Continental interior storm tracks, tritium deposition, and precipitation
isotopes at the Great Basin-Rocky Mountain physiographic provinces
transition zone, USA
Thirteen years of precipitation d2H,
d18O, and 3H data for three western
United States continental interior weather stations, supplemented with
60 years of precipitation data, have been analyzed. The stations are
located 1,000 to 2,000 km from four ocean moisture sources.
Precipitation was evaluated relative to storm track trajectory, the El
Niño-Southern Oscillation Oceanic Niño Index (INO), orography,
precipitation amount, air temperature, month, and season. The INO was
not fond to correlate with precipitation flux or isotopic composition.
Tritium deposition was evaluated relative to the ‘spring leak’,
thunderstorms, surface evaporation, storm tracks, and seasons. Local
meteoric water lines and the Global Meteoric Water Line were compared.
Winter precipitation is isotopically depleted and summer precipitation
is isotopically enriched. Factors affecting the stable isotopes include
winter cold cloud temperature, summer rain droplet partial evaporation,
gradual rain out, and multiple episodes of soil moisture re-evaporation
and subsequent re-precipitation.