European Geosciences Union c © 2005 Author(s). This work is licensed under a Creative Commons License. Atmospheric Chemistry and Physics Discussions Interactive comment on “Supersaturation, dehydration, and denitrification in Arctic cirrus”

• Main Author: B. Kärcher
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2005
• Subjects: Arctic; Langmuir
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.561.5085; http://www.cosis.net/copernicus/EGU/acpd/5/S540/acpd-5-S540_p.pdf?PHPSESSID=dace6ddc73fdb06eba86b0b36195604e

1. Equilibrium calculation for nitric acid uptake I agree with the reviewer that the novel concept of trapping deserves a more detailed discussion. In the revised manuscript, I will present both, a critical discussion and results from a more conventional calculation of uptake closer to previous estimates of nitric acid uptake. The results to be shown will be taken from an hypothetical simulation in which I calcu-late gas dissolution into STS particles as before, but do not allow HNO3 to be trapped. Rather, using the ice surface area density A, temperature T, and the remaining partial pressure of HNO3 pn, I compute the amount that would be adsorbed in equilibrium ac-S540 cording to the frequently employed dissociative Langmuir isotherm θ (e.g., Popp et al., 2004). The amount of HNO3 locally adsorbed per cm3 of air on ice crystals is given by c = Aσθ(T, pn), where σ is the maximum number of available surface sites and θ is calculated using the heat of adsorption Q = 10.5 kcal/mol (as in the baseline simulation) to ensure