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HONO retrievals in Beijing and Xianghe

HONO retrievals in Beijing and Xianghe. F. Hendrick 1 , K. Clémer 1,* , C. Fayt 1 , C. Hermans 1 , Y. Huan 1,2 , T. Vlemmix 1 , P. Wang 2 , and M. Van Roozendael 1. 1 Belgian Institute for Space Aeronomy (IASB-BIRA), Brussels, Belgium 2 Institute of Atmospheric Physics, Beijing, China

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HONO retrievals in Beijing and Xianghe

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  1. HONO retrievals in Beijing and Xianghe F. Hendrick1, K. Clémer1,*, C. Fayt1, C. Hermans1, Y. Huan1,2, T. Vlemmix1, P. Wang2, and M. Van Roozendael1 1Belgian Institute for Space Aeronomy (IASB-BIRA), Brussels, Belgium 2Institute of Atmospheric Physics, Beijing, China *Now at Institute of Astrophysics, KU Leuven, Belgium NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 1

  2. Nitrous acid (HONO) in the troposphere • HONO is a source of OH radicals through its photolysis, especially in the early morning: • HONO + h → OH + NO • HONO sources and sinks: Li et al., ACP, 2012 NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 2

  3. Why it is important to measure HONO ? • Formation mechanisms not well understood and poorly quantified, especially during daytime • Realistic simulations of HONO levels are difficult • Measurements can contribute to improve the modeling of the HONO and OH chemistry • HONO measurements are sparse in time because mainly resulting from field campaigns Continuous MAX-DOAS measurements of HONO can be highly valuable NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 3

  4. Observation sites Institute of Atmospheric Physics (06/2008 - 04/2009) (03/2010 till now ) NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 4

  5. DOAS settings • The following settings are used for the DOAS analysis: • Fitting window: 337-375 nm • Fitted species: HONO, NO2, O3, O4, BrO, HCHO, Ring effect • HONO XS: Stutz et al. (2000) at 296 K • For each scan, DSCDoff-axis = SCDoff-axis – SCDzenith of the scan used by the profiling algorithm NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 5

  6. MAX-DOAS retrieval algorithm MAXDOAS measurements LIDORT Apriori Atm: P,T Surface albedo Trace gas: , profile Aerosol: optical prop. DOAS HONO DSCD O4 DSCD DI DSCD DI Weighting functions Optimal estimation Aerosol vertical extinction profiles Clémer et al., AMT, 2010 Tropospheric HONO vertical profiles NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 6

  7. Aerosol extinction profile retrieval Beijing 21/01/2009 AM NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 7

  8. Comparison with AERONET data NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 8

  9. HONO vertical profile retrieval Beijing 21/01/2009 AM A priori: with SH = 0.5 km NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 9

  10. Impact of SH on the retrieval (1) Beijing 21/01/2009 AM A priori Retrieval NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 10

  11. Impact of SH on the retrieval (2) Beijing 21/01/2009 NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 11

  12. HONO VCD time-series NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 12

  13. Tropospheric NO2 VCD (geometrical approximation) HONO VCD time-series HONO VCD NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 13

  14. HONO and NO2 VCD correlation Beijing Xianghe NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 14

  15. Diurnal variation of surface HONO vmr (1) NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 15

  16. Comparison to CAREBeijing2006 data (1) NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 16

  17. Comparison to CAREBeijing2006 data (2) CAREBeijing2006 HONO measurements at Yufa: in-situ long-path absorption photometry (LOPAP); see Lu et al., ACPD, 2012 NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 17

  18. Concluding remarks • First HONO retrievals from MAX-DOAS observations at Beijing and Xianghe show promising results • HONO columns larger at Beijing • Good correlation between HONO and NO2 tropospheric columns, especially in the afternoon • Diurnal variation of HONO vmr in the 0-200m altitude range; Good agreement with CAREBeijing2006 data • On-going work: • NO2 profiles retrieval; correlation HONO and NO2 vmr in the 0-200m altitude range • Investigation of the [HONO]/[NO2] ratio • Estimation of the OH production from [HONO] and photolysis rate NORS/NDACC UV-VIS meeting, Brussels, 3-4 July 2012 18

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