bluuebunny/crossref_metadata_2025 huggingface dataset:
Decoupling strategy for large-scale multiphysics joint inversion
Authors: Molodtsov Dmitry , Kiyan Duygu , Bean Christopher
Published: March 2020

We present a generalized 3-D multiphysics joint inversion scheme with a focus on large-scale regional problems. One of the key features of this scheme is the formulation of the structure coupling as a sparsity-promoting joint regularization. This approach makes it possible to simplify the structure of the objective function and to keep the number of hyperparameters relatively low, so that the inversion framework complexity scales well with respect to the number of geophysical methods and possible reference models used. To further simplify adding geophysical solvers to the framework and to optimize the discretization, we propose an alternating minimization scheme that decouples the inversion and the joint regularization steps. Decoupling is achieved by introducing an auxiliary multi-parameter model. This allows the individual subproblems to make use of problem-tailored grids and specialized optimization algorithms. As we will see, this is in particular important for the regularization subproblem. In contrast to straightforward 'cooperative inversion' formulation, decoupled inversion steps appear to be regularized by a standard quadratic model-norm penalty, and as a result existing separate inversion codes can be used with minimal, if any, modifications. The developed scheme is applied to magnetotelluric, seismic and gravity data and tested on synthetic model examples.
Lapse Rate Characteristics in Ice Clouds Inferred from GPS RO and CloudSat Observations
Authors: Yang Shengpeng
Published: March 2020

GPS Radio Occultation (RO) cloudy profiles during a seven-year period from 2007 to 2013 over the globe are firstly selected and grouped into four types of ice clouds (e.g., nimbostratus, deep convective, cirrus, altostratus) based on collocated CloudSat data. Vertical temperature profiles within ice clouds below -20oC are then retrieved from GPS RO refractivity observations, in which the vertical profiles of ice water content required by the forward model of refractivity are obtained from CloudSat retrievals of ice water content. Vertical distributions of relative humidity and lapse rate within clouds are finally examined in terms of their occurrences, mean values and standard deviations. It is found that ice clouds have preferred values of relative humidity and lapse rate depending on cloud types and altitudes. Most altostratus ice clouds are located between 4-8 km with relative humidity between 55-75%. The cirrus clouds have a relative humidity around 60% and are located mostly above 6 km to as high as 13 km. Difference from cirrus and altostratus ice clouds, nimbostratus ice clouds that occur mostly in polar regions are found at all altitudes below 10 km with a relative humidity decreasing linearly from about 90% near the surface to about 60% around 6 km. Within deep convective ice clouds, the relative humidity also decreases linearly from about 100% around 2.5 km to about 60% around 9 km. The lapse rate slightly increases with altitude and its value ranges between 5-8oC km-1 within nimbostratus, deep convective and altostratus ice clouds. The lapse rate within cirrus clouds varies from 6oC km-1 to 9oC km-1. Vertical variations of the lapse rate derived from GPS RO cloudy retrievals compared favorably to those derived from radiosonde profiles. Both show the mean lapse rate increases with altitude from about 5oC km-1 around 3 km to about 7oC km-1 around 7 km, and the standard deviations are much smaller than the mean lapse rate.
New insights into secondary organic aerosol from nitrate oxidation of isoprene in the atmospheric simulation chamber SAPHIR
Authors: Fry Juliane L. , Brownwood Bellamy , Hohaus Thorsten , Turdziladze Avtandil , Carlsson Philip , Tsiligiannis Epameinondas , Hallquist Matthias , Novelli Anna , Fuchs Hendrik ,   NO3Isop Campaign at SAPHIR chamber, August 2018
Published: March 2020

Experiments at a set of atmospherically relevant conditions were performed in the atmospheric simulation chamber SAPHIR, investigating the oxidation of isoprene by the nitrate radical (NO3). A comprehensive set of instruments detected trace gases, radicals, aerosol properties and hydroxyl (OH) and NO3 radical reactivity. The chemical conditions in the chamber were varied to change the fate of the peroxy radicals (RO2) formed after the reaction between NO3 and isoprene, and seed aerosol of varying composition was added to initiate gas/aerosol partitioning. This presentation discusses observed gas/aerosol partitioning of the major organic nitrate products and summarizes the observations of secondary organic aerosol yield.
Potassium estimation of cotton leaves based on hyperspectral reflectance
Authors: Teixeira Adunias dos Santos , Oliveira Marcio Regys Rabelo , Moreira Luis Clenio Jario , Machado Francisca Ligia de Castro , Lopes Fernando Bezerra , Araújo Isabel Cristina da Silva
Published: March 2020

Potassium estimation on plant leaves can help monitor metabolic processes and plant health. The detailed study of hyperspectral data on leaves can therefore be a strong ally in the nutritional diagnosis of plants and can be applied to an on the go systems for precision farming application. In this study, reflectance spectra of cotton leaves were analysed for an assessment of potassium deficiency in cotton plants (Gossypium hirsutum L. ‘BRS 293’). The crop was planted in a greenhouse in the experimental area of the Federal University of Ceara (UFC), Fortaleza, Brazil.  Irrigated cotton plants were submitted to four different doses of potassium with twenty replications (n= 80) over 119 days. The following treatments were applied: 50%, 75%, 100% and 125% of the recommended potassium dose. Hyperspectral reflectance spectra data were collected using a Fieldspec ProFR 3 during full flowering, the phenological stage most demanding of potassium. Multivariate statistical techniques were applied to the raw data, the transformed data by derivative analysis, and by the technique of continuum removal. Band selection was carried out by the stepwise method in order to fit a PLSR model focused on identifying bands that are most sensitive to variations in potassium leaf concentrations. Model performance was evaluated by adjusted correlation coefficients – R2adj, root mean square error - RMSE, and residual prediction deviation - RPD. Validation results indicated that the PLSR model accounted for 82.0% of the variation in leaf potassium concentration, with a RMSE of 3.74 and RPD of 1.61. Therefore, the discrimination of potassium deficiencies in cotton using hyperspectral data was satisfactorily performed by a PLSR model composed of 13 wavelengths, of which most are commonly associated with moisture, lignin, cellulose, sugar and protein concentrations in cotton leaves.
A neural-based bio-regionalization of the Mediterranean Sea using satellite and Argo-float records
Authors: El Hourany Roy , Bowler Chris , Mejia Carlos , Crépon Michel , Thiria Sylvie
Published: March 2020

The regionalization of the Mediterranean Sea has been the subject of many studies. It is a miniature ocean where most of the processes of the global ocean are encountered (Lejeusne et al., 2010). Several features of the Mediterranean (near-tropical ocean in summer with a well-formed thermocline, near-polar ocean in winter with deep convection, multiple basins with different characteristics) make it a hotspot of marine biodiversity (Coll and al., 2010) and consequently vulnerable to climate change. It is therefore important to characterize the present state of the Mediterranean Sea with robust estimators in order to study the long-term evolution of this mesocosm.

We present a partitioning of the Mediterranean Sea in regions having well defined characteristics with respect to Sea Surface Temperature and surface chlorophyll observed by satellite, and Argo mixed layer depth. This regionalization was performed by using an innovative classification based on neural networks, the so-called 2S-SOM. Its major advantage is to consider the specificity of the variables by adding automatically, through machine learning, specific weights to each of them, which facilitates the classification and consequently highlights the regional correlations. The 2S-SOM provided a well differentiated regionalization of the Mediterranean Sea waters into seven bioregions governed by specific physical and biogeochemical processes such as Intermediate-water formation in the Aegean Sea, large surface currents in the Adriatic and the Alboran, deep winter convection phenomena in the Balearic and stratification phenomena during summer in the eastern part of the Mediterranean Sea.

Besides, in order to highlight the phytoplankton diversity in these regions, we processed the satellite ocean color observations with a specific neural network approach (SOM-PFT, El Hourany et al., 2019). As a result, specific phytoplankton communities characterized by their seasonal variability are associated with the obtained Mediterranean bioregions; the dominance of the Nanophytoplankton groups is largely observed in the western basin during the period ranging from autumn to spring. While the dominance of different types of cyanobacteria Synechococcus and Prochlorococcus is highlighted in summer and more precisely in the waters of the eastern basin. Diatoms dominate throughout the year in the coastal and shallow regions, which can be explained by the presence of terrigenous input necessary for the development of this type of phytoplankton. Diatoms also largely benefit from the strong deep convection in the Balearic Sea marked by a large bloom at the end of winter convection in March.

This work will be further extended to study the phytoplankton diversity at global scale using various data set from the Tara Oceans.
Multifactor colorimetric analysis on pH-indicator papers: an optimized approach for direct determination of ambient aerosol pH
Authors: Li Guo , Su Hang , Ma Nan , Zheng Guangjie , Kuhn Uwe , Li Meng , Klimach Thomas , Pöschl Ulrich , Cheng Yafang
Published: March 2020

Direct measurement of the acidity (pH) of ambient aerosol particles/droplets has long been a challenge for atmospheric scientists.  A novel and facile method was introduced recently by Craig et al. (2018), where the pH of size-resolved aerosol droplets was directly measured by two types of pH-indicator papers (pH ranges: 0 – 2.5 and 2.5 – 4.5) combined with RGB-based colorimetric analyses using a model of G-B (G minus B) versus pH2.  Given the wide pH range of ambient aerosols, we optimize the RGB-based colorimetric analysis on pH papers with a wider detection range (pH ~ 0 to 6).  Here, we propose a new model to establish the linear relationship between RGB values and pH: pHpredict = a×Rnormal + b×Gnormal + c×Bnormal.  This model shows a wider applicability and higher accuracy than those in previous studies, and is thus recommended in future RGB-based colorimetric analyses on pH papers.  Moreover, we identify one type of pH paper (Hydrion® Brilliant pH dip stiks, Lot Nr. 3110, Sigma-Aldrich) that is more applicable for ambient aerosols in terms of its wide pH detection range (0 to 6) and strong anti-interference capacity.  The determined minimum sample mass (~ 180 µg) highlights its potential to predict aerosol pH with a high time resolution (e.g., ≤ 1 hour).  We further show that the routinely adopted way of using pH color charts to predict aerosol pH may be biased by the mismatch between the standard colors on the color charts and the real colors of investigated samples.  Thus, instead of using the producer-provided color chart, we suggest an in-situ calibration of pH papers with standard pH buffers.

Reference:

Craig, et al., Direct determination of aerosol pH: Size-resolved measurements of submicrometer and supermicrometer aqueous particles. Analytical Chemistry, 90 (19), 11232-11239, 2018.

Cheng, et al., Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China. Science Advances, 2 (12), e1601530, 10.1126/sciadv.1601530, 2016.

Zheng, et al., Exploring the severe winter haze in Beijing: The impact of synoptic weather, regional transport and heterogeneous reactions. Atmospheric Chemistry and Physics, 15, 2969-2983, 2015.

Li, et al., Multifactor colorimetric analysis on pH-indicator papers: an optimized approach for direct determination of ambient aerosol pH, Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2019-394, in review, 2019.
Cortical deformation in the Aguacaliente-Navarro fault system (Central Valley, Costa Rica) from Geodetic data (GNSS and InSAR)
Authors: Portela Fernández Juan José , Staller Vázquez Alejandra , Béjar Pizarro Marta
Published: March 2020

The Central Valley, Costa Rica, is subject to moderate seismicity, related to the Central Costa Rica Deformation Belt: a region with diffuse deformation, where Caribbean, Cocos and Nazca Plates, as well as the Panama Micro-plate, interact.  The Eastern part of the valley is dominated by the Aguacaliente-Navarro fault system. The city of Cartago was destroyed by an earthquake Ms 6.4 in 1910, associated with the rupture of the Aguacaliente fault. Volcanic unrest –mainly in Turrialba Volcano, with recent activity reported- is present in the area, thus resulting in a very complex interaction zone, where seismic hazard studies are crucial.

In this context, we process GNSS observations from five different campaigns -2012, 2014, 2016, 2018 and 2020- in 13 stations in the area, in order to estimate their Caribbean-fixed velocities, hence the regional cumulative strain. Additionally, we use both InSAR and GNSS data to measure volcanic deformation, aiming to refine the computed velocities by removing volcanic deformation from the tectonic signal.

The refined velocities allow us to asses a more precise cumulative strain for the Aguacaliente-Navarro fault system, which is useful to improve seismic hazard assessment in Cartago, one of the most important cities in the region.
Rapid Antarctic ice sheet retreat under low atmospheric CO2
Authors: Beltran Catherine , Golledge Nicholas R. , Ohneiser Christian , Kowalewski Douglas E. , Sicre Marie-Alexandrine , Hageman Kimberly J. , Smith Robert O. , Wilson Gary S. , Mainié François
Published: March 2020

Over the last 5 Million years, outstanding warm interglacial periods (i.e. ‘super-interglacials’) occurred under low atmospheric CO2 levels that may feature extensive Antarctica ice sheet collapse. Here, we focus on the extreme super-interglacial known as Marine Isotope Stage 31 (MIS31) that took place 1.072 million years ago and is the subject of intense debate.

Our Southern Ocean organic biomarker based paleotemperature reconstructions show that the surface ocean was warmer by ~5 °C than today between 50 °S and the Antarctic ice margin. We used these ocean temperature records to constrain the climate and ice sheet simulations to explore the impact of ocean warming on the Antarctic ice sheets. Our results show that low amplitude short term oceanic modifications drove the collapse of the West Antarctic Ice Sheet (WAIS) and deflation of sectors of the East Antarctic Ice Sheet (EAIS) resulting in sustained sea-level rise of centimeters to decimeters per decade.

We suggest the WAIS retreated because of anomalously high Southern Hemisphere insolation combined with the intrusion of Circumpolar Deep Water onto the continental shelf under poleward-intensified winds leading to a shorter sea ice season and ocean warming at the continental margin. Under this scenario, the extreme warming we observe likely reflects the extensively modified oceanic and hydrological circulation patterns following ice sheet collapse. Our work highlights the sensitivity of the Antarctic ice sheets to relatively minor oceanic and/or atmospheric perturbations that could be at play in the near future.
Using the Aerodyne Mobile Laboratory to characterize industrial emissions in Southern California
Authors: Daube Conner , Dyroff Christoph , Fortner Edward , Krechmer Jordan , Majluf Francesca , Yacovitch Tara , Herndon Scott
Published: March 2020

During late 2019, the Aerodyne Mobile Laboratory sampled numerous industrial areas primarily in the County of Los Angeles, California, USA. Commercial and laboratory-grade instruments were used to analyze the gaseous and particulate composition of ambient air samples while operating in mobile and stationary modes. Measurements of CO2, CH4, and N2O were collected in addition to several specific hazardous air pollutants. Short-lived plumes from a wide variety of industries and broader regional trends were observed. Multi-day measurements at identified sources and overnight sampling added depth and context to these findings. Results from this characterization of industrial emission sources, including analysis of both greenhouse gases and pollutants in the urban environment, will be presented.
Investigating the Causes of Roads Deterioration in the Form of Potholes using Non-Destructive Testing
Authors: Naveed Muhammad , Turrakheil Kanishka S. , Tosti Fabio , Alani Amir M.
Published: March 2020

Potholes are one of the public’s main local concerns as they cost a lot to the economy in terms of repair bills, delays while repairs are carried out and vehicle wear-and-tear. According to the Annual Local Authority Road Maintenance (ALARM) survey, eliminating the pothole backlog in England and Wales would cost £9.8bn and take a decade to complete despite increased local roads investment. The aim of this study is to research why potholes occur in the first place using non-destructive testing (NDT) and potential remedies in terms of the development of effective design and innovative materials to prevent their formation in future.

To investigate the causes of potholes formation, in-situ use of NDT methods such as ground-penetrating radar (GPR) has proven effectiveness as roads remain in continuous use. Analysis of GPR data can provide information on layer depths, material condition, moisture, voiding, reinforcement and location of other features [1, 2, 3].

Through our results, we will test two hypothesis; (i) shallow potholes are formed on loss of adhesion of the surface course, (ii) deep potholes are formed due to the loss of bearing capacity or settlement of the subgrade. Poor drainage in combination of heavy loads trigger shallow potholes while extreme wetting-drying cycles as a result of climate change decayed subgrade conditions of the pavement.

Results presented in this abstract are part of a PhD project funded by the University of West London.

 

References

[1] Saarenketo, T. and T. Scullion (2000). Road evaluation with ground penetrating radar. Journal of Applied Geophysics (43): 119–138.

[2] Benedetto, A., Tosti, F., Bianchini Ciampoli, L., and F. D’Amico (2016). An overview of ground-penetrating radar signal processing techniques for road inspections. Signal Processing (132): 201-209.

[3] Benedetto, A., Benedetto, F., and F. Tosti (2012). GPR applications for geotechnical stability of transportation infrastructures. Nondestructive Testing and Evaluation, 27 (3): 253–262.
Understanding drought stress in winter wheat using UAV thermal and multispectral data
Authors: Antoniuk Vita , Peng Junxiang , Manevski Kiril , Sørensen Kirsten Kørup , Larsen Rene , Andersen Mathias Neumann
Published: March 2020

This abstract is for SUPPORT APPLICATION.

Drought is the most significant stress that reduces crop yield, hence, agricultural irrigation is the major consumer of freshwater worldwide. There is everlasting need to improve irrigation applications in order to increase water use efficiency and save water. Conventional methods to estimate crop water status and within-field variability are precise, yet, highly demanding for time and manpower. Remote sensing in the reflective and the emissive spectrum with unmanned aerial vehicle (UAV) holds potential to detect drought stress by observing canopy status over a larger area. A common method to detect drought stress using UAV thermal imagery is the Crop Water Stress Index (CWSI), which does needs improvement and parametrization for cereal crops such as winter wheat.
Field experiment with winter wheat was performed in 24 plots (30 m x 30 m) under three different irrigation regimes in 2018 (drought year) and 2019 (normal year) in Denmark. Thermal and multispectral data on UAV scale were collected during the growth period. Plant physiology, i.e., stomatal conductance, leaf water potential and canopy cover was measured, in addition to soil water content. Crop water deficit was estimated through comparison of the variability of canopy temperature and plant physiological changes. The resulting correlation pointed on clear possibility to quantify crop water status using thermal data, which is useful to develop a site-specific application of irrigation. Further work involves parameterization of CWSI and calculation of and comparison with other indices to test for improvements.
Determination on iron species in plagioclase crystals toward the understanding on the magnetite exsolution
Authors: Nakada Ryoichi , Sato Masahiko , Ushioda Masashi , Tamura Yujiro , Yamamoto Shinji
Published: March 2020

Speciation analysis of Fe in single plagioclase crystals separated from two different gabbros was performed to understand the crystallization mechanisms of magnetite exsolution. Iron species in single crystals were measured using Fe K- and LIII-edge X-ray absorption fine structure (XAFS) analysis. The K-edge pre-edge analysis showed variation in the averaged valence state of Fe in plagioclase crystals even if they had been separated from the same gabbro that was further confirmed by the LIII-edge analysis. The K-edge pre-edge analysis also suggests the various degrees of contribution from tetrahedral Fe. The mixing of tetrahedral and octahedral Fe leads to an underestimation of the averaged valence state of Fe for the K-edge pre-edge analysis; thus, we adopted the LIII-edge result for the valence state of Fe in plagioclase crystals. Iron K-edge extended XAFS (EXAFS) analysis of two plagioclase crystals separated from the same gabbro clearly showed different coordination environments. A weakening of EXAFS oscillation was recognized in one sample, because two Fe‒O bonds (Fe3+‒O1 and Fe2+‒O2) cancelled out the oscillations of each other. The EXAFS spectrum of the other plagioclase crystal suggested a homogeneous distribution of Fe. The content of exsolved magnetite in these crystals is nearly identical, indicating that the exsolution of magnetite in plagioclase crystal had been completed before the temperature decrease that stopped the ordering of Fe ions in tetrahedral sites.

Reference: Nakada et al. (2019) G-Cubed, vol. 20 (11), 5319-5333.
Mapping the Oxidizing Capacity of the Global Remote Troposphere
Authors: Nicely Julie , Wolfe Glenn , St. Clair Jason , Hanisco Thomas , Liao Jin , Oman Luke , González Abad Gonzalo ,   ATom Science Team
Published: March 2020

Observations from the NASA Atmospheric Tomography Mission (ATom) have elucidated a strong relationship between the production of hydroxyl radical (OH), the primary oxidant of the troposphere, and formaldehyde (HCHO), a major product of the oxidation of methane and other hydrocarbons.  We present a proxy for global over-ocean OH based on this principle, using remote observations of HCHO from the Ozone Monitoring Instrument (OMI).  Analysis of summer and wintertime remote OH from this proxy suggest a near-constant mean concentration of 1.03 ± 0.25 × 106 cm−3 and a Northern Hemisphere to Southern Hemisphere over-ocean OH ratio of 0.89 ± 0.06 averaged over both seasons (1s uncertainties).  We also share ongoing efforts to expand on this approach by refining the scaling factors that relate OH production to HCHO as a function of CO, NOx, and VOCs, with the goal of extending the proxy over land as well as across the OMI record.
In situ measurement for tropospheric OH radical by Laser Induced Fluorescence technique during STORM campaign
Authors: Wang Fengyang , Hu Renzhi , Xie Pinhua , Wang Yihui , Lou Shengrong , Lu Keding , Zhang Guoxian , Liu Jianguo , Liu Wenqing
Published: March 2020

Hydroxyl (OH) play an essential role in atmospheric chemistry. OH radical is an indicator of atmospheric oxidation and self-purification, which determines the removal of most trace gases in the atmosphere, such as CO, SO2, NO2, CH4 and other volatile organic compounds (VOCs). A ground-based system for measurement of tropospheric OH radical by Laser Induced Fluorescence technique (AIOFM-LIF) was developed and integrated into a mobile observation platform for field observation. Ambient air expands through a 0.4 mm nozzle to low pressure. OH radical is irradiated by the 308 nm laser pulse at a repetition rate of 8.5 kHz, accompanying the release fluorescence of the A2Σ+(v’=0)—X2Πi(v’’=0) transition at 308 nm with the resultant fluorescence being detected by gated photon counting. The detection sensitivity of AIOFM-LIF system was calibrated by a portable standard OH radical source based on water photolysis-ozone actinometry. Following laboratory and field calibrations to characterise the instrument sensitivity, OH radical detection limits were (1.84±0.26) × 105 cm-3 and (3.69±0.52) × 105 cm-3 at night and noon, respectively. During “A comprehensive STudy of the Ozone foRmation Mechanism in Shenzhen” (STORM) campaign, AIOFM-LIF system was deployed in Shenzhen, China, and OH radical concentration was obtained validly except for the rainy days. Mean diurnal variation of HOx radical concentration was obtained, and the peak was 6.6×106 cm-3 which appeared around 12:00 at noon. A general good agreement of OH radical concentration with j(O1D) was observed with a high correlation (R2 =0.77), which illustrates that photolysis of ozone is an important source of OH radical during this campaign. A box model was applied to simulate the concentrations of OH at this field site, the primary production of OH radical was generally dominated by photolysis of O3, HONO, HCHO, while the other production was contributed by calculated species (OVOCs).
Application of UAV in measurements of earth structure deformation
Authors: Bochniarz Agata , Wójcik Anna , Puniach Edyta , Ćwiąkała Paweł
Published: March 2020

Unmanned Aerial Vehicles (UAV) are currently one of the most popular methods of colleting photogrammetric data. A short time of data acquisition and low costs are the key advantages of this solution, especially important during cyclical measurements of various types of objects.

The aim of this paper is to assess the possibility of using images obtained from UAV to determine the deformation of earth structures. The object of measurement was Krakus Mound located in Cracow (Poland). It is one of the oldest mounds in Cracow, preserved to this day. The history of this hill is unknown but it is assumed that the mound was built in stages. In 2013, the site was renovated.

As a part of the research, between 2015 and 2019, cyclic photogrammetric flights were carried out over Krakus Mound. For this purpose, DJI S900 aircraft equipped with a non-metric visible light camera Sony Alpha a6000 was used. The measurements were taken every year in spring and autumn. In total, 7 measurement sessions were performed, during which the coordinates of ground control points and check points were measured each time. As part of fieldwork, numerous comparative measurements were also carried out using other surveying instruments, such as GNSS receivers, total stations and terrestrial laser scanner.

This paper presents the results of research aimed at observing the geometry of the mound in 2015-2019. Low-altitude images obtained in combination with the Structure from Motion technique allowed to generate photogrammetric products to determine the deformation of the object. Generated UAV-derived point clouds and digital terrain models were used for the analyses. They were compared with reference data, i.e. photogrammetric products created on the basis of data obtaining during the first UAV flight and the results of total station and satellite measurements. This made it possible to determine the influence of the low vegetation on the results of measurements and to check whether the object is deforming. The research also included terrestrial laser scanning of the mound and usage of available LiDAR data to compare scanning data with low-altitude photogrammetric products. Numerous analyses allowed to create methodology of inventory measurements of earth structure covered with low vegetation using UAV-based photogrammetry. 
Land use effects on C-N-and P stocks and greenhouse gas fluxes in agroecosystems in southern Chile
Authors: Perez-Quezada Jorge , Cano Silvia , Ibaceta Patricia , Aguilera David , Salazar Osvaldo , Galleguillos Mauricio , Osborne Bruce
Published: March 2020

Agricultural and animal production are normally considered activities that degrade soils and are sources of greenhouse gases (GHG), such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Here, we present a detailed description of the carbon (C), nitrogen (N) and phosphorus (P) stocks in croplands (CR), grasslands (GR), native shrublands (NS) and invasive shrublands (IS) at three locations of northern Chiloé Island, southern Chile. Also, using a portable chamber system (1 m3), the three GHG fluxes were measured one day per month, for one year (2018). The results showed that the larger total stocks of C and N were found at the NS sites, with values of 50.5 ± 4.3 kg m-2 and 2.96 ± 0.54 kg m-2, respectively. In contrast, the larger stock of P was observed at the GR sites, with a value of 0.51 ± 0.08 kg m-2. Comparisons of the total ecosystem stocks showed no significant differences among  the agroecosystems but differed from values reported for a forest in Chiloé, which revealed a significant loss in C (58.6%) and N (11.1%) stocks in the agroecosystems, while the P stock increased by 92% compared to the forest. As net sources of CO2 acted the CR sites; net sources of CH4 were the CR, GR and IS sites; and net sources of N2O were the CR sites. The GHG balance showed that the CR sites behaved as a net source (388 g CO2-eq m-2 year-1), while GR (-1248 g CO2-eq m-2 year-1), NS (-1097 g CO2-eq m-2 year-1) and IS (-1928 g CO2-eq m-2 year-1) acted as sinks. This indicates that croplands could make an important contribution to local and regional GHG emissions. In a wider context, these results indicate that the regulation of land use conversions for agricultural use might be an effective tool to combat climate change, potentially reducing GHG emissions.
Impact of drought on C forms and fluxes in the soil – plant continuum
Authors: Rumpel Cornelia , Sanaullah Muhammad , Mora Maria de la Luz , Calabi Floody Marcela , Chabbi Abad
Published: March 2020

Global change is likely to increase the drought periods, which may have significant consequences for the turnover of SOM, in particular through their effect on plants. The aim of the study was to assess different compartments of the soil – plant continuum for their response to drought stress by combining field and laboratory experiments. We focused on three common grassland species (Lolium perenne, Festuca arundinacea and Dactylis glomerata) found to constitute grasslands of the temperate climate. We investigated drought impact on (1) plant biochemistry and potential mineralization of this material in soil, (2) decomposition of aboveground plant leaf litter of different quality, (3) plant-mediated soil C fluxes including (4) soil microbial biomass and their enzyme activities in the rhizosphere.

            Plant elemental and biochemical composition showed contrasting changes depending on the species in response to drought stress. The changes in elemental and biochemical composition of leaf litter, ultimately influenced its mineralization in soil. Drought stress highly modified the decomposition dynamics of litter from the three grassland species as a function of litter quality.

                 Moreover, drought stress resulted in significant decrease in both shoot and root biomass in monocultures, while root biomass did not change when they were grown in mixture. Under drought stress, we observed higher belowground allocation of photosynthates and the drought had reduced root-derived respiration. This resulted in significant changes of soil enzyme activities.

                Our results suggest that plant species and community composition strongly influenced drought effects in the rhizosphere. Thus, management interventions should aim at influencing rhizosphere processes through their impact on microbial activities affecting C, N and water cycles. Plant community composition and in particular the introduction of legumes might be a tool to attenuate drought stress not only because of different water use efficiency by plants, but also by their indirect effects on these processes.
A Global Map of Renormalised Mantle Dynamic Topography
Authors: Kusznir Nick , Cowie Leanne
Published: March 2020

Comparison of predicted mantle dynamic topography with observed residual topography shows that the amplitude of predicted dynamic topography is too great (Cowie & Kusznir, EPSL, 2018). This over prediction of dynamic topography amplitude most probably arises from uncertainties in the conversion of seismic velocity anomalies from mantle tomography into density anomalies and uncertainties in upper and lower mantle viscosity structure, both of which are required to compute predicted dynamic topography.

Dynamic topography renormalisation, consisting of its rescaling and shifting, is determined by comparing predicted dynamic topography with observed residual topography for “normal” oceanic crust where observations are less prone to errors than for continents, margins and oceanic plateaus. Renormalisation is then applied globally to generate an improved map of dynamic topography for the continents, other remaining oceanic areas, and the Antarctic and Arctic polar regions. An important caveat is that the renormalisation can only be calibrated for oceanic regions, and we assume that the same rescaling of predicted mantle dynamic topography can be applied to the continents.

We present and examine a new global map of mantle dynamic topography produced by renormalising the predicted dynamic topography of Steinberger et al. (2017) which includes seismic tomography above 220 km depth to determine shallow upper mantle densities.

Renormalised maximum amplitudes of mantle dynamic topography uplift for East Africa, the S.W. Pacific and Iceland are 1000, 750 and 750 m respectively. For mantle dynamic subsidence in the Argentine Basin of the S. Atlantic, the maximum amplitude is -750 m. Elongated regions of mantle dynamic uplift are predicted for the Western Cordillera of North America and West Antarctica with maximum values of 500 and 750 m respectively.

 
The NASA Mass Change Designated Observable Study: Progress and Future Plans
Authors: Wiese David , Boening Carmen , Zlotnicki Victor , Luthcke Scott , Loomis Bryant , Rodell Matthew , Sauber Jeanne , Bearden David , Chrone Jonathan , Horner Scott , Webb Frank , Bienstock Bernard , Tsaoussi Lucia
Published: March 2020

The 2017-2027 US National Academy of Sciences Decadal Survey for Earth Science and Applications from Space classified mass change as one of five designated observables having the highest priority in terms of Earth observations required to better understand the Earth system over the next decade.  In response to this designation, NASA initiated multi-center studies with an overarching goal of defining observing system architectures for each designated observable.  Here, we discuss the progress made and future plans for the Mass Change Designated Observable study. Progress includes the development of a Science and Applications Traceability Matrix, a tool that links science objectives to measurement techniques and accuracies,  for the 15 science and applications objectives listed in the Decadal Survey, as well as the definition of as many as three different architectural classes for which to achieve those objectives.  We will describe the Value Framework that is under way to assess and evaluate each observing system architectural option.  Preliminary results assessing the science value versus cost/risk of observing system architectures will be presented. In addition, future plans for the Mass Change Designated Observable Study will be discussed.
Why is there a Zonal Wave 3 pattern in the Southern Hemisphere extratropical circulation?
Authors: Goyal Rishav , Jucker Martin , Sen Gupta Alex , England Matthew
Published: March 2020

Studies of the Southern Hemisphere (SH) extratropical circulation are dominated by investigations of the zonally symmetric component of the Southern Annular Modular (SAM). However, there are significant asymmetries embedded in the zonal flow. In particular, a zonal wave 3 (ZW3) pattern is one of the dominant features of the SH circulation on daily, seasonal and interannual timescales. While the ZW3 circulation has had significant impacts on meridional heat transport and Antarctic sea ice extent in recent years, the physical mechanisms responsible for its presence still remain elusive. In this study, we use the Community Earth System Model (CESM) to understand the mechanisms that give rise to and modulate the ZW3 pattern in the SH extratropics. We examine, among other things, the popular belief that the ZW3 pattern is present due to the existence of three separate land-masses in the SH, namely Australia, Africa and South America, and whether it is modulated by both the land-ocean contrast and tropical forcing.
Development, verification and validation of a three-dimensional groundwater flow model for ESM
Authors: Miura Yosuke , Yoshimura Kei
Published: March 2020

  Groundwater is one of the important water resources in the world and Groundwater flow is linked with surface water strongly. Many studies on groundwater are conducted in a local scale or focused on affect-ing surface water in a global scale. In current Earth System Model, fixed and constant one-dimensional vertical grid is used in unsaturated zone. In real world, the thickness of unsatu-rated zone depends on the climate and it is considered that there are limitations of runoff process expression especially in humid mountainous area. In this study, we developed three-dimensional groundwater flow model as ESM which can represent the variably saturated flow and groundwa-ter storativity. Since, this model is eventually coupled with Land Surface Model, it is possible to track the underground water flow using boundary conditions of recharge and surface water level.

  We verified accuracy of the code using one & two-dimensional infiltration problem, three-dimensional groundwater pumping problem, and hillslope problem. Our model was com-pared with other researchers results, experimental data, analytical solutions. In consequence, our model was able to get accurate results. Subsequently, we conducted validation in Central valley, California, USA. The reason of chose this region is that this region is a semi-arid region, ground-water is used for irrigation and well pumping data is accessible. Over the world, groundwater use is more important in arid or semi-arid region than in humid area, and also highly utilized as agri-cultural water. Central valley has representativeness of groundwater use. In addition, the famous groundwater model, MODFLOW, was used to evaluate water resource management in this region. As well as MODFLOW, we calibrated hydraulic conductivity with 24 observation sites during 1961 - 2003 to validate. 156 observation points excluded 24 calibration points were used as vali-dation in same period. In the near future, we will confirm the difference between one-dimension and three dimensions setting of the unsaturated zone with respect to runoff process.
Using ArcticDEM to identify and quantify pan-Arctic retrogressive thaw slump activity
Authors: Dai Chunli , Jones Melissa , Howat Ian , Liljedahl Anna , Lewkowicz Antoni , Freymueller Jeffrey
Published: March 2020

With the increased availability and coverage of high resolution satellite imagery, characterizing processes at the pan-Arctic scale is now possible. This baseline pan-Arctic product will enable us to highlight areas for future research efforts and to standardize observations that are currently locally or regionally focused. The ArcticDEM project (www.arcticdem.org) has released a large collection of 2 meter resolution Digital Elevation Models (DEMs) for all land areas above 60 °N. These DEMs are created using high resolution (~0.5 m) stereo paired satellite images (by DigitalGlobe and include Worldview- 1 (launched 2007), 2 (2009), 3 (2014) and GeoEye-1 (2008) satellites). Using repeat DEMs, we are developing algorithms for automated detection to identify and quantify land surface topographic changes from Arctic volcano eruptions and mass wasting events to create a pan-Arctic mass wasting inventory, including retrogressive thaw slumps. Currently, retreat rates reported for retrogressive thaw slumping activity differ between studies, and our dataset will enable rates to be standardized for slump activity after 2007. Furthermore, our mass wasting inventory will enable us to investigate the triggers of mass wasting events and to analyze the linkages to the contributing factors including climate, topography, and geology. We will be presenting preliminary results focusing specifically on retrogressive thaw slumps, including time series analysis for topographic change detection and using field observations for validation. We welcome collaborators who can share the field or remote sensing observations to aid in our validation efforts.
Atmospheric composition changes in CMIP6 experiments over the North Atlantic region
Authors: Griffiths Paul , Keeble James , O'Connor Fiona , Archibald Alexander , Pyle John ,   UKESM1 AerChemMIP team
Published: March 2020

A grand challenge in the field of chemistry-climate modelling is understanding the connection between anthropogenic emissions, atmospheric composition and the radiative forcing of trace gases and aerosols.

The 6th phase of the Coupled Model Intercomparison Project (CMIP6) includes a number of climate model experiments that can be used for this purpose.  AerChemMIP [Collins et al.2017] focuses on calculating the radiative forcing of gases and aerosol particles over the period 1850 to 2100, and comprises several tiers of experiments designed to attribute the effect of changes in emissions. 

The UK Earth System Model, UKESM-1, is a novel climate model developed for CMIP6  [Sellar et al., 2019] and is a community research tool for studying past and future climate.  It includes a detailed treatment of tropospheric chemistry, interactive BVOC emissions and extensive stratospheric chemistry.

The North Atlantic Climate System is an area of current interest [Robson et al., 2020] and is the focus of the UKRI 'ACSIS' project.  ACSIS brings together scientists from a range of different specialisms to understand complex changes in the North Atlantic climate system.    By understanding how these changes relate to external drivers of climate, such as human activity, or natural variability, ACSIS aims to improve our capability to detect, explain and predict changes in the North Atlantic climate system.

We present an analysis of the evolution of atmospheric composition over the period 1950-2015. The work is based on a recent global multi-model evaluation of tropospheric ozone for CMIP6 [Griffiths et al., 2020] , but focuses on changes over the North Atlantic region in UKESM-1.  We draw on CMIP and AerChemMIP simulations to provide an initial survey of the response of this region to changing emissions , focusing on atmospheric composition and attempting attribution from a series of targeted experiments involving perturbed emissions .
Size-resolved effective density of submicron particles during autumn in the North China Plain
Authors: Zhou Yaqing , Ma Nan , Wang Zhibin , Xie Linhong , Xie Baofang , Zhu Shaowen , Pan Xihao , Wu Sen , Su Hang , Cheng Yanfang
Published: March 2020

Effective density is one of the most important physical property of atmospheric aerosols, which is link to particle formation and aging process. Combined characterization of density, chemical composition and source evolution of aerosol is crucial for understanding their interactions and effects on environment and climate. The effective density of sub-micrometer aerosol particles was investigate at a heavily polluted rural site in the North China Plain from 16 October to 1 November 2019. A tandem technique coupling a Centrifugal Particle Mass Analyzer (CPMA) with a differential mobility analyzer (DMA) and a Condensation Particle Counter (CPC) were used to determine the effective density of ambient aerosol particles with selected diameters of 50, 100, 150, 220 and 300 nm. The measured effective density is higher during clean period than pollution period, with average values ranged from 1.13 to 1.36 g/cm3, which is lower than the reported values in Shanghai and Beijing. Similar diurnal cycles of effective density are observed for the five diameters, that is, started to increase in the morning and reached a peak in the afternoon around 13:00-16:00, then decreased and remained at a relative low value during the night. Two valleys are found during morning and evening rush hours for particle diameter smaller than 150 nm, which is likely to stem from the higher fresh emissions such as BC, BBOA and HOA. In most cases, measured particle effective density shows a single-modal distribution. But during clean days, bimodal distribution was observed with an extra low-density mode peaking at around 0.5 -1.0 g/cm3, which may be attributed to freshly emitted soot particles.
Accelerated wind conditions: spectral shape evolution and turbulent kinetic energy dissipation from laboratory and field measurements
Authors: Robles-Diaz Lucia , Ocampo-Torres Francisco J. , Branger Hubert
Published: March 2020

A determined shape of the energy wave spectrum can be estimated from a given fetch and wind speed. Also, several studies have characterized the balance of the turbulent kinetic energy under the effect of waves and currents under constant wind conditions. However, deeper research is needed in order to characterize the wind-wave generation processes under non-stationary wind conditions. In this way, to be able to determine the uncertainty on not considering accelerated wind events in the air-sea momentum exchange estimations.

Periods of accelerated winds were analyzed from experimental and field data. On one hand, several laboratory experiments were carried out in a large wind-wave facility at the Institut Pytheas (Marseille-France). Momentum fluxes were estimated from hot wire anemometry and, the free surface displacement was measured along the wave tank by resistance and capacitance wire probes. Also, the surface drift current was measured from a profiling acoustic velocimeter. During these experiments, the wind speed goes from 2 m/s to reach the maximum wind speed of 13 m/s. A constant wind acceleration characterizes each test. On the other hand, the field data were obtained from an Oceanographic and Marine Meteorology Buoy (BOMM) located in the Gulf of Mexico, from July 2018 to February 2019. The BOMM was equipped with a sonic anemometer, capacitance wires, and an inertial motion unit. Both sets of data are characterized by a high sampling rate that allows us to directly estimate the wind stress over the sea surface. Also, provide us with useful information about the evolution of the wave spectra and enable us to determine the dissipation rate of turbulent kinetic energy. It was observed that the wind acceleration has a direct effect on the momentum transfer efficiency from the wind to the wave field and that the momentum transfer is reduced as wind acceleration increases.