Relating isotopic composition of precipitation to atmospheric patterns and local land-atmosphere coupling strength

Investigations of land-atmosphere coupling have shown that surface conditions significantly influence local boundary layer development and precipitation likelihood. How significant this local forcing and regional moisture recycling is in comparison to larger synoptic-scale dynamics is an area of much uncertainty and importance, especially when trying to diagnose the influence of local land management practices such as irrigation on regional precipitation patterns and drought relief. Stable isotope analysis has long been a useful tool for tracing movement throughout the water cycle. In this study, both reanalysis data and stable isotope samples of precipitation events are used to quantify the role that local moisture recycling plays in precipitation at the Konza Prairie LTER. From 2001 to 2014 samples of all precipitation events over 5mm were collected and δ¹⁸O and δD values measured. Self-organizing maps (SOM) are used to identify a comprehensive range of regional meteorological states from ERA-interim reanalysis data. Precipitation events for the summer season are categorized according to these synoptic conditions and the contributions of locally recycled moisture in precipitation for each SOM category are investigated using isotopic features. Classification of precipitation events by SOM, which should have similar distributions of δ¹⁸O and δD, allows the study of changes in the influence of local moisture recycling over the course of the 14 years of observations.