bluuebunny/crossref_metadata_2025 huggingface dataset:
 Environmental standards for the concentration of hydrocarbons in soils
Authors: Buzmakov Sergei
Published: March 2021

Soils are the main component in biogeocenoses. More than 30 types and subtypes of soils are represented in the territory of the Perm region (Russia); however, in the oil-producing areas, the main share of soils is Albicluvisols/Retisols, Calcaric Leptosols, Luvic Phaeozems, Greyzamic Phaeozems and Folic Fluvisols. These soils cover a large area of the Perm region and are the basis for the existence of typical coniferous-deciduous forests and forest-steppe biogeocenoses. In this regard, the question of the impact of oil pollution of these soils on plants, animals and humans is relevant.

The ecological safety of microbocenosis, phytocenosis, zoocenosis and humans depends on the state of the soil. Soil contamination, including pollution by oil and refined products, negatively affects the state of all components of the cenosis.

The aim of the present study was to investigate the relationship between soil type and the response of test organisms of various organismic levels to oil pollution, to determine the most sensitive criterion for assessing the safe concentration of oil in each type of soil.

As a result of the environmental assessment, it was possible to identify patterns between the type of oil-contaminated soil and the state of test organisms of various organismic levels. The use of direct experimental methods, as well as software products, made it possible to assess the impact of oil pollution in various types of soils on microbial and plant test organisms, to assess the impact on aquatic organisms.
Study of the sea ice impact on primary production in the Barents and Kara Seas in past and future climates
Authors: Martyanov Stanislav D. , Dvornikov Anton Y. , Ryabchenko Vladimir A. , Sein Dmitry V.
Published: March 2021

A regional coupled eco-hydrodynamic model of the Barents and Kara Seas based on the MITgcm has been developed. The biogeochemical module is based on a 7-component model of pelagic biogeochemistry including the ocean carbon cycle. This regional model allows revealing and explaining the main mechanisms of the interaction between marine dynamic and biogeochemical processes in the Barents and Kara Seas under a changing climate. We present the main results of simulations for the past (1975-2005) and future (2035-2065) climate.

A clear relationship between the marginal ice zone area and primary production has been obtained, proving the importance of this zone in the functioning of the marine ecosystem. The interannual variability of the integrated primary production and the total sea ice area demonstrates an antiphase behavior, which means that the reduced sea ice cover area in the previous winter is one of the main reasons for the increase in primary production in the current year.

The model simulations demonstrate that, of all the external factors, sea ice area plays a primary role in the formation of primary production: in the overwhelming majority of cases, the contribution of the ice area prevails, and the pattern "more ice - less primary production" and vice versa is fulfilled in the Barents and Kara Seas. The effect of a decrease of incoming short-wave radiation becomes significant only when a significant decrease of the ice area occurs.

Compared to the period 1975-2005, the simulated total primary production in the Barents and Kara Seas is much higher for the period 2035-2065, while the sea ice area significantly decreases.

A regression dependence has been obtained for the total annual primary production as a function of sea ice area and incoming short-wave radiation. Its validity is verified for both past (dependent) and future (independent) climatic periods. It justifies the use of such simple statistical model for quick estimates of the primary production in the Barents and Kara Seas.

Acknowledgements: The research was performed in the framework of the state assignment of the Ministry of Science and Higher Education of Russia (theme No. 0128-2021-0014). This work used resources of the Deutsches Klimarechenzentrum (DKRZ) granted by its Scientific Steering Committee (WLA) under project ID ba1206.
The Atlantic Meridional Overturning Circulation (AMOC) simulated during interglacials and its impact on climate
Authors: Jiang Zhiyi , Brierley Chris , Thornalley David , Sax Sophie
Published: March 2021

The Atlantic Meridional Overturning Circulation (AMOC) is a key mechanism of poleward heat transport and an important part of the global climate system. How it responded to past changes inforcing, such as experienced during Quaternary interglacials, is an intriguing and open question. Previous modelling studies suggest an enhanced AMOC in the mid-Holocene compared to the pre-industrial period. In previous simulations from the Palaeoclimate Modelling Intercomparison Project (PMIP), this arose from feedbacks between sea ice and AMOC changes, which also depended on resolution. Here I present aninitial analysis of the recently available PMIP4 simulations. This shows the overall strength of the AMOC does not markedly change between the mid-Holocene and piControl experiments (at least looking at the maximum of the mean meridional mass overturning streamfunction below 500m at 30oN and 50oN). This is not inconsistent with the proxy reconstructions using sortable silt and Pa/Th for the mid-Holocene. Here we analyse changes in the spatial structure of the meridional overturning circulation, along with their fingerprints on the surface temperature (computed through regression). We then estimate the percentage of the simulated surface temperature changes between the mid-Holocene and pre-industrial period that can be explained by AMOC. Furthermore, the analysis for the changes in the AMOC spatial structure has been extended to see if the same patterns of change hold for the last interglacial. The simulations will be compared to existing proxy reconstructions, as well as new palaeoceanographic reconstructions.
Hydraulic constraints and stomatal optimization
Authors: Buckley Thomas
Published: March 2021

The classical Cowan-Farquhar approach to identifying optimal stomatal conductance treats total water loss as an imposed constraint. That approach can conflict, both physically and economically, with biophysical constraints on water transport. In this talk, I will illustrate these conflicts and discuss alternative approaches -- recently pioneered by Sperry, Wolf, Eller, and their colleagues -- that aim to penalize excessive transpiration by explicitly incorporating hydraulic risk, using hydraulic vulnerability curves (VCs). In this context, I will present preliminary efforts to determine whether VCs accurately reflect the actual probabilistic risk posed by low water potentials (that is, the expected reduction in total carbon gain), as well as an extension to the recent analytical solution by Eller et al.
Clearer than mud? Using environmental DNA to track historical shifts in lake communities.
Authors: Pearman John , Biessy Laura , Thomson-Laing Georgia , Reyes Lizette , Shepherd Claire , Howarth Jamie , Rees Andrew , Li Xun , Vandergoes Marcus , Wood Susie , Lakes380 Team
Published: March 2021

A continuous record of environmental history is stored in lake sediments providing an avenue to explore current and historical lake communities. Traditionally paleolimnological methods have focussed on macroscopic indicators (e.g. pollen, chronomids, diatoms) to investigate environmental changes but the application of environmental DNA techniques has enabled the investigation of microbial communities and other soft bodied organisms through time. The ‘Our lakes’ health; past, present, future (Lakes380)’ project aims to combined traditional and molecular methods to explore shifts in biological communities over the last 1,000 years (pre-human arrival in New Zealand). Sediments cores have been collected from a wide diversity of lakes across New Zealand and 16S rRNA gene metabarcoding approaches of both DNA and RNA applied to reveal how microbial community changes across time and especially in response to the arrival of humans and associated changes to the landscape and lake environments. We further investigate the changes in inferred metabolic potential of the microbial communities as the taxonomic composition of the lake differs over time. Finally, we combine these novel molecular methods with hyperspectral scanning and pollen data to increase the knowledge of changes in lake communities and identifying the timing of changes in lake health. The combination of methodologies provides a greater understanding of the environmental history of lake systems and will help to inform management decisions relating to the restoration and protection of lake health.
Mapping and statistical procedures applied to extract topographical features of fluvial terraces and erosive surfaces. 
Authors: Martinez-Murillo Juan F. , Carruana-Herrera David
Published: March 2021

In recent decades, a huge advance in data collection has favoured the study of many questions related to geomorphic processes and associated landforms (Viles, 2016). This increment in data collection let face new questions and develop new methodologies in Geomorphology (Sofia et al., 2020). In this way, geomorphometry is a challenging discipline with the objective of quantify land-surface analysis and extract as well as detect geomorphological elements (Guyon and Elisseeff, 2008). As result, this discipline complement classis geomorphological maps with others extracted from digital elevation models providing land-surface metrics to investigate the full spectrum of geomorphology (Seijmonsbergen et al., 2011).

In this study, we investigate the extraction of topographical features from fluvial terraces and erosive surfaces by means of mapping procedures applied to a digital elevation model (spatial resolution of 5x5 m) using ArcGIS 10.7. This procedure was focussed on the quantification of elements (altitude, slope angle, length, and curvature, exposure) to characterize morphological elements that may define the presence of fluvial terraces as well as erosive surfaces. A Principal Component Analysis was performed to validate that procedure.

The procedure was conducted in two study areas: detection of fluvial terraces from the watershed of Guadalmedina river as well as of erosive surfaces in Sierras Subbéticas Geopark, both areas located in southern Spain.
River parametrisation of the JULES land surface model for improved runoff routing at the global scale.
Authors: Koutroulis Aristeidis , Grillakis Manolis , Mathison Camilla , Burke Eleanor
Published: March 2021

The JULES land surface model has a wide ranging application in studying different processes of the earth system including hydrological modeling [1]. Our aim is to tune the existing configuration of the global river routing scheme at 0.5o spatial resolution [2] and improve river flow simulation performance at finer temporal scales. To do so, we develop a factorial experiment of varying effective river velocity and meander coefficient, components of the Total Runoff Integrating Pathways (TRIP) river routing scheme. We test and adjust best performing configurations at the basin scale based on observations from GRDC 230 stations that exhibiting a variety of hydroclimatic and physiographic conditions. The analysis was focused on watersheds of near-natural conditions [3] to avoid potential influences of human management on river flow. The HydroATLAS database [4] was employed to identify basin scale descriptive hydro-environmental indicators that could be associated with the components of the TRIP. These indicators summarize hydrologic and physiographic characteristics of the drainage area of each flow gauge. For each basin we select the best performing set of TRIP parameters per basin resulting to the optimal efficiency of river flow simulation based on the Nash–Sutcliffe and Kling–Gupta efficiency metrics. We find that better performance is driven predominantly by characteristics related to the stream gradient and terrain slope. These indicators can serve as descriptors for extrapolating the adjustment of TRIP parameters for global land configurations at 0.5o spatial resolution using regression models.

 

[1] Papadimitriou et al 2017, Hydrol. Earth Syst. Sci., 21, 4379–4401

[2] Falloon et al 2007. Hadley Centre Tech. Note 72, 42 pp.

[3] Fang Zhao et al 2017 Environ. Res. Lett. 12 075003

[4] Linke et al 2019, Scientific Data 6: 283.
The July 2019 explosive activity of Ubinas Volcano, Peru
Authors: Apaza Fredy , Kern Christoph , Ortega Mayra , Miranda Rafael
Published: March 2021

Ubinas is a stratovolcano located in the Central Volcanic Zone of the Andes. It is one of the most active volcanoes in Peru, with more than 26 eruptive episodes recorded in the last 500 years (VEI 1-3). Its latest eruption began in early 2019, whit the occurrence of some distal VT seismicity accompanied by low levels of LP seismicity and in sometimes high frequency seismic signals associated with rockfalls. Concurrently, SO2 emissions increased from a few hundred to over 1,000 t/d between January and June while no significant ground deformation could be detected. Throughout the month of June, SO2 emissions climbed further to over 4,000 t/d, proximal VT swarms began to occur beneath the volcanic edifice, and deformation measurements indicated a pressurization of the system. This ramp-up in activity culminated with an explosive eruption on 19 July 2019 (07:28:49 UTC). The eruption released a cumulative energy of 336 MJ and vented an estimated 4.6x106 m3 of volcanic ash, making this one of the most energetic eruptive events of the last decade. Filled with hot gas and ash, the eruptive column reached 6,500 meters above the volcanic vent, with blocks and ballistic projectiles that reached 3.5 km from the crater and fragments up to 2.5 cm in diameter reported in the Ubinas town, 6.5 km to the southeast. By the time the eruption ended, up to 4 kg/m2 of tephra had fallen at this distance. Most of the plume was dispersed in east to southeast directions, crossing the regions of Moquegua, Puno. Ashfall was observed as far as Oruro, Bolivia, some 180 km from the volcano. Subsequent analyses of monitoring data and eruptive products allow classification of this event as a VEI 2 eruption caused by a rapid magmatic intrusion to shallow depths below the volcanic edifice.
Intraseasonal variations of Ocean Heat Content in the tropical Indian and Pacific Ocean
Authors: Chandra Ashneel , Keenlyside Noel , Svendsen Lea , Singh Awnesh
Published: March 2021

The ocean heat content (OHC) is an important thermodynamical parameter in the Earth’s climate system as about 90% of the Earth’s Energy Imbalance (EEI) is stored in the ocean. It is therefore important to understand how this quantity varies on different timescales and how different thermodynamical and dynamical processes affect it. On intraseasonal timescales, there is a two-way interaction between the atmosphere and ocean whereby atmospheric forcing leads to ocean dynamics causing changes in OHC and OHC, in turn, possibly playing a role in affecting the intensity of the Madden-Julian Oscillation (MJO) through air-sea interactions. In this study, we focus on the variations of OHC in the equatorial Indian and Pacific Ocean on intraseasonal timescales. A heat budget analysis for the upper 100 m was performed using HYCOM Reanalysis for the period 2005 – 2015. The simple three-term heat budget comprised of a surface heat flux term (Q), an advection and adiabatic redistribution term (ADV) and finally a residual term (RES) to account for processes not resolved using the reanalysis product. When averaged over the equatorial Pacific Ocean, the heat budget analysis shows that the ADV and RES terms contributed the most to the ocean heat content tendency (OHCT). Zonal wind anomalies are observed to excite intraseasonal Kelvin waves in the equatorial Pacific Ocean. These Kelvin waves are associated with the eastward advection of intraseasonal OHC anomalies from the western Pacific warm pool to the central Pacific. This eastward propagation of intraseasonal OHC anomalies associated with Kelvin waves is seen to contribute to the warming leading to El Niño events such as the 2009 El Niño. In the Indian Ocean, intraseasonal OHC anomalies along the equator were seen to be in phase with the MJO as revealed by the negative intraseasonal outgoing longwave radiation (OLR) anomalies, while the off-equatorial intraseasonal OHC anomalies were seen to be out of phase with the MJO. Off-equatorial intraseasonal OHC anomalies in the Indian Ocean may be a useful parameter to investigate further as it may provide the residual heat energy for air-sea interactions for subsequent MJO events and hence improve subseasonal predictability.
Assessing global biogeophysical effects of reconstructed land use and land cover change on climate since 1950 using a coupled land–atmosphere–ocean model
Authors: Huang Huilin , Xue Yongkang , Chilukoti Nagaraju , Liu Ye , Chen Gang , Diallo Ismaila
Published: March 2021

Land use and land cover change (LULCC) is one of the most important forcings affecting climate in the past century. This study evaluates the global biogeophysical LULCC impacts in 1950–2015 by employing an annually updated LULCC map in a coupled land–atmosphere–ocean model. The difference between LULCC and control experiments shows an overall land surface temperature (LST) increase by 0.48 K in the LULCC regions and a widespread LST decrease by 0.18 K outside the LULCC regions. A decomposed temperature metric (DTM) is applied to quantify the relative contribution of surface processes to temperature changes. Furthermore, while precipitation in the LULCC areas is reduced in agreement with declined evaporation, LULCC causes a southward displacement of the intertropical convergence zone (ITCZ) with a narrowing by 0.5°, leading to a tripole anomalous precipitation pattern over the warm pool. The DTM shows that the temperature response in LULCC regions results from the competing effect between increased albedo (cooling) and reduced evaporation (warming). The reduced evaporation indicates less atmospheric latent heat release in convective processes and thus a drier and cooler troposphere, resulting in a reduction in surface cooling outside the LULCC regions. The southward shift of the ITCZ implies a northward cross-equatorial energy transport anomaly in response to reduced latent/sensible heat of the atmosphere in the Northern Hemisphere, where LULCC is more intensive. Tropospheric cooling results in the equatorward shift of the upper-tropospheric westerly jet in both hemispheres, which, in turn, leads to an equatorward narrowing of the Hadley circulation and ITCZ.
Two parameters are required for a Budyko function to describe the land-atmosphere interaction
Authors: Kim Daeha , Chun Jong Ahn
Published: March 2021

While the Budyko framework has been a simple and convenient tool to assess runoff (Q) responses to climatic and surface changes, it has been unclear how parameters of a Budyko function represent the vertical land-atmosphere interactions. Here, we explicitly derived a two-parameter equation by correcting a boundary condition of the Budyko hypothesis. The correction enabled for the Budyko function to reflect the evaporative demand (Ep) that actively responds to soil moisture deficiency. The derived two-parameter function suggests that four physical variables control surface runoff; namely, precipitation (P), potential evaporation (Ep), wet-environment evaporation (Ew), and the catchment properties (n). We linked the derived Budyko function to a definitive complementary evaporation principle, and assessed the relative elasticities of Q to climatic and land surface changes. Results showed that P is the primary control of runoff changes in most of river basins across the world, but its importance declined with climatological aridity. In arid river basins, the catchment properties play a major role in changing runoff, while changes in Ep and Ew seem to exert minor influences on Q changes. It was also found that the two-parameter Budyko function can capture unusual negative correlation between the mean annual Q and Ep. This work suggests that at least two parameters are required for a Budyko function to properly describe the vertical interactions between the land and the atmosphere.
Exploring the future hydrology of a Canadian Rockies glacierized catchment and its sensitivity to meteorological forcings
Authors: Aubry-Wake Caroline , Pomeroy John W.
Published: March 2021

Glacierized mountain areas are witnessing strong changes in their streamflow generation processes, influencing their capacity to provide crucial water resources to downstream environments. Shifting precipitation patterns, a warming climate, changing snow dynamics and retreating glaciers are occurring simultaneously, driven by complex physical feedbacks. To predict and diagnose future hydrological behaviour in these glacierized catchments, a semi-distributed, physically-based hydrological model including both on and off-glacier process representation was applied to Peyto basin, a 21 km2 glacierized alpine catchment in the Canadian Rockies. The model was forced with bias-corrected outputs from a dynamically downscaled, 4-km resolution Weather and Research Forecasting (WRF) simulation, for the 2000-2015 and 2085-2100 period.  The future WRF runs had boundary conditions perturbed using RCP8.5 late century climate.  The simulations show by the end-of-century, the catchment shifts from a glacial to a nival regime. The increase in precipitation nearly compensates for the decreased ice melt associated with glacier retreat, with a decrease in annual streamflow of only 7%. Peak flow shifts from July to June and August streamflow is reduced by 68%. Changes in blowing snow transport and sublimation, avalanching, evaporation and subsurface water storage also contribute to the strong hydrological shift in the Peyto catchment. A sensitivity analysis to uncertainty in forcing meteorology reveals that streamflow volume is more sensitive to variations in precipitation whereas streamflow timing and variability are more sensitive to variations in temperature. The combination of the temperature and precipitation variations caused substantial changes both in the future snowpack and in the streamflow pattern. By including high-resolution atmospheric modelling and unprecedented both on and off-glacier process-representation in a physically-based hydrological model, the results provide a particularly comprehensive evaluation of the hydrological changes occurring in high-mountain environments in response to climate change.
Using Volcanic Geochemistry and Seismic Tomography to Refine Global Models of Mantle Temperature and Plate Thickness
Authors: Ball Patrick , White Nicky , Maclennan John , Stephenson Simon
Published: March 2021

The thermochemical structure of lithospheric and asthenospheric mantle exert primary controls on surface topography and volcanic activity. Volcanic rock compositions and mantle seismic velocities provide indirect observations of this structure. Here, we compile and analyze a global database of the distribution and composition of Neogene-Quaternary intraplate volcanic rocks. By integrating this database with seismic tomographic models, we show that intraplate volcanism is concentrated in regions characterized by slow upper mantle shear-wave velocities and by thin lithosphere (i.e. < 100 km). We observe a negative correlation between shear-wave velocities at depths of 125-175 km and melt fractions inferred from volcanic rock compositions. Furthermore, mantle temperature and lithospheric thickness estimates obtained by geochemical modeling broadly agree with values determined from tomographic models that have been converted into temperature. Intraplate volcanism often occurs in regions where uplifted (but undeformed) marine sedimentary rocks are exposed. Regional elevation of these rocks can be generated by a combination of hotter asthenosphere and lithospheric thinning. Therefore, the distribution and composition of intraplate volcanic rocks through geologic time will help to probe past mantle conditions and surface processes.
Polygonal impact craters reveal a global fracture pattern on Mercury
Authors: Yazici Isik Su , Klimczak Christian
Published: March 2021

Mercury’s surface displays a rich history in impact cratering and tectonic activity, which both provide insight into the geological evolution of the innermost planet. Global contraction, the volume decrease of the planet associated with a long, sustained period of cooling, and tidal despinning, the slowing of rotation to lock Mercury in its current 3:2 spin-orbit resonance with the sun, are both thought to have played an important role on the observed systematic variations of preferred orientations of thrust fault-related landforms across the planet. While these landforms show preferred north-south orientations in the equatorial and mid-latitudes, they show random or concentric (east-west) orientations at the poles. Other fractures, such as joints, are likely present on Mercury, too, but their expressions are too subtle to be identified unless they are utilized as crater rims during the emplacement of impact craters. Fracture sets that existed in the bedrock prior to impact are widely accepted to produce crater rims showing straight rim segments that overall result in polygonal plan-view shapes of the impact structures, with perhaps the most prominent example Meteor Crater, Arizona. To test if regional fracture sets actually governed the shape of polygonal impact craters on Mercury, we have rigorously mapped all impact craters with diameters between 20 to 400 km. A total of 7,146 impact craters were mapped using Mercury Surface Space ENvironment GEochemistry and Ranging (MESSENGER) global image and topography datasets. After analyzing the shape, lengths, and orientations of 124,671 rim segments, we assessed if these rim segments contain additional information about systematic tectonic patterns. Our results show a strong preferred east-west orientation of straight crater rims at the poles, while in the mid-latitude and equatorial regions, they only have weak north-south or random orientations. That straight crater rims to show preferred east-west orientation at the poles is consistent with observed fault orientations by previous studies. However, we observe a lack of correlation of straight crater rim orientations and mapped faults at the equatorial and mid-latitudinal regions. These results have implications for and will enable further quantitative investigations of the global tectonics and fault reactivation on Mercury.
Advancing Data Curation and Archiving: an Application of Coding to Lab Management in the Geosciences
Authors: Latham Tierney , Beck Catherine , Wegter Bruce , Wu Ahra
Published: March 2021

Increases in technology have rapidly advanced the capabilities and ubiquity of scientific instrumentation. Coupled with the demand for increased transparency and reproducibility in science, these advances have necessitated new systems of data management and archival practices. Laboratories are working to update their methods of data curation in line with these evolving best-practices, moving data from often disorderly private domains to publicly available, collaborative platforms. At the Hamilton Isotope Laboratory (HIL) of Hamilton College, the isotope ratio mass spectrometer (IRMS) is utilized across STEM disciplines for a combination of student, faculty, and course-related research, including both internal and external users. With over 200 sets of analytical runs processed in the past five years, documenting instrument usage and archiving the data produced is crucial to maintaining a state-of-the-art facility. However, previous to this project, the HIL faced significant barriers to proper data curation, storage, and accessibility including: a) data files were produced with variable format and nomenclature; b) data files were difficult to interpret without explanation from the lab technician; c) key metadata tying results to respective researchers and projects were missing; d) accessibility to data was limited due to storage on an individual computer; and e) data curation was an intellectual responsibility and burden for the lab technician. Additionally, as the HIL is housed within an undergraduate institution, the high rate of turnover for lab groups created additional barriers to the preservation of long-term, institutional knowledge, as students worked with the HIL for a year or less. These factors necessitate the establishment of new data management practices to ensure accessibility and longevity of scientific data and metadata. In this project, 283 Excel files of previously recorded data generated by the HIL IRMS were modified and cleaned to prepare data for submission to EarthChem, a public repository for geochemical data. Existing Excel files were manually manipulated, several original R code scripts were generated and employed, and procedures were established to backtrace projects and collect key metadata. Most critically, a new internal system of data collection was established with standardized nomenclature and framework. For future usage of the IRMS, data will be exported directly into a template compatible with EarthChem, thereby removing barriers for principal investigators (PIs) and research groups to archive their data in the public domain upon completion of their projects and publications.
Artificial Intelligence and machine learning model for spatial and temporal prediction of drought in the Colombia Caribbean region.
Authors: Herrera Daissy , Aristizábal Edier
Published: March 2021

Drought is one of the most critical hydrometeorological phenomena in terms of impacts to society because it affects soil water content, and consequently, crop production and human diets, in some cases under critical conditions, drought produces starving and people migration. Although Colombia is a tropical country, there are areas of the territory that have periods of drought that cause important economic damages such as fires, death loss in cattle, reduction of the capacity to supply water to persons, impacts to agriculture and fish farming.

Due to recent advances in terms of spatial and temporal resolutions of remote sensing and Artificial Intelligence techniques, it is possible to develop Automatic Learning Models supported on historic information. In this research was built a classifier  Random Forest (RF) and Bagged Decision Tree Classifier (DTC) model to predict, spatial and temporal drought occurrence in Colombia, using remote sensing data as land surface temperature, precipitation, soil water contentl, and evapotranspiration, and macro climatic variables information as ONI, MEI and SOI.  It was used the Standardized Precipitation Index (SPI) with 3-month time scale, that allows identifying agricultural drought events. The results showed that Random Forest provides the best outcomes. In terms of recall and precision, RF produced 0.84 and 0.59 and DTC brought a 0.8 and 0.33, respectively, to predict drought. The above, evidence that models could overestimate the number of times where drought occurs, in contrast with normal or humid conditions. On the other hand, False Positive and False Negative rates are important facts for measuring the development of models. In this case, the FP and FN rates are 7.5% and 2% for RF and 21% and 2.5% for DTC respectively, that means that both models made fewer mistakes predicted real drought events, but had more errors forecasting real normal or humid condition, especially, DTC model. RF can provide a better performance predicting drought and normal/humid conditions in contrast with DTC. The implementation of the developed model can allow governmental entities assessment and monitor agricultural drought over time. Taking, in consequence, actions to mitigate the impacts of droughts in their territories.
Predicting Soil erosion based on the machine learning in Loess Plateau of China 
Authors: Huang Chenlu , Yang Qinke
Published: March 2021

Soil erosion is one of the global ecological and environmental problems, which is an important factor leading to land degradation. To scientifically and effectively control soil erosion, it’s necessary to improve soil erosion evaluation methods that can obtain the actual rates of soil erosion, rather than potential erosion. For this, about 300 sampling units deployed in the Loess Plateau used as the basic data in our study, combining the seven soil erosion factors (rainfall-runoff erosivity factor, soil erodibility factor, slope length and steepness factor, biological-control factor, engineering-control factor, tillage practices factor) involved in the CSLE model and 50 soil erosion covariates related to climate, soil, topography, vegetation, human activities, etc. Using machine learning methods to establish an optimal model, and spatially predict the soil erosion rate and make a soil erosion mapof the entire study area. The prediction results show that the explanation degree of the random forest spatial prediction model is 73%. Among the selected optimal characteristic parameters, terrain and vegetation-related variables are the most important factors affecting soil erosion, from high to low, the order is LS > B > NDVI (May to September). Compared to previous studies with USLE/RUSLE/CSLE and GIS integrated mapping methods, or sampling survey based interpolation method, improvements in this paper can be concluded to : (1) the use of machine learning instead of simple multiply by soil erosion factors (linear regression), (2) higher resolution interpretation results supported by the project of “Pan-Third Pole Project”, which provide soil erosion that closed to the actual rates of soil erosion. (3) considerate additional related covariates such as population density, precipitation, soil conservation measures and so on. Further development of soil erosion prediction could provide a more accurate soil erosion evaluation method. This method can not only monitor and evaluate soil erosion in real time, and provide the possibility for the dynamic change analysis? of soil erosion in the future, but also help decision makers take effective measures in the process of mitigating soil erosion risk.
Constraining ice core chronologies with 39Ar and 81Kr
Authors: Ritterbusch Florian , Ahn Jinho , Gu Ji-Qiang , Jiang Wei , Lee Giyoon , Lu Zheng-Tian , Shao Lili , Tian Lide , Tong A-min L. , Yang Guo-Ming
Published: March 2021

Paleoclimate reconstructions from ice core records can be hampered due to the lack of a reliable chronology, especially when the stratigraphy is disturbed and conventional dating methods cannot be readily applied. The noble-gas radioisotopes 81Kr and 39Ar can in these cases provide robust constraints as they yield absolute, radiometric ages. 81Kr (half-life 229 ka) covers the time span of 50-1300 ka, which is particularly relevant for polar ice cores, whereas 39Ar (half-life 269 a) with a dating range of 50-1800 a is suitable for high mountain glaciers. For a long time the use of 81Kr and 39Ar for dating of ice samples was hampered by the lack of a detection technique that can meet its extremely small abundance at a reasonable sample size.

Here, we present 81Kr and 39Ar dating of Antarctic and Tibetan ice cores with the detection method Atom Trap Trace Analysis (ATTA), using 5-10 kg of ice for 81Kr and 2-5 kg for 39Ar. Recent advances in further decreasing the sample size and increasing the dating precision will be discussed. Current studies include 81Kr dating in shallow ice cores from the Larsen Blue ice area, East Antarctica, in order to retrieve climate signals from the last glacial termination. Moreover, an 39Ar profile from a central Tibetan ice core has been obtained in combination with layer counting based on isotopic and visual stratigraphic signals. The presented studies demonstrate how 81Kr and 39Ar can constrain the age range of ice cores and complement other methods in developing an ice core chronology.

 

[1] Z.-T. Lu, Tracer applications of noble gas radionuclides in the geosciences, Earth-Science Reviews 138, 196-214, (2014)
[2] C. Buizert, Radiometric 81Kr dating identifies 120,000-year-old ice at Taylor Glacier, Antarctica, Proceedings of the National Academy of Sciences, 111, 6876, (2014)

[3] L. Tian, 81Kr Dating at the Guliya Ice Cap, Tibetan Plateau, Geophysical Research Letters, (2019)

http://atta.ustc.edu.cn
Streamflow change induced by climate change and vegetation recover in a karst region of southwest China
Authors: Cai Lianbin , Chen Xi , Zhang Zhicai
Published: March 2021

In carbonate rock regions, the bedrock compositions strongly influence regolith properties that, in turn, might play the primary role in plant growth and hydrological processes. Since bedrock experiences uneven weathering processes due to different regolith materials in a karst area, how hydrological functions of bedrock layer and overlying vegetation rely on the bedrock weathering degree is seldom investigated. The objectives of this study are to quantify the impacts of climate change and reforestation on runoff in a watershed with two main bedrocks (dissolvable carbonate rock in karst area and detrital rock in non-karst area) in southwest China. The analyses are firstly executed by decomposion of the hydro-meteorological series into two series (T1, 1992-2003 and T2, 2004-2015), which have different hydro-meteorological responses due to reforestation. This study investigates the impacts of climate change and reforestation on runoff using two approaches: the sensitivity-based approach (Budyko hypothesis) is applied to estimate the overall watershed change in runoff attributed to human activities and climate change, and a distributed hydrological model based on simple soil water balance routing is used to estimate change in runoff and hydrographs in the two main bedrock areas. The results show that the hydrological modelling overestimates climate induced decrease of streamflow (88.6%), compared to estimated result by the Budyko formula (76.6%). The decrease of mean precipitation from T1 to T2 in the non-carbonate area is very close to the carbonate area, the proportion of the climate change induced decrease of streamflow in the non-carbonate area (86.3%) is less than the carbonate area (90.5%), indicating that the drier climate tendency takes a greater effect on decrease of streamflow in the carbonate area than the non-carbonate area. By contrast, there is a greater alteration of land cover/use in the non-carbonate area than the carbonate area. These findings will help develop a better understanding of the impact of climate change and reforestation on runoff in southwest China.
Load-Tide Sensitivity to 3-D Earth Structure
Authors: Martens Hilary R , Boehm Christian , van Driel Martin , Khan Amir
Published: March 2021

Earth deformation caused by the tidal redistribution of ocean mass is governed by the material properties of Earth's interior. Surface displacements induced by ocean tidal loading can exceed several centimeters over periods of hours. The rich spectrum of elastic and gravitational responses of the solid Earth produced by the load tides are predominantly sensitive to crust and upper-mantle structure, and inverting load-tide observations for Earth structure can complement independent constraints inferred from seismic tomography and Earth's body tides. 

Global Navigation Satellite Systems (GNSS) record the load-tide displacements with sub-millimeter precision and at high temporal resolution on the order of minutes. Recent studies have demonstrated agreement between predicted and GNSS-observed oceanic load tides in several regions worldwide to a similar level of accuracy. However, residuals between load-tide observations and predictions, which have been limited to spherically symmetric models for Earth structure, exhibit spatially coherent patterns that cannot be fully explained by random measurement or tide-model error and therefore present key opportunities to refine our understanding of Earth's 3-D structure at depths important to mantle convection and plate tectonics. 

Here, we present a novel numerical approach based on a preconditioned conjugate-gradient solver and the spectral-element method to investigate the sensitivities of Earth's load tides to 3-D variations in elastic Earth structure, including ellipticity, topography, and lateral contrasts in elasticity, density and crustal thickness. We leverage and extend the Salvus high-performance library to include gravitational physics and to solve quasi-static problems. High-order shape transformations and adaptive mesh refinement allow us to capture the spatial heterogeneity of the ocean tides with kilometer resolution as well as the large scale of exterior domain, which is needed to model the gravitational potential at reasonable computational cost. We perform a series of benchmark tests to verify the 3-D numerical-modeling approach against established quasi-analytical methods for modeling load-induced Earth deformation (LoadDef software). We then compute the sensitivities of load-induced surface displacements to 3-D Earth structure in two ways: (1) direct comparison of predicted surface displacements computed using 1-D and 3-D Earth models, and (2) direct computation of derivatives of surface displacements with respect to density and elasticity structure using the adjoint method.

Additional high-impact applications of the surface-load modeling capabilities include: quantifying seasonal fluctuations in mountain snowpack, tracking the depletion of groundwater reservoirs during periods of drought, improving constraints on ocean-tide models and refining the load-tide corrections employed in GNSS signal processing.
Improving representation of zero flows in probabilistic hydrological modelling of ephemeral catchments
Authors: Kavetski Dmitri , McInerney David , Thyer Mark , Lerat Julien , Kuczera George
Published: March 2021

Ephemeral catchments, where streamflow is frequently zero or negligible, are common across the world yet difficult to model reliably. This paper evaluates probabilistic approaches for modelling streamflow in ephemeral catchments, with a focus on the description of predictive uncertainty using residual error models.

We compare an explicit treatment of zero flows using a censoring approach versus a simpler pragmatic approach where the lower streamflow bound of zero is applied in prediction only. Following a theoretical exposition, empirical comparisons are reported using a daily rainfall-runoff model (GR4J), four residual error schemes (based on log, log-sinh and Box-Cox (BC) transformations with power parameter L = 0.2 and 0.5), 74 Australian catchments with diverse hydroclimatology, and five performance metrics, including reliability, precision, bias and proportion of zero flow days.

The explicit approach is most beneficial in "mid-ephemeral" catchments (5-50% zero flows) where it offers substantial improvements over the pragmatic approach. The BC0.2 and BC0.5 transformations are Pareto optimal: BC0.2 achieves better characterisation of predictive uncertainty, whereas BC0.5 attains lower volumetric bias. In "low-ephemeral" catchments (<5% zero flows) the pragmatic approach is sufficient, whereas in "high-ephemeral" catchments (>50% zero flows) both approaches incur limitations and further method development is warranted. The findings provide guidance on improving probabilistic streamflow predictions in ephemeral catchments.
Citation and credit: The role of researchers, journals, and repositories to ensure data, software and samples are linked to publications with proper attribution.  
Authors: Stall Shelley , Glaves Helen , Hanson Brooks , Lehnert Kerstin , Robinson Erin , Wyborn Lesley
Published: March 2021

The Earth, space, and environmental sciences have made significant progress in awareness and implementation of policy and practice around the sharing of data, software, and samples.  In specific, the Coalition for Publishing Data in the Earth and Space Sciences (https://copdess.org/) brings together data repositories and journals to discuss and address common challenges in support of more transparent and discoverable research and the supporting data.  Since the inception of COPDESS in 2014 and the completion of the Enabling FAIR Data Project in 2019, work has continued on the improvement of availability statements for data and software as well as corresponding citations.  

As the broad research community continues to make progress around data and software management and sharing, COPDESS is focused on several key efforts. These include 1) supporting authors in identifying the most appropriate data repository for preservation, 2) validating that all manuscripts have data and software availability statements, 3) ensuring data and software citations are properly included and linked to the publication to support credit, 4) encouraging adoption of best practices. 

We will review the status of these current efforts around data and software sharing, the important role that repositories and researchers have to ensure that automated credit and attribution elements are in place, and the recent publications on software citation guidance from the FORCE11 Software Implementation Working Group.
Light absorption and fluorescence characteristics of water-soluble organic compounds in carbonaceous particles at a typical remote site in the southeastern Himalayas and Tibetan Plateau
Authors: Zhang Chao , Chen Meilian , Kang Shichang , Yan Fangping , Li Chaoliu
Published: March 2021

Carbonaceous particles play an important role in climate change, and the increase in their emission and deposition causes glacier melting in the Himalayas and the Tibetan Plateau (HTP). This implies that studying their basic characteristics is crucial for a better understanding of the climate forcing observed in this area. Thus, we investigated characteristics of carbonaceous particles at Yaze village, a typical remote site of southeastern HTP.  The results showed that the organic carbon and elemental carbon concentrations at this study site were 1.86 ± 0.84 and 0.18 ± 0.09 μg m-3, respectively, which were much lower than those reported for other frequently monitored stations in the same region. Thus, these values reflect the background characteristics of the study site. Additionally, the absorption coefficient per mass (α/ρ) of water-soluble organic carbon (WSOC) at 365 nm was 0.60 ± 0.19 m2 g-1, which was lower than those reported for other remote stations in the HTP. This value could be attributed to a lower and higher contribution of mineral dust and secondary organic carbon, respectively. Multi-dimensional fluorescence analysis showed that the WSOC consisted of approximately 37% and 63% protein and humic-like components, respectively, and the latter was identified as the determining component of light absorption ability of the WSOC. Combined the significant relationships between WSOC and sulfate ion, potassium ion, and nitrate ion with the air masses at the study site originated primarily from South Asia, it is suggested that the levels of carbonaceous particles in Yaze village were predominantly influenced by emissions from South Asia.