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MM5 SIMMULATIONS OF SFBA TO SAC/SJV TRANSPORT DURING 30 JULY- 2 AUG 2000 CCOS OZONE EPISODE by

MM5 SIMMULATIONS OF SFBA TO SAC/SJV TRANSPORT DURING 30 JULY- 2 AUG 2000 CCOS OZONE EPISODE by Tesfamichael B. Ghidey: LBNL, SJSU, DRI. OUTLINE. SYNOPTIC SUMMARY 700 MB SFC MM5 CONFIGURATION WINDS: MESO CONVENTION FULL BARB = 1 M/S FLAG = 5 M/S RESULTS DOMAIN 1: SYNOPTIC WINDS

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MM5 SIMMULATIONS OF SFBA TO SAC/SJV TRANSPORT DURING 30 JULY- 2 AUG 2000 CCOS OZONE EPISODE by

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  1. MM5 SIMMULATIONS OF SFBA TO SAC/SJV TRANSPORT DURING 30 JULY- 2 AUG 2000 CCOS OZONE EPISODE by Tesfamichael B. Ghidey: LBNL, SJSU, DRI

  2. OUTLINE • SYNOPTIC SUMMARY • 700 MB • SFC • MM5 CONFIGURATION • WINDS: MESO CONVENTION • FULL BARB = 1 M/S • FLAG = 5 M/S • RESULTS • DOMAIN 1: SYNOPTIC WINDS • DOMAIN 3: MEOS WINDS: LIV, SAC, & SJV SEQUENTIAL OZONE EPISODE DAYS • CONCLUSION

  3. NWS 700 hPa PREVIEW:1200 UTC ( = 0500 PDT) Movement of inland-H causes episodes • Pre-episode: over Nevada • Episode days: • moves SW to SJV • intensifies • Post-episode: dissipates

  4. Before ozone episodes: offshore G. C. High; synoptic High in Nevada; boundary-Low between Highs; SSW-flow over SFBA H H

  5. SAC ozone day: SJV-H at max intensity; SW flow over SFBA H H

  6. NWS Surface PREVIEW: 1200 UTC or 0500 PDT Warm-core upper-H projects down to a Sfc inverted thermal-L • Pre-episode: over Nevada • Episode days: moves over SJV & intensifies • Post-episode: weakens

  7. B/F ozone episodes: warm core “inverted thermal L” from Sea of Cortez to S-Nevada; secondary open-L into northern CA; NW-flow over SFBA & S-flow over SAC L L

  8. LIV episode day: trough moves NW, forms closed low, with N-S axis thru central CA; SE-flow over Sac L

  9. MM5 configuration • Version 3.6.0 • Three domains • 36, 12, 4 km • 55 x 55, 91 x 91, 190 x 190 grid points • 32 sigma levels • up to 100 mb • first full sigma level at 19 m • GDAS IC and BC • Analysis nudging only for V and T for • 36 km domain • above PBL • No obs nudging • Five layer soil model, Gayno-Seaman PBL • Start: 1200 UTC on 28 July and went for 7.5 days • LBNL LINUX single processor: 15 days

  10. D01 D03 D02

  11. Validation of 10-m dd

  12. MM5 Domain-1: 700 hPa WINDS PREVIEW • NWS charts • gave only approx p-center locations • cannot give flow details in SFBA, Carquinez Straits, & SJV • Thus need MM5 to show • Pre-episode H: E of SFBA over NEV • Episode days: bulge from H extends westward over SFBA • Post-episode H: back to E of SFBA over AZ

  13. (B/F episodes) MM5 correct: offshore H; H in SE Nev; boundary-L; but S-flow over SFBA vs. NWS SW L H H

  14. SAC episode day: Syn H to Utah with (now NE-SW) “bulge” (vs. NWS-H over SJV) L now S in Cal (vs. NWS: E over CA/AZ border); correct SW flow over SFBA to Sac H H L

  15. MM5 Domain-1: SFC WINDS PREVIEW AT 12 UTC (= 05 PDT) • Movement to N of thermal L from S-CA sequentially cause episodes • Convergence into LIV • Increased flow to Sac from SFBA • Increased flow into SJV from SFBA • Moves offshore • Domain-3 Flow details

  16. B/F episodes: warm-core thermal-L to S-Nevada & 2nd CA-L to N (both correct); NW-flow over coast & SFBA (correct) and con-flow over SAC (vs NWS S-flow) L L

  17. SAC episode: S-Low moved N & N-Low moved bit S (NWS showed only closed-L as gone); now more W-flow to Sac L L

  18. DOMAIN-3: 700 hPa PREVIEW (2100 UTC or 0400 PDT) • Offshore-H formation & Fresno-eddy movement cause episodes • Initial flow from S does not produce SFBA to Sac transport • Syn-H formation directs SFBA flow to Sac & con-current Fresno-eddy blocks SFBA flow into SJV • When eddy moves to N • SFBA flow into Sac is blocked • SFBA flow into SJV is allowed

  19. Pre-episode: uniform S-flow

  20. SAC episode: H moved to W at coast (vs bulge from CV to coast in D-1); Fresno eddy N of D-1 position (blocks flow into SJV from SFBA; W flow over SFBA (vs. NWS S-flow) directly to SAC H L

  21. SJV episode: Fresno eddy moved N & H moves inland (both better defined than in D-1); flow around eddy blocks SFBA flow to SAC, but forces it S into SJV L H

  22. DOMAIN-3: SUMMARY OF SFC TRANSPORT TO LIVERMORE (KEY HOURS) • Daytime confluence of 3-flows E of LIV (on Mt peak) causes episode • Flow from N from Carquinez Straits • Flow from W thru GGG • Upslope flow on E-side of hills E of LIV • For episode need • Strong confluence • Low speeds • Obs first and then MM5

  23. Sfc winds-obs at 0700 PST (1500 UTC) on 31 July (LIV episode morning) Note con flow into LIV

  24. Sfc wind-obs at 1400 PST (2100 UTC) on 31 July (LIV episode afternoon) Note flow from N into LIV and out to E

  25. Pre-episode afternoon (1400 PDT): W flow thru GGG & weak con E of Liv

  26. Episode afternoon (1400 PDT): W flow thru GGG & strong con E of Liv

  27. DOMAIN 3: SFC TRANSPORT TO SAC SUMMARY • TRANSPORT FROM SFBA BLOCKED BY OPPOSING FLOW ON DAYS BEFORE AND AFTER SAC EPISODE • TRANSPORT FROM SFBA NOT BLOCKED ON DAY OF SAC EPISODE

  28. LIV-episode late-afternoon (1800 PDT): flow to SAC from SFBA blocked

  29. SAC-episode late-afternoon (1800 PDT): flow to SAC from SFBA not blocked

  30. DOMAIN 3: SFC TRANSPORT TO SJV SUMMARY • TRANSPORT FROM SFBA TO SJV MUST NOT BE BLOCKED BY OPPOSING FLOWS • FLOW INTO SJV MUST • NOT BE TOO FAST • SHOW CONFLUENCE

  31. SAC EPISODE NIGHT: TRANSPORT TO SJV FROM SFBA IS BLOCKED

  32. SJV EPISODE NIGHT: TRANSPORT TO SJV FROM SFBA & CON WINDS

  33. CONCLUSION • SMALL CHANGES IN 700 hPa-H & SFC-L POSITIONS CAUSED SEQUENTIAL DAILY OZONE MAX IN LIV, SAC, & SJV • NWS CHARTS COULD NOT DISCERN DETAILS OF CHANGES, BUT MM5 COULD • MM5 • MATCHED NWS PATTERNS &MESO-OBS REASONABLY WELL • PROVIDED ADDITIONAL DETAILS

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