The EGU General Assembly最新文献

{"title":"GNSS Interferometric Reflectometry for Station Location Suitability Analysis","authors":"J. Verbeurgt, E. Van De Vijver, C. Stal, A. De Wulf","doi":"10.5194/EGUSPHERE-EGU21-4707","DOIUrl":"https://doi.org/10.5194/EGUSPHERE-EGU21-4707","url":null,"abstract":"<p>National geodetic reference systems can be continuously monitored using applications of Global Navigation Satellite Systems (GNSS). Within these reference systems, Continuously Operating GNSS Reference Stations (CORSs) are often employed to provide 24/7 satellite tracking data. Understanding the influence of the surroundings of a CORS on the recorded satellite tracking data is indispensable for quality analysis of both acquired data and station location suitability. One of the main sources of inaccurate tracking data is the result of the combined reception of direct as well as indirect, environment-reflected satellite signals by the CORS, in which the latter can be considered interference compromising the signal&#8217;s accuracy. The magnitude of this interference is usually evaluated by the Signal-to-Noise Ratio (SNR), a parameter stored by default in the RINEX interchange format for raw GNSS data. The technique of GNSS Interferometric Reflectometry (GNSS-IR) exploits the availability of the SNR data and has been frequently used for applications such as soil moisture monitoring, detection of vegetation water content, measuring snowfall or determining water levels. In this research, we propose to employ GNSS-IR to investigate the effect of the surrounding on a CORS in order to evaluate station location suitability. More specifically, this will be done by using the signal to estimate the Reflector Height (RH), which depends on the reflector roughness (i.e. the roughness of the surface surrounding the CORS). The quality of this estimation will be validated by comparing with the actual measurement of the RH of the CORS on site.</p><p>In our approach, a statistically sound method is developed quantifying the stability of the RH determination. The proposed methodology consists of using Lomb-Scargle periodograms to select the dominant oscillation frequency of each satellite track SNR data, followed by an analysis and filtering of the peak amplitudes. This leads to the analysis product: number of significant peak amplitudes for an individual CORS over (sub-)daily timeframes. With historical data covering long time periods, statistical analysis of the (sub-)daily timeseries allows for reviewing the station location suitability. In Belgium, CORS are located on two typical positions: in Flanders, the 32 antennas are mainly installed on rooftops of buildings; in Wallonia, the 23 antennas are installed on a concrete pole next to highways. There is no evidence of one choice of station position being more suitable than the other. However, cars are known to be an important factor in signal reflections. In our analysis of station suitability, &#160;the effect of cars passing by on the highway near a Walloon CORS, but also movements on, e.g., parking lots next to buildings with a rooftop CORS, will be investigated. With the developed methodology, guidelines for station location selection could be further developed, together with a system to continuously monito","PeriodicalId":22413,"journal":{"name":"The EGU General Assembly","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82040380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optical properties of smoke particules from Australian 2019-20 wildfires derived from lidar measurements at the French Antarctic station Dumont d’Urville","authors":"Florent Tencé, J. Jumelet, A. Sarkissian, S. Bekki, S. Khaykin","doi":"10.5194/EGUSPHERE-EGU21-12466","DOIUrl":"https://doi.org/10.5194/EGUSPHERE-EGU21-12466","url":null,"abstract":"Australia experienced an unprecedented fire season from August 2019 to March 2020, now colloquially named as Black Summer. As a warming climate could tend to enhance wildfire seasons, it is critical to study their impact on a large scale : pyrocumunolimbus (pyroCb) events directly inject large quantities of material into the stratosphere, from which aerosols can then be transported due to the general circulation patterns. Stratospheric aerosols have an important impact on the radiative budget of the Earth : directly, through the change in albedo they imply, and indirectly, enhancing nucleation processes. \u0000The pyrocumunolimbus events triggered by these wildfires between 2019/12/29 and 2020/01/04 raised the stratospheric aerosol load of the Southern Hemisphere to a rarely observed level and we hereby present the optical signatures and characterization of the smoke-related aerosols detected at the French Antarctic station Dumont d'Urville (66.6°S - 140°E) since their first detection in november 2019 and their presence throughout the 2020 year after long range transport. Combined with satellite measurements from OMI and OMPS, lidar measurements allow us to follow the time evolution of these aerosol layers, their vertical distribution in altitude as well as their optical properties and assessment of the lidar ratio. As the groundbased instrumental coverage remains sparse in the Southern Hemisphere and especially in Antarctica, such events highlight the importance of running monitoring programs at high latitudes.","PeriodicalId":22413,"journal":{"name":"The EGU General Assembly","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85904437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Use of environmental management data for mass flow estimations of plastic debris in rivers: The Seine River and The Huveaune River, France.","authors":"R. Tramoy, J. Gaspéri, É. Blin, I. Poitou, B. Tassin","doi":"10.5194/EGUSPHERE-EGU21-6088","DOIUrl":"https://doi.org/10.5194/EGUSPHERE-EGU21-6088","url":null,"abstract":"<p>Methods to quantify plastic transport in rivers have greatly improved during the past few years. As a first approach, visual counting is currently the simplest way to assess plastic transport with minimal effort and cost. It usually results in underestimations of plastic input into the sea of about one to two order of magnitude when compared to models such as the Jambeck&#8217;s approach. The latter shows statistical weaknesses and data availability issues leading to large uncertainties, while visual counting miss the water column compartment and often has a low spatiotemporal representativeness. In order to give another ground-truth estimation of plastic transport able to challenge both models and visual counting, we developed innovative methods based on environmental management data in the Seine estuary (500 m³/s) and the Huveaune River ( 2 m³/s; Marseille, France). First, we used data from institutional cleaning in the Seine estuary that consist in litter collection on riverbanks. Their efficiency was measured based on capture-recapture design. Mass flows of plastic debris were then calculated based on the capture rate over one year, the estimation of the fraction of plastic debris which are never collected (hidden or too small) and the assumption that all plastic debris strand on riverbanks. Second, we used data from bar screens spaced of 3 cm in the Huveaune, a small urban river flowing in Marseille, South France. All the water column is screened, and captured waste are automatically collected in dumpsters. Grab sampling were performed after a dry, a wet and a flood period. The corresponding annual mass flows of plastic debris was then calculated relative to the mean fraction of time corresponding to those hydrological periods over 2017 and 2018. Annual mass flows of plastic debris were normalized to the population in both basins. Although methods were different, mass flows of plastic debris per capita are very similar with 8.5 &#8211; 13.6 g/cap/yr for the Seine River and 2.4 &#8211; 14.9 g/cap/yr for the Huveaune River. This is one to two order of magnitude lower than the Jambeck&#8217;s approach. However, when focusing on the fraction ending into the Sea, bar screens in Marseille enable to decrease the mass flow of plastic debris of about one additional order of magnitude, while cleaning of riverbanks decreases it of about 10%. This is related to the nature of the rivers that calls for different solutions, screening the whole Seine River being a tricky idea. Nevertheless, when normalized to water volume, the Huveaune River is visually much more polluted (16.4&#8211;102.2 mg/m³) than the Seine estuary (9.0&#8211;14.5 mg/m³). In conclusion, environmental management data can help to estimate mass flows of plastic debris and calls for better consideration. However, they often need an improved scientific framework.</p>","PeriodicalId":22413,"journal":{"name":"The EGU General Assembly","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87853510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spectral X-ray computed micro tomography: a tool for 3-dimensional chemical imaging","authors":"J. Sittner, M. Merkulova, J. Godinho, A. Renno, V. Cnudde, M. Boone, T. de Schryver, D. van Loo, A. Roine, J. Liipo, B. Guy, S. Dewaele","doi":"10.5194/EGUSPHERE-EGU21-9974","DOIUrl":"https://doi.org/10.5194/EGUSPHERE-EGU21-9974","url":null,"abstract":"<p>Image-based analytical tools in geosciences are indispensable for the characterization of minerals, but most of them are limited to the surface of a polished plane in a sample and lack 3D information. X-ray micro computed tomography (micro CT) provides the missing 3D information of the microstructures inside samples. However, a major drawback of micro CT in the characterization of minerals is the lack of chemical information that makes mineral classification challenging.</p><p>Spectral X-ray micro computed tomography (Sp-CT) is a new and evolving tool in different applications such as medicine, security, material science, and geology. This non-destructive method uses a multi-pixel photon-counting detector (PCD) such as cadmium telluride (CdTe) in combination with a conventional CT scanner (TESCAN CoreTOM) to image a sample and detect its transmitted polychromatic X-ray spectrum. Based on the spectrum, elements in a sample can be identified by an increase in attenuation at specific K-edge energies. Therefore, chemically different particles can be distinguished inside a sample from a single CT scan. The method is able to distinguish elements with K-edges in the range from 25 to 160 keV, which applies to elements with Z > 48 (Sittner et al., 2020).</p><p>We present results from various sample materials. Different pure elements and element oxides were measured to compare the position of theoretical and measured K-edge energies. All measured K-edge energies are slightly above the theoretical value, but based on the results a correction algorithm could be developed. Furthermore, different monazite grains were investigated, which can be divided into two groups with respect to the content of different RE elements on the basis of the spectrum: La-Ce-rich and La-Ce-poor. In addition, samples from the Au-U Witwatersrand Supergroup demonstrate the potential applications of Sp-CT for geological samples. We measured different drill core samples from the Kalkoenkrans Reef at the Welkom Gold field. Sp-CT can distinguish gold, uraninite and galena grains based on their K-edge energies in the drill core without preparation.</p><p>Sittner, J., Godinho, J. R. A., Renno, A. D., Cnudde, V., Boone, M., De Schryver, T., Van Loo, D., Merkulova, M., Roine, A., & Liipo, J. (2020). Spectral X-ray computed micro tomography: 3-dimensional chemical imaging. X-Ray Spectrometry, September, 1&#8211;14.</p>","PeriodicalId":22413,"journal":{"name":"The EGU General Assembly","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84005253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of artificial recharge on submarine groundwater discharge: a Belgian case study","authors":"M. Paepen, K. Walraevens, T. Hermans","doi":"10.5194/EGUSPHERE-EGU21-7495","DOIUrl":"https://doi.org/10.5194/EGUSPHERE-EGU21-7495","url":null,"abstract":"<p>The Belgian coastal phreatic aquifer is mostly characterized by salty/brackish pore water at shallow depth. The eolian dunes delimiting the sandy beach are one of the few locations where fresh potable water can be found. The drinking water demand of the coastal region is putting high pressure on these water resources, especially during the touristic summer season. Also, the dryer summers that were faced over the last years increase the need for solutions.</p><p>At Oostduinkerke, the Intercommunale Waterleidingsmaatschappij van Veurne-Ambacht (IWVA) combines the pumping of groundwater in the dunes with artificial surface (since 2002) and underground recharge (since 2014) for more sustainable exploitation. The infiltrating water is treated effluent from a nearby sewage treatment plant (Aquafin, Wulpen). The recharge in the dunes reduces the risk of attracting salty/brackish water from the North Sea and the lower lying polder area in the South and allows for more stable groundwater levels, especially around the infiltration lake.</p><p>To assess the efficiency of the managed aquifer recharge project, we collected electrical resistivity tomography (ERT) data offshore, on the beach, and part of the dunes. Marine continuous resistivity profiling (CRP) were performed during both low and high tide. The latter provide a good overlap with the land ERT. The profiles were collected in front of the IWVA site, as well as, to the west and east, to assess the lateral variation of the salt-freshwater distribution in the aquifer. Based on the electrical resistivity distribution, we are able to identify the patterns of submarine groundwater discharge (SGD) and saltwater intrusion in the study area.</p><p>The infiltration of treated wastewater directly affects the piezometric levels of the surrounding area. Before the exploitation started in the dunes (1947), the natural freshwater heads were higher west of the infiltration area, due to the presence of a shallow clay layer (Vandenbohede et al., 2008). The higher hydraulic heads are also seen on recent groundwater models (Lebbe, 2017), but despite the larger hydraulic gradient in the West, the pore water resistivity seems to be higher in front of the IWVA site based on our data. Also, the zone of discharge is found below the low water line in front of the infiltration site, while it is seen on the beach to the west and east. We can assume that the SGD flux is largest in front of the recharge site (Paepen et al., 2020). Therefore, SGD seems to be enhanced by artificial recharge in this area. Further research is needed to validate this.</p><p>Lebbe, L. (2017). Grondwatermodel van de geplande wijzigingen in waterwinning Sint-Andr&#233;. Opdrachtgever: Intercommunale Waterleidingsmaatschappij van Veurne Ambacht (IWVA).</p><p>Paepen, M., Hanssens, D., Smedt, P. D., Walraevens, K., & Hermans, T. (2020). Combining resistivity and frequency domain electromagnetic methods to investigate submarine groundwater discharge in t","PeriodicalId":22413,"journal":{"name":"The EGU General Assembly","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91338172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the current accuracy of altimetry satellite orbits","authors":"S. Rudenko, D. Dettmering, M. Bloßfeld, J. Zeitlhöfler, Riva Alkahal","doi":"10.5194/EGUSPHERE-EGU21-12148","DOIUrl":"https://doi.org/10.5194/EGUSPHERE-EGU21-12148","url":null,"abstract":"<p><span>Precise orbits of altimetry satellites are a prerequisite for the investigation of global, regional, and coastal sea levels together with their changes, since accurate orbit information is required for the reliable determination of the water surface height (distance between the altimeter position in space and the water surface). Orbits of altimetry satellites are nowadays usually computed using DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite), SLR (Satellite Laser Ranging), and, of some satellites, GPS (Global Positioning System) observations of a global network of tracking stations. Significant progress in the improvement of altimetry satellite orbit quality has been achieved in the last 30 years. However, the differences of the sea level and its trend computed using up-to-date orbit solutions derived at various institutions using different software packages, types of observations (DORIS+SLR as compared to GPS+DORIS) and different up-to-date models still exceed the requirements of the Global Climate Observing System for the uncertainties of the regional sea level </span><span>(< 1 cm) and its trend (< 1 mm/year). </span></p><p><span>In this study, we evaluate the current accuracy of orbits of altimetry satellites derived by various institutions in the state-of-the-art reference frames using up-to-date background models for precise orbit determination by using various observation types. We present some results of our analysis of geographically correlated errors and radial orbit differences for various orbit solutions. We also discuss </span><span>possible reasons </span><span>causing the orbit differences and potential ways to reduce them. </span></p>","PeriodicalId":22413,"journal":{"name":"The EGU General Assembly","volume":"578 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77010169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The influence of Antarctic and Greenland ice loss on polar motion: an assessment based on GRACE and multi-mission satellite altimetry","authors":"F. Göttl, A. Groh, M. Kappelsberger, Undine Strößenreuther, L. Schröder, V. Helm, M. Schmidt, F. Seitz","doi":"10.5194/egusphere-egu21-2564","DOIUrl":"https://doi.org/10.5194/egusphere-egu21-2564","url":null,"abstract":"<p>Increasing ice loss of the Antarctic and Greenland Ice Sheets (AIS, GrIS) due to global climate change affects the orientation of the Earth&#8217;s spin axis with respect to an Earth-fixed reference system (polar motion). Ice mass changes in Antarctica and Greenland are observed by the Gravity Recovery and Climate Experiment (GRACE) in terms of time variable gravity field changes and derived from surface elevation changes measured by satellite radar and laser altimeter missions such as ENVISAT, CryoSat-2 and ICESat. Beside the limited spatial resolution, the accuracy of GRACE ice mass change estimates is limited by signal noise (meridional error stripes), leakage effects and uncertainties of the glacial isostatic adjustment (GIA) models, whereas the accuracy of satellite altimetry derived ice mass changes is limited by waveform retracking, slope related relocation errors, firn compaction and the density assumption used in the volume-to-mass conversion.</p><p>&#160;</p><p>In this study we use different GRACE gravity field models (CSR RL06M, JPL RL06M, ITSG-Grace2018) and satellite altimetry data (from TU Dresden, University of Leeds, Alfred Wegener Institute) to assess the accuracy of the gravimetry and altimetry derived polar motion excitation functions. We show that due to the combination of individual solutions, systematic and random errors of the data processing can be reduced and the robustness of the geodetic derived AIS and GrIS polar motion excitation functions can be increased. Based on these investigations we found that AIS mass changes induce the pole position vector to drift along the 60&#176; East meridian by 2 mas/yr during the study period 2003-2015, whereas GrIS mass changes cause the pole vector to drift along the 45&#176; West meridian by 3 mas/yr.</p>","PeriodicalId":22413,"journal":{"name":"The EGU General Assembly","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75788330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution of solar wind flows from the inner corona to 1 AU: constraints provided by SOHO UVCS and SWAN data","authors":"A. Bemporad, O. Katushkina, V. Izmodenov, D. Koutroumpa, E. Quémerais","doi":"10.5194/egusphere-egu21-11921","DOIUrl":"https://doi.org/10.5194/egusphere-egu21-11921","url":null,"abstract":"<p>The Sun modulates with the solar wind flow the shape of the whole Heliosphere interacting with the surrounding interstellar medium. Recent results from IBEX and INCA experiments, as well as recent measurements from Voyager 1 and 2, demonstrated that this interaction is much more complex and subject to temporal and heliolatitudinal variations than previously thought. These variations could be also related with the evolution of solar wind during its journey through the Heliosphere. Hence, understanding how the solar wind evolves from its acceleration region in the inner corona to the Heliospheric boundaries is very important.</p><p>In this work, SWAN Lyman-&#945; full-sky observations from SOHO are combined for the very first time with measurements acquired in the inner corona by SOHO UVCS and LASCO instruments, to trace the solar wind expansion from the Sun to 1 AU. The solar wind mass flux in the inner corona was derived over one full solar rotation period in 1997, based on LASCO polarized brightness measurements, and on the Doppler dimming technique applied to UVCS Lyman-&#945; emission from neutral H coronal atoms due to resonant scattering of chromospheric radiation. On the other hand, the SWAN Lyman-&#945; emission (due to back-scattering from neutral H atoms in the interstellar medium) was analyzed based on numerical models of the interstellar hydrogen distribution in the heliosphere and the radiation transfer. The SWAN full-sky Lyman-&#945; intensity maps are used for solving of the inverse problem and deriving of the solar wind mass flux at 1 AU from the Sun as a function of heliolatitude. First results from this comparison for a chosen time period in 1997 are described here, and possible future applications for Solar Orbiter data are discussed.</p>","PeriodicalId":22413,"journal":{"name":"The EGU General Assembly","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85339939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modelling Mineral-Scaling in Geothermal Reservoirs Using Both a Local Equilibrium and a Kinetics Approach","authors":"A. Hussain, N. Khoshnevis, B. Meulenbroek, Wouter R.L. van der Star, H. Bruining, J. Claringbould, A. Reerink, K. Wolf","doi":"10.5194/EGUSPHERE-EGU21-16033","DOIUrl":"https://doi.org/10.5194/EGUSPHERE-EGU21-16033","url":null,"abstract":"<p>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; When producing heat from a geothermal well, the produced water cools down in the heat exchanger, and experiencing a lower pressure in the surface processing-facility (1 &#8211; 10 bar) than in the reservoir (100 &#8211; 300 bar). The decrease in pressure may cause gas to come out of solution. This decrease in temperature and degassing of the produced water may cause precipitation and dissolution (mineralization) to occur. After the produced water is cooled down, it is reinjected into the reservoir through an injection well. Mineralization in the reservoir restricts the flow path of the injected water, resulting in reduced injectivity. Consequently, more energy is required by the injection pump, which results in additional costs, and thereby reduces the project&#8217;s economic return.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; <br>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; When numerically modeling mineralization in a geothermal reservoir, accounting for the reaction kinetics can be computationally expensive. The simulations can be made less expensive by assuming local equilibrium between the reactants and reaction-products; but using this approach might give results that are not in agreement with experimental findings. <br>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Here we present an analytical model for mineral precipitation in a low-enthalpy geothermal reservoir. We compare the kinetics of the relevant reaction terms with respect to the transport terms (heat and flow) to determine whether the local equilibrium approach (LEA) or kinetics approach (KA) is appropriate for modeling a specific reaction. We focus on the near-wellbore region in the reservoir, where precipitation can behave as a &#8216;skin&#8217;; when assuming radial-flow, precipitation in the near-wellbore region has a more dramatic impact on the injectivity than precipitation further downstream in the reservoir.&#160;&#160;&#160;&#160;&#160;&#160; <br>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Using numerical simulations we validate the approach to use different methods of geochemical modelling based on the reaction speed and its potential impact on computation time. <br>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Based on our analysis on mineralization in the near-wellbore-region, the three different reaction regimes can be distinguished when comparing the time-scale of reaction to the time-scale of transport, viz.: (1) <strong>fast reactions</strong> (mineralization can be considered instantaneous and modelling these reactions using LEA or KA does not lead to significantly different simulation results); (2) <strong>very slow reactions</strong> (no significant change in ion concentrations in the region of interest, whether these r","PeriodicalId":22413,"journal":{"name":"The EGU General Assembly","volume":"199 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79670149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monitoring and Modelling of ionospheric disturbances by means of GRACE, GOCE and Swarm in-situ observations","authors":"M. Schmidt, A. Goss, E. Erdogan","doi":"10.5194/egusphere-egu21-14214","DOIUrl":"https://doi.org/10.5194/egusphere-egu21-14214","url":null,"abstract":"<p>The main objective of the ESA-funded project COSTO (Contribution of Swarm data to the prompt detection of Tsunamis and other natural hazards) is to better characterize, understand and discover coupling processes and interactions between the ionosphere, the lower atmosphere and the Earth&#8217;s surface as well as sea level vertical displacements. Together with our project partners from the University of Warmia and Mazury (UWM), the National Observatory of Athens (NOA) and the Universitat Politecnica de Catalunya (UPC) we focus in COSTO to tsunamis that are the result of earthquakes (EQ), volcano eruptions or landslides.</p><p>In the scope of COSTO a roadmap was developed to detect the vertical and horizontal propagation of Travelling Ionospheric Disturbances (TID) in the observations of Low Earth Orbiting (LEO) satellites. Under the assumption that the TIDs triggered by tsunamis behave in approximately the same way for different EQ / tsunami events, this roadmap can be applied also to other events. In this regard, the Tohoku-Oki EQ in 2011 and the Chile EQ in 2015 were studied in detail. The aim of investigating these events is to detect the TIDs in the near vicinity of the propagating tsunami. Thereby, given tsunami propagation models serve as a rough orientation to determine the moments in time and positions for which there is co-location with selected LEO satellites/missions, namely GRACE, GOCE and Swarm. GOCE with an altitude of around 280km and the GRACE satellites with an altitude of around 450km flew over the region where the Tohoku-Oki tsunami was located, about 2.5 hours after the EQ. Using wavelet transform, similar signatures with periods of 10-30 seconds could be detected in the top-side STEC observations of GOCE as well as in the Ka-band observations of GRACE at the time of the overflight. These signatures can be related to the gravity wave originating from the tsunami. Similar signatures were detected in the signals from the GRACE Ka-band observations and in the Swarm Langmuir Probe measurements at an altitude of 450 km for the 2015 Chile tsunami. These roadmap studies provided the first opportunity to observe the vertical and horizontal tsunami induced gravity waves in the ionosphere.</p>","PeriodicalId":22413,"journal":{"name":"The EGU General Assembly","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88200528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}