TY - GEN A1 - Heistermann, Maik A1 - Bogena, Heye A1 - Francke, Till A1 - Güntner, Andreas A1 - Jakobi, Jannis A1 - Rasche, Daniel A1 - Schrön, Martin A1 - Döpper, Veronika A1 - Fersch, Benjamin A1 - Groh, Jannis A1 - Patil, Amol A1 - Pütz, Thomas A1 - Reich, Marvin A1 - Zacharias, Steffen A1 - Zengerle, Carmen A1 - Oswald, Sascha T1 - Soil moisture observation in a forested headwater catchment: combining a dense cosmic-ray neutron sensor network with roving and hydrogravimetry at the TERENO site Wüstebach T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Cosmic-ray neutron sensing (CRNS) has become an effective method to measure soil moisture at a horizontal scale of hundreds of metres and a depth of decimetres. Recent studies proposed operating CRNS in a network with overlapping footprints in order to cover root-zone water dynamics at the small catchment scale and, at the same time, to represent spatial heterogeneity. In a joint field campaign from September to November 2020 (JFC-2020), five German research institutions deployed 15 CRNS sensors in the 0.4 km2 Wüstebach catchment (Eifel mountains, Germany). The catchment is dominantly forested (but includes a substantial fraction of open vegetation) and features a topographically distinct catchment boundary. In addition to the dense CRNS coverage, the campaign featured a unique combination of additional instruments and techniques: hydro-gravimetry (to detect water storage dynamics also below the root zone); ground-based and, for the first time, airborne CRNS roving; an extensive wireless soil sensor network, supplemented by manual measurements; and six weighable lysimeters. Together with comprehensive data from the long-term local research infrastructure, the published data set (available at https://doi.org/10.23728/b2share.756ca0485800474e9dc7f5949c63b872; Heistermann et al., 2022) will be a valuable asset in various research contexts: to advance the retrieval of landscape water storage from CRNS, wireless soil sensor networks, or hydrogravimetry; to identify scale-specific combinations of sensors and methods to represent soil moisture variability; to improve the understanding and simulation of land–atmosphere exchange as well as hydrological and hydrogeological processes at the hillslope and the catchment scale; and to support the retrieval of soil water content from airborne and spaceborne remote sensing platforms. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1272 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-567756 SN - 1866-8372 IS - 1272 SP - 2501 EP - 2519 ER - TY - JOUR A1 - Heistermann, Maik A1 - Bogena, Heye A1 - Francke, Till A1 - Güntner, Andreas A1 - Jakobi, Jannis A1 - Rasche, Daniel A1 - Schrön, Martin A1 - Döpper, Veronika A1 - Fersch, Benjamin A1 - Groh, Jannis A1 - Patil, Amol A1 - Pütz, Thomas A1 - Reich, Marvin A1 - Zacharias, Steffen A1 - Zengerle, Carmen A1 - Oswald, Sascha T1 - Soil moisture observation in a forested headwater catchment: combining a dense cosmic-ray neutron sensor network with roving and hydrogravimetry at the TERENO site Wüstebach JF - Earth system science data : ESSD N2 - Cosmic-ray neutron sensing (CRNS) has become an effective method to measure soil moisture at a horizontal scale of hundreds of metres and a depth of decimetres. Recent studies proposed operating CRNS in a network with overlapping footprints in order to cover root-zone water dynamics at the small catchment scale and, at the same time, to represent spatial heterogeneity. In a joint field campaign from September to November 2020 (JFC-2020), five German research institutions deployed 15 CRNS sensors in the 0.4 km2 Wüstebach catchment (Eifel mountains, Germany). The catchment is dominantly forested (but includes a substantial fraction of open vegetation) and features a topographically distinct catchment boundary. In addition to the dense CRNS coverage, the campaign featured a unique combination of additional instruments and techniques: hydro-gravimetry (to detect water storage dynamics also below the root zone); ground-based and, for the first time, airborne CRNS roving; an extensive wireless soil sensor network, supplemented by manual measurements; and six weighable lysimeters. Together with comprehensive data from the long-term local research infrastructure, the published data set (available at https://doi.org/10.23728/b2share.756ca0485800474e9dc7f5949c63b872; Heistermann et al., 2022) will be a valuable asset in various research contexts: to advance the retrieval of landscape water storage from CRNS, wireless soil sensor networks, or hydrogravimetry; to identify scale-specific combinations of sensors and methods to represent soil moisture variability; to improve the understanding and simulation of land–atmosphere exchange as well as hydrological and hydrogeological processes at the hillslope and the catchment scale; and to support the retrieval of soil water content from airborne and spaceborne remote sensing platforms. Y1 - 2022 U6 - https://doi.org/10.5194/essd-14-2501-2022 SN - 1866-3516 SN - 1866-3508 VL - 14 IS - 5 SP - 2501 EP - 2519 PB - Copernicus CY - Katlenburg-Lindau ER - TY - JOUR A1 - Heistermann, Maik A1 - Francke, Till A1 - Scheiffele, Lena A1 - Petrova, Katya Dimitrova A1 - Budach, Christian A1 - Schrön, Martin A1 - Trost, Benjamin A1 - Rasche, Daniel A1 - Güntner, Andreas A1 - Doepper, Veronika A1 - Förster, Michael A1 - Köhli, Markus A1 - Angermann, Lisa A1 - Antonoglou, Nikolaos A1 - Zude, Manuela A1 - Oswald, Sascha T1 - Three years of soil moisture observations by a dense cosmic-ray neutron sensing cluster at an agricultural research site in north-east Germany JF - Earth system science data : ESSD N2 - Cosmic-ray neutron sensing (CRNS) allows for the estimation of root-zone soil water content (SWC) at the scale of several hectares. In this paper, we present the data recorded by a dense CRNS network operated from 2019 to 2022 at an agricultural research site in Marquardt, Germany - the first multi-year CRNS cluster. Consisting, at its core, of eight permanently installed CRNS sensors, the cluster was supplemented by a wealth of complementary measurements: data from seven additional temporary CRNS sensors, partly co-located with the permanent ones; 27 SWC profiles (mostly permanent); two groundwater observation wells; meteorological records; and Global Navigation Satellite System reflectometry (GNSS-R). Complementary to these continuous measurements, numerous campaign-based activities provided data by mobile CRNS roving, hyperspectral im-agery via UASs, intensive manual sampling of soil properties (SWC, bulk density, organic matter, texture, soil hydraulic properties), and observations of biomass and snow (cover, depth, and density). The unique temporal coverage of 3 years entails a broad spectrum of hydro-meteorological conditions, including exceptional drought periods and extreme rainfall but also episodes of snow coverage, as well as a dedicated irrigation experiment. Apart from serving to advance CRNS-related retrieval methods, this data set is expected to be useful for vari-ous disciplines, for example, soil and groundwater hydrology, agriculture, or remote sensing. Hence, we show exemplary features of the data set in order to highlight the potential for such subsequent studies. The data are available at doi.org/10.23728/b2share.551095325d74431881185fba1eb09c95 (Heistermann et al., 2022b). Y1 - 2023 U6 - https://doi.org/10.5194/essd-15-3243-2023 SN - 1866-3508 SN - 1866-3516 VL - 15 IS - 7 SP - 3243 EP - 3262 PB - Copernics Publications CY - Katlenburg-Lindau ER - TY - THES A1 - Rasche, Daniel T1 - Cosmic-ray neutron sensing for the estimation of soil moisture T1 - Cosmic-Ray Neutron Sensing zur Messung der Bodenfeuchte BT - from the atmosphere to the near-surface and to larger depths N2 - Water stored in the unsaturated soil as soil moisture is a key component of the hydrological cycle influencing numerous hydrological processes including hydrometeorological extremes. Soil moisture influences flood generation processes and during droughts when precipitation is absent, it provides plant with transpirable water, thereby sustaining plant growth and survival in agriculture and natural ecosystems. Soil moisture stored in deeper soil layers e.g. below 100 cm is of particular importance for providing plant transpirable water during dry periods. Not being directly connected to the atmosphere and located outside soil layers with the highest root densities, water in these layers is less susceptible to be rapidly evaporated and transpired. Instead, it provides longer-term soil water storage increasing the drought tolerance of plants and ecosystems. Given the importance of soil moisture in the context of hydro-meteorological extremes in a warming climate, its monitoring is part of official national adaption strategies to a changing climate. Yet, soil moisture is highly variable in time and space which challenges its monitoring on spatio-temporal scales relevant for flood and drought risk modelling and forecasting. Introduced over a decade ago, Cosmic-Ray Neutron Sensing (CRNS) is a noninvasive geophysical method that allows for the estimation of soil moisture at relevant spatio-temporal scales of several hectares at a high, subdaily temporal resolution. CRNS relies on the detection of secondary neutrons above the soil surface which are produced from high-energy cosmic-ray particles in the atmosphere and the ground. Neutrons in a specific epithermal energy range are sensitive to the amount of hydrogen present in the surroundings of the CRNS neutron detector. Due to same mass as the hydrogen nucleus, neutrons lose kinetic energy upon collision and are subsequently absorbed when reaching low, thermal energies. A higher amount of hydrogen therefore leads to fewer neutrons being detected per unit time. Assuming that the largest amount of hydrogen is stored in most terrestrial ecosystems as soil moisture, changes of soil moisture can be estimated through an inverse relationship with observed neutron intensities. Although important scientific advancements have been made to improve the methodological framework of CRNS, several open challenges remain, of which some are addressed in the scope of this thesis. These include the influence of atmospheric variables such as air pressure and absolute air humidity, as well as, the impact of variations in incoming primary cosmic-ray intensity on observed epithermal and thermal neutron signals and their correction. Recently introduced advanced neutron-to-soil moisture transfer functions are expected to improve CRNS-derived soil moisture estimates, but potential improvements need to be investigated at study sites with differing environmental conditions. Sites with strongly heterogeneous, patchy soil moisture distributions challenge existing transfer functions and further research is required to assess the impact of, and correction of derived soil moisture estimates under heterogeneous site conditions. Despite its capability of measuring representative averages of soil moisture at the field scale, CRNS lacks an integration depth below the first few decimetres of the soil. Given the importance of soil moisture also in deeper soil layers, increasing the observational window of CRNS through modelling approaches or in situ measurements is of high importance for hydrological monitoring applications. By addressing these challenges, this thesis aids to closing knowledge gaps and finding answers to some of the open questions in CRNS research. Influences of different environmental variables are quantified, correction approaches are being tested and developed. Neutron-to-soil moisture transfer functions are evaluated and approaches to reduce effects of heterogeneous soil moisture distributions are presented. Lastly, soil moisture estimates from larger soil depths are derived from CRNS through modified, simple modelling approaches and in situ estimates by using CRNS as a downhole technique. Thereby, this thesis does not only illustrate the potential of new, yet undiscovered applications of CRNS in future but also opens a new field of CRNS research. Consequently, this thesis advances the methodological framework of CRNS for above-ground and downhole applications. Although the necessity of further research in order to fully exploit the potential of CRNS needs to be emphasised, this thesis contributes to current hydrological research and not least to advancing hydrological monitoring approaches being of utmost importance in context of intensifying hydro-meteorological extremes in a changing climate. N2 - Wasser, das als Bodenfeuchte in der ungesättigten Bodenzone gespeichert ist, beeinflusst zahlreiche hydrologische Prozesse. Sie ist von großer Bedeutung für hydrometeorologische Extremereignisse, da sie sowohl die Prozesse zur Entstehung von Hochwassereignissen beeinflusst als auch pflanzenverfügbares Wasser in Dürreperioden bereitstellt, in denen Regen ausbleibt. Vor allem Bodenfeuchte in tieferen Schichten des Bodens wird zum Beispiel durch die geringere Dichte an Pflanzenwurzeln langsamer aufgenommen und reduziert. Die Bodenfeuchte in diesen tieferen Schichten kann daher vor allem in Trockenperioden zum Überleben der Pflanzen in landwirtschaftlichen Gebieten und natürlichen Ökosystemen beitragen. Im Kontext hydro-meteorologischer Extremereignisse kommt der Bodenfeuchte so eine besondere Bedeutung zu und ist daher Teil nationaler Monitoring- und Anpassungsstrategien an sich verändernde Klimabedingungen. Cosmic-Ray Neutron Sensing (CRNS) ist ein geophysikalisches Messverfahren, das natürlich vorkommende Neutronen aus kosmischer Strahlung zur Bodenfeuchtebestimmung nutzt. Die Intensität der über dem Boden gemessenen Neutronen ist dabei abhängig von der Menge anWasserstoff in der Umgebung des Neutronendetektors. Da in den meisten Bereichen an Land die Bodenfeuchte den größten Teil des Wasserstoffs ausmacht, lassen Veränderungen in der gemessenen Neutronenintensität auf veränderte Bodenfeuchtebedingungen schließen. Ein Vorteil dieser nichtinvasiven Methode ist ihr großer Messbereich von mehreren Hektar. Die, selbst über kurze Distanzen und Zeiträume auftretenden, Unterschiede werden somit repräsentativ gemittelt und gemessene Bodenfeuchtewerte können so besser für Vorhersagemodelle von Hochwasser- und Dürreereignissen genutzt werden. Trotz des Potentials von CRNS für das Monitoring von Bodenfeuchte bleiben zahlreiche offene Forschungsfragen, von denen einige im Rahmen dieser Arbeit betrachtet werden. Hierzu zählt die Bestimmung und Korrektur von Einflussgrößen, die das Neutronensignal zusätzlich zur Bodenfeuchte beeinflussen. Ebenso gehört die Ableitung von Bodenfeuchte aus dem Neutronensignal selbst sowie der Umgang mit stark unterschiedlichen Bodenfeuchtebedingungen im Messbereich dazu. Obwohl CRNS einen großen horizontalen Messbereich besitzt, ist die Messtiefe auf die oberen ca. 30 cm des Bodens begrenzt. Hierzu werden Ansätze untersucht, die Bodenfeuchte mathematisch in größere Tiefen zu extrapolieren und sie direkt dort zu messen, indem Neutronendetektoren in Bohrlöchern installiert werden. Mit der Betrachtung der Forschungsfragen kann diese Arbeit einen wichtigen Beitrag zur Weiterentwicklung von CRNS und der Anwendbarkeit der Methode z.B. im Rahmen nationaler Monitoring-Programme leisten, denen im Kontext zunehmend intensiverer hydro-meteorologischer Extremereignisse eine besondere Bedeutung zukommt. KW - cosmic-ray neutron sensing KW - soil moisture KW - Cosmic-Ray Neutron Sensing KW - Bodenfeuchte KW - soil hydrology KW - geophysics KW - Bodenhydrologie KW - Geophysik Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-636465 ER -