1. Effect of temporal averaging of vertical eddy diffusivity on the forecast accuracy of surface O3
Pius Lee, Youhua Tang, Jeff McQueen, Ho-Chun Huang,
Marina Tsildulko, Geoff DiMego, Sarah Lu and Geoff DiMego
NOAA/NCEP
Environmental Modeling Center
Ivanka Stajner, Ken Carey, and Paula Davidson
Office and Science and Technology, NWS
Jon Pleim, Rohit Mathur, Hsin-Mu Lin, Daiwen Kang,
George Pouliot, Jeff Young, Shaocai Yu, Daniel Tong, Tianfang Chai
U.S. EPA

2. Elevated O3 episode Aug 3rd, 2006

3. Sensitivity cases Case name Description Base
Real-time NCEP production CMAQ-4.5 RADM PBL scheme
NAM Kh
Directly read in NAM instantaneous Kh to plug in CMAQ’s vertical diffusion
NAM hrly Kh
As above but uses hourly averaged Kh ( scheme used is analogous to precip buckets emptied at full hours )

4. Kz (m2 s-1) over Table Mountain, CA
on August 2nd-3rd,
18UTC
Ozonesonde launched
at 20:52UTC
20UTC
21UTC
00UTC
TKE-PBL
Inferred PBLH
From ozonesonde
Temporal smoothing
used in this study
postponed vigorous
turbulent mixing.

5. Kz (m2 s-1) over Boulder, CO
on August 2nd-3rd
19UTC
TKE-PBL
Inferred PBLH
From ozonesonde
20UTC
23UTC
02UTC
Ozonesonde launched
at 19:28UTC

6. Kz (m2 s-1) over Huntsville, AL
on August 2nd,
TKE-PBL
Inferred PBLH
From ozonesonde
15UTC
17UTC
21UTC
18UTC
Ozonesonde launched
at 17:36UTC

7. Kh (m2 s-1) over Beltsville, MD
on August 2nd,
TKE-PBL
Inferred PBLH
From ozonesonde
19UTC
15UTC
23UTC
20UTC
Ozonesonde launched
at 19:18UTC

8. Time-height on NO2 at Table Mountain on Aug 2nd-3rd, 2006
NAM Kh
Base
NAM hrly Kh
There is considerable amount
of NO2 at night. (Table Mount is roughly 80 km to the North east of L.A. at elevation of 2285 m.)

9. 18UTC, 2nd 21UTC, 2nd 02UTC, 3rd 00UTC, 3rd
Surface O3 diff cases: Kh - hrly_Kh on Aug 2nd-3rd, 2006
18UTC, 2nd
21UTC, 2nd
02UTC, 3rd
00UTC, 3rd
Very minor difference; if any is due to delayed mixing

10. Time-height on O3 at Table Mountain on Aug 2nd-3rd, 2006
NAM Kh
Base
At 2285 m
foggy near
ground
NAM hrly Kh
Inferred PBLH
From ozonesonde

11. Time-height on O3 at Boulder on Aug 2nd-3rd, 2006
NAM Kh
Base
Inferred PBLH
From ozonesonde
NAM hrly Kh

12. Time-height on O3 at Huntsville on Aug 2nd-3rd, 2006
NAM Kh
Base
Inferred PBLH
From ozonesonde
NAM hrly Kh

13. Time-height on O3 at Beltsville on Aug 2nd-3rd, 2006
NAM Kh
Base
Rather large
overshot of
PBLH
NAM hrly Kh
Inferred PBLH
From ozonesonde

14. Summary Direct use of NAM Kh has been attempted by:
Use of instantaneous Kh at hourly data exchange from NAM
Use hourly averaged Kh from NAM
These two approaches both showed better agreement in reflecting atmospheric column where turbulent mixing actually takes place when looking at selected sites during the studies period of August 2nd, 2006.
There is not much impact on daily maximum surface O3 concentration, as Kh temporal averaging tends to delay the peak occurrence by some 10’s minutes but does not alter the hourly or 8 h daily max.

15. Backups

16. Correlation of daily 8h max O3 with AIRNOW obs (7/30-8/4, 2008)PC UM
Base
NAM Kh
NAM hrly Kh SE RM NE LM

17. RSME of daily 8h max O3 with AIRNOW obs (7/30-8/4, 2008)PC UM RM SE
Base
NAM Kh
NAM hrly Kh LM NE

18. PBL-Height verification across CONUS between July20-27, 2006
12 hr PBL verification
from launcher runs;
Valid 00z