{"id":{"repo_id":"tu-berlin","oai_identifier":"oai:depositonce.tu-berlin.de:11303/21675"},"canonical_url":"https://search.dev.ndltd.org/etd/tu-berlin/oai:depositonce.tu-berlin.de:11303/21675","repository":{"repo_id":"tu-berlin","name":"Technische Universität Berlin","base_url":"https://api-depositonce.tu-berlin.de/server/oai/request"},"display":{"title":"The Hemispherical Blackbody (HSBB) for improved traceability of longwave downward radiation","abstract":"In this work, the establishment of a new and metrologically solid traceability chain for the detection of atmospheric longwave downward radiation is presented. Key component of this traceability chain is a new reference cavity blackbody, the Hemispherical Blackbody of the Physikalisch-Technische Bundesanstalt. As a result, climate relevant atmospheric irradiance measurements are via the Hemispherical Blackbody strictly linked to the national standards of the Radiation Temperature Scale of the Physikalisch-Technische Bundesanstalt and consequently to the International System of Units. The new traceability chain serves as a much needed independent validation and metrological improvement of the already existing traceability of the reference for longwave downward radiation measurements. It will therefore pave the way for a consistent traceability of worldwide longwave downward radiation measurements independent of possible specific artefacts hold by a single institute. By this, the expanded uncertainties of longwave downward radiation measurements will then be significantly reduced from currently approximately 10 W/m2 to approximately 2 W/m2. More specifically, longwave downward radiation refers to the infrared radiation that is emitted in the atmosphere and incident on the surface of the Earth. It is directly related to the greenhouse effect of the Earth and therefore particularly interesting for climate related research in the context of climate change. Measurements of longwave downward radiation take place on weather stations and research institutes around the world in areas of different climate conditions. In order to ensure reliability and traceability of the worldwide measurement data, the detecting radiometers need to be calibrated regularly. In the past, a set of stable radiometers, the World Infrared Standard Group operated at the Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center, provided the reference for global longwave downward radiation measurements. Efforts have been made in recent years to overcome specific issues through an improved traceability for longwave downward radiation measurements leading to substantially reduced measurement uncertainties. This will result in an enhancement of the credibility and significance of worldwide longwave downward radiation measurements and therefore an improved prediction accuracy of climate change related trends. The current reference for longwave downward radiation measurements is the well-established blackbody Tilted Bottom Cavity BB2007 operated at the Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center. In order to complete the redefinition of the traceability of longwave downward radiation measurements and consequently effecting a scale change, the traceability of the Tilted Bottom Cavity BB2007 was in need of independent validation and more strict linkage to the International System of Units. Both aims have been accomplished in this work by using the Hemispherical Blackbody, thus providing the Tilted Bottom Cavity BB2007 with a new possible traceability chain. In detail, the Hemispherical Blackbody is an infrared radiation emitting calibration source and was developed, elaborately characterised and calibrated at the Physikalisch-Technische Bundesanstalt. It was developed specifically for the calibration of radiometers measuring longwave downward radiation. By providing a sufficiently constant effective emissivity for different viewing conditions, radiation thermometer measurements at normal incidence can be linked to calibration measurements with wide-angle viewing radiometers. These radiometers used for longwave downward radiation measurements have a hemispherical acceptance angle. The target irradiance standard uncertainty provided by the Hemispherical Blackbody amounts to 0.5 W/m2. Several cross check measurements are shown in this work to verify the consistency in the calibration of the Hemispherical Blackbody. In addition, application measurements were performed with typical radiometers for longwave downward radiation and a critical parameter for the calibration was identified. Finally, comparison measurements between the Tilted Bottom Cavity BB2007 and the Hemispherical Blackbody are shown. These measurements were performed with a dedicated radiation thermometer, an Infrared Integrating Sphere Instrument and a pyrgeometer. The large majority of the obtained data points show agreement within 0.5 W/m2. To conclude, the good agreement that was found in both radiation temperature and irradiance provided by the two reference blackbodies, the Tilted Bottom Cavity BB2007 and the Hemispherical Blackbody, serves as an independent validation of the traceability of the Tilted Bottom Cavity BB2007. These bilateral comparison measurements of the irradiance scales for longwave downward radiation were successful and have far-reaching consequences as outlined above. The typical blackbody operating temperatures representing the irradiance levels of longwave downward radiation range from -20 °C to 20 °C. The corresponding dominant infrared wavelength spectrum ranges from approximately 4 µm to 50 µm. Most of the content presented in this dissertation is based on two publications, namely [1,2], which were written throughout the research project presented in this work. [1] M. Feierabend et al. “Development and operation of the Hemispherical Blackbody (HSBB) for the calibration of infrared radiometers with a hemispherical acceptance angle”. In: Optics Express 30 (2022), pp. 46991-47003. [2] M. Feierabend et al. „Bilateral comparison of irradiance scales between PMOD/WRC and PTB for longwave downward radiation measurements”. In: Metrologia 60 (2023), p. 025010.","abstract_html":"In this work, the establishment of a new and metrologically solid traceability chain for the detection of atmospheric longwave downward radiation is presented. Key component of this traceability chain is a new reference cavity blackbody, the Hemispherical Blackbody of the Physikalisch-Technische Bundesanstalt. As a result, climate relevant atmospheric irradiance measurements are via the Hemispherical Blackbody strictly linked to the national standards of the Radiation Temperature Scale of the Physikalisch-Technische Bundesanstalt and consequently to the International System of Units. The new traceability chain serves as a much needed independent validation and metrological improvement of the already existing traceability of the reference for longwave downward radiation measurements. It will therefore pave the way for a consistent traceability of worldwide longwave downward radiation measurements independent of possible specific artefacts hold by a single institute. By this, the expanded uncertainties of longwave downward radiation measurements will then be significantly reduced from currently approximately 10 W/m2 to approximately 2 W/m2. More specifically, longwave downward radiation refers to the infrared radiation that is emitted in the atmosphere and incident on the surface of the Earth. It is directly related to the greenhouse effect of the Earth and therefore particularly interesting for climate related research in the context of climate change. Measurements of longwave downward radiation take place on weather stations and research institutes around the world in areas of different climate conditions. In order to ensure reliability and traceability of the worldwide measurement data, the detecting radiometers need to be calibrated regularly. In the past, a set of stable radiometers, the World Infrared Standard Group operated at the Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center, provided the reference for global longwave downward radiation measurements. Efforts have been made in recent years to overcome specific issues through an improved traceability for longwave downward radiation measurements leading to substantially reduced measurement uncertainties. This will result in an enhancement of the credibility and significance of worldwide longwave downward radiation measurements and therefore an improved prediction accuracy of climate change related trends. The current reference for longwave downward radiation measurements is the well-established blackbody Tilted Bottom Cavity BB2007 operated at the Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center. In order to complete the redefinition of the traceability of longwave downward radiation measurements and consequently effecting a scale change, the traceability of the Tilted Bottom Cavity BB2007 was in need of independent validation and more strict linkage to the International System of Units. Both aims have been accomplished in this work by using the Hemispherical Blackbody, thus providing the Tilted Bottom Cavity BB2007 with a new possible traceability chain. In detail, the Hemispherical Blackbody is an infrared radiation emitting calibration source and was developed, elaborately characterised and calibrated at the Physikalisch-Technische Bundesanstalt. It was developed specifically for the calibration of radiometers measuring longwave downward radiation. By providing a sufficiently constant effective emissivity for different viewing conditions, radiation thermometer measurements at normal incidence can be linked to calibration measurements with wide-angle viewing radiometers. These radiometers used for longwave downward radiation measurements have a hemispherical acceptance angle. The target irradiance standard uncertainty provided by the Hemispherical Blackbody amounts to 0.5 W/m2. Several cross check measurements are shown in this work to verify the consistency in the calibration of the Hemispherical Blackbody. In addition, application measurements were performed with typical radiometers for longwave downward radiation and a critical parameter for the calibration was identified. Finally, comparison measurements between the Tilted Bottom Cavity BB2007 and the Hemispherical Blackbody are shown. These measurements were performed with a dedicated radiation thermometer, an Infrared Integrating Sphere Instrument and a pyrgeometer. The large majority of the obtained data points show agreement within 0.5 W/m2. To conclude, the good agreement that was found in both radiation temperature and irradiance provided by the two reference blackbodies, the Tilted Bottom Cavity BB2007 and the Hemispherical Blackbody, serves as an independent validation of the traceability of the Tilted Bottom Cavity BB2007. These bilateral comparison measurements of the irradiance scales for longwave downward radiation were successful and have far-reaching consequences as outlined above. The typical blackbody operating temperatures representing the irradiance levels of longwave downward radiation range from -20 °C to 20 °C. The corresponding dominant infrared wavelength spectrum ranges from approximately 4 µm to 50 µm. Most of the content presented in this dissertation is based on two publications, namely [1,2], which were written throughout the research project presented in this work. [1] M. Feierabend et al. “Development and operation of the Hemispherical Blackbody (HSBB) for the calibration of infrared radiometers with a hemispherical acceptance angle”. In: Optics Express 30 (2022), pp. 46991-47003. [2] M. Feierabend et al. „Bilateral comparison of irradiance scales between PMOD/WRC and PTB for longwave downward radiation measurements”. In: Metrologia 60 (2023), p. 025010.","abstract_has_math":false,"creators":["Feierabend, Moritz Carl"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Richter, Mathias","Woggon, Ulrike"],"committee_chairs":[],"committee_members":[],"year":2024,"date_issued":"2024","date_published":"2024","updated_at":"2026-07-27T21:28:47Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":["https://creativecommons.org/licenses/by/4.0/"],"identifier_entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://doi.org/10.14279/depositonce-20476"],"render_values":[{"text":"https://doi.org/10.14279/depositonce-20476","href":"https://doi.org/10.14279/depositonce-20476","code":true}]}]},"links":{"outbound_url":"https://depositonce.tu-berlin.de/handle/11303/21675","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Richter, Mathias","Woggon, Ulrike"]},{"key":"dc:creator","label":"Author","values":["Feierabend, Moritz Carl"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2024-06-12T09:38:19Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2024-06-12T09:38:19Z"]},{"key":"dc:date.issued","label":"Date","values":["2024"]},{"key":"dc:type","label":"Dc Type","values":["Doctoral Thesis"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights.uri","label":"Rights URI","values":["https://creativecommons.org/licenses/by/4.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://depositonce.tu-berlin.de/handle/11303/21675","https://doi.org/10.14279/depositonce-20476"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["In this work, the establishment of a new and metrologically solid traceability chain for the detection of atmospheric longwave downward radiation is presented. Key component of this traceability chain is a new reference cavity blackbody, the Hemispherical Blackbody of the Physikalisch-Technische Bundesanstalt. As a result, climate relevant atmospheric irradiance measurements are via the Hemispherical Blackbody strictly linked to the national standards of the Radiation Temperature Scale of the Physikalisch-Technische Bundesanstalt and consequently to the International System of Units. The new traceability chain serves as a much needed independent validation and metrological improvement of the already existing traceability of the reference for longwave downward radiation measurements. It will therefore pave the way for a consistent traceability of worldwide longwave downward radiation measurements independent of possible specific artefacts hold by a single institute. By this, the expanded uncertainties of longwave downward radiation measurements will then be significantly reduced from currently approximately 10 W/m2 to approximately 2 W/m2. More specifically, longwave downward radiation refers to the infrared radiation that is emitted in the atmosphere and incident on the surface of the Earth. It is directly related to the greenhouse effect of the Earth and therefore particularly interesting for climate related research in the context of climate change. Measurements of longwave downward radiation take place on weather stations and research institutes around the world in areas of different climate conditions. In order to ensure reliability and traceability of the worldwide measurement data, the detecting radiometers need to be calibrated regularly. In the past, a set of stable radiometers, the World Infrared Standard Group operated at the Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center, provided the reference for global longwave downward radiation measurements. Efforts have been made in recent years to overcome specific issues through an improved traceability for longwave downward radiation measurements leading to substantially reduced measurement uncertainties. This will result in an enhancement of the credibility and significance of worldwide longwave downward radiation measurements and therefore an improved prediction accuracy of climate change related trends. The current reference for longwave downward radiation measurements is the well-established blackbody Tilted Bottom Cavity BB2007 operated at the Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center. In order to complete the redefinition of the traceability of longwave downward radiation measurements and consequently effecting a scale change, the traceability of the Tilted Bottom Cavity BB2007 was in need of independent validation and more strict linkage to the International System of Units. Both aims have been accomplished in this work by using the Hemispherical Blackbody, thus providing the Tilted Bottom Cavity BB2007 with a new possible traceability chain. In detail, the Hemispherical Blackbody is an infrared radiation emitting calibration source and was developed, elaborately characterised and calibrated at the Physikalisch-Technische Bundesanstalt. It was developed specifically for the calibration of radiometers measuring longwave downward radiation. By providing a sufficiently constant effective emissivity for different viewing conditions, radiation thermometer measurements at normal incidence can be linked to calibration measurements with wide-angle viewing radiometers. These radiometers used for longwave downward radiation measurements have a hemispherical acceptance angle. The target irradiance standard uncertainty provided by the Hemispherical Blackbody amounts to 0.5 W/m2. Several cross check measurements are shown in this work to verify the consistency in the calibration of the Hemispherical Blackbody. In addition, application measurements were performed with typical radiometers for longwave downward radiation and a critical parameter for the calibration was identified. Finally, comparison measurements between the Tilted Bottom Cavity BB2007 and the Hemispherical Blackbody are shown. These measurements were performed with a dedicated radiation thermometer, an Infrared Integrating Sphere Instrument and a pyrgeometer. The large majority of the obtained data points show agreement within 0.5 W/m2. To conclude, the good agreement that was found in both radiation temperature and irradiance provided by the two reference blackbodies, the Tilted Bottom Cavity BB2007 and the Hemispherical Blackbody, serves as an independent validation of the traceability of the Tilted Bottom Cavity BB2007. These bilateral comparison measurements of the irradiance scales for longwave downward radiation were successful and have far-reaching consequences as outlined above. The typical blackbody operating temperatures representing the irradiance levels of longwave downward radiation range from -20 °C to 20 °C. The corresponding dominant infrared wavelength spectrum ranges from approximately 4 µm to 50 µm. Most of the content presented in this dissertation is based on two publications, namely [1,2], which were written throughout the research project presented in this work. [1] M. Feierabend et al. “Development and operation of the Hemispherical Blackbody (HSBB) for the calibration of infrared radiometers with a hemispherical acceptance angle”. In: Optics Express 30 (2022), pp. 46991-47003. [2] M. Feierabend et al. „Bilateral comparison of irradiance scales between PMOD/WRC and PTB for longwave downward radiation measurements”. In: Metrologia 60 (2023), p. 025010.","Diese Arbeit behandelt die Etablierung einer neuen und soliden metrologischen Rückführungskette für die Messung der atmosphärischen Gegenstrahlung. Zentraler Bestandteil dieser Rückführungskette ist ein neuer Referenz-Hohlraumstrahler, der Hemispherical Blackbody der Physikalisch-Technischen Bundesanstalt. Infolgedessen werden klimarelevante atmosphärische Bestrahlungsstärke-Messungen über den Hemispherical Blackbody direkt mit den nationalen Normalen der Strahlungstemperatur-Skala der Physikalisch-Technischen Bundesanstalt und folglich mit dem Internationalen System der Einheiten verknüpft. Die neue Rückführungskette dient als lange benötigte unabhängige Validierung und metrologische Verbesserung der bereits existierenden Rückführung der Referenz für Messungen der atmosphärischen Gegenstrahlung. Sie wird damit den Weg ebnen dafür, dass die weltweiten Messungen der atmosphärischen Gegenstrahlung eine konsistente Rückführung bekommen, die unabhängig ist von möglichen Artefakten eines einzelnen Instituts. Auf diese Weise werden dann die erweiterten Unsicherheiten der Messungen der atmosphärischen Gegenstrahlung signifikant reduziert werden von aktuell ungefähr 10 W/m2 auf etwa 2 W/m2. Die atmosphärische Gegenstrahlung bezeichnet die Infrarotstrahlung, die in der Atmosphäre emittiert und auf der Erdoberfläche empfangen wird. Sie ist direkt verknüpft mit dem Treibhauseffekt der Erde und folglich besonders interessant für die Klimaforschung im Kontext des Klimawandels. Messungen der atmosphärischen Gegenstrahlung werden auf Wetterstationen und Forschungseinrichtungen auf der ganzen Welt in unterschiedlichen Klimazonen durchgeführt. Um die Zuverlässigkeit und Rückführung der weltweiten Messdaten sicherzustellen, müssen die für die Messungen betriebenen Radiometer regelmäßig kalibriert werden. In der Vergangenheit diente die World Infrared Standard Group, die eine Gruppe von stabilen Radiometern darstellt und am Physikalisch-Meteorologischen Observatorium Davos / World Radiation Center betrieben wird, als Referenz für die globalen Messungen der atmosphärischen Gegenstrahlung. Bemühungen wurden in den letzten Jahren aufgebracht, um mithilfe einer verbesserten Rückführung der Messungen der atmosphärischen Gegenstrahlung spezifische Probleme zu beheben, wobei die neue Rückführung dann zu deutlich geringeren Messunsicherheiten führt. Diese wird dann in eine Steigerung der Bedeutung und Vertrauenswürdigkeit der Messungen der atmosphärischen Gegenstrahlung und damit in eine verbesserte Vorhersagegenauigkeit für die mit dem Klimawandel zusammenhängenden Trends resultieren. Die gegenwärtige Referenz für die Messungen der atmosphärischen Gegenstrahlung ist der etablierte Schwarzkörper Tilted Bottom Cavity BB2007, der am Physikalisch-Meteorologischen Observatorium Davos / World Radiation Center betrieben wird. Um die Neudefinition der Rückführung der Messungen der atmosphärischen Gegenstrahlung abzuschließen und folglich eine Skalenänderung zu bewirken, bedurfte die Rückführung des Tilted Bottom Cavity BB2007 einer unabhängigen Validierung und direkteren Verknüpfung mit dem Internationalen System der Einheiten. Beide Ziele wurden in dieser Arbeit mithilfe des Hemispherical Blackbody erreicht, wodurch der Tilted Bottom Cavity BB2007 folglich eine neue Möglichkeit der Rückführung erhalten hat. Der Hemispherical Blackbody ist hierbei eine Infrarotstrahlung emittierende Kalibrierquelle und wurde an der Physikalisch-Technischen Bundesanstalt entwickelt, aufwändig charakterisiert und kalibriert. Er wurde speziell für die Kalibrierung von Radiometern entwickelt, die die atmosphärische Gegenstrahlung messen. Da der Hemispherical Blackbody einen effektiven Emissionsgrad aufweist, der konstant genug ist für verschiedene Detektionsbedingungen, können die mit einem Strahlungsthermometer durchgeführten Messungen, bei denen senkrecht einfallende Strahlung detektiert wird, verknüpft werden mit der Kalibrierung von Radiometern, die Strahlung aus einem weiten Raumwinkel empfangen. Derartige Radiometer, die für die Messung der atmosphärischen Gegenstrahlung verwendet werden, haben einen hemisphärischen Akzeptanzwinkel. Die vorgegebene Standard-Unsicherheit in der Bestrahlungsstärke, die der Hemispherical Blackbody aufweisen soll, beträgt 0.5 W/m2. Verschiedene Kontrollmessungen werden in dieser Arbeit gezeigt, um die Konsistenz in der Kalibrierung des Hemispherical Blackbody zu verifizieren. Ebenso wurden Anwendungsmessungen mit Radiometern durchgeführt, die typischerweise für die Messung der atmosphärischen Gegenstrahlung verwendet werden, und es wurde ein kritischer Parameter für die Kalibrierung identifiziert. Zuletzt werden die Vergleichsmessungen zwischen dem Tilted Bottom Cavity BB2007 und dem Hemispherical Blackbody gezeigt. Diese Messungen wurden mit einem spezifischen Strahlungsthermometer, einem Infrared Integrating Sphere Instrument und einem Pyrgeometer durchgeführt. Die große Mehrheit der aufgenommenen Datenpunkte zeigt eine gute Übereinstimmung innerhalb von 0.5 W/m2. Zusammenfassend dient die gute Übereinstimmung, die sowohl in Strahlungstemperatur als auch in Bestrahlungsstärke zwischen den beiden Referenz-Schwarzkörpern, dem Tilted Bottom Cavity BB2007 und dem Hemispherical Blackbody, bestimmt wurde, als unabhängige Validierung der Rückführung des Tilted Bottom Cavity BB2007. Diese bilateralen Vergleichsmessungen der Bestrahlungsstärke Skalen für die atmosphärische Gegenstrahlung waren erfolgreich und haben weitreichende Auswirkungen wie bereits oben dargelegt. Der Temperaturbereich, in dem die Schwarzkörper typischerweise betrieben werden und der den Bestrahlungsstärken der atmosphärischen Gegenstrahlung entspricht, reicht von -20 °C bis 20 °C. Der zugehörige dominierende infrarote Spektralbereich umfasst die Wellenlängen von etwa 4 µm bis 50 µm. Ein Großteil des Inhalts dieser Dissertation basiert auf zwei Veröffentlichungen, nämlich [1,2], die im Laufe des hier präsentierten Forschungsprojektes verfasst wurden. [1] M. Feierabend et al. “Development and operation of the Hemispherical Blackbody (HSBB) for the calibration of infrared radiometers with a hemispherical acceptance angle”. In: Optics Express 30 (2022), pp. 46991-47003. [2] M. Feierabend et al. „Bilateral comparison of irradiance scales between PMOD/WRC and PTB for longwave downward radiation measurements”. In: Metrologia 60 (2023), p. 025010."]},{"key":"dc:title","label":"Title","values":["The Hemispherical Blackbody (HSBB) for improved traceability of longwave downward radiation"]}]}],"canonical_facts":{"dc:contributor.advisor":["Richter, Mathias","Woggon, Ulrike"],"dc:creator":["Feierabend, Moritz Carl"],"dc:date.accessioned":["2024-06-12T09:38:19Z"],"dc:date.available":["2024-06-12T09:38:19Z"],"dc:date.issued":["2024"],"dc:description.abstract":["In this work, the establishment of a new and metrologically solid traceability chain for the detection of atmospheric longwave downward radiation is presented. Key component of this traceability chain is a new reference cavity blackbody, the Hemispherical Blackbody of the Physikalisch-Technische Bundesanstalt. As a result, climate relevant atmospheric irradiance measurements are via the Hemispherical Blackbody strictly linked to the national standards of the Radiation Temperature Scale of the Physikalisch-Technische Bundesanstalt and consequently to the International System of Units. The new traceability chain serves as a much needed independent validation and metrological improvement of the already existing traceability of the reference for longwave downward radiation measurements. It will therefore pave the way for a consistent traceability of worldwide longwave downward radiation measurements independent of possible specific artefacts hold by a single institute. By this, the expanded uncertainties of longwave downward radiation measurements will then be significantly reduced from currently approximately 10 W/m2 to approximately 2 W/m2. More specifically, longwave downward radiation refers to the infrared radiation that is emitted in the atmosphere and incident on the surface of the Earth. It is directly related to the greenhouse effect of the Earth and therefore particularly interesting for climate related research in the context of climate change. Measurements of longwave downward radiation take place on weather stations and research institutes around the world in areas of different climate conditions. In order to ensure reliability and traceability of the worldwide measurement data, the detecting radiometers need to be calibrated regularly. In the past, a set of stable radiometers, the World Infrared Standard Group operated at the Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center, provided the reference for global longwave downward radiation measurements. Efforts have been made in recent years to overcome specific issues through an improved traceability for longwave downward radiation measurements leading to substantially reduced measurement uncertainties. This will result in an enhancement of the credibility and significance of worldwide longwave downward radiation measurements and therefore an improved prediction accuracy of climate change related trends. The current reference for longwave downward radiation measurements is the well-established blackbody Tilted Bottom Cavity BB2007 operated at the Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center. In order to complete the redefinition of the traceability of longwave downward radiation measurements and consequently effecting a scale change, the traceability of the Tilted Bottom Cavity BB2007 was in need of independent validation and more strict linkage to the International System of Units. Both aims have been accomplished in this work by using the Hemispherical Blackbody, thus providing the Tilted Bottom Cavity BB2007 with a new possible traceability chain. In detail, the Hemispherical Blackbody is an infrared radiation emitting calibration source and was developed, elaborately characterised and calibrated at the Physikalisch-Technische Bundesanstalt. It was developed specifically for the calibration of radiometers measuring longwave downward radiation. By providing a sufficiently constant effective emissivity for different viewing conditions, radiation thermometer measurements at normal incidence can be linked to calibration measurements with wide-angle viewing radiometers. These radiometers used for longwave downward radiation measurements have a hemispherical acceptance angle. The target irradiance standard uncertainty provided by the Hemispherical Blackbody amounts to 0.5 W/m2. Several cross check measurements are shown in this work to verify the consistency in the calibration of the Hemispherical Blackbody. In addition, application measurements were performed with typical radiometers for longwave downward radiation and a critical parameter for the calibration was identified. Finally, comparison measurements between the Tilted Bottom Cavity BB2007 and the Hemispherical Blackbody are shown. These measurements were performed with a dedicated radiation thermometer, an Infrared Integrating Sphere Instrument and a pyrgeometer. The large majority of the obtained data points show agreement within 0.5 W/m2. To conclude, the good agreement that was found in both radiation temperature and irradiance provided by the two reference blackbodies, the Tilted Bottom Cavity BB2007 and the Hemispherical Blackbody, serves as an independent validation of the traceability of the Tilted Bottom Cavity BB2007. These bilateral comparison measurements of the irradiance scales for longwave downward radiation were successful and have far-reaching consequences as outlined above. The typical blackbody operating temperatures representing the irradiance levels of longwave downward radiation range from -20 °C to 20 °C. The corresponding dominant infrared wavelength spectrum ranges from approximately 4 µm to 50 µm. Most of the content presented in this dissertation is based on two publications, namely [1,2], which were written throughout the research project presented in this work. [1] M. Feierabend et al. “Development and operation of the Hemispherical Blackbody (HSBB) for the calibration of infrared radiometers with a hemispherical acceptance angle”. In: Optics Express 30 (2022), pp. 46991-47003. [2] M. Feierabend et al. „Bilateral comparison of irradiance scales between PMOD/WRC and PTB for longwave downward radiation measurements”. In: Metrologia 60 (2023), p. 025010.","Diese Arbeit behandelt die Etablierung einer neuen und soliden metrologischen Rückführungskette für die Messung der atmosphärischen Gegenstrahlung. Zentraler Bestandteil dieser Rückführungskette ist ein neuer Referenz-Hohlraumstrahler, der Hemispherical Blackbody der Physikalisch-Technischen Bundesanstalt. Infolgedessen werden klimarelevante atmosphärische Bestrahlungsstärke-Messungen über den Hemispherical Blackbody direkt mit den nationalen Normalen der Strahlungstemperatur-Skala der Physikalisch-Technischen Bundesanstalt und folglich mit dem Internationalen System der Einheiten verknüpft. Die neue Rückführungskette dient als lange benötigte unabhängige Validierung und metrologische Verbesserung der bereits existierenden Rückführung der Referenz für Messungen der atmosphärischen Gegenstrahlung. Sie wird damit den Weg ebnen dafür, dass die weltweiten Messungen der atmosphärischen Gegenstrahlung eine konsistente Rückführung bekommen, die unabhängig ist von möglichen Artefakten eines einzelnen Instituts. Auf diese Weise werden dann die erweiterten Unsicherheiten der Messungen der atmosphärischen Gegenstrahlung signifikant reduziert werden von aktuell ungefähr 10 W/m2 auf etwa 2 W/m2. Die atmosphärische Gegenstrahlung bezeichnet die Infrarotstrahlung, die in der Atmosphäre emittiert und auf der Erdoberfläche empfangen wird. Sie ist direkt verknüpft mit dem Treibhauseffekt der Erde und folglich besonders interessant für die Klimaforschung im Kontext des Klimawandels. Messungen der atmosphärischen Gegenstrahlung werden auf Wetterstationen und Forschungseinrichtungen auf der ganzen Welt in unterschiedlichen Klimazonen durchgeführt. Um die Zuverlässigkeit und Rückführung der weltweiten Messdaten sicherzustellen, müssen die für die Messungen betriebenen Radiometer regelmäßig kalibriert werden. In der Vergangenheit diente die World Infrared Standard Group, die eine Gruppe von stabilen Radiometern darstellt und am Physikalisch-Meteorologischen Observatorium Davos / World Radiation Center betrieben wird, als Referenz für die globalen Messungen der atmosphärischen Gegenstrahlung. Bemühungen wurden in den letzten Jahren aufgebracht, um mithilfe einer verbesserten Rückführung der Messungen der atmosphärischen Gegenstrahlung spezifische Probleme zu beheben, wobei die neue Rückführung dann zu deutlich geringeren Messunsicherheiten führt. Diese wird dann in eine Steigerung der Bedeutung und Vertrauenswürdigkeit der Messungen der atmosphärischen Gegenstrahlung und damit in eine verbesserte Vorhersagegenauigkeit für die mit dem Klimawandel zusammenhängenden Trends resultieren. Die gegenwärtige Referenz für die Messungen der atmosphärischen Gegenstrahlung ist der etablierte Schwarzkörper Tilted Bottom Cavity BB2007, der am Physikalisch-Meteorologischen Observatorium Davos / World Radiation Center betrieben wird. Um die Neudefinition der Rückführung der Messungen der atmosphärischen Gegenstrahlung abzuschließen und folglich eine Skalenänderung zu bewirken, bedurfte die Rückführung des Tilted Bottom Cavity BB2007 einer unabhängigen Validierung und direkteren Verknüpfung mit dem Internationalen System der Einheiten. Beide Ziele wurden in dieser Arbeit mithilfe des Hemispherical Blackbody erreicht, wodurch der Tilted Bottom Cavity BB2007 folglich eine neue Möglichkeit der Rückführung erhalten hat. Der Hemispherical Blackbody ist hierbei eine Infrarotstrahlung emittierende Kalibrierquelle und wurde an der Physikalisch-Technischen Bundesanstalt entwickelt, aufwändig charakterisiert und kalibriert. Er wurde speziell für die Kalibrierung von Radiometern entwickelt, die die atmosphärische Gegenstrahlung messen. Da der Hemispherical Blackbody einen effektiven Emissionsgrad aufweist, der konstant genug ist für verschiedene Detektionsbedingungen, können die mit einem Strahlungsthermometer durchgeführten Messungen, bei denen senkrecht einfallende Strahlung detektiert wird, verknüpft werden mit der Kalibrierung von Radiometern, die Strahlung aus einem weiten Raumwinkel empfangen. Derartige Radiometer, die für die Messung der atmosphärischen Gegenstrahlung verwendet werden, haben einen hemisphärischen Akzeptanzwinkel. Die vorgegebene Standard-Unsicherheit in der Bestrahlungsstärke, die der Hemispherical Blackbody aufweisen soll, beträgt 0.5 W/m2. Verschiedene Kontrollmessungen werden in dieser Arbeit gezeigt, um die Konsistenz in der Kalibrierung des Hemispherical Blackbody zu verifizieren. Ebenso wurden Anwendungsmessungen mit Radiometern durchgeführt, die typischerweise für die Messung der atmosphärischen Gegenstrahlung verwendet werden, und es wurde ein kritischer Parameter für die Kalibrierung identifiziert. Zuletzt werden die Vergleichsmessungen zwischen dem Tilted Bottom Cavity BB2007 und dem Hemispherical Blackbody gezeigt. Diese Messungen wurden mit einem spezifischen Strahlungsthermometer, einem Infrared Integrating Sphere Instrument und einem Pyrgeometer durchgeführt. Die große Mehrheit der aufgenommenen Datenpunkte zeigt eine gute Übereinstimmung innerhalb von 0.5 W/m2. Zusammenfassend dient die gute Übereinstimmung, die sowohl in Strahlungstemperatur als auch in Bestrahlungsstärke zwischen den beiden Referenz-Schwarzkörpern, dem Tilted Bottom Cavity BB2007 und dem Hemispherical Blackbody, bestimmt wurde, als unabhängige Validierung der Rückführung des Tilted Bottom Cavity BB2007. Diese bilateralen Vergleichsmessungen der Bestrahlungsstärke Skalen für die atmosphärische Gegenstrahlung waren erfolgreich und haben weitreichende Auswirkungen wie bereits oben dargelegt. Der Temperaturbereich, in dem die Schwarzkörper typischerweise betrieben werden und der den Bestrahlungsstärken der atmosphärischen Gegenstrahlung entspricht, reicht von -20 °C bis 20 °C. Der zugehörige dominierende infrarote Spektralbereich umfasst die Wellenlängen von etwa 4 µm bis 50 µm. Ein Großteil des Inhalts dieser Dissertation basiert auf zwei Veröffentlichungen, nämlich [1,2], die im Laufe des hier präsentierten Forschungsprojektes verfasst wurden. [1] M. Feierabend et al. “Development and operation of the Hemispherical Blackbody (HSBB) for the calibration of infrared radiometers with a hemispherical acceptance angle”. In: Optics Express 30 (2022), pp. 46991-47003. [2] M. Feierabend et al. „Bilateral comparison of irradiance scales between PMOD/WRC and PTB for longwave downward radiation measurements”. In: Metrologia 60 (2023), p. 025010."],"dc:identifier.uri":["https://depositonce.tu-berlin.de/handle/11303/21675","https://doi.org/10.14279/depositonce-20476"],"dc:language.iso":["en"],"dc:rights.uri":["https://creativecommons.org/licenses/by/4.0/"],"dc:title":["The Hemispherical Blackbody (HSBB) for improved traceability of longwave downward radiation"],"dc:type":["Doctoral Thesis"]},"updated_at":"2026-07-27T21:28:47Z"}