Periodic Reporting for period 3 - ISLAS (Isotopic links to atmopheric water's sources)
Periodo di rendicontazione: 2021-08-01 al 2023-01-31
The hydrological cycle, with its feedbacks related to water vapour and clouds, is the largest source of uncertainty in weather prediction and climate models. Particularly processes that occur on scales smaller than the model grid lead to errors, which can compensate one another, making them difficult to detect and correct for. Undetectable compensating errors critically limit the understanding of hydrological extremes, the response of the water cycle to a changing climate, and the interpretation of paleoclimate records. Stable water isotopes have a unique potential to serve as the needed constraints, as they provide measures of moisture origin and of the phase change history.
During the ERC-funded research project ISLAS, we will follow the water as it moves through the atmosphere. From changes in the stable isotope composition of the water, we can obtain an unprecedented picture of how the atmospheric part of the water cycle works. Obtaining a clearer picture on how water travels from the oceans through the atmosphere until it returns back to the surface as snow or rain is key in the prediction of weather extremes and feedbacks in the climate system. Within the ISLAS project, we make use of a natural laboratory in the European Arctic to follow the water from source to sink. We employ laboratory experiments, a sequence of field measurements with novel instrumentation, and with computer representations of the atmosphere to quantify the contribution of different processes during evaporation, transport and precipitation processes from the stable isotope composition of water vapor. In particular, we attempt to sample the same airmass several times in sequence, in order to observe the progressive alteration of an airmass as it is being processed in a weather system. In addition to new insight and conceptual understanding, the resulting key datasets will serve as a valuable new constraints of evaporation and precipitation processes in the next generation of weather prediction and climate models.
During the ERC-funded research project ISLAS, we will follow the water as it moves through the atmosphere. From changes in the stable isotope composition of the water, we can obtain an unprecedented picture of how the atmospheric part of the water cycle works. Obtaining a clearer picture on how water travels from the oceans through the atmosphere until it returns back to the surface as snow or rain is key in the prediction of weather extremes and feedbacks in the climate system. Within the ISLAS project, we make use of a natural laboratory in the European Arctic to follow the water from source to sink. We employ laboratory experiments, a sequence of field measurements with novel instrumentation, and with computer representations of the atmosphere to quantify the contribution of different processes during evaporation, transport and precipitation processes from the stable isotope composition of water vapor. In particular, we attempt to sample the same airmass several times in sequence, in order to observe the progressive alteration of an airmass as it is being processed in a weather system. In addition to new insight and conceptual understanding, the resulting key datasets will serve as a valuable new constraints of evaporation and precipitation processes in the next generation of weather prediction and climate models.
The main work within ISLAS is geared towards filling critical knowledge gaps in the stable isotope fractionation theory for cold environments, overcoming limitations of available observations through innovative measurement approaches, and obtaining a unique Lagrangian dataset of the atmospheric water vapour isotope composition that reaches from evaporation to precipitation.
We have completed a first field deployment of measurements of the water isotope composition in the source region of Arctic weather systems. A versatile system allowed to sample the lowermost atmosphere over snow and leads in sea ice during cold-air outbreak conditions at Ny Ålesund in spring 2020. Extensive, distributed observations of precipitation at high resolution are analyzed for progressive alteration during the passage of the same weather system at several locations. A forecast system for Lagrangian flight experiments has been tested in spring 2021, using a controlled weather balloon as forecasting target. The isotope measurement system is being integrated into an aircraft rack, to operate during a field campaign in 2022.
We have completed a first field deployment of measurements of the water isotope composition in the source region of Arctic weather systems. A versatile system allowed to sample the lowermost atmosphere over snow and leads in sea ice during cold-air outbreak conditions at Ny Ålesund in spring 2020. Extensive, distributed observations of precipitation at high resolution are analyzed for progressive alteration during the passage of the same weather system at several locations. A forecast system for Lagrangian flight experiments has been tested in spring 2021, using a controlled weather balloon as forecasting target. The isotope measurement system is being integrated into an aircraft rack, to operate during a field campaign in 2022.
Based on a evolving, revised view of the atmospheric water cycle as a system comprised of a continuity of water vapour with short and long lifetimes, we collect observations that allow to decipher the continuous processing of atmospheric waters by weather systems on a regional scale. Making these novel kind of observations requires testing of new field equipment in the laboratory and the field. We thereby focus on evaporation at high latitudes, precipitation from high-latitude weather systems, and airborne observations connection between start and end of the water cycle.
The Nordic Seas are an ideal case of such a natural laboratory, with distinct evaporation events, shallow transport processes, and swift precipitation formation. The high-resolution, high-precision isotope data acquired so far, and in the forthcoming field measurements, provide a combined view of established and novel natural isotopic source tracers and set new benchmarks for climate models. A unique palette of sophisticated model tools is currently being developed and verified, allowing to plan for the most suitable measurement conditions, and to decipher, synthesize and exploit these observations, and to identify compensating errors between water cycle processes in models. The ISLAS project will thus form a cornerstone for the use of stable isotopes to constrain models for weather and climate prediction, and for improved understanding of the hydrological cycle.
The Nordic Seas are an ideal case of such a natural laboratory, with distinct evaporation events, shallow transport processes, and swift precipitation formation. The high-resolution, high-precision isotope data acquired so far, and in the forthcoming field measurements, provide a combined view of established and novel natural isotopic source tracers and set new benchmarks for climate models. A unique palette of sophisticated model tools is currently being developed and verified, allowing to plan for the most suitable measurement conditions, and to decipher, synthesize and exploit these observations, and to identify compensating errors between water cycle processes in models. The ISLAS project will thus form a cornerstone for the use of stable isotopes to constrain models for weather and climate prediction, and for improved understanding of the hydrological cycle.