MM5 SIMMULATIONS OF MESOSCALE TRANSPORT FROM THE SFBA TO SACRAMENTO & SJV DURING A CCOS 30 JULY-02 AUG OZONE EPISODE By Tesfamichael B. Ghidey, LBNL, SJSU Robert D. Bornstein, SJSU Robert Van Buskirk, LBNL 3 June 2004 Prepared for BAAQMD

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 Start: 1200 UTC on 28 July Length: 7.5 days Length: 7.5 days LBNL LINUX single processor: 15 days LBNL LINUX single processor: 15 days

Output focus-areas V (meso format; m/s): barb = 1, flag = 5 V (meso format; m/s): barb = 1, flag = 5 36 km synoptics: 36 km synoptics: NWS vs MM5 4 km (sub-areas) 4 km (sub-areas) –SFBA + C. Valley: regional transport –Carquinez St.: flow split into CV –Livermore: ozone max

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

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

Surface NWS PREVIEW: 1200 UTC or 0500 PDT Note: Warm-core upper-H projects down- ward to form sfc inverted thermal L Note: Warm-core upper-H projects down- ward to form sfc inverted thermal L Pre-episode: over Nevada Pre-episode: over Nevada Episode days: moves over SJV and intensifies Episode days: moves over SJV and intensifies Post-episode: weakens Post-episode: weakens

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

MM5 Domain-1: 700 hPa WINDS PREVIEW NWS charts approximate pressure center locations NWS charts approximate pressure center locations Cannot give flow details in SFBA, Car- quinez Strait, & SJV Cannot give flow details in SFBA, Car- quinez Strait, & SJV MM5 simulations show MM5 simulations show –Pre-episode H: E of SFBA over Nev –Episode days: bulge from H extends westward over SFBA –Post-episode H: back E of SFBA over Az

H H H SJV episode: L correctly gone; inland H moves S to Az/Utah border; bulge forms correctly into 2 nd H (vs. “apparent split” obs); Fresno eddy forms (not in obs); NW flow over SFBA correctly curves S to SJV (vs SE flow over SFBA) L

MM5 Domain-1: SFC WINDS PREVIEW (12 UTC OR 05 PDT) Movement (N & then S) of thermal L from S-CA cause episodes Movement (N & then S) of thermal L from S-CA cause episodes –Convergence into LIV –Increased flow to Sac from SFBA –Increased flow into SJV from SFBA –Moves offshore Flow details in Domain-3 Flow details in Domain-3

L L SJV episode day: not much change in Lows (correct); more flow S into SJV

DOMAIN-3: 700 hPa PREVIEW (2100 UTC or 0400 PDT) SFBA + CV FOCI SFBA + CV FOCI 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 Newly formed H directs SFBA flow to Sac & con- current eddy blocks SFBA flow into SJV Newly formed H directs SFBA flow to Sac & con- current eddy blocks SFBA flow into SJV When eddy moves to N When eddy moves to N –SFBA flow into Sac blocked –SFBA flow into SJV allowed

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 E of LIV (on Mt peak) causes episode (max ozone on Mt peak) Daytime confluence E of LIV (on Mt peak) causes episode (max ozone on Mt peak) –Flow from N from Carquinez Straits –Flow from W thru GGG –Upslope from E-side of hills E of LIV For episode need For episode need –Strong confluence –Low speeds

Episode afternoon (1400 PDT): W flow thru GGG & strong con into Eastern 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

THE END