Environmental Engineering Reference
In-Depth Information
3.3 Effect of Temporal Averaging of Vertical Eddy
Diffusivity on the Forecast Quality of Surface Ozone
Concentration of the National Air Quality Forecast
Pius Lee
1
, Daewon Byun
1
, Ariel Stein
1
, You-Hua Tang
2
, Hsin-Mu Lin
3
,
Ho-Chun Huang
2
, Sarah Lu
2
, Marina Tsidulko
2
, Jeff McQueen
4
, Daniel
Tong
3
, Shaocai Yu
3
, Tianfeng Chai
3
,
Dongchul Kim
2
, Ivanka Stajner
5
,
and Paula Davidson
6
1
Air Resource Lab., NOAA, 1315 East West Highway, Room 3316, Silver Spring,
MD 20910, USA
2
Scientific Applications International Corporation, Beltsville, MD, USA
3
Science and Technology Corp., Hampton, VA, USA
4
Environmental Modeling Center, National Centers for Environmental Prediction, NWS,
MD, USA
5
Noblis Inc. Fairfax, VA, USA
6
Office of Science and Technology, NWS, Silver Spring, MD, USA
Abstract
Air Quality forecast models are employed to provide numerical guidance
for forecasters to issue timely ozone and particulate matter concentration forecast
pertinent to human health exposures to the communities they serve. The National
Centers for Environmental Prediction (NCEP), National Weather Service Weather
Research and Forecasting Non-hydrostatic Mesoscale Model (WRF/NMM) has
been coupled off-line with the EPA Community Multi-scale Air Quality (CMAQ)
model in 2003 to form the National Air Quality Forecast Capability (NAQFC).
Coupling of the turbulent mixing processes of the meteorological driver and
CMAQ has been a challenge. WRF/NMM uses the Mellor-Yamada-Janjic (MYJ)
turbulence mixing scheme in the boundary layer. The option of directly using MYJ
provided vertical eddy diffusivity to calculate turbulent mixing of the atmospheric
chemical constituents in CMAQ has been tested. This study investigated the effect
of various temporal averaging treatments of vertical eddy diffusivity in redistributing
ozone in the boundary layer. Model predicted concentration structures of ozone
resulting from these various temporal treatments of vertical eddy diffusivity have
been studied and verified using AIRNOW, an EPA surface ozone concentration
network, and ozone-sonde data.
