Extreme changes in stable hydrogen isotopes and precipitation characteristics in a landfalling Pacific storm
Article first published online: 13 NOV 2008
Copyright 2008 by the American Geophysical Union.
Geophysical Research Letters
Volume 35, Issue 21, November 2008
How to Cite
2008), Extreme changes in stable hydrogen isotopes and precipitation characteristics in a landfalling Pacific storm, Geophys. Res. Lett., 35, L21808, doi:10.1029/2008GL035481., , , , , and (
- Issue published online: 13 NOV 2008
- Article first published online: 13 NOV 2008
- Manuscript Accepted: 30 SEP 2008
- Manuscript Revised: 11 SEP 2008
- Manuscript Received: 25 JUL 2008
- precipitation collector;
- atmospheric river;
- stable isotopes
 With a new automated precipitation collector we measured a remarkable decrease of 51‰ in the hydrogen isotope ratio (δ2H) of precipitation over a 60-minute period during the landfall of an extratropical cyclone along the California coast on 21 March 2005. The rapid drop in δ2H occurred as precipitation generation transitioned from a shallow to a much deeper cloud layer, in accord with synoptic-scale ascent and deep “seeder-feeder” precipitation. Such unexpected δ2H variations can substantially impact widely used isotope-hydrograph methods. From extreme δ2H values of −26 and −78‰, we calculate precipitation temperatures of 9.7 and −4.2°C using an adiabatic condensation isotope model, in good agreement with temperatures estimated from surface observations and radar data. This model indicates that 60 percent of the moisture was precipitated during ascent as temperature decreased from 15°C at the ocean surface to −4°C above the measurement site.