Incorporation of Pacific SSTs in a Time Series Model toward a Longer-Term Forecast for the Great Salt Lake Elevation

Abstract

A recent study identified a pronounced lagged relationship between the Great Salt Lake's (GSL) elevation and the central tropical Pacific sea surface temperatures (SST) at the 10-15-year time scale. Using this relationship, a principal component analysis of historical time series of SST and local precipitation (P) was used in the construction of a lagged regression model to predict first the GSL elevation tendency and, from there, the GSL elevation. The combined principal component-lagged regression model was able to replicate and forecast turnarounds in the GSL elevation-that is, where prolonged increasing trends were followed by persistent decreases and vice versa. The coupling of the two time series is somewhat different from previous nonparametric, nonlinear time series methods developed for shorter-term (1-2 year) forecasts of the GSL volume. Moreover, by not accounting for interannual variability in the model, a forecast out to 6 years was feasible and was shown to intersect the 2009 and 2010 observations of the GSL elevation.

Added value from 576 years of tree-ring records in the prediction of the Great Salt Lake level

“…However, the GSL level forecast, developed by Gillies et al (2011), exhibited a wet bias that persisted for two decades followed by a dry bias for roughly a similar time span (Fig. 1b).…”

“…1b) therefore records regional hydroclimate variability, especially at low frequencies Mann et al, 1995;Wang et al, 2010Wang et al, , 2012. Climate forecasts for both the GSL level and volume have been attempted: For example, atmospheric circulation indices have been explored as to their role in controlling the GSL level (Moon and Lall, 1996;Gillies et al, 2011;Wang et al, 2012). Additionally, time-series modeling techniques have been developed in order to predict future GSL levels, though most of the models are only applicable over the short-term of 1-2 years (Lall et al, , 2006.…”

“…The coherency occurs through a unique atmospheric teleconnection excited during the transition phases of this 10-15 year oscillation; this affects precipitation within and around the Great Basin through a trans-Pacific atmospheric wave train . With regard to the connection that was discovered, Gillies et al (2011) developed a principal component-lagged regression model that was able to predict the GSL level out as far as 8 years (Fig. 1b).…”

“…Such biases of prolonged wet/dry apparently are linked to multi-decadal variability, notably a 30-50 year oscillation (Wang et al, 2012), which also influences the hydroclimate in and around the GSL watershed (Gray et al, 2004). At the time, multi-decadal variability was not incorporated within the GSL model of Gillies et al (2011); this was due to the insufficient length of the historical observational data ($100 years). Noticing the data gap, DeRose et al (2014DeRose et al ( ) developed a 576-year (1429DeRose et al ( -2005 reconstruction of the GSL level tendency (water year minus previous water year; Fig.…”

“…Given the aforementioned progress in precipitation reconstructions and the inherent limitation in Gillies et al's (2011) technique in predicting the GSL level (i.e. not being able to account for multidecadal variability), we hypothesized that a much longer period of record of lake level, i.e.…”