Coherence between the Great Salt Lake Level and the Pacific Quasi-Decadal Oscillation

Abstract

The lake level elevation of the Great Salt Lake (GSL), a large closed basin lake in the arid western United States, is characterized by a pronounced quasi-decadal oscillation (QDO). The variation of the GSL elevation is very coherent with the QDO of sea surface temperature anomalies in the tropical central Pacific (also known as the Pacific QDO). However, such coherence denies any direct association between the precipitation in the GSL watershed and the Pacific QDO because, in a given frequency, the precipitation variation always leads the GSL elevation variation. Therefore, the precipitation variation is phase shifted from the Pacific QDO. This study investigates the physical mechanism forming the coherence between the GSL elevation and the Pacific QDO. Pronounced and coherent quasi-decadal signals in precipitation, streamflow, water vapor flux, and drought conditions are found throughout the Great Basin. Recurrent atmospheric circulation patterns develop over the Gulf of Alaska during the warm-to-cool and cool-to-warm transition phases of the Pacific QDO. These circulation patterns modulate the water vapor flux associated with synoptic transient activities over the western United States and, in turn, lead to the QDO in the hydrological cycle of the Great Basin. As the GSL integrates the hydrological responses in the Great Basin, the hydrological QDO is then transferred to the GSL elevation. Because the GSL elevation consistently lags the precipitation by a quarter-phase (about 3 yr in the quasidecadal time scale), these processes take an average of 6 yr for the GSL elevation to eventually respond to the Pacific QDO. This creates a half-phase delay of the GSL elevation from the Pacific QDO, thereby forming the inverse, yet coherent, relationship between them. Tree-ring reconstructed precipitation records confirm that the quasi-decadal signal in precipitation is a prominent feature in this region.

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

“…It is also noteworthy that Gillies et al's GSL forecast, that began in 2008 and lead up to 2015 (delineated and indicated by arrow in Fig. 1b increase in the GSL level had yet to occur; this circumstance supported the connection proposed in Wang et al (2010), i.e. that the so-called Pacific Quasi-Decadal Oscillation (QDO) figured as a dominant climate phenomenon in the Intermountain West and was a strong contemporary driver of the region's hydroclimate.…”

“…Due to its large surface area that is contained within a closed basin, fluctuations in the GSL level duly reflect the hydroclimate conditions of the region: i.e. the highest water mark lags after the peak in the precipitation regime (of the region's prominent wet-dry cycle) while the lowest water mark occurs after the onset of the low point in the precipitation regime (Wang et al, 2010), a condition oftentimes created by persistent drought. The lake level fluctuation (Fig.…”

“…The lake level fluctuation (Fig. 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).…”

“…Focusing on the decadal-scale variability of the GSL level, Wang et al (2010) discovered that the GSL level is highly coherent with, yet opposite to, the tropical central Pacific sea surface temperature (SST) anomalies at the 10-15 year timescale. 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 .…”

Climatology of the U.S. Inter-Mountain West

“…In other words, only an indirect link or a coincidence can explain such an association between the Pacific QDO and the precipitation source of the GSL. Wang et al (2010a) investigated this phenomenon and found that the quasi-decadal variation in the IMW precipitation consistently lags the Pacific QDO by a quarter-phase, i.e. 3 years after the peak of the warm-phase Pacific QDO occurs, an anomalous trough develops over the Gulf of Alaska and enhances the IMW precipitation (similar to the situation in Fig.…”