Reconstructing Summer Precipitation with MXD Data from Pinus sylvestris Growing in the Stockholm Archipelago

• Published in: Atmosphere
• Main Authors: Eva Rocha, Björn E. Gunnarson, Steffen Holzkämper
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2020
• Subjects: dendroclimatology; maximum latewood density; Sweden; precipitation reconstruction; light rings; Meteorology. Climatology; QC851-999; North Atlantic; North Atlantic oscillation
• Online Access: https://doi.org/10.3390/atmos11080790; https://doaj.org/article/c899699418d24a4f8c4073dd46d94781

Maximum latewood density (MXD) chronologies have been widely used to reconstruct summer temperature variations. Precipitation signals inferred from MXD data are, however, rather scarce. In this study, we assess the potential of using MXD data derived from Scots pine ( Pinus sylvestris L. ) growing in the Stockholm archipelago (Sweden) to reconstruct past precipitation variability. In this area, slow-growing pine trees emerge on flat plateaus of bedrock outcrops with thin or absent soil layers and are, therefore, sensitive to moisture variability. A 268-year-long MXD chronology was produced, and climate–growth relationships show a significant and robust correlation with May–July precipitation (P MJJ r = 0.64, p < 0.01). The MXD based May–July precipitation reconstruction covers the period 1750–2018 CE and explains 41% of the variance ( r 2 ) of the observed precipitation (1985–2018). The reconstruction suggests that the region has experienced more pluvial phases than drought conditions since the 1750s. The latter half of the 18th century was the wettest and the first half of the 19th century the driest. Climate analysis of “light rings” (LR), latewood layers of extreme low-density cells, finds their occurrence often coincides with significantly dry (<41 mm precipitation) and warmer (1–2 °C above average temperature), May–July conditions. Our analysis suggests that these extremes may be triggered by the summer North Atlantic Oscillation (SNAO).