Reconstructing Summer Upper-Level Flow In The Northern Rocky Mountains Using An Alpine Larch (Larix Lyallii) Tree-Ring Chronology

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Evan E. Montpellier (Creator)
Institution
Appalachian State University (ASU )
Web Site: https://library.appstate.edu/
Advisor
Peter T. Soule

Abstract: Mid-latitude mesoscale weather in the climatological summer is heavily influenced by fluctuations in synoptic-scale circulation patterns. Previous research has linked Arctic amplification to alterations in summer synoptic climatology, leading to more extreme weather events in the mid-latitudes. In this study we reconstruct seasonal (JJA) upper-level (500 hPa) atmospheric flow for four geographic locations in the mid-latitudes using an alpine larch (Larix lyallii Parl.) tree-ring chronology derived from western Montana. Our goal is to assess the long-term (400+ year) stability of upper-level flow to place the observed trends in a historical context. Spatial pattern correlations indicate that tree growth increases when meridional flow and zonal flow are strong west (r = 0.504, p = 0.001, n = 37) and north (r = 0.642, p < 0.001, n = 37) of the study site, respectively. Tree growth declines when meridional flow and zonal flow are strong east (r = -0.497, p = 0.001, n = 37) and south (r = -0.584, p < 0.001, n = 37) of the study site, respectively. Our 444-year climate reconstructions of 500 hPa flow show that ridging is becoming more intense in recent decades while troughs are declining in intensity.

Additional Information

Publication
Thesis
Montpellier, E. (2018). "Reconstructing Summer Upper-Level Flow In The Northern Rocky Mountains Using An Alpine Larch (Larix Lyallii) Tree-Ring Chronology." Unpublished Master’s Thesis. Appalachian State University, Boone, NC.
Language: English
Date: 2018
Keywords
Tree-ring research, Climate reconstruction, Arctic amplification, Upper-level flow, Western Montana

Email this document to