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

OZONE EPISODE

by

Tesfamichael B. Ghidey: LBNL, SJSU, DRI

OUTLINEOUTLINE

• SYNOPTIC SUMMARY SYNOPTIC SUMMARY – 700 MB700 MB– SFCSFC

• MM5 CONFIGURATIONMM5 CONFIGURATION• WINDS: MESO CONVENTIONWINDS: MESO CONVENTION

• FULL BARB = 1 M/SFULL BARB = 1 M/S• FLAG = 5 M/SFLAG = 5 M/S

• RESULTSRESULTS– DOMAIN 1: SYNOPTIC WINDSDOMAIN 1: SYNOPTIC WINDS– DOMAIN 3: MEOS WINDS:DOMAIN 3: MEOS WINDS:

LIV, SAC, & SJV SEQUENTIAL OZONE LIV, SAC, & SJV SEQUENTIAL OZONE EPISODE DAYSEPISODE DAYS

• CONCLUSIONCONCLUSION

NWS 700 hPa PREVIEW:NWS 700 hPa PREVIEW:1200 UTC ( = 0500 PDT)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 SJVmoves SW to SJV– intensifiesintensifies

• Post-episode: dissipatesPost-episode: dissipates

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

HH HH

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

HH

HH

NWS Surface PREVIEW: NWS Surface PREVIEW: 1200 UTC or 0500 PDT1200 UTC or 0500 PDT

Warm-core upper-H projects down to a Warm-core upper-H projects down to a

Sfc inverted thermal-L Sfc inverted thermal-L – Pre-episode: over Nevada Pre-episode: over Nevada – Episode days: moves over SJV & Episode days: moves over SJV &

intensifiesintensifies– Post-episode: weakensPost-episode: weakens

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

over SAC over SAC

LL

LL

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

LL

MM5 configurationMM5 configuration• Version 3.6.0Version 3.6.0• Three domains Three domains

– 36, 12, 4 km36, 12, 4 km– 55 x 55, 91 x 91, 190 x 190 grid points 55 x 55, 91 x 91, 190 x 190 grid points

• 32 sigma levels 32 sigma levels – up to 100 mbup to 100 mb– first full sigma level at 19 m first full sigma level at 19 m

• GDAS IC and BCGDAS IC and BC• Analysis nudging only for V and T forAnalysis nudging only for V and T for

– 36 km domain36 km domain– above PBLabove PBL

• No obs nudgingNo obs nudging• Five layer soil model, Gayno-Seaman PBLFive layer soil model, Gayno-Seaman PBL• Start: 1200 UTC on 28 July and went for 7.5 daysStart: 1200 UTC on 28 July and went for 7.5 days• LBNL LINUX single processor: 15 daysLBNL LINUX single processor: 15 days

D01D01

D02D02

D03D03

Validation of 10-m ddValidation of 10-m dd

MM5 Domain-1: 700 hPa WINDS PREVIEW

• NWS charts NWS charts – gave only approx p-center locationsgave only approx p-center locations– cannot give flow details in SFBA, cannot give flow details in SFBA,

Carquinez Straits, & SJVCarquinez Straits, & SJV

• Thus need MM5 to showThus need MM5 to show– Pre-episode H: E of SFBA over NEVPre-episode H: E of SFBA over NEV– Episode days: bulge from H extends Episode days: bulge from H extends

westward over SFBAwestward over SFBA– Post-episode H: back to E of SFBA over AZ Post-episode H: back to E of SFBA over AZ

HL

H

(B/F episodes) MM5 correct: offshore H; H in SE Nev; boundary-L;(B/F episodes) MM5 correct: offshore H; H in SE Nev; boundary-L; but S-flow over SFBA vs. NWS SWbut 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 SAC episode day: Syn H to Utah with (now NE-SW) “bulge” (vs. NWS-H over SJV) SJV) L now S in Cal (vs. NWS: E over CA/AZ border); correct SW flow over SFBA to L now S in Cal (vs. NWS: E over CA/AZ border); correct SW flow over SFBA to SacSac

MM5 Domain-1: SFC WINDS PREVIEW AT 12 UTC (= 05

PDT) • Movement to N of thermal L from S-Movement to N of thermal L from S-

CA sequentially cause episodesCA sequentially cause episodes– Convergence into LIVConvergence into LIV– Increased flow to Sac from SFBAIncreased flow to Sac from SFBA– Increased flow into SJV from SFBAIncreased flow into SJV from SFBA– Moves offshoreMoves offshore

• Domain-3 Flow detailsDomain-3 Flow details

L

L

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

L

SAC episode: S-Low moved N & N-Low moved bit S (NWS showed SAC episode: S-Low moved N & N-Low moved bit S (NWS showed only closed-L as gone); now more W-flow to Saconly 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 Offshore-H formation & Fresno-eddy movement cause episodesmovement cause episodes

• Initial flow from S does not produce SFBA to Initial flow from S does not produce SFBA to Sac transportSac transport

• Syn-H formation directs SFBA flow to Sac & Syn-H formation directs SFBA flow to Sac & con-current Fresno-eddy blocks SFBA flow con-current Fresno-eddy blocks SFBA flow into SJVinto SJV

• When eddy moves to NWhen eddy moves to N– SFBA flow into Sac is blockedSFBA flow into Sac is blocked– SFBA flow into SJV is allowed SFBA flow into SJV is allowed

Pre-episode: uniform S-flowPre-episode: uniform S-flow

HL

SAC episode: H moved to W at coast (vs bulge from CV to coast in D-1); Fresno eddy N of D-1 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 SACposition (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); 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 SJVflow 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 Daytime confluence of 3-flows E of LIV (on Mt peak) causes episodeMt peak) causes episode– Flow from N from Carquinez StraitsFlow from N from Carquinez Straits– Flow from W thru GGGFlow from W thru GGG– Upslope flow on E-side of hills E of LIVUpslope flow on E-side of hills E of LIV

• For episode needFor episode need– Strong confluenceStrong confluence– Low speedsLow speeds

• Obs first and then MM5Obs 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 LivPre-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 LivEpisode afternoon (1400 PDT): W flow thru GGG & strong con E of Liv

DOMAIN 3: SFC TRANSPORT TO SAC SUMMARY

• TRANSPORT FROM SFBA BLOCKED BY TRANSPORT FROM SFBA BLOCKED BY OPPOSING FLOW ON DAYS BEFORE OPPOSING FLOW ON DAYS BEFORE AND AFTER SAC EPISODEAND AFTER SAC EPISODE

• TRANSPORT FROM SFBA NOT TRANSPORT FROM SFBA NOT BLOCKED ON DAY OF SAC EPISODEBLOCKED ON DAY OF SAC EPISODE

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

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

DOMAIN 3: SFC TRANSPORT TO SJV SUMMARY

• TRANSPORT FROM SFBA TO SJV TRANSPORT FROM SFBA TO SJV MUST NOT BE BLOCKED BY MUST NOT BE BLOCKED BY OPPOSING FLOWSOPPOSING FLOWS

• FLOW INTO SJV MUST FLOW INTO SJV MUST – NOT BE TOO FAST NOT BE TOO FAST – SHOW CONFLUENCESHOW CONFLUENCE

SAC EPISODE NIGHT: TRANSPORT TO SJV FROM SFBA IS BLOCKEDSAC EPISODE NIGHT: TRANSPORT TO SJV FROM SFBA IS BLOCKED

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

CONCLUSIONCONCLUSION• SMALL CHANGES IN 700 hPa-H & SFC-L SMALL CHANGES IN 700 hPa-H & SFC-L

POSITIONS CAUSED SEQUENTIAL DAILY POSITIONS CAUSED SEQUENTIAL DAILY OZONE MAX IN LIV, SAC, & SJV OZONE MAX IN LIV, SAC, & SJV

• NWS CHARTS COULD NOT DISCERN NWS CHARTS COULD NOT DISCERN DETAILS OF CHANGES, BUT MM5 COULDDETAILS OF CHANGES, BUT MM5 COULD

• MM5 MM5 – MATCHED NWS PATTERNS &MATCHED NWS PATTERNS & MESO-OBS MESO-OBS

REASONABLY WELL REASONABLY WELL – PROVIDED ADDITIONAL DETAILSPROVIDED ADDITIONAL DETAILS