Uptake of NO y on wave‐cloud ice particles

In a flight through a wave cloud during SUCCESS on 2 May 1996, simultaneous forward‐ and aft‐facing NO y inlets were used to infer the amount of condensed‐phase NO y present on ice particles that were up to a few minutes old. Condensed‐phase amounts were 25–75 pptv, or 10–20% of gas‐phase NO y . Given the rapid HNO 3 uptake on ice observed in the laboratory, a model calculation implies that virtually all of the gas‐phase HNO 3 will be depleted in the first 1–2 minutes after the appearance of ice. Thus the NO y observations are consistent with the laboratory results only if the ambient HNO 3 /NO y ratio is 10–20%.