Changes in southeastern USA summer precipitation event types using instrumental (1940-2018) and tree-ring (1790-2018) data

We examined short- and long-term changes in precipitation event types using instrumental (1940-2018) and tree-ring (1790-2018) data from North Carolina, USA. We documented the amount and frequency of summer (July-September) precipitation events using daily weather station data. Stationary front precipitation (SFP) represented 71% of total summer rainfall and SFP and convective uplift combined (i.e., quasi-stationary precipitation, QSP) represented 87%. SFP (r = 0.52, p < 0.01) and QSP (r = 0.61, p < 0.01) precipitation reconstructions from a montane longleaf pine latewood chronology both recorded significant declines during 1940-2018, matching the instrumental record. Conversely, no significant change in either SFP or QSP occured during the full reconstruction indicating the instrumental decline was unmatched throughout 1790-1939. Our method demonstrates that variations in latewood growth can be attributed to specific precipitation event types and that the relative contribution of each event type can be quantified over a multi-century period.