Continuous, near-real-time observations of water stable isotope ratios during rainfall and throughfall events

摘要: Abstract. The water isotopic composition of throughfall is affected by complex diffusive exchange with ambient vapour, evaporative enrichment heavy isotopes, and mixing processes in the tree canopy. All interception occur simultaneously space time, generating a complex pattern depth composition. This pattern ultimately cascades through entire hydrologic system is therefore crucial for isotope studies catchment hydrology, where recharge areas are often forested, while reference meteorological stations are generally open. For quasi real-time observation water isotopic ( δ18O δ2H ) both gross precipitation throughfall, we developed an approach combining a membrane contactor (Membrana) a laser-based Cavity Ring-Down Spectrometer (CRDS, Picarro), obtaining readings every 2 s. A setup two CRDS instruments parallel analysing gross precipitation and was used continuous of the temporal effect interception on stable isotopes of water. All devices were kept small to minimize dead volume time lags of only 4 min from rainfall collectors isotope analysers increase resolution observations. Complementarily, variables recorded at high temporal resolution same location. achieved evolution discrete liquid or event-based bulk samples measurements allows direct comparison data common meteorological measurements. Future improvements spatial representativeness will make our even more powerful tool towards detailed insight into the dynamic contributing during events.