Journal article
Tropospheric NO2 measurements using a three-wavelength optical parametric oscillator differential absorption lidar
Atmospheric measurement techniques, Vol.14(6), pp.4069-4082
06/04/2021
DOI: 10.5194/amt-14-4069-2021
Abstract
The conventional two-wavelength differential absorption lidar (DIAL) has measured air pollutants such as nitrogen dioxide (NO2). However, high concentrations of aerosol within the planetary boundary layer (PBL) can cause significant retrieval errors using only a two-wavelength DIAL technique to measure NO2. We proposed a new technique to obtain more accurate measurements of NO2 using a three-wavelength DIAL technique based on an optical parametric oscillator (OPO) laser. This study derives the three-wavelength DIAL retrieval equations necessary to retrieve vertical profiles of NO2 in the troposphere. Additionally, two rules to obtain the optimum choice of the three wavelengths applied in the retrieval are designed to help increase the differences in the NO2 absorption cross-sections and reduce aerosol interference. NO2 retrieval relative uncertainties caused by aerosol extinction, molecular extinction, absorption of gases other than the gas of interest and backscattering are calculated using two-wavelength DIAL (438 and 439.5 nm) and three-wavelength DIAL (438, 439.5 and 441 nm) techniques. The retrieval uncertainties in aerosol extinction using the three-wavelength DIAL technique are reduced to less than 2% of those when using the two-wavelength DIAL technique. Moreover, the retrieval uncertainty analysis indicates that the three-wavelength DIAL technique can reduce more fluctuation caused by aerosol backscattering than the two-wavelength DIAL tech- nique. This study presents NO2 concentration profiles which were obtained using the HU (Hampton University) three-wavelength OPO DIAL. As a first step to assess the accuracy of the HU lidar NO2 profiles, we compared the NO2 profiles to simulated data from the Weather Research and Forecasting Chemistry (WRF-Chem) model. This comparison suggests that the NO2 profiles retrieved with the three-wavelength DIAL technique have similar vertical structure and magnitudes typically within +/- 0.1 ppb compared to modeled profiles.
Details
- Title: Subtitle
- Tropospheric NO2 measurements using a three-wavelength optical parametric oscillator differential absorption lidar
- Creators
- Jia Su - Hampton UniversityM. Patrick McCormick - Hampton UniversityMatthew S. Johnson - Ames Research CenterJohn T. Sullivan - Goddard Space Flight CenterMichael J. Newchurch - University of Alabama in HuntsvilleTimothy A. Berkoff - Langley Research CenterShi Kuang - University of Alabama in HuntsvilleGuillaume P. Gronoff - Langley Research Center
- Resource Type
- Journal article
- Publication Details
- Atmospheric measurement techniques, Vol.14(6), pp.4069-4082
- Publisher
- Copernicus Gesellschaft Mbh
- DOI
- 10.5194/amt-14-4069-2021
- ISSN
- 1867-1381
- eISSN
- 1867-8548
- Number of pages
- 14
- Grant note
- 551150-211150 / PIRT project - US Army Research, Development and Engineering Command (AQC) Center (DOD) under HU PIRT NA16SEC4810008 / National Oceanic and Atmospheric Administration Cooperative Science Center for Earth System and Sciences and Remote Sensing Technologies (NOAA-CESSRST)
- Language
- English
- Date published
- 06/04/2021
- Academic Unit
- Iowa Technology Institute
- Record Identifier
- 9984721218002771
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