant root exerted a stronger positive effect on aggregate stability than soil during plant secondary succession on the Loess Plateau, China
Authors: xiao lie , Li Peng
Published: March 2020

The stability of soil aggregates is an indicator of restoration of soil in degraded ecosystems. A multitude of factors such as properties of plant roots and soil have been suggested to contribute to aggregate stability, but little information is available on the relative importance of these factors in temperate grass zones. We examined how root and soil properties modified aggregate stability along a gradient of secondary succession grassland on the Loess Plateau in China. We selected three cropland abandoned for 3, 10, and 16-year and measured the distribution of aggregates, mean weight diameter (MWD), bulk and aggregate-associated soil organic carbon (SOC) and glomalin-related soil protein (GRSP) contents, root biomass density, root length density, and specific root length (SRL). Compared with 3-year site, the amount of large macroaggregates (>2 mm) and aggregate stability (indicated by MWD) at 16-year site increased by 25.6% and 8.5%. The higher MWD contributed the most to the accumulation of SOC in large and small macroaggregates and to the accumulation of GRSPs in microaggregates (<0.25 mm). SRL was significantly positively correlated with MWD. Redundancy analysis (RDA) showed that soil and plant variables together explained 89.1% of the aggregate distribution variation. Partial RDA further revealed that soil variables solely explained 6.4% of the variation, plant root variables explained 47.9% of the variation, and interaction of soil and plant variables accounted for 34.8% of the variation. Our study indicated that increased soil aggregate stability during plant secondary succession depended on both plant roots and aggregate-associated SOC and GRSPs, and plant root exerted a stronger influence on soil aggregate stability than soil. Allowing secondary succession may be a promising strategy for restoring degraded ecosystems on the plateau.
Topographic forcing from East Asia and North America in the northern winter stratosphere and their mutual interference
Authors: Ren Rongcai , Xia Xin , Rao Jian
Published: March 2020

This study uses the stratosphere-resolved Whole Atmosphere Community Climate Model to demonstrate the “independent” and “dependent” topographic forcing from the topography of East Asia (EA) and North American (NA), and their “joint” forcing in the northern winter stratosphere. The mutual interference between the EA and NA forcing is also demonstrated. Specifically, without EA, an independent NA can also, like EA, induce a severe polar warming and weakening of the stratospheric polar vortex. While EA favors a displacement of the polar vortex toward Eurasia, NA favors a displacement toward the North America–Atlantic region. However, the independent-EA-forced weakening effect on the polar vortex can be largely decreased and changes to a location displacement when NA exists, and the interference the other way around is even more critical, being able to completely offset the independent-NA-forced effect, because EA can substantively obstruct NA’s effect on the tropospheric wave pattern over the Eurasia–Pacific region. The much stronger/weaker interference of EA/NA is associated with its stronger/weaker downstream weakening effect on the zonal flow that impinges on NA/EA. The mutual interference always tends to further destruct the upward wave fluxes over the eastern North Pacific and enhance the downward wave fluxes over NA. The overall changes in upward wave fluxes, as well as that in the Rossby stationary wavenumber responsible for the stratospheric changes, are related to changes in the zonal-mean flow pattern. The joint effects of EA and NA, rather than being a linear superimposition of their independent effects, are largely dominated by the effects of EA.
GeoEra HOVER WP7 – Harmonized vulnerability to pollution mapping of the upper aquifer
Authors: Günther Andreas , Broda Stefan , Duscher Klaus , Reichling Jörg , Schomburgk Susanne , Elster Daniel , Bimalyuk Boris , Cerar Sonja , Hansen Birgitte , Hickey Caoimhe , Ikonen Juuso , Herms Ignasi , Kontodimos Kostas , Velázquez David Pulido , Persa Diana , Janetz Silvio , Witthoeft Melanie , Arustiene Jurga , Gal Nora , Nidental Magdalena ,   GEOERA HOVER WP7 TEAM
Published: March 2020

45 Geological Survey Organisations (GSOs) from 32 European countries developed an ERA-NET Co-Fund Action: Establishing the European Geological Surveys Research Area to deliver a Geological Service for Europe (GeoERA). The GeoEra project HOVER (Hydrogeological processes and Geological settings over Europe controlling dissolved geogenic and anthropogenic elements in groundwater of relevance to human health and the status of dependent ecosystems) aims to gain understanding of the controls on groundwater quality across Europe using the combined expertise and data held by member states. Objectives of the HOVER work package 7 (WP7) are i) review of existing index methods for assessing the vulnerability of the upper aquifer to pollution and selection of the methods to be applied at the pilot and pan-EU scale, ii) compilation and harmonization of input data sets required for assessing vulnerability, and iii) assessment of aquifer vulnerability to pollution (both in maps and 2-d schematic cross sections).

The selected methodology adopted in this project is DRASTIC, which will be applied in ten pilot areas and at the pan-European scale. In karst regions, however, the COP method will be applied in the pilots. This is accompanied with comparisons with the outcomes of existing national vulnerability assessments. It is anticipated to validate the resulting vulnerability maps at the pilot level using available groundwater nitrate contamination information.
Effects of plant diversity on soil carbon in diverse ecosystems: a global meta-analysis
Authors: Chen Han
Published: March 2020

Soil organic carbon (SOC) is a valuable resource for mediating global climate change and securing food production. Despite an alarming rate of global plant diversity loss, uncertainties concerning the effects of plant diversity on SOC remain, because plant diversity not only stimulates litter inputs via increased productivity, thus enhancing SOC, but also stimulates microbial respiration, thus reducing SOC. By analysing 1001 paired observations of plant mixtures and corresponding monocultures from 121 publications, we show that both SOC content and stock are on average 5 and 8% higher in species mixtures than in monocultures. These positive mixture effects increase over time and are more pronounced in deeper soils. Microbial biomass carbon, an indicator of SOC release and formation, also increases, but the proportion of microbial biomass carbon in SOC is lower in mixtures. Moreover, these species‐mixture effects are consistent across forest, grassland, and cropland systems and are independent of background climates. Our results indicate that converting 50% of global forests from mixtures to monocultures would release an average of 2.70 Pg C from soil annually over a period of 20 years: about 30% of global annual fossil‐fuel emissions. Our study highlights the importance of plant diversity preservation for the maintenance of soil carbon sequestration in discussions of global climate change policy.
Vegetation-Climate-Water coupling in a changing environment
Authors: Liu Zhiyong
Published: March 2020

The directionality of the response of gross primary productivity (GPP) to climate has been shown to vary across the globe. This effect has been hypothesized to be the result of the interaction between multiple bioclimatic factors, including environmental energy (i.e. temperature and radiation) and water availability. This is due to the tight coupling between water and carbon cycling in plants and the fact that temperature often drives plant water demand. Using GPP data extracted from 188 sites of FLUXNET2015 and observation-driven terrestrial biosphere models (TBMs), we disentangled the confounding effects of temperature, precipitation and carbon dioxide on GPP, and examined their long-term effects on productivity across the globe. Based on the FLUXNET2015 data, we observed a decline in the positive effect of temperature on GPP, while the positive effects of precipitation and CO2 were becoming stronger during 2000–2014. Using data derived from TBMs between 1980 and 2010 we found similar effects globally. The modeled data allowed us to investigate these effects more thoroughly over space and time. In arid regions, the modeled response to precipitation increased since 1950, approximately 30 years earlier than in humid regions. We further observed the negative effects of summer temperature on GPP in arid regions, suggesting greater aridity stress on productivity under global warming. Our results imply that aridity stress, triggered by rising temperatures, has reduced the positive influence of temperature on GPP, while increased precipitation and elevated CO2 may alleviate negative aridity impacts.