bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal variability of greenhouse gas and reactive gas emission factors during a two-week-long tropical peatland experimental burn
Authors: Hu Yuqi , Smith Thomas E L , Santoso Muhammad Agung , Amin Hafiz Muhammad Fahid , Christensen Eirik G , Cui Wuquan , Purnomo Dwi Marhaendro Jati , Palamba Pither , Nugroho Yulianto Sulistyo , Rein Guillermo
Published: March 2020

Smoke from peatland wildfires contributes significantly to global greenhouse gas (GHG) emissions, while reactive gases and particulates cause transboundary haze episodes. Haze is the large-scale accumulation of smoke at low altitudes, especially frequent in Southeast Asia during dry periods. Understanding emissions from peatland fires plays a vital role in calculating GHG budgets, forecasting haze events and modelling future climate change. However, only a handful of field studies or laboratory experiments on tropical peat fire smoke have been undertaken to date. Of the few studies that have investigated tropical peatland fire emissions, there exists substantial inter-study variabilities of emission factors (EFs) with some gas emission factors varying by a factor of 10 between studies. Explaining the nature of such variability remains a challenge. In August/September 2018 in Riau, Indonesia, we carried out the first field-scale experimental burn on a tropical peatland (the GAMBUT Workshop), aiming to understand how fires ignite, how they spread, and how emissions vary across the life-cycle of a peatland fire. Our site was a heavily degraded tropical peatland subjected to long-term drainage, logging, and agricultural conversion. Here we present the field measurements of gas emissions from the fire experiment. Open-path Fourier transform infrared spectroscopy (OP-FTIR) was used to retrieve mole fractions of 13 gas species. EFs from 40 measurement sessions over two weeks of burning during different fire stages (e.g., slash and burn ignition, smouldering spread or suppression) and weather events (e.g., wind or rainfall) were calculated and reported. We present field evidence to indicate that EFs vary significantly among fire stages and weather events. Heterogenous physicochemical properties of our peatland site (e.g. moisture content, inorganic content and bulk density) were also found to affect the EFs. We discuss the implications for air quality forecasting, suggesting the necessity for more complex mapping of peatland heterogeneity/land-use for emissions inventories and temporally variable emissions factors, depending on the time since the initiation of a fire event.
Emergence of the projected trends in the tropical oceans from background climate noise in CMIP5 simulations
Authors: Suresh Gopika , Suresh Iyyappan , Izumo Takeshi , Vialard Jerome , Lengaigne Matthieu
Published: March 2020

Anthropogenic forcing induces a Sea Surface Temperature (SST) warming and sea level rise. While these globally-averaged signals are clearly detectable, it is more difficult to detect regional deviations from these global trends, due to the strong aliasing by internal climate variability. Yet, changes in SST gradients are thought to influence the frequency of extreme IOD events and the impacts of extreme ENSO events, while regional sea level and rainfall changes have strong societal implications. Here, we investigate if such regional signals are already detectable in the tropics.

To that end, we apply the “emergence time” concept (i.e. when the climate change signal irreversibly emerges from the background climate “noise”) on historical simulations combined with RCP8.5 projections from the Coupled Model Intercomparison Project (CMIP5). By 2100, CMIP5 projections indicate a warming in relative SST (RSST), i.e. the SST change relative to its tropical mean, in the equatorial Atlantic, equatorial Pacific and Arabian Sea, and a RSST cooling (i.e. weaker warming than the tropical average) in the three subtropical gyres of the southern hemisphere. These models also project positive signals in relative Sea Level Anomalies (RSLA) in the Arabian Sea, 10°N-20°N band in the Pacific, and Benguela upwelling, and negative ones in the central Pacific, south-eastern Pacific and Indian Oceans. Rainfall increases over the equatorial Pacific and India, and decreases over Central America, the southern tropical Pacific and Atlantic. We define a regional trend as detectable when it emerges in more than 80% of the models in the CMIP5 database. With this choice, none of the RSST, RSLA and precipitation signals mentioned above are currently detectable in CMIP5. In the coming decade, the RSST warming in the Arabian Sea, cooling in the southeastern Pacific Ocean and rainfall reduction over central America become detectable, according to CMIP5. The equatorial Atlantic relative warming, Arabian Sea RSLA rise and equatorial Pacific precipitation increase would emerge before 2050. The equatorial Pacific RSST warming, southeastern Indian Ocean RSST cooling, and monsoon rainfall increase over India also become detectable before 2100. Our estimates of the emergence time could help planning a targeted observational strategy in regions, where CMIP5 indicate strong trends, and thus to verify CMIP5 projections in those regions.
Mineral sources of magnetic anomalies: Insights from scanning magnetic microscopy
Authors: McEnroe Suzanne , Pastore Zeudia , Church Nathan , Langenhorst Falko , Oda Hirokuni
Published: March 2020

Development in instrumentation and technology now allows for mapping of magnetic anomalies, caused by spatial variations in magnetization in the source materials, over a wide range of scales, from the millimeter mineral scale to the km crustal scale.

Traditional rock magnetic methods, used to investigate the magnetization in natural rock samples, are bulk measurements, which cannot be directly correlated to the individual mineral phases, or particles.  Scanning magnetic microscopy is a high-resolution mapping technique that allows for detailed investigation of the magnetization in natural rock samples. The technique generates a map of the magnetic field distribution over a planar surface of a rock sample with sub-millimeter resolution that can be used to correlate specific magnetic signals to the underlying mineralogy. This information is vital for an understanding of the origin of rock bulk behavior measured in both the laboratory, and in magnetic surveys.

Here we use 3D magnetic modeling to investigate the sources of the magnetic anomalies mapped over a sample thin section. The oxide grains in the thin sections are modeled using information from optical and electron microscopy (SEM and TEM) to constrain the source geometry, and with magnetic property data. The internal geometry of the oxide mineral phases (exsolution lamellae, intergrowths, symplectites) and compositions are constrained by EMP and TEM. 

Magnetic scans aid in locating the magnetic sources, and resolving the different magnetic components contributing to the bulk rock properties.  By modeling the small-scale variations in the oxides the direction and intensity of the magnetic grains are determined.  Aeromagnetic and ground magnetic data from the sample locations are used in conjunction with thin section magnetic mapping. Thin section results can be up-scaled to compare with ground and aeromagnetic data.
Modeling of the power generation from wind turbines with high spatial and temporal resolution
Authors: Lehneis Reinhold , Manske David , Schinkel Björn , Thrän Daniela
Published: March 2020

The share of wind power in the generation of electricity has increased significantly in recent years and, despite its volatility, variable energy from wind turbines has become an essential pillar for the power supply in many countries around the world. To investigate the effects of increasing variable renewables on power grids, the environment or electricity markets, detailed power generation data from wind turbines with high spatial and temporal resolution are often mandatory. The lack of freely accessible feed-in time series, for example due to data protection regulations, makes it necessary to determine the wind power feed-in for a required region and period with the help of numerical simulations. Our contribution demonstrates how such a numerical simulation can be developed using publicly available wind turbine and weather data. Herein, a novel model approach will be presented for the wind-to-power conversion, which utilizes a sixth-order polynomial for the specific power curve of a wind turbine. After such an analytical representation is derived for a certain turbine, its output power can be easily calculated using the wind speed and air temperature at its hub height. For proof of concept and model validation, measured feed-in time-series of a geographically and technically known wind turbine are compared with the simulated time-series at a high temporal resolution of 10 minutes. In order to determine the power generation for larger regions or an entire country the derived numerical simulation is also carried out for an ensemble of almost 26 thousand onshore wind turbines in Germany with a total capacity of about 44 GW. With this ensemble, first simulation results with municipal and hourly resolution can be presented for an annual period.
Bi-temporal Monitoring the Spatial Pattern and Variations of the Surface Urban Heat Island in three Chinese Coastal Megacities: A Comparative Study of Guangzhou, Hangzhou, and Shanghai.
Authors: Liu Fei
Published: March 2020

The side-effect of booming urbanization on the ecosystem and climate system has been continuously exacerbating. The coastal metropolises are located at the interface between land and ocean, unavoidably influenced by multiple aspects of the terrestrial environments, aquatic ecosystems, and urban developments. Thus, the environmental health of coastal metropolis should be more concerned. In this study, targeting Guangzhou, Hangzhou, and Shanghai, an attempt was made to evaluate the spatiotemporal patterns and variations of surface urban heat island (SUHI) in three coastal metropolises of China based on Landsat-derived land surface temperatures (LST) and land cover data. The results indicate that overall, within a nearly 15-year interval, the extents of hot spots in three metropolises were significantly expanded, the spatial patterns of SUHI have been transformed from monocentric to polycentric high-LST clusters, which were identical to the trend of urban expansion. However,  these three metropolises possess distinct features in terms of the thermal layouts and land cover/use composition. Although the total area of SUHI hot spots in Shanghai has surged, the intensity of some hot spots has been a shrink. Besides, the interactions and associations between SUHI and urban development were investigated using spatial regression analysis. The urban composition and configuration considerably affected the intensity of SUHI. Terrain morphology constrained the SUHI. Prolific population growth had a continuing effect on SUHI formation. The proportion of forests displayed a consistently critical influence on easing the adverse of SUHI. Additionally, it is essential to appropriately consider the impacts of water in the comparative analysis of different thermal environments. However, water might be treated as a time-invariant factor and have a limited effect on the bi-temporal comparison for each metropolis. These findings suggest the policy-makers and urban planners should balance and optimize the land cover/use configurations with accommodating the increasing population, reasonably maximize the reservations of the greenbelt and green space under improving the utilization of urban infrastructures and constructions.
Using GIS techniques for automatic mapping of gullies in the Moldavian Plateau, Romania
Authors: Codru Ionut - Costel , Niacsu Lilian
Published: March 2020

Gully erosion represents one of the major environmental problems within the agricultural hilly areas of Moldavian Plateau, Romania. Deforestations, made in the last two centuries, and unsustainable agricultural techniques made the Moldavian Plateau a very susceptible area especially to soil erosion, gullying and landsliding. Beside the human influence that accelerated the process, gully erosion is a natural hazard that occurred from heavy rain falls and water concentrations in catchment areas. The most important natural induced factors that influenced gully head retreat in the Moldavian Plateau are the landform features, favorable lithology, land cover changes under improper human impact on the background of specific climacteric conditions such as heavy rain falls, snow melt and or freeze-thaw phenomenon. The Moldavian Plateau is the area that has one of the biggest densities of gullies in Europe, and, because of its large population of gullies and lack of materials, techniques and time no comprehensive inventory was made. Due to the appearance of high resolution LIDAR images and the evolution of GIS software in recent years, a lot of researchers, from all around the world, tried to identify gullies and quantify them using these modern techniques. For this research, morphometric features (e.g. profile curvature and a 360⁰ hillshading grid with eight points of lightening distributed at a distance of 45 azimuth degrees) derived from LIDAR were used for a more facile mapping of gullies. These morphometric features were classified using different classification method. To evaluate the quality of the results, a shapefile with gully contours had been created by digitizing the banks of the gully. The results of the manually digitized shapefile were confronted with the results of the automatic morphometric features obtained in this research. The combination of hillshading grids that were used in this research covered a very big part of the surfaces occupied by gullies, excepting the gullies affected by landslides that were hardly recognized. Also, the derived profile curvature identified the banks of the gully in a very accurate way.
Global trends of soil organic carbon based on soil moisture and ensemble learning
Authors: Guevara Mario , Vargas Rodrigo
Published: March 2020

The response of SOC spatial variability to different soil moisture conditions has not been explored at the global scale in part due to the lack of continuous information of these variables across large areas of the world. Analyzing this relationship could be useful to reduce the current uncertainty around SOC distribution and change. Large scale models and SOC mapping efforts contrast with country specific SOC maps, and large uncertainties on SOC magnitudes and patterns remain across large areas of the world. Our main objective was to explore SOC trends using soil moisture values as prediction factors. Using SOC point data from the World Soil Information Service (WoSIS, n=87002 point data between the years 1991 and 2015) we applied a cross validation-based ensemble learning approach to generate continuous SOC maps in a quinquennial basis (limited to 0-30 cm depth). The cross validated root mean squared error (RMSE) of our ensemble for the period 1991 -1995 varied from 32 to 33 g/kg while the correlation between modeled and observed data varied from r=0.45 to r=0.55. The accuracy of SOC estimates increased for the period 2011-2015 (r=0.75 to r=0.81 and RMSE= 20 to 23 g/kg). However the lower RMSE (16 to 17 gr/kg) was found for the years 2001-2005 (r=52 to r=58). Trend detection analysis applied to SOC predictions reveal areas showing significant (p-value < 0.05) positive trends across ~2.7 million km2 at the global scale ranging from 0.3 to 29 g/kg. Significant negative trends of SOC were found across ~3.6 million km2 at the global scale ranging from -22.2 to -0.3 g/kg. Main SOC losses were found across North America, Europe, central Africa, and Siberia. Our results quantifying the response of soils to changing soil moisture conditions contribute with new insights that are useful for the development of soil carbon monitoring systems.
Warm Cloud Microphysical Properties and their Associated Raindrop Size Distributions over Northern Taiwan
Authors: Matondang Christin Afrin , Liu Chian-Yi
Published: March 2020

Warm clouds have a huge impact on radiative forcing and also precipitation properties. Knowledge about their raindrop size distribution (RSDs) is useful in realizing rain integral parameter and in the understanding of precipitation microphysics. Unfortunately, as a result of the discontinuity of spatiotemporal observation, obtaining a detailed process that occurs in warm clouds is still challenging. In this study, we try to identify the characteristics of cloud microphysical processes in warm rain formation over Northern Taiwan. The detailed analysis is conducted by using a combination of Joss-Waldvogel Disdrometer (JWD) and Himawari-8 in North Taiwan from December 2017 to January 2018.

The preliminary result shows that different rainfall intensity can build different kinds of RSDs.  In Taiwan winter season, warm rain has a lower concentration of midsize and large raindrops as compared to mixed and cold rain. However, small raindrops are more dominant than middle and large drops for warm rain. It is found that both microphysical properties (Cloud Optical Thickness/COT, Cloud Liquid Water Path/CLWP, and Cloud Effective Radius/CER) and Gamma parameter distribution are varied as the rain rate varied. A lower rain rate (e.g., drizzle) has resulted from a wider range of cloud microphysical properties while a higher rain rate (e.g., stronger rain rate) has resulted from certain ranges of cloud microphysical properties. The Gamma parameter distribution shows more homogenous distribution as the rain rate increase.

 
Paleo-drip rates from trace metal concentrations in stalagmites: An inverse modeling problem with data uncertainties
Authors: Goswami Bedartha , Hartland Adam , Hu Chaoyong , Hoepker Sebastian , Fox Bethany R. S. , Marwan Norbert , Breitenbach Sebastian F. M.
Published: March 2020

The concentration of trace elements such as Ni, Co, and Cu in a stalagmite is determined by (i) the amount of these elements present in so-called organic-metal complexes (OMCs) that trap the ionic forms of such elements in the dripwater, and (ii) the amount that is able to decay from the OMCs into the aqueous phase, from where the elements can adsorb to the growing stalagmite surface (and remain captured within the stalagmite crystal structure). A statistical treatment of the decay of a population of trace element ions from OMCs allow us to model the rates at which the dripwater dropped from the roof of the cave on to the stalagmite’s surface. The problem is however made challenging due to: (i) the lack of reliable monitoring data that quantifies the relationship between OMC trace metal ion concentration and stalagmite trace metal ion concentration, and (ii) the presence of chronological uncertainties in our estimates of trace element concentrations at past time points from the depth-based measurements along the stalagmite. We present here a semi-heuristic, semi-theoretical approach that estimates dripwater rates using a theoretical model based on the population-level chemical kinetics of trace element decay from OMCs, and a heuristic choice of calibration data sets based on precipitation and temperature from nearby weather station data. Our approach is applied to trace metal data from the Heshang Cave in southeastern China, and we are able to reconstruct a driprate proxy time series — a first quantitative hydrological proxy record presented along with well-defined estimates of uncertainty.
Spatiotemporal changes in the hydrological state of temporary streams in a pre-alpine headwater catchment
Authors: Assendelft Rick , van Meerveld Ilja
Published: March 2020

Temporary streams are common in headwater catchments and serve as important ecological and hydrological links between these catchments and downstream perennial rivers. However, our understanding of temporary streams in headwater catchments is limited due to a lack of high spatiotemporal resolution data of the three main hydrological states of these streams: dry streambed, standing water and flowing water. In this study, we used a custom designed multi-sensor monitoring system to collect high spatiotemporal resolution state data of the temporary streams in the 0.12 km2 upper Studibach catchment, a pre-alpine headwater catchment in Alptal, Switzerland. The monitoring system was installed at 30 locations in the stream network. The state data was used to determine: (1) the temporary stream regime for every monitoring location based on the permanence of each hydrological state, (2) the state change thresholds (antecedent soil moisture, precipitation amount and intensity, and discharge at the outlet) for every monitoring location, and (3) the state change patterns in the stream network during precipitation events. The temporary stream regimes, and the state change thresholds and patterns were compared to topographic, land cover and channel characteristics to determine if these factors can explain the variability in temporary stream dynamics. The results show that there are four different landscape areas with distinctive temporary stream dynamics in the catchment, and that a steep forested section with coarse streambed material often disconnects the flowing parts of the upper and lower stream network.
In-depth understanding of component temperatures over sparsely vegetated surfaces
Authors: Li Mingsong , Zhou Ji
Published: March 2020

Ground-based component temperatures are important inputs to model the energy exchange between the heterogeneous land surface and atmosphere. Although some excellent researches have been done, factors affecting the ground-based component temperatures over sparsely vegetated surface are still needed for further understanding. In order to obtain an in-depth understanding of component temperatures, a MUlti-Scale Observation Experiment on land Surface temperature (MUSOES) was designed and performed in a nature oasis with highly heterogeneous vegetated surface in the downstream of Heihe River basin, northwest China. The MUSOES was under the framework of the Heihe Watershed Applied Telemetry Experimental Research (HiWATER). During the intensive observation period, between July 20th and August 20th of 2014, surface temperatures were obtained at two scales around two hydrometeorological observatory stations: the mixed forest station (MFS) and the superstation (SUP). At MFS, six and four component temperatures were identified from the measurements of scale I (scale of thermal infrared (TIR) imagers) and scale II (scale of TIR radiometers), respectively. Due to the dense shrubs and absence of trees at SUP, two component temperatures were identified under each scale. Results show that intrinsic characteristics influence the variability of temperature between components and within a component. For the component temperatures measured by TIR imager, the mean differences between sunlit soil, shrub, and tree canopy were 17.9 K and 7.0 K at MFS; the mean difference between soil and shrub was 17.7 K at SUP. At the direction-level and pixel-level, the components exhibit different internal temperature differences. Furthermore, the component temperatures significantly affected by the illumination condition, viewing direction, and instrument type. Deviation exists between the component temperatures measured by the TIR radiometer and the TIR imager and depends on the components (e.g. 6.7 K for soil and -7.9 K for shrub at SUP). The TIR radiometer faces great challenge to measure the component temperature with good spatial representativeness over highly heterogeneous surface. Findings from this study can benefit our understandings of the attribute and ground observation of component temperatures, and promote the further study of the energy exchange between the heterogeneous land surface and atmosphere.
Observed local drivers of rainfall variability and changes in the Rio Santa Basin, Tropical Andes of Peru
Authors: Klein Cornelia , Gurgiser Wolfgang , Maussion Fabien
Published: March 2020

The climate in the Rio Santa basin (Peruvian Andes) is characterized by a strong seasonality, with a wet season reaching its maximum intensity from December to March. Understanding the characteristics and variability of rainfall during the wet season is fundamental for small-scale farmers based on rain-fed agriculture, and is one of the main objectives of the recently started AgroClim-Huaraz project (http://agroclima-huaraz.info). Based on a combination of rain gauge observations and ERA5 reanalysis data, we demonstrate that the occurrence of local wet and dry spells in the Rio Santa basin is strongly connected to large scale circulation patterns that are known to drive such rainfall variability in the wider tropical Andes. Changes in upper-tropospheric zonal wind and the location of the Bolivian High pressure system therefore crucially affect the local water availability. 

On large spatio-temporal scales, this connection was claimed to have already caused a decrease in precipitation in the Central Andes in response to global warming and could be associated with a projected four-fold increase of dry years by 2100. Consequently, it is of great importance to (i) evaluate the validity of this drying by trend analyses from different sources and (ii) understand the implications of a potential large-scale trend from a local perspective that takes into account the heterogeneity of rainfall distributions in complex terrain. 

We therefore use ERA5 to evaluate whether and how observed changes in this teleconnection affect local atmospheric conditions and convective environments. In addition, we infer associated potential trends in rainfall frequency and extremes, cloud cover and convective intensity for the Rio Santa Basin from CHIRPS rainfall estimates and GRIDSAT brightness temperatures down to a resolution of 4-7km for 1983-2019.

Based on observations, our results illustrate how large-scale climatic changes may translate into smaller scales. This will in further steps not only help to validate and constrain regional dynamical downscaling attempts but also inform about the representativeness of coarser-scale climate projections for local conditions in Andean valleys.

 
PPP or network solution for detection of surface displacements?
Authors: Sumaya Hael
Published: March 2020

Detection of the recent crustal deformation of the Upper Rhine Graben, which is part of the European Cenozoic rift system, is of interest for geoscience researcher. In April 2008 the Geodetic Institute of Karlsruhe Institute of Technology KIT and the Institut de Physique du Globe de Strasbourg (Ecole et Observatoire des Scences de laTerre) established an international joint venture called GURN (GNSS Upper Rhine Graben Network). GRUN network consists now of approximately 100 permanently operating reference stations.

The GPS observations acquired at these sites between 2002 and 2017 have been processed in different methods applying state-of-the art strategies and parameters. The resulting GPS coordinate time series have been analysed in order to extract the surface velocities for horizontal and vertical components. In this research, we will discuss the results by using different strategies of GNSS data reprocessing, PPP comparing to network solution. Advantages and disadvantages between both solutions for this kind of GNSS application, intraplate deformation, will be presented. The velocity of the height component will be also compared with the results of levelling data. One strategy or a combined solution should be selected to detect the detailed information on the present-day intraplate deformation of the Upper Rhine Graben.
End-Member Modeling Analyses (EMMA) of pseudo-Thellier style experiments to derive absolute paleointensities from lavas
Authors: van Grinsven Liz , van Leeuwen Tristan , de Groot Lennart
Published: March 2020

Over the past years several groups have made efforts to calibrate the ‘pseudo-Thellier’ technique to obtain paleointensities from materials that acquired their natural remanent magnetizations thermally, while avoiding heating the samples during the experiments. These calibrations revolve around mapping laboratory induced Anhysteretic Remanent Magnetizations (ARMs) to thermally acquired Natural Remanent Magnetizations (NRMs).

One approach has been to plot pseudo-Thellier slopes against paleointensities that are either known (for very young lavas) or result from different paleointensity techniques. Although the obtained calibration relation is linear and closely follows the data, the relation worryingly misses the origin, i.e. a pseudo-Thellier slope of 0 leads to a paleointensity of up to 14.7 µT. Currently, there is no satisfying explanation for this non-zero axis intercept. Another approach has been to calibrate the mapping between the TRM and ARM by giving (thermally stable) samples a remanent magnetization and force the calibration through the origin. Although to the current state of our knowledge this is theoretically correct, the mismatch between the calibration relation and the data introduced by this approach is evident. So far, neither of these approaches yielded a generically applicable and theoretically acceptable mapping between ARMs and TRMs.

Naturally occurring basalts, however, are assemblages of magnetic minerals differing in grain size, shape, and chemistry. Here we take a new approach to the interpretation of pseudo-Thellier data by trying to find end-members for the ARMs, through nonnegative matrix factorization, that represent these different magnetic minerals in the samples. With the idea that the quantity of these end-members in the different ARMs are related to the original NRMs intensities. We use a set of 580 samples from different volcanic edifices (Hawaii, Mt. Etna, Tenerife, Gran Canaria, and Iceland) that recently cooled in the Earth’s magnetic field, so in known field strengths. The first results that we will present are encouraging and address the current challenges with obtaining absolute paleointensities from lavas with a pseudo-Thellier approach.
Interacting abiotic, biochemical and management factors explain soil organic carbon in Pyrenean grasslands
Authors: Rodríguez Antonio , Canals Rosa Maria , Plaixats Josefina , Albanell Elena , Debouk Haifa , García-Pausas Jordi , San Emeterio Leticia , Jiménez Juan José , Sebastià M.-Teresa
Published: March 2020

Grasslands are one of the major sinks of terrestrial soil organic carbon (SOC). Understanding how environmental and management factors drive SOC is challenging because there are scale-dependent effects, and large scale drivers affecting SOC both directly and through drivers working at fine spatial scales. Here we address how regional and landscape factors, and grazing management, soil properties and nutrients, and herbage quality factors affect SOC in mountain grasslands in the Pyrenees. Taking advantage of the high variety of environmental heterogeneity in the Pyrenees, we fitted a set of models with explicative purposes including variables that comprise a wide range of environmental and management conditions. We found that temperature seasonality (MMT) was the most important abiotic driver of SOC in our study. MMT was positively related to SOC but only under certain conditions: exposed hillsides, steep slopes and relatively highly grazed areas. High MMT conditions probably are more favourable for plant biomass production, but landscape and grazing management factors buffer the conversion of this biomass into SOC. Concerning biochemical SOC predictors, we obtained some unexpected interaction effects between grazer type, soil nutrients and herbage quality. Soil N was a crucial factor modulated by effects of livestock species and neutral-detergent fibre content of vegetation. Herbage recalcitrance effects varied depending on grazer species. These results highlight the need to expand knowledge about grassland SOC drivers under different environmental and management conditions.

 
Using atmospheric in situ mobile measurements to monitor urban methane emissions
Authors: Ars Sebastien , Wunch Debra , Ajmeri Tazeen , Arrowsmith Colin , Beauregard Genevieve , Cruz Rica , Gillespie Lawson , Heerah Sajjan , Knuckey Emily , Lavoie Juliette , Macdonald Cameron , Mostafavi Pak Nasrin , Nguyen Sheryl , Phillips Jaden L. , Vogel Felix
Published: March 2020

Despite the Paris Agreement, greenhouse gas (GHG) concentrations in the atmosphere continue to increase because of the anthropogenic activities, and this is inducing catastrophic effects. Past studies revealed that urban areas are responsible of a large part of these emissions and many cities already started to implement climate actions to reduce their GHG emissions and address climate change. The effectiveness of these actions depends on accurate knowledge of the many sources of GHG in each city, so that efforts are focused on the sources whose emission reduction would be the most effective. Atmospheric measurements are useful to locate and characterize these sources and to monitor the evolution of their emissions. Different approaches have been developed during the past decades including stationary and mobile surface-based in situ measurements, remote sensing of solar absorption spectra from space and from the ground, or aircraft-based observations. All these techniques are complementary and provide information about urban GHG emissions at different scales.

In situ mobile measurements of methane mixing ratios have been performed in the two largest cities of Canada using 1) a high-precision gas analyzer providing continuous measurements, 2) a weather station measuring wind speed and direction, and 3) a GPS recording coordinates during the campaigns. These mobile surveys allow rapid screening of large areas, the revisit of specific sites to monitor the evolution of their emissions over time, and can therefore improve our understanding of the emissions at local scale. Methane emissions of the Greater Toronto Area (GTA) have been intensively investigated since 2018 with a total of 84 days of measurements corresponding to a distance of about 8,000 km. A one-week campaign has also been realized in November 2019 in Montreal corresponding to a distance of about 1,100 km. Methane enhancements observed during these surveys have been identified, classified into three categories depending on their magnitudes and areas, and attributed to potential sources, several of which are not catalogued in FLAME-GTA, the point source level inventory developed for the Toronto metropolitan area. Important methane sources in the GTA have been surveyed regularly since 2018 and their emissions have been estimated using an inverse modeling framework with a Gaussian model and compared to the inventory-based estimates of FLAME-GTA.

 
Crustal architecture of the largest pull-apart basin in East Antarctica unveiled
Authors: Crispini Laura , Ferraccioli Fausto , Armadillo Egidio , Läufer Andreas , Ruppel Antonia
Published: March 2020

The West Antarctic Rift System (WARS) is known to have experienced distributed/wide mode extension in the Cretaceous, followed by narrow mode and variably oblique extension/transtension in the Cenozoic, the latter potentially linked to the onset of oceanic seafloor spreading within the Adare Basin (Davey et al., 2016, GRL). However, onshore the extent and impact of Cenozoic extension and transtension within the Transantarctic Mountains sector of East Antarctica is currently much less well-constrained from a geophysical perspective.

Here we combine aeromagnetic, aerogravity, land-gravity and bedrock topography imaging to help constrain the extent, architecture and kinematics of the largest Cenozoic pull-apart basin recognised so far in East Antarctica, the Rennick Graben (RG).

Enhanced potential field imaging reveals the extent of a Jurassic tholeiitic Large Igneous Province preserved within the RG and the inherited structural architecture of its basement, including remnants of uplifted ca 530-500 Ma arc basement in the northern Wilson Terrane and a ca 490-460 Ma subglacial thrust fault belt separating the Cenozoic western flank of the RG from the eastern margin of Wilkes Subglacial Basin (WSB).

The architecture of the RG is best explained in terms of a major composite right-lateral pull-part basin that extends from the Oates Coast to the Southern Cross Mountains block. We propose that Cenozoic strike-slip deformation kinematically connected the RG with both the western edge of the WARS and the eastern margin of the WSB. An earlier phase of left-lateral strike slip deformation is also emerging from recent geological field work in the study region but only relatively subtle offsets in aeromagnetic anomaly patterns are visible in currently available regional datasets.

We conclude that the RG is part of a wider distributed region of the continental lithosphere in East Antarctica that was deformed in response to an evolving Cenozoic transtensional tectonic setting that may have also affected enigmatic sub-basins such as the Cook Basins in the adjacent WSB region.
Sources, sinks, and transport of nutrients across a mixed-use headwater catchment in north-central Ohio
Authors: Costa Jr Ozeas
Published: March 2020

In many ecosystems on land and sea, the supply of nutrients is a key factor controlling the nature and diversity of plant life, the population dynamics of both grazing animals and their predators, and vital ecological processes such as plant productivity and the cycling of carbon and soil minerals. Over the last century, runoff from farms and cities, along with land cover and land use changes, have drastically altered the mass balance of nutrients in aquatic systems, affecting both their ecological functioning and the living communities they support. Here we present the results of a multi-year nutrient assessment of streams and lakes from the Mohican Watershed, in North-Central Ohio, which drains to the Ohio River and into the Gulf of Mexico. A total of 64 streams and 8 lakes/reservoirs have been sampled periodically since the summer of 2008. A GIS-based landscape model was used to examine the relationships between streams and their catchments. Land use data from NLCD was used to select representative reach-catchment areas in one of four categories: forested, developed, cropland, and pasture. Nutrient concentrations (NO2; NO3; NH4; PO4) were measured and used for calculation of nutrient fluxes within the watershed. Sampling was undertaken during both baseflow and stormflow conditions in order to evaluate the effects of precipitation on nutrient transport. In order to assess nutrient contribution from atmospheric deposition, rainwater samples were also analyzed. Our results show that nutrient fluxes are highly controlled by the land use of the reach-catchment and by precipitation events. In addition, there is a marked shift between local and external controls on biogeochemical processes under baseflow and stormflow conditions. During stormflow, nutrient input is primarily hydrologically controlled. During baseflow, biological processes dominate both the production and removal of nutrient ions from the stream. This short-term hydrological variability is compounded by the effects of long-term geomorphic and climatic changes, and an increase of over 15% in nutrient export was observed during wetter years.
Climate shocks and the supply and demand for climate governance
Authors: Rowan Sam
Published: March 2020

Existing studies have demonstrated substantial and robust effects of temperature shocks on economic growth, agricultural output, labor productivity, conflict, and health. These studies help clarify the impacts of climate change on social and economic systems, yet the relationship between climate shocks and political outcomes are less well identified. What effect do climate shocks have on states' climate policies? In this paper, I estimate the relationship between national-level temperature and rainfall shocks and the supply and demand for international climate governance. Temperature shocks may increase the salience of climate change in national politics and lead political leaders to adjust policies to match. Similarly, temperature shocks may have material consequences that induce adaptation---one avenue being to use international institutions to coordinate a global response to climate impacts. I argue that the responsiveness of national governments to climate shocks is conditioned by the political and natural context in which governments operate. Specifically, I expect that democratic governments will be more responsive to climate shocks, as will countries that are more vulnerable to the impacts of climate change. I assess whether countries that experience more frequent and more severe climate shocks participate more in international climate politics and adjust their climate policies. I examine four sets of outcomes at the national level: (1) membership in international institutions that govern climate change, (2) the provision and receipt of climate finance, (3) representation at the UN climate conferences, and (4) national climate policies. As the climate changes, we are developing stronger evidence about the underlying natural relationships, but the heterogenous effects across socio-political contexts are less well understood. This paper contributes to our understanding of how climate change shapes national policy and with it the ability of countries to manage and adapt to climate change.
Balanced subsampling of future regional climate ensembles of opportunity
Authors: Fernández Jesús , Frías María Dolores
Published: March 2020

International model intercomparison initiatives, such as CORDEX or CMIP5, along with several relatively recent projects at international and national level, provide a wealth of model simulations of future regional climate. In a recent work, Fernandez et al (2019) collected 196 different future climate change projections over Spain, considering data from ENSEMBLES, ESCENA, EURO- and Med-CORDEX, along with their driving global climate projections from CMIP3 and CMIP5. This ensemble mixed different multi-model initiatives in an ensemble of opportunity, in the sense that it does not respond to any scientific design beyond the exploration of multi-model uncertainty. This ensemble of opportunity is not only the result of the mixture of different initiatives, but also responds to the lack of a balanced experimental design within most of the initiatives. Many of the initiatives -especially those unfunded, such as CORDEX- are carried out on a voluntary basis, with no strong constraint in the global climate models (GCMs) used as boundary conditions or in the number of contributing members per regional climate model (RCM).

Fernandez et al (2019) found in this ensemble a strong influence of the driving GCM on the regional climate change signal, along with favored GCMs, selected by many regional climate modelling groups to the detriment of GCMs publishing their output later or not at all. In this work, we quantitatively assess the impact of unbalanced GCM-RCM ensembles. For this purpose, we subsampled the ensemble of opportunity to obtain balanced sets of members according to different “what-if” situations: What if all RCMs had contributed a single member to the ensemble? What if each GCM had been dynamically downscaled only once? What if a given GCM/RCM had not contributed to the ensemble? For each hypothesis, there are a number of alternative sub-ensembles, which are used to evaluate uncertainty.

Acknowledgement:

This work is partially funded by the Spanish government through MINECO/FEDER co-funded projects INSIGNIA (CGL2016-79210-R) and MULTI-SDM (CGL2015-66583-R). 

References:

Fernández, J., et al. (2019) Consistency of climate change projections from multiple global and regional model intercomparison projects. Clim Dyn 52:1139. https://doi.org/10.1007/s00382-018-4181-8
EMS and MCS macroseismic intensities assessed in Italy are equivalent?
Authors: Vannucci Gianfranco , Gasperini Paolo , Laura Gulia , Barbara Lolli
Published: March 2020

The most of intensity assessments provided by the large (more than 100000 intensity observations) Italian macroseismic database (DBMI15) were made using the traditional Mercalli-Cancani-Sieberg (MCS) scale but in most recent macroseismic surveys in Italy even the European Macroseismic Scale (EMS) scale was used by some research groups. In principle, MCS and EMS scales should give almost the same intensities if only damage to traditional masonry buildings is considered for MCS estimates. Some doubts remain on this equivalence even if MCS and EMS intensities were actually used as they were coincident, as in the case of or the compilation of the CPTI15 catalog used for seismic hazard assessment in Italy. In this work we compared intensity estimates made using both scales for the traditional (expert) estimates made for the same localities of some recent earthquakes as well as community intensities provided by on line questionnaires “Hai Sentito Il Terremoto” (HSIT) collected by INGV. We computed linear regressions between the two sets of intensity estimates and also compared the earthquake parameters (locations magnitude and fault orientations) computed by the Boxer code, using independently the two sets of intensities.
Present state of marginal mountain permafrost in South Eastern Europe
Authors: Sirbu Flavius , Onaca Alexandru , Ardelean Florina , Magori Brigitte , Urdea Petru
Published: March 2020

Permafrost exists in the highest mountains of SE Europe (South Carpathians, Rila, Pirin) in small isolated patches, where local topography and landforms provide conditions for winter ground cooling and for shading and ground thermal isolation during summer.

We present a summary of the present state of mountain permafrost in the study area by analyzing the results of ERT (electrical resistivity tomography) and GPR (ground penetrating radar) profiles together with thermal measurements of ground surface and air performed at the sites of documented permafrost occurrence. The results are put in context with recent climate evolution by a decade of thermal measurements in the South Carpathians and three years in the Rila and Pirin Mountains.

Despite differences in air temperature and snow cover timing and thickness the permafrost extent remains constant at the study sites. The active layer is thick (between 5-10 m), whereas the permanently frozen layers vary in thickness even for the same study site, and are relatively thin compared to sites located in the Alps or the Andes, indicating that the existing permafrost is in imbalance with the current climate. Snow cover is probably the most important factor in seasonal evolution, controlling both the winter cooling and the summer thermal decupling of ground and air temperature. Recent evolution shows a tendency of shifting the snow cover period with later deposit and later thaw which favors permafrost conditions. We also observe a significant difference between Southern Carpathians and Rila and Pirin mountains, with snow patches lasting until late summer, August or September, in the later.

However snow cover present strong local variations in terms of thickness and isolating proprieties which makes it the least study and least understood factor in mountain permafrost dynamics in SE Europe.