Investigating the vertical aerosol distribution above the Arctic sea ice with a tethered balloon

Autor: Pilz, Christian
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Druh dokumentu: Text<br />Doctoral Thesis
DOI: 10.5194/amt-15-6889-2022
Popis: Die Arktis erwärmt sich aus noch nicht vollständig geklärten Gründen drei- bis viermal schneller als der Rest der Erde. Wolken, die den Energiehaushalt der Oberfläche und den vertikalen Transport von Wärme und Feuchtigkeit über dem Meereis signifikant beeinflussen, werden durch die oft begrenzte Verfügbarkeit von tröpfchenbildenden Aerosolpartikeln beeinflusst. Diese Aerosol-Wolken-Wechselwirkungen sind schwer zu erfassen, da die untere Troposphäre zumeist komplex geschichtet ist. In dieser Doktorarbeit werden drei neue wissenschaftliche Veröffentlichungen vorgestellt, die unternommenen wurden, um die vertikale Aerosolverteilung über dem arktischen Meereis mit einem Fesselballon zu untersuchen. Im ersten Schritt wurde eine neue Aerosolmessplattform, genannt CAMP, für Fesselballoneinsätze konzipiert. CAMP beinhaltet vier mobile Instrumente in einem Gehäuse, das vor Umwelteinflüssen schützt, zur Messung der Mikrophysik von Aerosolpartikeln. Die Sensoren wurden gründlich kalibriert und charakterisiert und die Leistung der Plattform in Feldtests bewertet. Im zweiten Schritt wurden während einer Forschungsexpedition in der zentralen Arktis Fesselballonmessungen von einer Eisscholle aus durchgeführt. Neben CAMP wurden vier weitere Instrumentenpakete mit dem Ballon geflogen, um die atmosphärische Grenzschicht zu charakterisieren. Die gewonnenen Daten wurden validiert und der wissenschaftlichen Gemeinschaft frei zur Verfügung gestellt. Im dritten Schritt wurden vierunddreißig Aerosolprofile analysiert und die Auswirkungen des Luftmassenursprungs und der Troposphärenstruktur auf die vertikale Aerosolverteilung bewertet. Die Ergebnisse der Studie zeigten, dass die Aerosolpartikel oberhalb der Grenzschicht für Wolken-Wechselwirkung von wesentlicher Bedeutung sind. Eine Analyse der Kopplung zwischen Wolke und Oberfläche zeigte deutlich, dass der vertikale Transport von Aerosolen von der Oberfläche zur Wolkenbasis in entkoppelten Wolkenfällen gehemmt war. Sekundäre Partikelbildung nach dem Transport von Vorläuferdämpfen von südlich des Eisrandes führte zu hohen Konzentrationen kleinerer Partikel oberhalb der Grenzschicht. In einem anderen Fall unterstützten hohe Mengen größerer Partikel die Bildung einer dichten Nebelschicht nach dem Ferntransport. Diese Arbeit hat gezeigt, dass es möglich ist, qualitativ hochwertige Aerosolmessungen mit Fesselballons in einer abgelegenen Region und unter schwierigen Umweltbedingungen durchzuführen. Die gewonnenen Daten und die bereitgestellten Analysen ermöglichen neue Einblicke in die vertikale Aerosolverteilung über dem Meereis. Zusammenfassend lässt sich sagen, dass diese Arbeit dazu beiträgt, unser Verständnis von Aerosol-Wolken-Wechselwirkungen über dem Arktischen Meereis zu erweitern.:Contents 1 Introduction ... ... ... ... ... ... ... ... ... .... 1 1.1 Aerosol particles in the Arctic ... ... ... ... ... ... ... ... ... .... 1 1.2 The lower troposphere above the Arctic sea ice ... ... ... ... ... ... ... 4 1.3 Aerosol measurements with tethered balloons ... ... ... ... ... ... .... 6 1.4 Objectives ... ... ... ... ... ... ... ... ... ... ... ... ... ... 7 2 Methodology ... ... ... ... ... ... ... ... ... .... 9 2.1 The cubic aerosol measurement platform (CAMP) ... ... ... ... ... .... 9 2.1.1 Platform design ... ... ... ... ... ... ... ... ... ... .... . 9 2.1.2 Instrumentation ... ... ... ... ... ... ... ... ... ... .... 10 2.1.3 First field deployments ... ... ... ... ... ... ... ... ... .... 11 2.2 Tethered balloon measurements above the Arctic sea ice ... ... ... ... .... 12 2.2.1 The MOSAiC expedition ... ... ... ... ... ... ... ... .... . 12 2.2.2 Tethered balloon operations ... ... ... ... ... ... ... ... .... 13 2.2.3 Deployed instrument packages ... ... ... ... ... ... ... ... ... 13 2.2.4 Data validation and availability ... ... ... ... ... ... ... .... . 14 2.3 Data analysis ... ... ... ... ... ... ... ... ... ... ... ... .... 14 2.3.1 Back trajectories ... ... ... ... ... ... ... ... ... ... .... 14 2.3.2 Cloud borders ... ... ... ... ... ... ... ... ... ... ... ... 15 2.3.3 Inversion detection algorithm ... ... ... ... ... ... ... ... ... 16 2.3.4 Tropospheric structure ... ... ... ... ... ... ... ... ... .... 16 3 Results and Discussion ... ... ... ... ... ... ... ... ... .... 17 3.1 First publication ... ... ... ... ... ... ... ... ... ... ... .... . 17 3.2 Second publication ... ... ... ... ... ... ... ... ... ... ... .... 39 3.3 Third publication ... ... ... ... ... ... ... ... ... ... ... .... . 51 4 Summary and Outlook ... ... ... ... ... ... ... ... ... .... 79 4.1 First publication ... ... ... ... ... ... ... ... ... ... ... .... . 79 4.2 Second publication ... ... ... ... ... ... ... ... ... ... ... .... 80 4.3 Third publication ... ... ... ... ... ... ... ... ... ... ... .... . 81 4.4 Outlook ... ... ... ... ... ... ... ... ... ... ... ... ... .... 82 List of Abbreviations ... ... ... ... ... ... ... ... ... .... 85 List of Figures ... ... ... ... ... ... ... ... ... .... 85 References ... ... ... ... ... ... ... ... ... .... 89 Appendices ... ... ... ... ... ... ... ... ... .... i A Appendix ... ... ... ... ... ... ... ... ... .... i A.1 Publications included in the Doctoral Thesis and Author’s contributions ... .... i A.2 Contributions to other publications as co-author during the PhD ... ... .... . iii A.3 Colophon ... ... ... ... ... ... ... ... ... ... ... ... ... .... iv
The Arctic is warming three to four times faster than the rest of the Earth for reasons that are not yet fully understood. Clouds, which significantly affect the surface energy budget and the vertical transport of heat and moisture above sea ice, are influenced by the often limited availability of droplet-forming aerosol particles. However, aerosol-cloud interactions are challenging to assess due to the commonly complex structured lower troposphere. This doctoral thesis presents three novel scientific publications that detail the steps taken to investigate the vertical aerosol distribution above the Arctic sea ice with a tethered balloon. In the first step, the new cubic aerosol measurement platform (CAMP) was designed for tethered balloon deployments. CAMP contains four mobile instruments in an environmentally robust housing for measuring aerosol particle microphysics. The sensors were thoroughly calibrated and characterized, and the platform performance was evaluated in field tests. Secondly, tethered balloon measurements were performed from an ice floe during a research expedition into the central Arctic. CAMP and four other instrument packages were deployed with the balloon to characterize the atmospheric boundary layer. The obtained data were validated and made freely available to the scientific community. Lastly, thirty-four aerosol profiles were analyzed, and the impact of the air mass origin and the lower tropospheric structure on the vertical aerosol distribution was evaluated. The study results showed that the aerosol particles above the boundary layer are essential for interactions with low-level clouds. An analysis of the cloud-surface coupling state clearly demonstrated inhibited vertical transport of aerosols from the surface to the cloud base in decoupled cloud cases. Secondary particle formation initiated by low-level transport of precursor vapors from south of the ice edge caused high concentrations of smaller particles above the boundary layer. In another case, high amounts of larger particles supported the formation of a dense fog layer after long-range transport. This thesis demonstrated the feasibility of providing high-quality aerosol measurements with tethered balloons from a remote region under challenging environmental conditions. The obtained data and the provided analysis enable novel insights into the vertical aerosol distribution above the sea ice. In conclusion, this work contributes to expanding our understanding of aerosol-cloud interactions in the Arctic.:Contents 1 Introduction ... ... ... ... ... ... ... ... ... .... 1 1.1 Aerosol particles in the Arctic ... ... ... ... ... ... ... ... ... .... 1 1.2 The lower troposphere above the Arctic sea ice ... ... ... ... ... ... ... 4 1.3 Aerosol measurements with tethered balloons ... ... ... ... ... ... .... 6 1.4 Objectives ... ... ... ... ... ... ... ... ... ... ... ... ... ... 7 2 Methodology ... ... ... ... ... ... ... ... ... .... 9 2.1 The cubic aerosol measurement platform (CAMP) ... ... ... ... ... .... 9 2.1.1 Platform design ... ... ... ... ... ... ... ... ... ... .... . 9 2.1.2 Instrumentation ... ... ... ... ... ... ... ... ... ... .... 10 2.1.3 First field deployments ... ... ... ... ... ... ... ... ... .... 11 2.2 Tethered balloon measurements above the Arctic sea ice ... ... ... ... .... 12 2.2.1 The MOSAiC expedition ... ... ... ... ... ... ... ... .... . 12 2.2.2 Tethered balloon operations ... ... ... ... ... ... ... ... .... 13 2.2.3 Deployed instrument packages ... ... ... ... ... ... ... ... ... 13 2.2.4 Data validation and availability ... ... ... ... ... ... ... .... . 14 2.3 Data analysis ... ... ... ... ... ... ... ... ... ... ... ... .... 14 2.3.1 Back trajectories ... ... ... ... ... ... ... ... ... ... .... 14 2.3.2 Cloud borders ... ... ... ... ... ... ... ... ... ... ... ... 15 2.3.3 Inversion detection algorithm ... ... ... ... ... ... ... ... ... 16 2.3.4 Tropospheric structure ... ... ... ... ... ... ... ... ... .... 16 3 Results and Discussion ... ... ... ... ... ... ... ... ... .... 17 3.1 First publication ... ... ... ... ... ... ... ... ... ... ... .... . 17 3.2 Second publication ... ... ... ... ... ... ... ... ... ... ... .... 39 3.3 Third publication ... ... ... ... ... ... ... ... ... ... ... .... . 51 4 Summary and Outlook ... ... ... ... ... ... ... ... ... .... 79 4.1 First publication ... ... ... ... ... ... ... ... ... ... ... .... . 79 4.2 Second publication ... ... ... ... ... ... ... ... ... ... ... .... 80 4.3 Third publication ... ... ... ... ... ... ... ... ... ... ... .... . 81 4.4 Outlook ... ... ... ... ... ... ... ... ... ... ... ... ... .... 82 List of Abbreviations ... ... ... ... ... ... ... ... ... .... 85 List of Figures ... ... ... ... ... ... ... ... ... .... 85 References ... ... ... ... ... ... ... ... ... .... 89 Appendices ... ... ... ... ... ... ... ... ... .... i A Appendix ... ... ... ... ... ... ... ... ... .... i A.1 Publications included in the Doctoral Thesis and Author’s contributions ... .... i A.2 Contributions to other publications as co-author during the PhD ... ... .... . iii A.3 Colophon ... ... ... ... ... ... ... ... ... ... ... ... ... .... iv
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