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 \u3c 0.01) and QSP (r = 0.61, p \u3c 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