North Platte Snowpack Reconstructions Using Dendrochronology

April 1^st Snow Water Equivalent (SWE) reconstructions were generated using tree-ring chronologies for the Upper North Platte River Basin (UNPRB), located in north-central Colorado and south-eastern Wyoming. To regionalize April 1^st snowpack data from 11 SNOw TELemetry stations (SNOTEL stations), Varimax Rotated Principal Components Analysis (PCA) was used. For the 11 station regionalization, the reconstruction explained 42% of the variance in the instrumental record and extended the record to 1378 (632 years). Retained tree-ring chronologies included those that were stable and positively correlated at 99% confidence levels or higher with the regional snowpack data for a 60–year overlapping period of record from 1940 to 1999. Stepwise Linear Regression was performed for the overlapping (calibration) period to develop regression models for the reconstructions. Eleven stations were individually reconstructed of which three stations (Dry Lake, Old Battle, and Lake Irene) explained variances greater than 40%. A contour plot of the R² values for all 11 stations revealed that the more statistically skillful reconstructions were for stations spatially adjacent to the tree-ring chronologies used in the regression models. When the two individual stations with the lowest explained variance were removed from the 11 station snowpack regionalization, the new nine station regionalization reconstruction explained 45% of the variance over the same 632 year period.