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Harald Sodemann 

Organization: University of Bergen

Years Using Picarro: 13 Years

Analyzer(s) Used: L2130-i, L2140-i

 

 

 

 

 


Studying the life cycle of water vapour in the atmosphere, from evaporation, transport with weather systems, and precipitation.

About My Research

We study the life cycle of water vapour in the atmosphere, from evaporation, transport with weather systems, and precipitation. Stable water isotopes of water vapour have long been used as a climate variable to understand the role of water in the Earth system. In-situ measurements with CRDS technology reveal the large signals that are present in water isotopes on much shorter times, from minutes to days. These isotope signals are of large value for research communities that are not traditionally involved with isotopes, such as meteorology. Our research has started to bridge the gap between climate and weather research to build better prediction models. One main limitation is that the current traditional observation methods are often exclusively focused on surface-based measurements, such as precipitation. However, to fully test and improve model capabilities, measurements need to take the full spatial range into account, and in particular include information in the vertical dimension, from the ground up.

By providing the observations that are needed to test atmospheric models that simulate water isotope processes, we enable a comparison of models and observations. Such comparison also requires to properly take into account measurement uncertainties, and correction for analytical artifacts. Here we have over the last years continuously made relevant contributions with regard to how measurements can be corrected and their uncertainty be quantified.

We have conducted a range of field experiments in the past years that cover different scales, regions, and phenomena. These data sets are being made available to the scientific community, allowing to exploit the potential of isotope measurements for weather to climate research.

How Picarro Analyzers Helped

We research the life cycle of water vapour in the atmosphere, from evaporation, transport with weather systems, and precipitation. Picarro analyzers have helped us to understand the connection between the detailed processes at the surface, dominated by atmospheric boundary layer turbulence, horizontal and vertical motions in the atmosphere, and processes of precipitation formation.

Airborne measurements are highly challenging, both in terms of logistics, dependency on the right conditions, and reliable instrumentation. We have pushed Picarro analyzers to their limits by embedding them in different platforms. From the bottom up, this includes profiling the lowermost atmospheric layers over Arctic fjords in extreme conditions, to sampling the boundary layer with ultralight aircraft in the European Alps, and bringing Picarro analyzers into severe icing conditions on a research aircraft.

Picarro CRDS technology is a key factor in this research. By enabling in-situ high-frequency measurements of the water vapour isotope composition, we can acquire the ambient signals at the scale that is needed to advance the scienctific understanding.

One example for this decisive technological advantage compared to what was available in past decades is the detailed insight we gained from the ultralight aircraft measurements over temporal, horizontal and vertical variation of the water isotopes in complex terrain. With their standard rack design, the Picarro analyzer could fit on the passenger seat of an ultralight aircraft, and be flown from a 50 m grass landing strip for several hours, while at the same time providing useful measurements at high resolution. The robustness and even foregiveness of the Picarro analyzers is key in daring such unconventional research approaches.