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Assimilation of Surface Chemical Species into Canadian GEM-MACH Model

This project aims to assimilate surface chemical species observations into the Canadian GEM-MACH model using optimal interpolation. The methodology, impact on air quality forecasts, and future work plans are discussed.

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Assimilation of Surface Chemical Species into Canadian GEM-MACH Model

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  1. Assimilation of surface chemical species observations into the Canadian GEM-MACH model using optimal interpolation Alain Robichaud, Richard Ménard ASTD/AQRD Dorval, QC (with the collaboration of Yulia Zaitseva, CMC)

  2. Outline • Goal of the project • Methodology • OA and verification • Impact on AQ forecast 24-48 hrs • Summary and conclusions • Milestones and future work

  3. Basic equations (OI) Xa = Xb + K (y – HXb) • K = (HPf)t * (H(HPf)t+R)-1 • 1) H(HPf(k1,k2))t = σf(k1)*σf(k2)*exp { - |x(k1)- x(k2)|/(Lc } • 2) (HPf(i,j,k1))t = σf(i,j)*σf(k1)*exp { - |x(i,j)- x(k1)|/(Lc} N ~ < 1500 A A: positive definite (trace (A) > 0; det |A| > 0) Error stats obtained from Hollingsworth and Lönnberg’s method (1986) Hypothesis: σf(i,j) and Lc are constant over the whole domain However, a sensitivity analysis was done: it turns out that those 2 parameters are quite sensitive and can be tuned to achieved a better optimization. 3) Scaling of error statistics (χ2  N)and regional bias correction Robichaud and Ménard (2014), ACP 4) Obs from AIRNOW, NAPS and CAPMON network ( ~ 1200 for Ozone and 700 for PM2.5)

  4. Methodology for assimilation (I) n levels Lz a 1 0 1.0 - 1) Average of partitioning ratio sub-species mass TXX1/total PM2.5 for the whole month of July 2012 (from GEMMACH-10 model outputs, v 1.3.8) (obtain pratio) - 2) Produce a RPN/standard file of the partitioning ratio TXX1/PM2.5 for TSU1,TOC1,TEC1,TPC1,TNI1,TAM1 and TCM1 (e.g. mass fraction) - 3) Use the analysis increments PM2.5 OA a) project in the vertical the analysis increment (linear decrease over n model levels) (obtain a(HY)) b) multiply by the appropriate partitioning ratio TXX1/PM2.5

  5. Methodology ii INCR(HY,TXX1)=INCR(sfc)PM2.5* a(HY)* pratio(TXX1) for PM2.5 INCR(HY,TXX1)=INCR(sfc)O3 * a(HY) for O3 • 4) store (TXX1-1(HY,TXX1) + INCR(HY,TXX1)) and put it in field TXX1o and restart the model • 5) verify scores for 24 or 48 hour forecasts with independent obs O3 and PM2.5 (AIRNOW/EPA and NAPS/CAPMON data) July 2012 Weight for vertical projection Partitioning ratio

  6. OA- Ozone MODEL OA OBS INCR

  7. OA-PM25 MODEL OA OBS INCR

  8. OA-PM10 MODEL OA OBS INCR

  9. Cross-validation Ozone-OA (July) model R OA R OA S S model

  10. Cross-validation PM2.5 – OA (July) model OA

  11. Air Quality Health Index mapping • Stieb et al (2008) Used for public forecast - Multi-pollutant index - Triggers warnings

  12. OA- AQHI

  13. Impact on forecast

  14. Impact of assimilation on O3Jul 2011 – run 00Z Model no assim and assim NO2 only Std dev R Assim O3&NO2 and Assim O3 only S Model and assim NO2 only Mean

  15. RATIO Sulfates/PM2.5 (pratio)

  16. Ratio Crustal Material/PM2.5 (pratio)

  17. Model no assim R With assim; Lz 10 or 20 levels With assim: Lz 2 levels S

  18. Model – no assim Withassim: Lz 20 LVLS Withassim: Lz 10 LVLS (avgheight BL) Withassim: Lz 2 LVLS

  19. Withassim: Lz 20 LVLS Withassim: Lz 10 LVLS Withassim: Lz 2 LVLS NO Assim

  20. Surface assimilation of TSU1Verification scores (24 hravg): % improvementmeanabsolutebias

  21. Surface assimilation of TSU1Verification scores (24 hravg): % improvementstdOmP

  22. Surface assimilation of TCM1Verification scores (24 hravg): % improvementmean ABSOLUTE OmP

  23. Surface assimilation of TCM1Verification scores (24 hravg): % improvementstdOmP

  24. Cross section: no assim vs assim 0.75 hy

  25. Surface assimilation of PM2.5 (July 2012)Verification scores (24 hravg): N ~ 172000 00Z run

  26. Summary & Conclusions 1)Very good results for SFC assimin GEMMACH-10 for PM2.5: verysign impact on forecastbeyond 48 h. For ozone, impact on forecastisonlysign. for the first 12 hours. 2) Sulfates, and crustal materialgivesignresults for PM2.5 assim. The success of the impact for a particular PM2.5 sub- speciesdepends on lifetime and abundance (strength of partitioning ratio) 3) on-line assimilation results are expected to giveevenbetterresults(REQUIRES FUSION OF TWO MAESTRO SUITES) 4) issues about multivariate assimilation, vertical correlationlength, how this system will fit within the framework of future assim system

  27. Milestones • OA for O3 and PM2.5 (transfered to oper CMC in 2013) • Historical OA available for warm season 2002-now for PM2.5 and Ozone (Robichaud and Ménard, 2014, ACP) • Extending OA for NO2, NO, PM10 and SO2 (willbetransfered to operations 2014-2015) (Zaitseva et al, poster session nb 1058) • AQHI- OA (willbetransferred to oper in 2014-2015) • Sfc data assimilation using OA-offline (currentexperimentsuccessfull for Ozone, Sulfates and Crustal material in GEM-MACH 1.3.8, Summer 2012) (Presentedhere) • Assimilation exp. extended to otherseasons, otherpollutants (PM10) • Fusion MAESTRO suites OA and GEM-MACH2 (on-line assim) and upgrade system for new model version • Produce high resolution OA 2.5 km for PANAM games (Toronto 2015; seepresentation C. Stroud et al, Wednesday 17:20 room 520A) and Alberta oilsandsproject

  28. Additional slides

  29. OA MAESTRO suite/home/pxarqj/arqj/aro/.suites/rdaqa

  30. GEM2- MAESTRO suite

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