bluuebunny/crossref_metadata_2025 huggingface dataset:
Short-Lived Climate Forcers over the Arctic between 1995 and 2015 as simulated by the GISS modelE2.1
Authors: Im Ulas , Tsigaridis Kostas , Whaley Cynthia H. , Faluvegi Gregory S. , Klimont Zbigniew , von Salzen Knut
Published: March 2020

The Arctic Monitoring and Assessment Programme (AMAP) is currently assessing the impacts of Short-Lived Climate Forcers (SLCF) on Arctic climate and air quality. In support of the assessment, we used the NASA Goddard Institute of Space Sciences (GISS) Earth System Model (modelE2.1), with prescribed sea surface temperature and sea-ice fraction, to simulate SLCF concentrations globally between 1995 and 2015. Two simulations were conducted, using the One-Moment Aerosol (OMA) and the Multiconfiguration Aerosol TRacker of mIXing state (MATRIX) aerosol modules. OMA is a mass-based scheme in which aerosols are assumed to remain externally mixed and have a prescribed and constant size distribution, while MATRIX is an aerosol microphysics scheme based on the quadrature method of moments, which is able to explicitly simulate the mixing state of aerosols. Anthropogenic emissions from the ECLIPSE v6b emissions database were used, along with emissions from aircrafts and open biomass burning from the Coupled Model Intercomparison Project Phase 6 (CMIP6), while the natural emissions of sea salt, DMS, isoprene and dust are calculated interactively. The simulated monthly surface concentrations of sulfate (SO4), black carbon (BC), organic carbon (OA), and ozone (O3) are compared with observations from a set of Arctic stations, extracted from the EBAS and IMPROVE databases, as well as a few additional locations. Simulated aerosol optical depths (AOD) are also compared with Advanced Very-High Resolution Radiometer (AVHRR). The study will present the evaluation of the modelE2.1 in simulating SLCF levels over the Arctic using different aerosol schemes, along with observed and simulated trends of SLCFs over the Arctic between 1995 and 2015.

 
The strong earthquake of 26 November 2019 (MW6.4) and its associate active tectonic of Durresi Region in Albania.
Authors: Ormeni Rrapo , Hoxha Ismail , Naco Petraq , Gego Dashi
Published: March 2020

On November 26, 2019, a strong earthquake (Mw6.4) occurred about 16 km, north of the Durresi city in the Adriatic Sea, and 35 km NW from the capital city of Tirana, in the western part of Albania. The main shock of November 26 at 15:20 (UTC) was followed by a great number of aftershocks.
The main event is not a shallow one, with the hypocentral depth at 39 km. This fact explains the localized destruction, not only in the epicentral zone but in a larger zone. This earthquake expresses the increase of recently seismic activity of the Adriatic seismogenic zone. The main shock has caused cracking of the earth, especially in the region where the epicenter of the earthquake is located. The largest cracks are in the vicinity of the Erzen river estuary.
These cracks have widths ranging from few cms to 1m and extending from several hundred meters to 1 km. The depth of cracking in some cases reaches into 2 meters. Those cracks are numerous and often create parallel systems between them that follow the current river bed or traces of the old river beds (paleoalvei).
Liquefaction phenomena have been observed extensively in the area between the villages of Juba and Hamallaj. In this area, there have been observed outflows of pressure water associated with sand and clays. The height of the water has often reached up to 1 meter around the water wells. The phenomenon of liquefaction in these areas has been associated with soil cracks of several cms wide and several tens of meters long.
Based on the neotectonic mapping and the focal mechanism of the mainshock, strike 219°, dip 40°, rake -90°, it is considered that the seismotectonic source that generated thisearthquake is related to NW-SE longitudinal tectonic of the Adriatic Sea. Based on the focal plane solutions provided by the IGEWE website, the mainshock was generated by the activation of an NW-SE striking thrust fault with the compression axes in the NE-SW direction.

Sea Adriatic neotectonic extend from Dalmatic coast to Ionian coast is an ancient tectonic, a reverse fault thrust, thus activated during the Quaternary geologic period to the present day, occasionally with strong earthquakes. The seismic movement has also caused a 10 cm elevation of the terrain in the epicenter of the earthquake, which has been accompanied by a coastline retreat in this area (Hamallaj beach).
The 21 September and 26 November 2019 earthquake sequences, as well as the 1926 seismic event that took place in the Durresi region, exhibit a rough NW−SE-trending structure, which is an active seismotectonic zone in western Albania, therefore constituting a threat for nearby urban areas.
NASA’s TropOMI Aerosol Products: Algorithm and Preliminary Evaluation Results
Authors: Ahn Changwoo , Torres Omar , Jaross Glen , Jethva Hiren , Xu Xiaoguang , Wang Jun , Tiruchirapalli Ramaswamy
Published: March 2020

The extended hyperspectral capability with improved spatial resolution of the S5-P/TROPOMI instrument makes it more useful than OMI for observing not only trace gases but also aerosols. We have developed a research algorithm (TROPOMAER) for retrieving aerosol properties from S5-P/TROPOMI L1-b (Version 01) radiances using a locally derived radiometric calibration. The TROPOMAER algorithm is based on the OMI aerosol algorithm (OMAERUV) which has been used for producing operational aerosol products for the last 14 years. In addition to the standard UV Aerosol Index (UVAI) product, TROPOMI measured radiances at 354 and 388 nm are used for retrieving Aerosol Extinction Optical Depth (AOD), Single Scattering Albedo (SSA) under cloud free conditions and above-cloud Aerosol Extinction Optical Depth (ACAOD). Collocated Suomi-NPP/VIIRS cloud mask product is also integrated with TROPOMAER for screening sub-pixel cloud contamination in the retrieved aerosol products. Initial evaluation results of TROPOMI aerosol products using AERONET AOD and SSA observations will be presented. We will also discuss preliminary results of new algorithmic approaches to retrieve aerosol layer height using TROPOMI Oxygen-B band observations, and aerosol type identification with SWIR measurements.
Intermittent freeze-melt pattern detected at the base of the Ronne Ice Shelf
Authors: Vankova Irena , Nicholls Keith
Published: March 2020

High salinity shelf water (HSSW) is a water mass that drives melting at the Ronne Ice Shelf, entering the sub ice shelf cavity at the western end of the ice front. To monitor the rate of ice shelf basal melting along the path of assumed HSSW inflow, a phase-sensitive radar (ApRES) was deployed and it sampled autonomously for over two years. Although the site is found to melt on average, the data show evidence of freezing occurring intermittently throughout the observed time period. Here we systematically investigate oceanographic processes that could give rise to these observations. Further, we address the question of whether ApRES can be used to quantify the rate of basal freezing.
Combining tomographic images and geodynamic modeling of past mantle flow: from simple analytical solutions to numerical inverse methods
Authors: Colli Lorenzo
Published: March 2020

Physics-based geodynamic modeling of mantle convection provide a unifying framework for solid-Earth sciences, explicitly linking together disparate fields such as tectonophysics, tomographic imaging, basin analysis, mantle mineralogy, geomorphology, global geodesy and the long-term chemical and thermal evolution of the mantle. Studying the evolution of mantle convection in time is particularly powerful as it reduces trade-offs, increase the possible linkages and the opportunities to cross-test hypotheses. But since mantle convection evolves over geologic timescales, its future evolution is precluded from us and we must focus on its past history.

Here I will show how geodynamic modeling of past mantle flow can be combined with tomographic imaging and geologic observations, highlighting the strengths of this approach and some of its potential pitfalls. I will use a series of case studies, starting from simple analytical solutions for channelized flow in the South Atlantic and Caribbean regions. I will move on to an application of sequential assimilation to the South China Sea, ending with computationally demanding large-scale numerical optimizations of past mantle flow.
Equations for climate change
Authors: Angelis Ioannis
Published: March 2020

 

 

Equations for climate change

 

The idea of this project, is to find the ecological footprint  of our school and make  estimations of the equivalent if we use reneawable energy(i.e. photovoltaic, or wind power).

This project came up , after a presentation  pupils of C class made about  the  disastrous bushfire in Australia this month and in Amazon, Brazil last  summer and how do these fires were affected by climate change.

This project is interdisciplinary involving mathematics , chemistry and phsyics.  Students  used Schoolbooks of the third grade to retrieve information , breaking thus, the student` s taboo that schoolbooks are useless outside the classroom!

 

The project`s duration is one month and it consists of the following actions:

 

Counting every day the number of plastic bottles used in the school.After  researching schoolbooks and internet, students estimate the amount of water and electric energy ( CO2 equivalent) that industry spent  to make these bottles as long as the amount of water and energy spent for recycling them . Comparing these findings with the amount of water into the bottle : 500ml. Conversation about recycling, banning plastic, consumption of energy.

Counting every day the number of paper used in the school.After researching the necessary information student estimate  the amount of water and electric energy ( CO2 equivalent) that industry spent  to make that paper as long as the amount of water and energy spent for recycling it. Conversation about recycling, reusing paper,  consumption of energy.

Counting every day for how many hours lamps, heaters, air condition etc are on , and estimating the electric energy spent (CO2 equivalent).

Estimate the photovoltaic power or wind turbine power needed to balance in annual basis the schools` energy consumption comparing them with the CO2 emissions of the previous findings.

Present these findings to the local community and   the municipal authority proposing them to initiate the insallation of renewable forms of energy in order to reduce the ecological footprint of the schools of our region.

Present case studies of isolated Greek islands pointing out  the economic and ecological outcomes of the installation of renewable forms of energy on them.

 

 

 
Twenty-Five Years of the International GNSS Service
Authors: Craddock Allison , Johnston Gary , Perosanz Felix , Dach Rolf , Meertens Charles , Moore Michael , Oyola Mayra
Published: March 2020

For over twenty-five years, the International Global Navigation Satellite System (GNSS) Service (IGS) has carried out its mission to advocate for and provide freely and openly available high-precision GNSS data and products.

The IGS is an essential component of the IAG’s Global Geodetic Observing System (GGOS), where it facilitates cost-effective geometrical linkages with and among other precise geodetic observing techniques, including: Satellite Laser Ranging (SLR), Very Long Baseline Interferometry (VLBI), and Doppler Orbitography and Radio Positioning Integrated by Satellite (DORIS). These linkages are fundamental to generating and accessing the International Terrestrial Reference Frame (ITRF).  As it enters its second quarter-century, the IGS is evolving into a truly multi-GNSS service, and at its heart is a strong culture of sharing expertise, infrastructure, and other resources for the purpose of encouraging global best practices for developing and delivering GNSS data and products all over the world.

This poster will present an update on current IGS products and operations, as well as highlights on recent organizational developments and community activities. The impacts and benefits of global cooperation and openly available data will be emphasized, and information about the IGS stations and network, contributions to the International Terrestrial Reference Frame solutions, and product applications will be presented. A summary of IGS products, with emphasis on analysis, coordination, applications, and their availability will be described. Information about efforts to form new groups supporting product generation within IGS open data and product policies will be included. Information about the themes and topics of discussion for the upcoming 2020 IGS Workshop in Boulder, Colorado, USA will also be provided.
Quantifying organic aerosol removal in the remote troposphere: Constraints on physical and chemical removal of OA provided by the ATom mission
Authors: Campuzano-Jost Pedro , Nault Benjamin , Schroder Jason , Jo Duseong , Day Douglas , Hodzic Alma , Tilmes Simone , Emmons Luisa , Ray Eric , Yu Pengfei , Bian Huisheng , Chin Mian , Colarco Peter , Newman Paul , Kodros Jack , Pierce Jeffrey , Schacht Jakob , Heinold Bernd , Tegen Ina , Jimenez Jose Luis ,   ATom Science Team
Published: March 2020

Organic aerosol (OA) is one of the major contributors to the PM2.5 burden both in the continental Northern Hemisphere and globally. Understanding its sources and aging is central to current air quality control strategies. For the remote troposphere, sparse in-situ data to date results in highly under constrained OA prediction models, with model diversity of up to three orders of magnitude in the recent AEROCOM-II comparison.  

In the course of the recent NASA Atmospheric Tomography (ATom) set of aircraft missions, we have acquired four unique global datasets of submicron aerosol concentration and composition over the remote Atlantic and Pacific Oceans. In the remote FT OA and sulfate are the main components (about 0.3 µg sm-3 in total, fairly constant outside of continental outflow. However, OA in the remote FT exhibits a much higher average carbon oxidation state than in continental airmasses (OSc up to +1 compared to -1 over the continents), much higher than assumed in most models. This also suggests a fairly hygroscopic OA. Nevertheless, in the cleanest/most remote parts of the global free troposphere (FT), sulfate predominates. This is not captured by current global models and suggests an additional chemical removal of OA (and possibly continuing formation of sulfate).

Using several different hydrocarbon-ratio based photochemical clocks in combination with back trajectories to infer the age of the airmasses sampled during ATom, we estimate that the lifetime of OA in the remote UT (after most of the convective removal has happened) is of the order of 4 days. In contrast, for chemically inert black carbon, the estimated removal timescale using the same method is significantly longer (about a week), in general agreement with previous estimates of physical removal that are used in models. The significantly shorter OA lifetime suggests an additional, chemical removal mechanism. This provides a key constraint for modeling of OA in the FT, based solely on measurements.  Both heterogeneous oxidation by OH and aerosol photolysis are possible pathways for OA removal that have been suggested previously. Sensitivity studies in CESM2 AND GEOS-Chem with updated chemistry and aerosol sources are used to constrain the relative importance of each pathway for OA removal during ATom.
Seasonal variability of evapotranspiration in the central Andes of Peru using eddy covariance techniques and empirical methods
Authors: Callañaupa Gutierrez Stephany Magaly , Segura Cajachagua Hans , Saavedra Miguel , Flores Jose , Cuxart Joan , Silva Yamina
Published: March 2020

In this study, the real evapotranspiration (ET) obtained using the eddy covariance (EC) technique from field crops located in the central Peruvian Andes (Huancayo Observatory, 12.04° S, 75.32°, 3350 msnm) is analyzed. Data from a sonic anemometer and a krypton hygrometer are used to estimate daily and monthly ET variability and to explore relationships with meteorological and surface variables. The results show that the mean value of daily evapotranspiration is estimated to be 3.45 mm/day during the wet season (January to March) while in the dry season (June to August) the value is 0.95 mm/day. In addition, linear regressions were used in order to evaluate the relationship of meteorological variables with evapotranspiration. As a result, solar radiation is the meteorological variable that has a strong relationship with evapotranspiration during the wet season (r2=0.76, p-value <0.005) and soil moisture during the dry season (r2=0.77, p-value <0.005). These results indicate a clear water-energy limitation depending on the season. Besides, the empirical evapotranspiration equations of FAO Penman-Monteith, Priestley-Taylor and Hargreaves were validated. Where the Priestley-Taylor equation is the empirical equation that best fits the observed data of evapotranspiration by EC (r2=0.70, p-value< 0.005).
Assessing the geodynamics of strongly arcuate subduction zones in the eastern Caribbean subduction setting
Authors: Fraters Menno , Spakman Wim , Thieulot Cedric , Van Hinsbergen Douwe
Published: March 2020

The eastern Caribbean Lesser-Antilles subduction system is a strongly arcuate subduction system. We have investigated the dynamics of this system through numerical modelling, demonstrating the developed capabilities and computational feasibility for assessing the 3D complexity and geodynamics of natural subductionsystems and applied this to the eastern Caribbean region. We show the geodynamic feasibility of westward directed trench-parallel slab transport through the mantle, i.e. slab dragging, on the northern segment of the slab, while the eastern segment of the slab is subducting by a mantle-stationary trench. The resistance of the mantle against slab dragging by the North American plate motion, as well as the deformation associated with the arcuate geometry of the slab, creates a complex 3D stress field in the slab that deviates strongly from the classical view of slab-dip aligned orientation of slab stress. More generally this means that the process of slab dragging may reveal itself in the focal mechanisms of intermediate and deep earthquakes. The characteristics of the arcuate subduction such as slab dragging and a complex 3D stress field as studied in the Caribbean region can be more generically applied to other arcuate subduction systems as well, such as the Izu-Bonin-Marianas or the Aleutians-Alaskasystems, where anomalous focal mechanisms of slabs are observed.
Dynamics of Coastal El Niño Events in present and future climates.
Authors: Kiefer Jil , Karamperidou Christina , DiNezio Pedro
Published: March 2020

Sudden and strong positive sea surface temperatures (SST) anomalies in the far eastern Pacific that are tied to the rather narrow NINO1+2 (0-10°S, 90°W-80°W) region are known as coastal El Niño events. In contrast to the well-studied features of typical basin-scale ENSO events, the frequency, origin and relevant processes of coastal El Niños are largely unknown. Here, we analyze their characteristics and future behavior using observational data and simulations with the Community Earth System Model (CESM), which exhibits skill in simulating precipitation, wind and SST fields associated with coastal El Niños. We find that tropical Pacific basin-scale ocean dynamics – in sharp contrast to a typical El Niño event  – play no major role in the evolution of a coastal El Niño. On the other hand, we find that atmospheric circulation anomalies from the Southern Hemisphere lead the evolution of coastal El Niño events, by causing warm SST anomalies that then propagate into the NINO1+2 region. Once initiated, local thermodynamical feedback processes such as cloud radiation feedbacks are responsible for the growth and decay of the events. Greenhouse gas forcing leads to an increase in the frequency of coastal El Niño events and a shift of their peak month in CESM simulations, related to a shallowing of the thermocline and changes in Rossby wave forcing from the Southern Hemisphere. In conclusion, based on our results, we will demonstrate the potential for increased predictability of coastal El Niño events, whose intense coastal SST warming and associated extreme precipitation poses a serious threat for local communities via loss of life and severe economic damage.
On the origin of seawater methylmercury in the Canadian Arctic: in-situ production vs. long-range advection
Authors: Wang Feiyue , Wang Kang
Published: March 2020

A subsurface enrichment of methylmercury (MeHg) has been observed at shallow depths (~100–300 m) in several regions of the Arctic Ocean. The spatial distribution of this subsurface seawater MeHg has been suggested to be responsible for the spatial variability in mercury concentrations of marine animals in the Canadian Arctic. The origin of the sub-surface MeHg in seawater, however, remains a subject of debate. In most other ocean basins, seawater MeHg typically peaks at deeper depths with a much lower dissolved oxygen content, and is thought to be produced in situ and in association with organic matter remineralization. In contrast, our water mass analysis suggests that MeHg enrichment in the shallow, well-oxygenated waters in the Canadian Arctic bears a signature that is most consistent with long-range transport of the Upper Halocline Pacific Water (UHW). Our results further show that seawater MeHg concentrations exhibit a significant correlation with a denitrification tracer, N*, and that the MeHg-to-N* slope decreases progressively from west to east across the Canadian Arctic. The negative N* values in the Canadian Arctic are known to have originated from denitrification in the productive Chukchi Sea shelf sediments, where anaerobic mercury methylation could also be favored. As MeHg- and N*-carrying UHW advects eastwards toward the Canadian Arctic, MeHg is progressively lost through demethylation, resulting in the observed decreasing trend in the MeHg-to-N* slope. The long-distance transport implies that the half-life of MeHg in Arctic seawater below the euphotic zone must be much longer than previously reported. This is supported by a critical literature review, which casts doubt on mercury methylation and demethylation rates previously determined from a seawater incubation approach due to unexplainable methylation and demethylation at time zero and poor fitting of the experimental data to first-order kinetics. Our results thus call for a better understanding of productive shelf sediments as potential MeHg “hotspots” in the Arctic and more reliable measurements of mercury methylation and demethlyation rates in the ocean.
Scientific Investigation and Monitoring Result of Potential Large Scale Landslide
Authors: Wang Kuo-Lung , Lin Ching-Weei , Lin Meei-Ling , Chen Rou-Fei , Hsu Ya-Ju , Kuo Chih-Yu , Chen Chien-Chih , Huang Hsin-Hua , Chang Kuo-Jen , Kuo Li-Wei , Ni Chuen-Fa , Lin Bo-Hung , Lee Yi-Hsuan , Yin Hsiao-Yuan , Feng Mei-Chen
Published: March 2020

It is always tricky to definite deep-seated or massive scale landslide investigation and monitoring. The scars could map from a high-resolution digital elevation model. However, the activity or sliding depth is merely difficult to define before installing a monitoring system. Lantai potential landslide area is selected for testing and demonstrating newly developed scientific investigation and monitoring techniques. Possible landslide scars have mapped from airborne lidar data, which provided a reference area for DInSAR analysis. More than ten years of DInSAR analysis shows an active/fast-moving area. The sliding plane and geological structure defined from customized earthquake stations and UAV LiDAR following with field verification. The background noise detection can define potential sliding planes from various precipitation events or earthquakes. GPS/leveling stations are installed to monitor ground deformation and verification from DInSAR results providing single point information to the whole area. The drilling holes’ depth is determined from earthquake stations analysis result, geological data, and sliding model from preliminary numerical analysis. Resistivity poles are installed at two holes from 100m beneath the ground surface with connected poles between these two holes to form a window shape monitoring system. The window shape Resistivity Image Profiling system can measure continuously providing not only geological structure variance and groundwater passing this window. New developed optical-fiber water pressure gauges are installed at different depths to verified groundwater pressure and water flow. The deformation system including extensometer, MEMS inclinometer, In-Plane Inclinometer, and Shape Acceleration Array are installed to provide direct displacements from the ground surface to underground. The sliding threshold is thus defined with various measurements from different monitoring methods and with different scales.
Effects of dissolved organic matter on sorption of benzotriazole to soil
Authors: Wu Lin , Dai Jin’e , Bi Erping
Published: March 2020

Dissolved organic matter (DOM) plays an important role in affecting the environmental behaviors of organic contaminants. Effects of two representative DOMs (dissolved humic acid (HA) and tannic acid (TA)) on sorption of benzotriazole (BTA) to a reference soil were investigated by batch experiments. The results indicated that TA had stronger sorption to soil than HA (initial solution pH=6.0±0.1). This is because that TA contains more carboxylic and phenolic groups than those of HA. In the solution with DOM, the enhanced sorption of BTA was caused by cumulative sorption resulting from sorbed DOM. Hydrogen bonding was proposed as the main binding mechanism between BTA and the sorbed DOM. When the solution pH at sorption equilibrium increased from 6.5 to 10.5, the electrostatic repulsion inhibited the sorption of BTA in solution with/without HA. In addition, less hydrogren bonds made the effect of HA in promoting BTA sorption decrease when solution pH changed from 6.5 to 10.5. Higher molecular weight fractions of HA could be preferentially sorbed by the soil, its enhancement on BTA sorption was more obvious than that of the low molecular weight fractions. These findings are conducive to a better understanding of environmental behaviors of BTA as well as other organic compounds with similar structure in the unsaturated zones.
Pre-earthquake processes associated with the M6.4 of Nov 26, 2017 In Albania. A Multi parameters analysis.
Authors: Ouzounov Dimitar , Pulinets Sergey , Guiliani Guiampaolo , Velichkova-Iotsova Sylviya , Kafatos Menas , Taylor Patrick
Published: March 2020

We present a multi parameters analysis of satellite and ground data that revealed a transient phenomenon in the atmosphere before the M6.4 earthquake in Albania on Nov 26, 2019. The observational methodology consists of data from five physical measurements: (1) Satellite Thermal Anomalies (data obtained from NOAA) on the top of the atmosphere; (2); Atmospheric chemical potential (ACP) obtained from the NASA assimilation models; (3); Measurement of Radon level variations (two gamma stations in Central Italy); (4) VHF propagation in the lower atmosphere from ground observations and; (5) Electron density variations in the ionosphere via GPS Total Electron Content (GPS/TEC)

On Nov 21, 2019 our NOAA STA daily analysis over the Mediterranean detected a strong abnormal pattern between Italy and Albania. We estimated that a possible earthquake could occur in the Adriatic Sea between Italy and Albania with M5.5+ and start cross parameter validation with other observations. On Nov 26 an earthquake occurred near STA anomaly of Nov 21. The epicenter of the M6.4 earthquake in Albania is situated about 500 kilometers NE of the two-radon monitoring stations in Central Italy. Real-time hourly data show an increase in both sensors on Nov 20 (6 days before the M6.4 of Nov 26, 2019). From the satellite data these increases in radon coincide with an increase in the atmospheric chemical potential (on Nov 21), measured near the epicentral area. VHF data observed from two stations located 300 km from the epicenter in Northeast Bulgaria, indicated an intensity modulation about 90 hours (3.5 days) before the mainshock. The GPS/Total Electron Content data indicated an increase of electron concentration in the ionosphere 1-2 days before the M6.4 earthquake. We observed a synergetic abnormal response from ground and satellite data, although the ground data (radon and VHF) sensors were far from the epicenter (500 and 300 km, respectively). Starting six days before the M6.4 Nov 26 earthquake, the anomalous patterns were inside the Dobrovolsky-Bowman area of preparation. We examined the possible correlation between different pre-earthquake anomalies and the relationship between magnitude and the spatial size of the preparation zone in the framework of the Lithosphere -Atmosphere -Ionosphere Coupling (LAIC) concept.
Evaluation of Noah-MP land-model uncertainties over sparsely vegetated sites on the Tibet Plateau
Authors: Zhang Guo , Chen Fei , Chen Yueli , Li Jianduo
Published: March 2020

Uncertainties in the Noah with multiparameterization (Noah-MP) land surface model are assessed through physics ensemble simulations in four sparsely vegetated sites located in the central and western Tibetan Plateau. The simulated hydrological components are evaluated using observations at those sites during the third Tibetan Plateau Experiment from August 1st, 2014 to August 1st, 2015. By using natural selection, the crucial subprocesses impacting the hydrological component simulations are identified. The effects of precipitation uncertainties and soil organic matter on the energy fluxes and water cycles are analyzed through a set of sensitivity experiments based on an optimal scheme set. The uncertainty analyses indicate that the greatest uncertainties are in the subprocesses of runoff (RNF) and groundwater, surface-layer parameterization and frozen soil permeability, along with the subprocesses of snow surface albedo and the lower boundary of soil temperature for the bare ground site but the subprocesses of the canopy resistance and soil moisture limiting factors for evaporation for the three alpine grassland sites. The sensitivity analyses reveal that more precipitation can increase the annual total net radiation (Rn), latent heat flux (LE) and RNF but decrease sensible heat flux (SH). Compared to the insufficient precipitation, the relatively small increase in precipitation results in the LE increase during the growing season at the Amdo and Baingoin sites but an RNF increase at the Nagqu site (sandy soil). However, when more precipitation was added, a greater proportion of the added water was distributed to the RNF at the Nagqu site and to the soil liquid water at the Amdo and Baingoin sites. The organic soil increases the annual total LE but reduces the annual total Rn, SH, and RNF. The effect of the soil organic matter on the LE and RNF at the Nagqu site (sandy soil), is greater than that at the other three sites (sandy loam soil).
Precipitation within EUREC4A: a multi-sensor ship-based approach to tackle warm rain processes
Authors: Acquistapace Claudia , Boeck Tobias
Published: March 2020

Trade wind cumulus clouds play a vital role in the Earth's radiation budget and produce up to 20% of the total precipitation in the tropics. However, we still don't know how they will respond to global warming. Precipitation from trade wind cumuli can alter cloud macroscopic properties and the boundary layer structure and dynamics.

Precipitation development in models is very uncertain, being dependent on simulation setup and microphysics. In particular, the autoconversion scheme dramatically affects precipitation flux, cloud structure, and organization. Currently, no evaluations of the different autoconversion schemes with observations reduced the uncertainties in rain processes. Precipitation can impact convection organization and circulation intensity with massive effects on climate sensitivity and its evaporation determines the intensity of cold pools and influences the cloud field organization. It is hence key to quantify evaporation rates and their spatiotemporal variability. Parametrizations of evaporation below cloud base are available but strongly depend on the drop size distribution of raindrops. Also, in the observations, evaporation rates are hard to observe directly.

Here, we would like to present the potential given by the observations collected on the Maria S. Merian ship during the EUREC4A campaign to estimate evaporation rates and provide advanced multi-sensor observations of rain onset and development. The synergy of multiple in-situ and remote-sensing from the ship as well as aircraft observations available will allow to constrain the autoconversion scheme in LES models and reduce the uncertainties connected to rain processes. Moreover, quantification of evaporation rates will clarify the role of precipitation in moisturizing the boundary layer in trade wind regions.

 
Environmental properties and microbial abundance explain soil nitrous oxide flux variation synergistically under the addition of nitrogen and water in temperate semi-arid steppe
Authors: Jiaqi Zhang , Yinghui Liu
Published: March 2020

  With the increasing of nitrogen(N) deposition and changing of precipitation patterns worldwide, large amounts of N are loaded in terrestrial ecosystem, resulting in soil nutrient imbalance and soil nitrous oxide(N2O) flux change. Nitrification and denitrification in soil are two major sources of N2O emission mediated by microorganisms. However, It is still unclear how the soil N2O flux and the abundance of nitrifiers and denitrifiers might change under the addition of N and water(W) in temperate semi-arid steppe. In this study, we established a one-year-long field experiment investigating how soil N2O flux, the abundance of nitrifiers and denitrifiers, and environmental properties, including soil pH, soil moisture, soil dissolved organic carbon content(DOC) and soil available N content responsed when N(NH4NO3 was applied at a rate of 4 g N·m-2·yr-1, which is equivalent to one time the annual nitrogen deposition) and/or W(water was applied at a rate of 112.5 mm·yr-1, which is equivalent to 30% of the annual rainfall) were added to temperate semi-arid steppe in northern China with the natural condition without any treatment as control. Quantitative PCR was used to analyze the abundance of ammonia oxidizers(ammonia-oxidizing bacteria and archaea amoA) and denitrifiers(nirS/nirK and nosZ). Our experimental results demonstrated that soil N2O emission decreased when W was added and W and N were added in temperate semi-arid steppe in northern China. The abundance of nirS and nosZ genes increased when W and N were added. Compared with AOA/AOBamoA and nirK genes, the abundance of nirS and nosZ genes is more sensitive to the addition of N and W. Soil N2O flux was negatively correlated with the abundance of nirS-denitrifier. The nirS gene abundance, soil pH and DOC were the main controls on soil N2O flux and totally explained 78.2% of the variation of soil N2O flux. The results of this study provide a theoretical basis for N cycle mechanism mediated by microorganisms and have practical significance for the prediction of N2O flux change in temperate semi-arid steppe under the background of global change.
A multi-tiered methane analytic framework for constraining budgets, point source attribution, and anomalous event detection
Authors: Cusworth Daniel , Duren Riley , Thorpe Andrew , Stavros Natasha , Bue Brian , Tapella Robert , Yadav Vineet , Miller Charles
Published: March 2020

Methane emissions monitoring is rapidly expanding with increasing coverage of surface, airborne, and satellite instruments. However, no single methane instrument or observing strategy can both close emission budgets and pinpoint point sources on regional to global scales. Instead, we present a multi-tiered data analytics system that synthesizes information across various instruments into a single analytic framework. We highlight an example in Los Angeles, where we combine surface measurements from the Los Angeles megacities project, mountaintop measurements from the CLARS-FTS instrument, airborne AVIRIS-NG point source emission estimates, and TROPOMI total column retrievals into a single analytic framework. Surface, mountaintop, and satellite measurements are assimilated into a methane flux inverse model to constrain basin-wide emissions and pinpoint sub-basin methane hotspots. We show an example of a large urban landfill, whose anomalous emissions were detected by the inverse system, and validated using AVIRIS-NG methane plume maps. This general approach of quantifying both methane area and point source emissions is an avenue not just for closing regional to global scale budgets, but also for understanding which emission sources dominate the budget (i.e., so called methane super-emitters). We finally show how this multi-tiered analytic framework can be improved with future satellite missions, and present examples of unexpectedly large methane emissions that were detected by a new generation of satellite imaging spectrometers.
Equatorial atmospheric zonal circulation changes over India Ocean during recent decades
Authors: Sharma Sahil , Ha Kyung-Ja
Published: March 2020

The equatorial zonal asymmetric (Walker) circulation causes changes in the tropical rainfall pattern which induces devastation flood and drought that considerably impact the lives of millions of people. However, understanding of changes in zonal circulation is not yet certain. Here we examine the robustness of changes in Indian Walker Circulation (IWC) characteristics using different reanalysis and observation datasets in terms of the linear trends of IWC. The meridional (5oS:5oN)  averaged vertical velocity using different datasets are used to precisely locate the ascending (94oE:104oE, eastern) and descending (35oE:45oE, western) branch of IWC. We analyzed the zonal sea level pressure (SLP) gradient, velocity potential (VP) at 850 and 200 hPa, surface zonal wind (SZW) and zonal mass stream function (ZMSF) anomalies over the period of 1980–2017. We found that the magnitude of ZMSF representing anticlockwise circulation has an increasing trend in all the datasets. This kind of change is physically in agreement with the changes of SLP and SZW (an increasing trend in westerlies over the central IO) while the VP shows the decreasing trend which is in agreement with the strengthening of IWC during the recent decades. JRA55 is the most reliable which shows the significant and highest trend among all other datasets. The change point detection using the Pettitt method is applied to the normalized mean of all datasets which determines that in the post-1997-98 there is a significant strengthening of IWC as compared to the pre-1997-98 which demonstrates that IWC is highly sensitive by super El-Nino. The attribution of this strengthening can be examined using the CMIP5/6 datasets to determine the relative contribution of anthropogenic warming and natural variability.
Investigation on the function of double tipping bucket for improvement of rainfall measurement
Authors: Zhao Cai , Jiufu Liu , Hongwei Liu , Aimin Liao , Minhan Liao
Published: March 2020

The double-tipping bucket rain gauge (SL3-1) is widely used in meteorological stations to minimize the systematic errors by the influence of rainfall intensity on TBRs in China. With two tipping buckets, the upper tipping bucket turns over and injects rainwater into the converging funnel, and the lower tipping bucket can record the rainfall. In this study, CFD (computational fluid dynamic) simulations and experiments were performed to investigate the function of the double tipping bucket for TBRs in different rainfall intensity. In simulation, the volume-of-fluid model and Reynolds-averaged Navier–Stokes realizable k-ε model and dynamic mesh method were used. In experiments, electric balances, with accuracy of 0.001 g, were used to determine the water volume of the upper tipping bucket outflow. It shows that, with a converging funnel, natural precipitation is uniformed at a certain intensity around 1.9mm/min to control the rainwater outflow into blow tipping bucket to measure rainfall and reduce systematic errors caused by different precipitation intensities. Experimental results demonstrate that the outflow curve of the upper tipping bucket has high correspond with simulation results in tipping process. These results can provide knowledge of advantages of double tipping bucket rain gauge in rainfall measurement and improve the structure designs of double tipping bucket for TBRs and obtain more accurate rainfall data.
Impact of different and time-varying land cover data sets in a regional climate model on regional and local climate over Europe
Authors: Zhang Mingyue , Helmert Jürgen , Tölle Merja
Published: March 2020

According to IPCC, Land use and Land Cover (LC) changes have a key role to adapt and mitigate future climate change aiming to stabilize temperature rise up to 2°C. Land surface change at regional scale is associated to global climate change, such as global warming. It influences the earth’s water and energy cycles via influences on the heat, moisture and momentum transfer, and on the chemical composition of the atmosphere. These effects show variations due to different LC types, and due to their spatial and temporal resolutions.  Thus, we incorporate a new time-varying land cover data set based on ESACCI into the regional climate model COSMO-CLM(v5.0). Further, the impact on the regional and local climate is compared to the standard operational LC data of GLC2000 and GlobCover 2009. Convection-permitting simulations with the three land cover data sets are performed at 0.0275° horizontal resolution over Europe for the time period from 1992 to 2015.

Overall, the simulation results show comparable agreement to observations. However, the simulation results based on GLC2000 and GlobCover 2009 (with 23 LC types) LC data sets show a fluctuation of 0.5K in temperature and 5% of precipitation. Even though the LC is classified into the same types, the difference in LC distribution and fraction leads to variations in climate simulation results. Using all of the 37 LC types of the ESACCI-LC data set show noticeable differences in distribution of temperature and precipitation compared to the simulations with GLC2000 and GlobCover 2009. Especially in forest areas, slight differences of the plant cover type (e.g. Evergreen or Deciduous) could result in up to 10% differences (increase or decrease) in temperature and precipitation over the simulation domain. Our results demonstrate how LC changes as well as different land cover type effect regional climate. There is need for proper and time-varying land cover data sets for regional climate model studies. The approach of including ESACCI-LC data set into regional climate model simulations also improved the external data generation system.

We anticipate this research to be a starting point for involving time-varying LC data sets into regional climate models. Furthermore, it will give us a possibility to quantify the effect of time-varying LC data on regional climate accurately.

Acknowledgement:

1: Computational resources were made available by the German Climate Computing Center (DKRZ) through support from the Federal Ministry of Education and Research in Germany (BMBF). We acknowledge the funding of the German Research Foundation (DFG) through grant NR. 401857120.

2: Appreciation for the support of Jürg Luterbacher and Eva Nowatzki.

 
Seismic hazard due to fluid injections
Authors: Davidsen Joern , Lord-May Cole , Baro Jordi , Eaton David
Published: March 2020

Earthquakes can be induced by natural and anthropogenic processes involving the injection or migration of fluids within rock formations. A variety of field observations has led to the formulation of three different and apparently contradicting paradigms in the estimation of the seismic hazard associated with fluid injections. Based on a unified conceptual model accounting for the non-homogeneous pore-pressure stimulation caused by fluid injection in a prestressed region, we show here that all three paradigms naturally coexist. The loading history and heterogeneity of the host medium determine which of the three paradigms prevails. This can be understood as a consequence of a superposition of two populations of events triggered at different pore-pressure levels with different Gutenberg-Richter b-values.
Characteristics of mechanical response and acoustic emission during granular shearing
Authors: Jiang Yao , Wang Gonghui
Published: March 2020

The shear behavior of granular materials has drawn considerable attention due to its great potential for various geophysical processes such as landslides and debris flows. Field and remote sensing observations reveal that the progressive maturation of these geophysical events may involve different styles of movement, such as stable creep, periodic slow sliding or accelerative sliding. Laboratory experiments also suggest that the mechanical conditions of granular materials may play a significant role in controlling diverse frictional behaviors, such as shear-rate weakening or strengthening. Furthermore, the granular frictional processes may involve abrupt perturbations of internal forces and release of strain energy. Such energy release events are manifested in the generation of high frequency (kHz-MHz) elastic waves, termed acoustic emissions (AEs), which deliver important information concerning the physical processes of granular shearing deformation.

A significant, though still inconclusive, body of research has been directed toward revealing possible mechanisms of AEs occurring on rock or among granular materials in shear. These studies attributed the generation of AEs to the formation of microcracks in intact rocks, the breaking of asperities between solid surfaces or the rearrangement of grain contacts. In this study, we performed laboratory tests on granular analogues composed of spherical glass beads in a ring shear configuration under conditions of room temperature and atmospheric humidity to examine whether the AE events are correlated with mechanical response. For measurements of elastic waves, a high-frequency AE transducer was installed near the shear plane. AE signals and mechanical data were synchronously sampled at the rate of 1 MHz using an additional recoding system.

The results show that (1) there is a strong correlation between the stress drop and the main acoustic burst; (2) the primary frequency bands are in the tens of kHz ranges for acoustic signals generated during granular shearing; (3) the onset of AE amplitudes precedes the impending global mechanical failures by several milliseconds.