Diagnosing Atmospheric Influences on the Interannual 18O/16O Variations in Western U.S. Precipitation

Water

Nikolaus H. Buenning¹  Lowell Stott¹  Lisa Kanner¹ 

[1] Department of Earth Sciences, University of Southern California, Zumberge Hall of Science (ZHS), 3651 Trousdale Pkwy, Los Angeles, CA 90089, USA; E-Mails:

关键词: water isotopes;    moisture advection;    condensation;    climate proxies;    precipitation;    hydroclimate;    global models;    western U.S.;   

DOI  :  10.3390/w5031116

来源: mdpi

【 摘 要 】

Many climate proxies in geological archives are dependent on the isotopic content of precipitation (δ¹⁸O_p), which over sub-annual timescales has been linked to temperature, condensation height, atmospheric circulation, and post-condensation exchanges in the western U.S. However, many proxies do not resolve temporal changes finer than interannual-scales. This study explores causes of the interannual variations in δ¹⁸O_p within the western U.S. Simulations with the Isotope-incorporated Global Spectral Model (IsoGSM) revealed an amplifying influence of post-condensation exchanges (i.e., raindrop evaporation and vapor equilibration) on interannual δ¹⁸O_p variations throughout the western U.S. Mid-latitude and subtropical vapor tagging simulations showed that the influence of moisture advection on δ¹⁸O_p was relatively strong in the Pacific Northwest, but weak over the rest of the western U.S. The vapor tags correlated well with interannual variations in the ¹⁸O/¹⁶O composition of vapor, an indication that isotopes in vapor trace atmospheric circulation. However, vertical-tagging simulations revealed a strong influence of condensation height on δ¹⁸O_p in California. In the interior of the western U.S., a strong temperature effect was found only after annual mean temperatures were weighted by monthly precipitation totals. These multiple influences on δ¹⁸O_p complicate interpretations of western U.S. climate proxies that are derived from isotopes in precipitation.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.