Multiphase modeling of nitrate photochemistry in the quasi-liquid layer (QLL): implications for NO x release from the Arctic and coastal Antarctic snowpack

• Main Authors: Boxe, C. S., Saiz-Lopez, A.
• Other Authors: Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Arctic; Antarctic; Antarc*
• Online Access: https://hal.science/hal-00304055; https://hal.science/hal-00304055/document; https://hal.science/hal-00304055/file/acpd-8-6009-2008.pdf

International audience We utilize a multiphase model, CON-AIR (Condense Phase to Air Transfer Model), to show that the photochemistry of nitrate (NO 3 ? ) in and on ice and snow surfaces, specifically the quasi-liquid layer (QLL), can account for NO x volume fluxes, concentrations, and [NO]/[NO 2 ](?=[NO]/[NO 2 ]) measured just above the Arctic and coastal Antarctic snowpack. Maximum gas phase NO x volume fluxes, concentrations and ? simulated for spring and summer range from 5.0×10 4 to 6.4×10 5 molecules cm ?3 s ?1 , 5.7×10 8 to 4.8×10 9 molecules cm ?3 , and ~0.8 to 2.2, respectively, which are comparable to gas phase NO x volume fluxes, concentrations and ? measured in the field. The model incorporates the appropriate actinic solar spectrum, thereby properly weighting the different rates of photolysis of NO 3 ? and NO 2 ? . This is important since the immediate precursor for NO, for example, NO 2 ? , absorbs at wavelengths longer than nitrate itself. Finally, one-dimensional model simulations indicate that both gas phase boundary layer NO and NO 2 exhibit a negative concentration gradient as a function of height although [NO]/[NO 2 ] are approximately constant. This gradient is primarily attributed to gas phase reactions of NO x with halogens oxides (i.e., as BrO and IO), HO x , and hydrocarbons, such as CH 3 O 2 .