Sensitivity of the North American monsoon to antecedent Rocky Mountain snowpack

Abstract

While the inverse relationship between antecedent snowpack in the Himalayas and Tibetan Plateau and subsequent monsoon rainfall in South and East Asia has been extensively studied and established, the potential for such a relationship between Rocky Mountain snowpack and the North American monsoon remains uncertain. The present study represents the first modeling assessment of this vital predictability issue, going beyond simple observational correlations, which fail to identify causality or a mechanism, by applying a regional climate model to demonstrate that a deep Rocky Mountain snowpack tends to hinder the poleward advance of the subtropical ridge and associated monsoon rainfall into the Southwest United States. A deep, extensive snowpack increases the surface albedo and provides an abundant surge of soil moisture, both of which reduce tropospheric temperatures in spring and early summer, weakening the land‐ocean thermal gradient and related monsoon system. This snow‐monsoon relationship, which may serve as a vital prediction tool of summer rainfall in the semi‐arid Southwest United States, has direct implications for regional water supply, streamflow, and biodiversity.

Moisture‐driven xylogenesis in Pinus ponderosa from a Mojave Desert mountain reveals high phenological plasticity

“…Cool and warm season precipitation are generally poorly correlated (Griffin et al, ). However, opposite‐sign anomalies have been observed in the last decades, suggesting that winter precipitation might have a regional effect on soil moisture, possibly generating a negative feedback on the intensity of the following monsoon (Gutzler, ; Lo & Clark, ; Notaro & Zarrin, ). The years 2015 and 2016 clearly encompassed one such opposite‐sign anomaly at the Sheep Range.…”

Rocky Mountain hydroclimate: Holocene variability and the role of insolation, ENSO, and the North American Monsoon

“…Furthermore, antecedent snowpack is known to affect the monsoon. Deep snowpack that persists later in the year reduces the land-sea thermal contrast, weakens the monsoon ridge and dampens monsoon rainfall intensity (Notaro and Zarrin, 2011 and references therein).…”

Analysis of Low-Frequency Precipitation Variability in CMIP5 Historical Simulations for Southwestern North America

“…The prevalence of seasonal-tomultidecadal drought in western North America suggests the importance of soil moisture in this region in terms of atmospheric feedbacks and the availability of water for local evaporation (Oglesby and Erickson 1989;Eltahir 1998). It has been theorized that the North American monsoon is influenced by the follow-on from winter and spring conditions, and that seasonal precipitation is strongly tied to land surface feedbacks in the region (Gutzler and Preston 1997;Gutzler 2000;Higgins et al 1998;Higgins and Shi 2000;Matsui et al 2003;Mo and Paegle 2000;Zhu et al 2005;Notaro and Zarrin 2011;Small 2001;Entekhabi et al 1992). Gutzler and Preston (1997) showed that suppressed monsoon precipitation during summer occurred in years with above normal snowpack in the southern Rocky Mountains, for 1961-90.…”