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FRINATEK-Fri prosj.st. mat.,naturv.,tek

Isotopic Transfer Rates During Water Phase Changes

Alternative title: Isotopiske overføringsforhold ved vannfaseendringer

Awarded: NOK 12.0 mill.

What insights would we gain by directly observing the processes that regulate atmospheric water vapor? The iTRANSFER project is poised to provide us with a precise and accurate means to accomplish this. Water, in its various forms, is not a homogenous substance. It comprises distinct types of water molecules, some with heavier isotopes due to the presence of additional neutrons. Leveraging advanced laser instruments, we can measure the relative composition of heavy and light water molecules in liquid, ice, and vapor. The unique behaviors exhibited by these molecules during phase transitions, such as evaporation or the formation of snow crystals, offer a pathway for directly studying the different water types in the atmosphere. However, to interpret our observations effectively, it is crucial to understand the governing laws under ideal conditions, where one parameter is varied at a time. The iTRANSFER project aims to provide an in-depth understanding of how temperature and humidity gradients influence the phase change transfer rate of various water molecules with unparalleled precision. What sets iTRANSFER apart is its use of ultra-precise laser instruments, enabling experiments with extremely small samples at unprecedented temporal resolution. Beyond enhancing our comprehension of Earth's water cycle, the research conducted through iTRANSFER will serve as a foundation for deciphering the water cycles on celestial bodies like Mars and the Moon. The project's findings could potentially offer valuable insights into the past evolution of the surfaces of these extraterrestrial objects, contributing to a better understanding of Earth's own formation. We have in 2023 achieved to develop a comprehensive experimental setup, which allows us to within a fraction of degree celsius control the conditions during phase change. With this experimental setup, we will be able to achieve true steady-state conditions, something, which has not been accomplished before. The experimental setup will further allow us to control the conditions automatically, which will allow more experiments to be conducted.

Water stable isotopologues in an air mass carry an integrative fingerprint of the ambient conditions due to the different molecular structures causing fractionation during phase change. This makes the water isotopic composition an important and useful proxy for quantifying the physical processes of the hydrological cycle on the Earth. The basis for research using water isotopologues is the equilibrium and kinetic fractionation factors during phase changes. Mounting experimental results and environmental observations have raised questions to the validity of our nearly half a centennial old description of isotopic equilibrium and kinetic fractionation factors describing the water isotopologue transfer rates during phase changes between solid, liquid, and vapor. This uncertainty in the formulations creates an ambiguous foundation on which the geoscientific community relies upon for providing understanding of the climate and environmental systems. This proposal consists of an experimental and modeling component that will establish an accurate basis for use of water isotopologues in studies of the terrestrial hydrological cycle by making accurate measurements of the equilibrium and kinetic fractionation factor. The project will operate based on the following three hypotheses addressed in separate work packages (WP): Hypothesis 1: Equilibrium fractionation factors for water isotopologues are not accurately determined for phase changes below 0°C (WP 1). Hypothesis 2: Kinetic fractionation factors for water isotopologues during evaporation are not accurate determined (WP 2). Hypothesis 3: More accurate fractionation factors will lead to better simulation in climate models of the water isotopologues in the atmosphere (WP 3).

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FRINATEK-Fri prosj.st. mat.,naturv.,tek