Title: Use of Lidar Backscatter to Determine the PBL Heights in New York City, NY
1Use of Lidar Backscatter to Determine the PBL
Heights in New York City, NY
- Jia-Yeong Ku, Chris Hogrefe, Gopal Sistla
- New York State Department of Environmental
Conservation - Albany, NY 12233
- And
- Shuki Chaw, Leona Charles, Barry Gross
- City College of City University of New York
- New York, NY 10031
2Objective
- Analyze Lidar Backscatter to determine PBL
Heights using Wavelet method - Demonstrate the potential of applying Lidar
Backscatter in the air quality forecast
evaluation
3Data
- Lidar measured backscatter signal
- PBL heights and aerosol extinction coefficients
out of WRF/CMAQ air quality forecast system
4Lidar System
- Lidar (Light Detection And Range) measures the
intensity of backscattered light as a function of
distance - The primary contribution of scattering is from
aerosol particles suspended in the air
5Lidar Backscatter
C calibration constant ß backscatter
coefficient a extinction coefficient
6CCNY Lidar Setup
Lidar data 1064 nm channel Temporal resolution
1 minute Vertical resolution 37.5 m
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11WRF/CMAQ Forecast System
- Meteorology/Emission Based on NECP/NWS 48-hr WRF
forecasts initialized at 1200 UTC and 2002/2004
emission inventory, processed with PREMAQ - Photochemical Model CMAQ (ver 4.51)
- Horizontal resolution 12 km
- vertical resolution 22 layers, lowest layer
40 m - Study periods July 31 August 2, 2006
12EDST
NWS Eta for CMAQ 22 sigma layer, 12
km, Lambert-Conformal
NWS Eta 12km 48hr Forecast Initialized at 1200
UTC
NWS Product Generator (horizontal interpolation)
NWS Eta-Post (vertical interpolation)
0800
1000
NWS CMAQ-Eta 12km O3 forecasts for Northeast (NE)
domain
1300
EPA stores emission input files at EPA NESC
1800
EPA gets Eta for CMAQ to EPA NESC
EPA gets NOAA AQ forecasting output (NE domain)
and archives at EPA NESC
2000
NYSDEC runs PREMAQ at EPA NESC to generate
model-ready meteorology and emissions
2100
Location EPA RTP Atmospheric Modeling Division
National Environmental
Supercomputing Center (NESC)
NYSDEC brings PREMAQ output (model-ready
emissions and meteorology) back to their Linux
cluster
2300
Location NY State Department of Environmental
Conservation (NYSDEC)
0100
NYSDEC runs CMAQ using PREMAQ model-ready
emissions and meteorology for near-realtime O3
and PM forecasts on NYSDEC Aspen Linux Cluster.
Postprocessing finishes by 0530 EDST Research
Mode Run alternate CMAQ version from 5.30 to
9.30 EDST
0530
13Modeling Domain
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15Analyze Lidar Backscatter for PBL Heights
- Boundary layer usually has much higher aerosol
concentration than free troposphere above. - The significant change in the backscatter across
the top of the BL provides a means of determining
PBL heights. - Wavelet provides a scale-dependent approach to
determine PBL height.
16Wavelet Covariance Transform
17The key of the wavelet analysis is the selection
of an appropriate dilation (vertical scale).
18 Compare PBL heights of Lidar measured and Model
predicted
- Lidar measures aerosol layers
- Model determines vertical mixing based on some
meteorological parameters, such as temperature
and wind field
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23Compare Lidar Backscatter and CMAQ Extinction
Coefficient
- Hourly and vertical averaged Lidar Backscatter
signal - Hourly extinction coefficient of CMAQ outputs
- A qualitative comparison both backscatter and
extinction coefficient reflect the aerosol and
humidity loading in the atmosphere
24July 31, 2006
25August 1, 2006
26August 2, 2006
27Summary
- A wavelet technique is applied to analyze the PBL
height using lidar backscatter measured in New
York City - WRF/CMAQ forecast system keeps track the lidar
measured PBL development well - WRF/CMAQ forecast system predicted the vertical
PM profile (in terms of extinction coefficient)
resemble to the backscatter vertical profile
under cloud free conditions - Development in the areas that we can directly
compare the aerosol optical products between
Lidar and model.