Analysis of NO2 and O3 variation in 2020 and 2021 and application to evaluate the GFS-CMAQ model forecast in New York city&#160;
Authors: Kulko Margarita , Liang Maggie , McQueen Jeff , Huang Ho-Chun , Strobach Edward , Wu Yonghua , Moshary Fred 
Published: March 2022

&lt;p&gt;The US National Ambient Air Quality Standard (NAAQS) dictates the limits on atmospheric pollutants, including the tropospheric ozone (O&lt;sub&gt;3&lt;/sub&gt;). Its exceedance of the limit typically happens in the summer because of changes in meteorology, chemistry, and emissions. Since O&lt;sub&gt;3&lt;/sub&gt; affects pulmonary function and has been linked to higher risks of depression and anxiety diagnoses, it is essential to understand O&lt;sub&gt;3&lt;/sub&gt; and its precursor nitrogen dioxide (NO&lt;sub&gt;2&lt;/sub&gt;) variations. In July 2021, the Finite Volume Cube-Sphere Dynamic Core in Global Forecasting System (FV3-based GFS) became the new meteorological driver coupled with the Environmental Protection Agency&amp;#8217;s Community Multiscale Air Quality System (CMAQ). Together they make up the National Air Quality Forecasting Capability (NAQFC), which provides hourly forecasts of a variety of atmospheric species and meteorological fields. Therefore, it is necessary to evaluate the model&amp;#8217;s output relevant to O&lt;sub&gt;3&lt;/sub&gt; production in an urban environment and investigate potential biases.&lt;/p&gt;&lt;p&gt;This study uses integrated remote sensing from a ceilometer, a wind LIDAR, the PANDORA spectrometer, and satellite Sentinel-5, and surface observations to investigate the spatial and temporal variability of NO&lt;sub&gt;2&lt;/sub&gt;, O&lt;sub&gt;3&lt;/sub&gt;, and planetary-boundary-layer height (PBLH) in August 2020 and 2021.&lt;/p&gt;&lt;p&gt;At first, surface-level and column NO&lt;sub&gt;2&lt;/sub&gt; was observed from the co-located in-situ samplers and the PANDORA spectrometers at City College of New York (CCNY) and Queens College (QC) sites in New York City area. Then, the NO&lt;sub&gt;2&lt;/sub&gt; and O&lt;sub&gt;3&lt;/sub&gt; temporal variations at the two sites were compared and indicated a strong correlation for O&lt;sub&gt;3&lt;/sub&gt; and a moderate correlation for NO&lt;sub&gt;2&lt;/sub&gt;. Meanwhile, the TROPOMI observations show spatial variation of tropospheric column NO&lt;sub&gt;2&lt;/sub&gt;.&lt;/p&gt;&lt;p&gt;The performance of the model&amp;#8217;s product was evaluated using integrated observations and showed to be in good agreement with observations for the surface O&lt;sub&gt;3&lt;/sub&gt; at the two sites for the month of August 2020. For the surface NO&lt;sub&gt;2&lt;/sub&gt;, the model forecast product generally showed similar diurnal variation but over-predicted the peak values likely related to complex urban emission sources and NO&lt;sub&gt;2&lt;/sub&gt; vertical mixing in the PBL. The correlation analysis of the model and observation data over weekdays and weekends were conducted that demonstrated the increased emission effects from the vehicular traffic during weekdays. The O&lt;sub&gt;3&lt;/sub&gt;-NO&lt;sub&gt;2&lt;/sub&gt; titration from the model showed good consistency with the observations. Additionally, O&lt;sub&gt;3&lt;/sub&gt;-NO&lt;sub&gt;2&lt;/sub&gt; variations from the month of August 2021 were evaluated and compared against the levels in 2020.&lt;/p&gt;