Affordable event and intra-event rain samplers: Improving isotopic datasets to understand meteorological processes

Carton, Cécile ; Barbecot, Florent ; Hélie, Jean-François

UQAM-Geotop

Birks, Jean

Innotech

Over the past two decades, stable isotopes of the water molecule (δ¹⁸O, δ¹⁷O and δ²H) have emerged as powerful tracers that have improved our understanding of hydrological processes across different spatial and temporal scales. In particular, they have proved to be an excellent source of information on the sources of water and trajectories leading to individual precipitation events. However, the high cost of commercialized rain samplers developed for isotopic analysis that are typically used by the scientific community, makes it difficult to instrument an area to achieve the high spatial and temporal resolution needed to study the dynamics of a meteorological event. Moreover, many developing countries cannot afford this type of samplers.

We have used a review of the literature to design two types of low-cost, simple and robust rain samplers capable of sampling precipitation for isotopic analysis on the event and intra-event scales. The intra-event sequential rain sampler was modified from an automatic surface water sampler, and is controlled by an electrical panel device allowing sampling over specific time periods (minutes to hours). These samplers were used in multiple tests to determine the minimum amount of rainfall each can sample, and to refine the design to minimize isotopic fractionation, both from post-sampling evaporation and equilibration. These new event and intra-event rain samplers will enable isotopic sampling of precipitation at spatial and temporal resolutions that have not previously been available, but that are needed to study meteorological processes in urban areas. All of the instructions for constructing and using these samplers will be made openly accessible to the scientific community. This open access and low-cost methodology will help democratize the use of isotopes in developing countries.