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Effect of artificial recharge on submarine groundwater discharge: a Belgian case study 人工补给对海底地下水排放的影响:以比利时为例
Pub Date : 2021-03-03 DOI: 10.5194/EGUSPHERE-EGU21-7495
M. Paepen, K. Walraevens, T. Hermans

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.

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.

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.

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.

Lebbe, L. (2017). Grondwatermodel van de geplande wijzigingen in waterwinning Sint-André. Opdrachtgever: Intercommunale Waterleidingsmaatschappij van Veurne Ambacht (IWVA).

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

比利时沿海潜水含水层以浅层含盐/微咸孔隙水为主。划定沙滩的风成沙丘是少数几个可以找到新鲜饮用水的地方之一。沿海地区的饮用水需求给这些水资源带来了很大的压力,特别是在旅游夏季。此外,过去几年我们面临的干燥夏季增加了对解决方案的需求。在Oostduinkerke, Intercommunale Waterleidingsmaatschappij van veurn - ambacht (IWVA)将抽取地下水与人工地表(自2002年起)和地下补给(自2014年起)相结合,以实现更可持续的开采。渗入的水是附近一家污水处理厂(Aquafin, Wulpen)处理过的废水。沙丘中的补给减少了从北海和南部低洼圩区吸引咸水/微咸水的风险,并允许更稳定的地下水水位,特别是在渗透湖周围。为了评估管理含水层补给项目的效率,我们收集了海上、海滩和部分沙丘的电阻率层析成像(ERT)数据。在低潮和涨潮期间均进行了连续电阻率剖面(CRP)测量。后者提供了一个很好的重叠与土地ERT。在IWVA遗址前以及西部和东部收集剖面,以评估含水层中盐-淡水分布的横向变化。根据电阻率分布,可以识别研究区内的海底地下水排放和盐水入侵模式。处理后废水的入渗直接影响周边地区的压敏水平。在沙丘开始开发之前(1947年),由于存在较浅的粘土层,自然淡水水头在入渗区以西较高(Vandenbohede et al., 2008)。在最近的地下水模型中也可以看到较高的水力水头(Lebbe, 2017),但是根据我们的数据,尽管西部的水力梯度较大,但IWVA站点前面的孔隙水电阻率似乎更高。此外,在渗透场地前的低潮线以下发现了排放区,而在西部和东部的海滩上看到了排放区。我们可以假设补给点前的SGD通量最大(Paepen et al., 2020)。因此,人工补给似乎可以增强该地区的SGD。需要进一步的研究来验证这一点。Lebbe, L.(2017)。Grondwatermodel van de geplande wijzigingen in waterwinning st - andr é[中文]:跨社区水资源管理(IWVA)。Paepen, M., Hanssens, D., Smedt, P. D., Walraevens, K., and Hermans, T.(2020)。结合电阻率法和频域电磁法对沿海地区海底地下水排放情况进行了研究。水文地球系统科学,24(7),3539-3555。Vandenbohede, A., Van Houtte, E., and Lebbe, L.(2009)。沿海地区可持续地下水开采:比利时的一个例子。环境地质,57(4):735-747。
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引用次数: 0
On the current accuracy of altimetry satellite orbits 论目前卫星测高轨道的精度
Pub Date : 2021-03-03 DOI: 10.5194/EGUSPHERE-EGU21-12148
S. Rudenko, D. Dettmering, M. Bloßfeld, J. Zeitlhöfler, Riva Alkahal

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 (< 1 cm) and its trend (< 1 mm/year).

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 possible reasons causing the orbit differences and potential ways to reduce them.

精确的测高卫星轨道是调查全球、区域和沿海海平面及其变化的先决条件,因为要可靠地确定水面高度(空间中高度计位置与水面之间的距离),就需要精确的轨道信息。目前,测高卫星的轨道通常是用卫星综合多普勒轨道和无线电定位(DORIS)、卫星激光测距(SLR)和一些卫星的全球跟踪站网络的全球定位系统(GPS)观测来计算的。近30年来,在提高测高卫星轨道质量方面取得了重大进展。然而,不同机构使用不同软件包、不同观测类型(与GPS+DORIS相比,多丽丝+SLR)和不同最新模式得出的最新轨道解计算出的海平面及其趋势的差异仍然超过了全球气候观测系统对区域海平面(< 1厘米)及其趋势(< 1毫米/年)的不确定性的要求。在本研究中,我们利用最新的背景模型,利用各种观测类型,在最先进的参考框架下,评估了不同机构获得的测高卫星的当前轨道精度。本文给出了对不同轨道解的地理相关误差和径向轨道差的分析结果。我们还讨论了造成轨道差异的可能原因和减少它们的可能方法。
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引用次数: 0
The influence of Antarctic and Greenland ice loss on polar motion: an assessment based on GRACE and multi-mission satellite altimetry 南极和格陵兰冰损对极地运动的影响:基于GRACE和多任务卫星测高的评估
Pub Date : 2021-03-03 DOI: 10.5194/egusphere-egu21-2564
F. Göttl, A. Groh, M. Kappelsberger, Undine Strößenreuther, L. Schröder, V. Helm, M. Schmidt, F. Seitz

Increasing ice loss of the Antarctic and Greenland Ice Sheets (AIS, GrIS) due to global climate change affects the orientation of the Earth’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.

 

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° 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° West meridian by 3 mas/yr.

由于全球气候变化,南极和格陵兰冰盖(AIS, GrIS)的冰损失增加,影响了地球自转轴相对于地球固定参考系(极运动)的方向。由卫星雷达和激光高度计任务(如ENVISAT、CryoSat-2和ICESat)测量的地表高程变化,通过重力恢复和气候实验(GRACE)观测到南极洲和格陵兰岛的冰质量变化。除了有限的空间分辨率外,GRACE估算冰质量变化的精度还受到信号噪声(经向误差条纹)、泄漏效应和冰川均衡调整(GIA)模式的不确定性的限制,而卫星测高估算冰质量变化的精度则受到波形重跟踪、坡度相关的重新定位误差、在本研究中,我们使用不同的GRACE重力场模型(CSR RL06M, JPL RL06M, ITSG-Grace2018)和卫星测高数据(来自德累斯顿工业大学,利兹大学,阿尔弗雷德韦格纳研究所)来评估重力和测高导出的极运动激励函数的准确性。结果表明,由于单个解的组合,可以减少数据处理的系统和随机误差,并且可以增加大地测量导出的AIS和GrIS极运动激励函数的鲁棒性。基于这些研究,我们发现AIS质量的变化导致极点位置矢量沿60°在2003-2015年研究期间,东子午线的变化幅度为2 mas/年,而GrIS质量变化导致极矢量沿45°漂移;西经偏移3马/年。
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引用次数: 0
Evolution of solar wind flows from the inner corona to 1 AU: constraints provided by SOHO UVCS and SWAN data 从内日冕到1au的太阳风流演化:SOHO UVCS和SWAN数据提供的约束
Pub Date : 2021-03-03 DOI: 10.5194/egusphere-egu21-11921
A. Bemporad, O. Katushkina, V. Izmodenov, D. Koutroumpa, E. Quémerais

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.

In this work, SWAN Lyman-α 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-α emission from neutral H coronal atoms due to resonant scattering of chromospheric radiation. On the other hand, the SWAN Lyman-α 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-α 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.

太阳通过太阳风流来调节整个日球层的形状,并与周围的星际介质相互作用。IBEX和INCA实验的最新结果,以及旅行者1号和2号最近的测量结果表明,这种相互作用比以前认为的要复杂得多,而且受时间和日冕变化的影响。这些变化也可能与太阳风在穿越日球层过程中的演变有关。因此,了解太阳风如何从日冕内的加速区演变到日球层边界是非常重要的。在这部作品中,SWAN Lyman-αSOHO的全天观测首次与SOHO UVCS和LASCO仪器在日冕内获得的测量结果相结合,以追踪太阳风从太阳到1au的扩张。1997年,基于LASCO偏振亮度测量和应用于UVCS的多普勒调光技术,推导了一个完整太阳旋转周期内日冕内的太阳风质量通量。色球辐射共振散射引起的中性H日冕原子发射。另一方面,SWAN Lyman-α基于星际氢在日球层中的分布和辐射传输的数值模型,分析了星际氢在日球层中的反向散射。SWAN全天空莱曼-α强度图用于求解反问题,并推导出距离太阳1au处的太阳风质量通量随太阳经度的函数。本文描述了1997年选定时间段比较的第一个结果,并讨论了太阳轨道器数据未来可能的应用。
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引用次数: 0
Modelling Mineral-Scaling in Geothermal Reservoirs Using Both a Local Equilibrium and a Kinetics Approach 用局部平衡和动力学方法模拟地热储层中的矿物结垢
Pub Date : 2021-03-03 DOI: 10.5194/EGUSPHERE-EGU21-16033
A. Hussain, N. Khoshnevis, B. Meulenbroek, Wouter R.L. van der Star, H. Bruining, J. Claringbould, A. Reerink, K. Wolf

              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 – 10 bar) than in the reservoir (100 – 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’s economic return.            
              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.
              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 ‘skin’; 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.      
              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.
              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) fast reactions (mineralization can be considered instantaneous and modelling these reactions using LEA or KA does not lead to significantly different simulation results); (2) very slow reactions (no significant change in ion concentrations in the region of interest, whether these r

& # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160;当从地热井中采热时,采出水在热交换器中冷却,并在地面处理设施中经历较低的压力(1 –10 bar)比储层(100 –300条)。压力的降低可能使气体从溶液中逸出。温度的降低和采出水的脱气可能导致沉淀和溶解(矿化)的发生。采出水冷却后,通过注水井将其重新注入储层。储层中的矿化限制了注入水的流动路径,导致注入能力降低。因此,喷射泵需要更多的能量,从而产生额外的成本,从而降低了项目的经济效益。                     & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160;当对地热储层中的矿化进行数值模拟时,计算反应动力学是非常昂贵的。通过假设反应物和反应产物之间的局部平衡,可以降低模拟的成本;但是使用这种方法可能会得到与实验结果不一致的结果。& # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160;本文提出了一个低焓地热储层矿物沉淀的分析模型。我们将相关反应项的动力学与输运项(热和流)进行比较,以确定局部平衡方法(LEA)或动力学方法(KA)是否适合模拟特定的反应。我们将重点放在储层的近井区域,在该区域,降水可以表现为“表皮”。当假设径向流动时,近井区域的降水对注入能力的影响比油藏下游的降水更大。     & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160;通过数值模拟,我们验证了基于反应速度及其对计算时间的潜在影响,使用不同的地球化学建模方法的方法。& # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160;根据我们对近井区矿化的分析,将反应的时间尺度与输运的时间尺度进行比较,可以区分出三种不同的反应模式,即:(1)快速反应(矿化可以认为是瞬时的,使用LEA或KA模拟这些反应不会导致显著的模拟结果差异);(2)非常缓慢的反应(无论这些反应是用LEA还是KA模拟的,感兴趣区域的离子浓度都没有显著变化);(3)反应/输运中间区(LEA的模拟结果与KA有显著差异)。& # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160;考虑到这些分类,可以简化当前的数值地球化学模型,同时仍然考虑到相关的矿化动力学。利用地热储层降水的数值模型对该方法进行了测试。& # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160; & # 160;
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引用次数: 0
Monitoring and Modelling of ionospheric disturbances by means of GRACE, GOCE and Swarm in-situ observations 利用GRACE、GOCE和Swarm原位观测对电离层扰动的监测和模拟
Pub Date : 2021-03-03 DOI: 10.5194/egusphere-egu21-14214
M. Schmidt, A. Goss, E. Erdogan

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’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.

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.

欧空局资助的项目COSTO(为及时发现海啸和其他自然灾害贡献Swarm数据)的主要目标是更好地表征、理解和发现电离层、低层大气和地球表面以及海平面垂直位移之间的耦合过程和相互作用。我们与来自瓦米亚和马祖里大学(UWM)、雅典国家天文台(NOA)和加泰罗尼亚理工大学(UPC)的项目合作伙伴一起,将COSTO重点放在地震(EQ)、火山爆发或山体滑坡引起的海啸上。在COSTO的范围内,制定了一个路线图,以探测低地球轨道卫星观测中行进电离层扰动(TID)的垂直和水平传播。假设海啸触发的tid对于不同的EQ /海啸事件的行为大致相同,那么该路线图也可以应用于其他事件。为此,对2011年的东北- oki情商和2015年的智利情商进行了详细的研究。调查这些事件的目的是在传播的海啸附近发现tid。因此,给定的海啸传播模型可以作为一个粗略的方向,以确定与选定的LEO卫星/任务(即GRACE、GOCE和Swarm)共定位的时刻和位置。在EQ约2.5小时后,高度约280公里的GOCE和高度约450公里的GRACE卫星飞越了Tohoku-Oki海啸所在的地区。利用小波变换,在GOCE的顶部STEC观测以及飞越时GRACE的ka波段观测中可以检测到周期为10-30秒的类似特征。这些特征可能与海啸产生的重力波有关。在GRACE ka波段观测和Swarm Langmuir探测器在450公里高度测量的2015年智利海啸信号中也发现了类似的特征。这些路线图研究首次提供了观测电离层中垂直和水平海啸引起的重力波的机会。
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引用次数: 1
The impact of severe storms on forecasting the Ionosphere-Thermosphere system through the assimilation of SWARM-derived neutral mass density into physics-based models 通过将swarm衍生的中性质量密度同化到基于物理的模式中,强风暴对电离层-热层系统预报的影响
Pub Date : 2021-03-03 DOI: 10.5194/egusphere-egu21-10552
I. Fernández-Gómez, A. Goss, M. Schmidt, M. Kosary, Timothy Kodikara, E. Forootan, C. Borries

The response of the Ionosphere - Thermosphere (IT) system to severe storm conditions is of great importance to fully understand its coupling mechanisms. The challenge to represent the governing processes of the upper atmosphere depends, to a large extent, on an accurate representation of the true state of the IT system, that we obtain by assimilating relevant measurements into physics-based models. Thermospheric Mass Density (TMD) is the summation of total neutral mass within the atmosphere that is derived from accelerometer measurements of satellite missions such as CHAMP, GOCE, GRACE(-FO) and Swarm. TMD estimates can be assimilated into physics-based models to modify the state of the processes within the IT system. Previous studies have shown that this modification can potentially improve the simulations and predictions of the ionospheric electron density. These differences could also be interpreted as an indicator of the ionosphere-thermosphere interaction. The research presented here, aims to quantify the impact of data satellite based TMD assimilation on numerical model results.

Subject of this study is the Coupled Thermosphere-Ionosphere-Plasmasphere electrodynamics (CTIPe) physics-based model in combination with the recently developed Thermosphere-Ionosphere Data Assimilation (TIDA) scheme. TMD estimates from the ESA’s Swarm mission are assimilated in CTIPe-TIDA during the 16 to the 20 of March 2015. This period was characterized by a strong geomagnetic storm that triggered significant changes in the IT system, the so-called St. Patrick day storm 2015. To assess the changes in the IT system during storm conditions due to data assimilation, the model results from assimilating SWARM mass density normalized to the altitude of 400 km are compared to independent thermospheric estimates like GRACE-TMDS. In order to evaluate the impact of the data assimilation on the ionosphere, the corresponding output of electron density is compared to high-quality electron density estimates derived from data-driven model of the DGFI-TUM.

电离层-热层(IT)系统对强风暴条件的响应对于充分认识其耦合机制具有重要意义。表示高层大气控制过程的挑战在很大程度上取决于对信息技术系统真实状态的准确表示,我们通过将相关测量结果吸收到基于物理的模型中来获得信息技术系统的真实状态。热层质量密度(TMD)是大气中总中性质量的总和,由CHAMP、GOCE、GRACE(-FO)和Swarm等卫星任务的加速度计测量得出。TMD估计可以被吸收到基于物理的模型中,以修改IT系统内流程的状态。先前的研究表明,这种修正可能会改善电离层电子密度的模拟和预测。这些差异也可以解释为电离层-热层相互作用的一个指标。本文的研究旨在量化基于数据卫星的TMD同化对数值模型结果的影响。本研究的主题是基于热层-电离层-等离子层耦合电动力学(CTIPe)物理模型,并结合最近发展的热层-电离层数据同化(TIDA)方案。2015年3月16日至20日期间,esa的Swarm任务的TMD估算值被CTIPe-TIDA同化。这一时期的特点是一场强烈的地磁风暴,引发了IT系统的重大变化,即所谓的2015年圣帕特里克日风暴。为了评估由于数据同化导致的风暴条件下IT系统的变化,将同化归一化到400 km高度的SWARM质量密度的模型结果与GRACE-TMDS等独立的热层估计进行了比较。为了评估数据同化对电离层的影响,将相应的电子密度输出与DGFI-TUM数据驱动模型得出的高质量电子密度估计进行了比较。
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引用次数: 0
Ionospheric VTEC Forecasting using Machine Learning 利用机器学习进行电离层VTEC预测
Pub Date : 2021-03-03 DOI: 10.5194/EGUSPHERE-EGU21-8907
Randa Natras, M. Schmidt
The accuracy and reliability of Global Navigation Satellite System (GNSS) applications are affected by the state of the Earth‘s ionosphere, especially when using single frequency observations, which are employed mostly in mass-market GNSS receivers. In addition, space weather can be the cause of strong sudden disturbances in the ionosphere, representing a major risk for GNSS performance and reliability. Accurate corrections of ionospheric effects and early warning information in the presence of space weather are therefore crucial for GNSS applications. This correction information can be obtained by employing a model that describes the complex relation of space weather processes with the non-linear spatial and temporal variability of the Vertical Total Electron Content (VTEC) within the ionosphere and includes a forecast component considering space weather events to provide an early warning system. To develop such a model is challenging but an important task and of high interest for the GNSS community. To model the impact of space weather, a complex chain of physical dynamical processes between the Sun, the interplanetary magnetic field, the Earth's magnetic field and the ionosphere need to be taken into account. Machine learning techniques are suitable in finding patterns and relationships from historical data to solve problems that are too complex for a traditional approach requiring an extensive set of rules (equations) or for which there is no acceptable solution available yet. The main objective of this study is to develop a model for forecasting the ionospheric VTEC taking into account physical processes and utilizing state-of-art machine learning techniques to learn complex non-linear relationships from the data. In this work, supervised learning is applied to forecast VTEC. This means that the model is provided by a set of (input) variables that have some influence on the VTEC forecast (output). To be more specific, data of solar activity, solar wind, interplanetary and geomagnetic field and other information connected to the VTEC variability are used as input to predict VTEC values in the future. Different machine learning algorithms are applied, such as decision tree regression, random forest regression and gradient boosting. The decision trees are the simplest and easiest to interpret machine learning algorithms, but the forecasted VTEC lacks smoothness. On the other hand, random forest and gradient boosting use a combination of multiple regression trees, which lead to improvements in the prediction accuracy and smoothness. However, the results show that the overall performance of the algorithms, measured by the root mean square error, does not differ much from each other and improves when the data are well prepared, i.e. cleaned and transformed to remove trends. Preliminary results of this study will be presented including the methodology, goals, challenges and perspectives of developing the machine learning model.
全球导航卫星系统(GNSS)应用的准确性和可靠性受到地球电离层状态的影响,特别是在使用单频观测时,这种观测主要用于大众市场的GNSS接收机。此外,空间天气可能是造成电离层强烈突然扰动的原因,对全球导航卫星系统的性能和可靠性构成重大风险。因此,在存在空间天气的情况下,电离层效应的准确校正和预警信息对全球导航卫星系统的应用至关重要。这种校正信息可以通过采用一个模型来获得,该模型描述了空间天气过程与电离层内垂直总电子含量(VTEC)的非线性时空变化之间的复杂关系,并包括考虑空间天气事件的预报分量,以提供预警系统。开发这样一个模型是具有挑战性的,但也是GNSS社区高度关注的重要任务。为了模拟空间天气的影响,需要考虑太阳、行星际磁场、地球磁场和电离层之间的一系列复杂的物理动力学过程。机器学习技术适用于从历史数据中寻找模式和关系,以解决对于需要大量规则(方程)的传统方法来说过于复杂的问题,或者还没有可接受的解决方案。本研究的主要目标是建立一个模型来预测电离层VTEC,考虑到物理过程,并利用最先进的机器学习技术从数据中学习复杂的非线性关系。本研究将监督学习应用于VTEC预测。这意味着模型是由一组(输入)变量提供的,这些变量对VTEC预测(输出)有一定的影响。具体而言,利用太阳活动、太阳风、行星际和地磁场等与VTEC变率相关的数据作为输入,预测未来的VTEC值。应用了不同的机器学习算法,如决策树回归、随机森林回归和梯度增强。决策树是最简单、最容易解释的机器学习算法,但预测的VTEC缺乏平滑性。另一方面,随机森林和梯度增强结合使用多元回归树,提高了预测精度和平滑度。然而,结果表明,以均方根误差衡量的算法的总体性能彼此之间差异不大,并且在数据准备充分(即清洗和转换以去除趋势)的情况下会有所提高。本研究的初步结果将包括开发机器学习模型的方法、目标、挑战和观点。
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引用次数: 1
Scattering ratio profiles retrieved from ALADIN/Aeolus and CALIOP/CALIPSO lidar observations: instantaneous overlaps, statistical comparison, and sensitivity to high clouds 从ALADIN/Aeolus和CALIOP/CALIPSO激光雷达观测中获取的散射比曲线:瞬时重叠、统计比较和对高云的敏感性
Pub Date : 2021-03-03 DOI: 10.5194/EGUSPHERE-EGU21-4746
A. Feofilov, H. Chepfer, V. Noel, M. Chiriaco
Clouds and aerosols play an important role in the Earth’s energy budget through a complex interaction with solar, atmospheric, and terrestrial radiation, and air humidity. Optically thick clouds efficiently reflect the incoming solar radiation and, globally, clouds are responsible for about two thirds of the planetary albedo. Thin cirrus trap the outgoing longwave radiation and keep the planet warm. Aerosols scatter or absorb sunlight depending on their size and shape and interact with clouds in various ways. Due to the importance of clouds and aerosols for the Earth’s energy budget, global satellite observations of their properties are essential for climate studies, for constraining climate models, and for evaluating cloud parameterizations. Active sounding from space by lidars and radars is advantageous since it provides the vertically resolved information. This has been proven by CALIOP lidar which has been observing the Earth’s atmosphere since 2006. Another instrument of this kind, CATS lidar on-board ISS provided measurements for over 33 months starting from the beginning of 2015. The ALADIN lidar on-board ADM/Aeolus has been measuring horizontal winds and aerosols/clouds since August 2018. More lidars are planned – in 2022, the ATLID/EarthCare lidar will be launched and other space-borne lidars are in the development phase. In this work, we compare the scattering ratio products retrieved from ALADIN and CALIOP observations. The former is aimed at 35 deg from nadir, it measures the atmospheric backscatter at 355nm from nadir, is capable of separating the molecular and particular components (HSRL), and provides the profiles with a vertical resolution of ~1km up to 20km altitude. The latter, operating at 532nm is aimed at 3 deg from nadir and measures the total backscatter up to 40 km. Its natural vertical resolution is higher than that of ALADIN, but the scattering ratio product used in the comparison is provided at ~0.5km vertical grid. We have performed a search of nearly simultaneous common volume observations of atmosphere by these two instruments for the period from 28/06/2019 through 31/12/2019 and analyzed the collocated data. We present the zonal averages of scattering ratios as well as the instantaneous profile comparisons and the statistical analysis of cloud detection, cloud height agreement, and temporal evolution of these characteristics. The preliminary conclusion, which can be drawn from this analysis, is that the general agreement of scattering ratio profiles retrieved from ALADIN and CALIOP observations is good up to 6-7 km height whereas in the higher atmospheric layers ALADIN is less sensitive to clouds than the CALIOP. This lack of sensitivity might be compensated by further averaging of the input signals and/or by an updating of the retrieval algorithms using the collocated observations dataset provided in the present work.
云和气溶胶通过与太阳、大气和地面辐射以及空气湿度的复杂相互作用,在地球的能量收支中发挥着重要作用。光学厚度的云有效地反射入射的太阳辐射,在全球范围内,云对行星反照率的贡献约占三分之二。薄卷云阻挡了长波辐射,使地球保持温暖。气溶胶根据其大小和形状散射或吸收阳光,并以各种方式与云相互作用。由于云和气溶胶对地球能量收支的重要性,对其性质的全球卫星观测对于气候研究、约束气候模式和评估云参数化至关重要。利用激光雷达和雷达从太空主动探测是有利的,因为它能提供垂直分辨率的信息。CALIOP激光雷达从2006年开始观测地球大气层,已经证实了这一点。另一种类似的仪器,国际空间站上的CATS激光雷达从2015年初开始提供了超过33个月的测量。自2018年8月以来,ADM/Aeolus上的ALADIN激光雷达一直在测量水平风和气溶胶/云。计划在2022年发射更多的激光雷达——ATLID/EarthCare激光雷达,其他星载激光雷达正处于开发阶段。在这项工作中,我们比较了从ALADIN和CALIOP观测中获得的散射比产品。前者瞄准距最低点35度,测量距最低点355nm的大气后向散射,能够分离分子和特殊成分(HSRL),并提供垂直分辨率为~1km至20km高度的剖面。后者在532nm处工作,目标距离最低点3度,测量总后向散射达40公里。它的自然垂直分辨率高于ALADIN,但比较中使用的散射比产品是在~0.5km的垂直网格上提供的。我们对这两种仪器在2019年6月28日至2019年12月31日期间几乎同时进行的大气共同体积观测进行了搜索,并分析了并置数据。我们给出了散射比的纬向平均值,以及瞬时剖面比较和云探测的统计分析,云高度一致,以及这些特征的时间演变。从这一分析中可以得出的初步结论是,ALADIN和CALIOP观测反演的散射比曲线在6-7 km高度范围内的一致性较好,而在较高的大气层中,ALADIN对云的敏感性低于CALIOP。这种灵敏度的不足可以通过输入信号的进一步平均和/或使用本工作中提供的并置观测数据集更新检索算法来补偿。
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引用次数: 0
Shallow geothermal energy potential of south-west Germany 德国西南部浅层地热能潜力
Pub Date : 2021-03-03 DOI: 10.5194/EGUSPHERE-EGU21-10010
Johannes M. Miocic

A large-scale transformation of the heating and cooling sector is needed to achieve the climate neutrality goals by 2050 as outlined in the European Green Deal. One frequently discussed option for reducing the greenhouse gas emissions is the widespread use of ground source heat pumps (GSHPs) for heating and cooling living spaces. Here, the technical potential of GSHPs to supply heat to buildings in the state of Baden-Württemberg, Germany, is analysed. This study is based on the yearly demand for heating energy at a building block scale, geological conditions, mean annual surface temperatures, as well as legal restrictions such as temperature differences at the heat pump, maximum monthly heat extraction rates as well as areas restricted from drilling. It is shown that for many densely populated areas many GSHPs would be needed to supply all the energy needed for heating. However, in less densely populated areas GSHPs can be used for heating. If future heating demand is lower due to wide-spread insulation retrofitting, GSHPs could supply most of the energy needed for heating even in densely populated areas.

要实现《欧洲绿色协议》中提出的到2050年实现气候中和的目标,供暖和制冷行业需要进行大规模转型。减少温室气体排放的一个经常讨论的选择是广泛使用地源热泵(GSHPs)来加热和冷却生活空间。在这里,分析了地源热泵为德国巴登- w ü符腾堡州的建筑物供热的技术潜力。这项研究是基于建筑物规模的年供暖能源需求,地质条件,年平均地表温度,以及法律限制,如热泵的温差,最大月度热量提取率以及限制钻井的区域。结果表明,对于许多人口稠密的地区,将需要许多地源热泵来提供供暖所需的全部能源。然而,在人口密度较低的地区,地源热泵可用于供暖。如果未来的供暖需求由于广泛的隔热改造而降低,即使在人口稠密的地区,地源热泵也可以提供大部分供暖所需的能源。
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引用次数: 1
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