Spaceborne Imaging Spectroscopy of the Three Phases of Water
Water is one of the most essential substances on Earth as it occurs in all three thermodynamic phases both in the atmosphere and the surface: solid water in terms of snow and ice grains, liquid water enclosed in-between ice crystals and leaves of vegetation, and gaseous water forming the water vapor...
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| Other Authors: | , , , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | https://refubium.fu-berlin.de/handle/fub188/35244 https://doi.org/10.17169/refubium-34962 https://nbn-resolving.org/urn:nbn:de:kobv:188-refubium-35244-0 |
| Summary: | Water is one of the most essential substances on Earth as it occurs in all three thermodynamic phases both in the atmosphere and the surface: solid water in terms of snow and ice grains, liquid water enclosed in-between ice crystals and leaves of vegetation, and gaseous water forming the water vapor in the atmosphere. The different phases of water control large amounts of the environmental energy cycle and a quantitative mapping on a global scale is of particular importance as it provides a valuable input to climate models and helps to understand underlying processes. The three phases of water show subtle differences in absorption shape in the optical range of the solar spectrum, so that a quantitative mapping requires high-resolution measurements of solar radiation reflected from Earth's surface. The technique of imaging spectroscopy provides such measurements, but has been almost entirely applied to small local scales based on airborne sensors. However, a new generation of orbital missions, including the Italian Hyperspectral Precursor of the Application Mission (PRISMA), NASA’s Earth Surface Mineral Dust Source Investigation (EMIT), the German Environmental Mapping and Analysis Program (EnMAP), ESA's Copernicus Hyperspectral Imaging Mission (CHIME), and NASA’s Surface Biology and Geology (SBG) designated observable, is expected to deliver high-resolution data both on a global scale and daily basis. This requests for independently applicable retrieval algorithms including a rigorous quantification of uncertainties. In this context, this thesis presents two new spectroscopic retrieval methods to quantify the three phases of water from space, which are aligned with future instrument characteristics, adapted to an increased atmospheric path as well as to a different ground sampling distance. Both algorithms use the optimal estimation formalism that assumes Gaussian error distribution and leverages prior knowledge as well as measurement noise in an inversion scheme that also produces posterior uncertainty ... |
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