Spring 2001 AGU Meeting Peroxy Radical Distribution During TOPSE and Implications for Ozone Photochemistry Christopher Cantrell and TOPSE Science Team

Spring 2001 AGU Meeting Outline Description of CIMS peroxy radical measurements Steady-state radical concentrations Budgets of radicals and O 3 during TOPSE Possible role of photochemistry in TOPSE O 3 trends

Spring 2001 AGU Meeting TOPSE in situ O 3

Spring 2001 AGU Meeting TOPSE Steady State HO 2 + RO 2

Spring 2001 AGU Meeting TOPSE Steady State OH

Spring 2001 AGU Meeting TOPSE O( 1 D)+H 2 O Rate

Spring 2001 AGU Meeting TOPSE Temperature

Spring 2001 AGU Meeting CIMS HO 2 and HO 2 +RO 2 Measurements Based on conversion of ambient peroxy radicals to gas-phase H 2 SO 4 –HO 2 + NO  OH + NO 2 –OH + SO 2 (O 2, H 2 O, M)  H 2 SO 4 Chemical ionization – Calibration –Photolysis of water vapor by nm radiation –Lamp flux by N 2 O actinometry

Spring 2001 AGU Meeting CIMS Inlets, rack, C130 photos

Spring 2001 AGU Meeting Steady-State Radical Concentrations Equation for each radical (OH, HO 2, CH 3 O 2 ) – Assume dX/dt << P or L, P-L  0 n equations and n unknowns (radical concentrations) Solve by iterative numerical method (Newton- Raphson). Requires initial estimate. Use measured quantities (NO x,CO, NMHCs, O 3, j- values, etc.) when available in equations Include HNO 4 chemistry (estimate of jHNO 4 ) Two calculations: effective CH 4, explicit treatment of NMHCs (and thus RO 2 )

Spring 2001 AGU Meeting Comparison of measurements and steady-state HO 2 +RO 2

Spring 2001 AGU Meeting TOPSE Measured & SS HO 2 +RO 2

Spring 2001 AGU Meeting TOPSE SS Peroxy Radical Ratios

Spring 2001 AGU Meeting TOPSE HOx Production & Loss

Spring 2001 AGU Meeting TOPSE HO x Production

Spring 2001 AGU Meeting Steady State HO 2 NO 2

Spring 2001 AGU Meeting TOPSE Net O 3 Production and Loss

Spring 2001 AGU Meeting TOPSE Net O 3 Production

Spring 2001 AGU Meeting TOPSE Net O 3 Production

Spring 2001 AGU Meeting Comparison with Other Studies

Spring 2001 AGU Meeting Acknowledgements NCAR –ACD –RAF/ATD NSF TOPSE Colleagues Churchill Airport Thule Air Base