Evaluation of several WRF/NMM- CMAQ vertical coupling configurations Pius Lee, Jeff McQueen, Marina Tsildulko, Geoff DiMego Sarah Lu and Bert Katz NOAA/NCEP Environmental Modeling Center Rohit Mathur, Hsin-Mu Lin, Daiwen Kang, Tanya Otte, Jon Pleim, George Pouliot, David Wong, Jeff Young, and Ken Schere U.S. EPA/ORD/ASMD and NOAA/OAR/ARL

WRF/NMM Hybrid Coordinate ground Pressure domain Sigma domain η1= 1; η2= 0 η 1 = 1; η 2 = 1 PTPT HYBRID PD T +P T η1= 0; η2= 0 Upper-levels Pressure Lower-levels σ-p Lin et al, Poster Session 3.1

WRF/NMM  ’ s limited to 0-1 Jacobian across the  -p interface Lin et al, Poster Session 3.1

Remarks on the hybrid layer cases (22L) 22 layers: Choose model layers aligned close to those used in the current National Air Quality Forecast System (AQFS). 14 lowest layers spanned ~ 2 km *(29L) 29 layers: Finer resolution than (a) in lowest 500m; top of PBL; and near tropopause. (40L) 40 layers: As fine as the met model for lowest 3.5 km. *29L result rather similar to that of 22L

Hybrid (a) 22L, (b) 29L, and (c) 40L

O3 episode (h max) Aug 3rd, 2006

22L-40L 40L reduced low bias for regions near Bakersfield 40L reduced high bias for regions near mid Long Island

Spatial verification for 22L

Spatial verification for 40L

Cross section on Central Valley, CA Cross section on Mid Long Island, NY

S S N N W W E E Bakersfield 1 pm Local PBL and Kz descriptions with less interoplation error O3

S S N N W WE E Bakersfield 1 am local O3 Resolves inversion better, retains more residual O3

NOy S S N N W W E E Bakersfield 1 pm Local Industrial plume from south.

S S N NW W E E Bakersfield 1 am localNOy Lower diffusivity Resulted in relatively un-dispersed plume heading eastward

Formaldehyde S S N NW W E E Bakersfield 1 pm Local A more concentrated plume of VOC and biogenic product coming from Southwest

S S N NW W E E Bakersfield 1 am local Formaldehyde Better description of residual and surface layers

CO S S N NW WE E Bakersfield 1 pm Local

S S N NW W E E Bakersfield 1 am localCO Better description of inversion, increased surface level concentrations

O3 S S N NW W E E Mid Long Island 4 pm local time Increased high bias for an offshore point to the south of Long Island Decrease high bias for New York City

S S N N W W E E O3 Mid Long Island 4 am local time Stronger inversion resulted in higher concentration in residual layer

S S N N W W E E Mid Long Island 4 pm local time NOy Better description of PBL also better description of sea breeze return flow

S S N N W W E E Mid Long Island 4 am local time NOy Species such as PAN will contribute to elevated surface O3 upon sunrise

S S N N W W E E Mid Long Island 4 pm local time Formaldehyde Reduction of high bias near New York City for VOC and biogenic photochemical products

S S N N W WE E Mid Long Island 4 am local time Formaldehyde Maintains a less dispersed plume of sea breeze return flow

Summary Three resolutions of a lower-levels σ-p terrain following and upper-levels pressure hybrid vertical co- ordinate systems have been tested: (a) 22L, (b) 29L, and ( c) 40L 40L is superior in two challenging localities: (1) Central Valley, CA: Perennial inversion; and Subsidence due to orographic and channel flows (2) Long Island, NY: Surrounding complex terrain and land-sea breezes Future work: Derivation of an Optimal vertical structure σ

22L-29L

29L-40L

Spatial verification for 29L

Definition based on a scatter plot a b c d

Definitions of measures

Categorical Statistics over 8/2-4, 2006 FCBFARPODCSIabcd 22L L L

S S N N W W E E Mid Long Island 4 pm local time Surface SOx

S SN N W W E E Mid Long Island 4 am local timeSurface SOx

S S N NW WE E Mid Long Island 4 pm local time Surface CO