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

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

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

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

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

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

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

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

D01 D02 D03

Validation of 10-m dd

MM5 Domain-1: 700 hPa WINDS PREVIEW NWS charts NWS charts –gave only approx p-center locations –cannot give flow details in SFBA, Carquinez Straits, & SJV Thus need MM5 to show 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

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

H H L 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

MM5 Domain-1: SFC WINDS PREVIEW AT 12 UTC (= 05 PDT) Movement to N of thermal L from S-CA sequentially cause episodes 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 Domain-3 Flow details

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

L 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

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

Pre-episode: uniform S-flow

H L 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

L H 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

DOMAIN-3: SUMMARY OF SFC TRANSPORT TO LIVERMORE (KEY HOURS) Daytime confluence of 3-flows E of LIV (on Mt peak) causes episode 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 For episode need –Strong confluence –Low speeds Obs first and then MM5 Obs first and then MM5

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

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

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

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

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

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

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

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

SAC EPISODE NIGHT: TRANSPORT TO SJV FROM SFBA IS BLOCKED

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

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