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Use 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.

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Presentation on theme: "Use 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."— Presentation transcript:

1 Use 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 And Shuki Chaw, Leona Charles, Barry Gross City College of City University of New York New York, NY 10031

2 Objective Analyze Lidar Backscatter to determine PBL Heights using Wavelet method Demonstrate the potential of applying Lidar Backscatter in the air quality forecast evaluation

3 Data Lidar measured backscatter signal PBL heights and aerosol extinction coefficients out of WRF/CMAQ air quality forecast system

4 Lidar 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

5 Lidar Backscatter C: calibration constant β: backscatter coefficient α: extinction coefficient

6 CCNY Lidar Setup Lidar data: 1064 nm channel Temporal resolution: 1 minute Vertical resolution: 37.5 m

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11 WRF/CMAQ Forecast System Meteorology/Emission: Based on NECP/NWS 48-hr WRF forecasts initialized at 12:00 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

12 NWS Eta 12km 48hr Forecast Initialized at 12:00 UTC NWS Eta-Post (vertical interpolation) NWS Product Generator (horizontal interpolation) NWS Eta for CMAQ 22 sigma layer, 12 km, Lambert-Conformal Location: National Weather Service (NWS) EPA gets Eta for CMAQ to EPA NESC EPA stores emission input files at EPA NESC Location: EPA RTP Atmospheric Modeling Division National Environmental Supercomputing Center (NESC) NYSDEC runs PREMAQ at EPA NESC to generate model-ready meteorology and emissions NYSDEC brings PREMAQ output (model-ready emissions and meteorology) back to their Linux cluster Location: NY State Department of Environmental Conservation (NYSDEC) NYSDEC runs CMAQ using PREMAQ model-ready emissions and meteorology for near-realtime O 3 and PM forecasts on NYSDEC Aspen Linux Cluster. Postprocessing finishes by 05:30 EDST Research Mode: Run alternate CMAQ version from 5.30 to 9.30 EDST EPA gets NOAA AQ forecasting output (NE domain) and archives at EPA NESC NWS CMAQ-Eta 12km O 3 forecasts for Northeast (NE) domain 08:00 10:00 13:00 20:00 18:00 21:00 23:00 01:00 05:30 EDST

13 Modeling Domain

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15 Analyze 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.

16 Wavelet Covariance Transform

17 The 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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23 Compare 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

24 July 31, 2006

25 August 1, 2006

26 August 2, 2006

27 Summary 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.


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