DIURNAL VARIATION OF WATER VAPOR ISOTOPOLOGUES ON THE CHAJNANTOR PLATEAU DURING THE AUSTRAL SPRING
The diurnal variation of water vapor isotopologues over the Chajnantor Plateau during the Austral Spring was investigated using a near continuous record of in situ water vapor isotopologues, numerical modeling, and routine meteorological measurements. On average, there is an approximately 34% increase in the mixing ratio coupled with an 11‰ increase in δ18O, 71‰ increase in δD, and 23‰ decrease in deuterium excess on the Plateau. This significant diurnal variation is a result of the mixing between dry, upper tropospheric air (dry end-member) and a small contribution (9-25%) of a continental (δD < -120‰) source of moisture (wet end-member). While the dry end-member continuously subsides on the Plateau, the continental source is advected onto the Plateau during the day due to a thermally induced, regional, diurnal circulation.
Diurnal variation, Water vapor isotopologues
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