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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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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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slide1

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
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
nws 700 hpa preview 1200 utc 0500 pdt
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
slide4

Before ozone episodes: offshore G. C. High; synoptic High in Nevada;

boundary-Low between Highs; SSW-flow over SFBA

H

H

nws surface preview 1200 utc or 0500 pdt
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
slide7

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

slide8

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

L

mm5 configuration
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
slide10

D01

D03

D02

mm5 domain 1 700 hpa winds preview
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
slide15

(B/F episodes) MM5 correct: offshore H; H in SE Nev; boundary-L;

but S-flow over SFBA vs. NWS SW

L

H

H

slide16

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

mm5 domain 1 sfc winds preview at 12 utc 05 pdt
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
slide18

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

slide19

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

domain 3 700 hpa preview 2100 utc or 0400 pdt
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
slide22

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

slide23

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

domain 3 summary of sfc transport to livermore key hours
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
slide25

Sfc winds-obs at 0700 PST

(1500 UTC) on 31 July

(LIV episode morning)

Note con flow into LIV

slide26

Sfc wind-obs at 1400 PST

(2100 UTC) on 31 July

(LIV episode afternoon)

Note flow from N into LIV and

out to E

domain 3 sfc transport to sac summary
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
domain 3 sfc transport to sjv summary
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
conclusion
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
ad