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With a new automated precipitation collector we measured a remarkable decrease of 51‰ in the hydrogen isotope ratio (δ 2H) 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 δ 2H 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 δ 2H variations can substantially impact widely used isotope-hydrograph methods. From extreme δ 2H 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...
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With a new automated precipitation collector we measured a remarkable decrease of 51‰ in the hydrogen isotope ratio (δ 2H) 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 δ 2H 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 δ 2H variations can substantially impact widely used isotope-hydrograph methods. From extreme δ 2H 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...
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Experimental observations collected during meteorological field studies conducted by the National Oceanic and Atmospheric Administration near the Russian River of coastal northern California are combined with SSM/I satellite observations offshore to examine the role of landfalling atmospheric rivers in the creation of flooding. While recent studies have documented the characteristics and importance of narrow regions of strong meridional water vapor transport over the eastern Pacific Ocean (recently referred to as atmospheric rivers), this study describes their impact when they strike the U.S. West Coast. A detailed case study is presented, along with an assessment of all 7 floods on the Russian River since the experimental...
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With a new automated precipitation collector we measured a remarkable decrease of 51‰ in the hydrogen isotope ratio (δ 2H) 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 δ 2H 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 δ 2H variations can substantially impact widely used isotope-hydrograph methods. From extreme δ 2H 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...
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