Land-Ocean Interactions in Arctic Coastal Waters: Ocean Colour Remote Sensing and Current Carbon Fluxes to the Arctic Ocean

• Main Author: Juhls, Bennet
• Other Authors: male, Fischer, Jürgen, Grosse, Guido
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2021
• Subjects: Carbon Fluxes; Ocean Colour Remote Sensing; Arctic; ddc:551; Arctic Ocean; Laptev Sea; Mackenzie River; Arktis*; Beaufort Sea; laptev; lena river; Mackenzie river; permafrost
• Online Access: https://refubium.fu-berlin.de/handle/fub188/29262; https://doi.org/10.17169/refubium-29009; https://nbn-resolving.org/urn:nbn:de:kobv:188-refubium-29262-0

Arctic rivers carry about 40 Tg of organic carbon per year into the Arctic Ocean, enough to change the colour of the surface water over entire shelf seas. Ongoing permafrost thaw mobilizes ancient organic matter in the Arctic Ocean’s watershed and, in particular, organic carbon that was previously preserved in the perennially frozen soils. Whereas the particulate fraction of organic matter is prone to settling and subsequent burial, the dissolved fraction of organic matter (DOM) can be transported over large distances and is quickly integrated and cycled within the aquatic environment. Therefore, monitoring of DOM and its carbon (DOC) in terms of fluxes, quality, transport routes and ultimate fate in the Arctic Ocean, is one of the goals of current polar research. In situ observations in the Arctic are challenging and costly and hold tremendous scientific value. Ocean Colour Remote Sensing (OCRS) is a powerful tool that can complement in situ observations by providing frequent and synoptic estimates of surface water DOM and DOC concentration via the coloured fraction of DOM (CDOM). However, use of OCRS in Arctic organic-rich waters is hampered by uncertainties and needs further evaluation and development. The goal of this thesis is to advance our knowledge of the quantity, origin, seasonal variability and fate of DOM and carbon transported from land to sea in the Arctic. Biogeochemical and bio-optical parameters of water across the fluvial and marine zones in two Arctic regions were collected. These in situ datasets include: 1) Lena River DOM measured at least bi-weekly for one full year, 2) Lena River and Laptev Sea Shelf DOM and optical parameters measured intermittently over 11 years and 3) a suite of water column optical, radiometric, and biogeochemical measurements from spring to fall in the Mackenzie River Delta and on the Beaufort Sea Shelf. These data are a unique and novel resource for testing OCRS atmospheric correction and CDOM retrieval algorithms and for improving satellite-derived DOC estimates ...