Dacic Natasha, Sullivan John T, Knowland K Emma, Wolfe Glenn M, Oman Luke D, Berkof Timothy A, Gronoff Guillaume P
Atmospheric Chemistry and Dynamics Lab, NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA.
Science Systems and Applications Inc. (SSAI), Lanham, MD, 20706, USA.
Atmos Environ (1994). 2020 Feb 1;222. doi: 10.1016/j.atmosenv.2019.117133. Epub 2019 Nov 16.
Recirculation of pollutants due to a bay breeze effect is a key meteorological mechanism impacting air quality near urban coastal areas, but regional and global chemical transport models have historically struggled to capture this phenomenon. We present a case study of a high ozone (O) episode observed over the Chesapeake Bay during the NASA Ozone Water-Land Environmental Transition Study (OWLETS) in summer 2017. OWLETS included a complementary suite of ground-based and airborne observations, with which we characterize the meteorological and chemical context of this event and develop a framework to evaluate model performance. Two publicly-available NASA global high-resolution coupled chemistry-meteorology models (CCMMs) are investigated: GEOS-CF and MERRA2-GMI. The GEOS-CF R value for comparisons between the NASA Sherpa C-23 aircraft measurements to the GEOS-CF resulted in good agreement (R: 0.67) on July 19 and fair agreement (R: 0.55) for July 20. Compared to surface observations, we find the GEOS-CF product with a 25 x 25 km grid box, at an hourly (R: 0.62 to 0.87) and 15-minute (R: 0.64 to 0.87) interval for six regional sites outperforms the hourly nominally 50 x 50 km gridded MERRA2-GMI (R: 0.53 to 0.76) for four of the six sites, suggesting it is better capable of simulating complex chemical and meteorological features associated with ozone transport within the Chesapeake Bay airshed. When the GEOS-CF product was compared to the TOLNet LiDAR observations at both NASA Langley Research Center (LaRC) and the Chesapeake Bay Bridge Tunnel (CBBT), the median differences at LaRC were -6 to 8% and at CBBT were ± 7% between 400 to 2000 m ASL. This indicates that, for this case study, the GEOS-CF is able to simulate surface level ozone diurnal cycles and vertical ozone profiles at small scales between the surface level and 2000 m ASL. Evaluating global chemical model simulations at sub-regional scales will help air quality scientists understand the complex processes occurring at small spatial and temporal scales within complex surface terrain changes, simulating nighttime chemistry and deposition, and the potential to use global chemical transport simulations in support of regional and sub-regional field campaigns.
由于海陆风效应导致的污染物再循环是影响城市沿海地区空气质量的关键气象机制，但区域和全球化学传输模型一直难以捕捉这一现象。我们展示了一个在2017年夏季美国国家航空航天局（NASA）臭氧水陆环境转变研究（OWLETS）期间切萨皮克湾观测到的高臭氧（O）事件的案例研究。OWLETS包括一系列互补的地面和机载观测数据，我们利用这些数据来描述该事件的气象和化学背景，并建立一个评估模型性能的框架。我们研究了两个公开可用的NASA全球高分辨率化学 - 气象耦合模型（CCMMs）：GEOS - CF和MERRA2 - GMI。在7月19日，将NASA的夏尔巴C - 23飞机测量数据与GEOS - CF进行比较时，GEOS - CF的R值显示出良好的一致性（R：0.67），7月20日为中等一致性（R：0.55）。与地面观测相比，我们发现对于六个区域站点，GEOS - CF产品在25×25千米网格箱下，每小时（R：0.62至0.87）和15分钟（R：0.64至0.87）的时间间隔下，在六个站点中的四个站点上优于每小时名义上50×50千米网格的MERRA2 - GMI（R：0.53至0.76），这表明它更有能力模拟切萨皮克湾流域内与臭氧传输相关的复杂化学和气象特征。当将GEOS - CF产品与NASA兰利研究中心（LaRC）和切萨皮克湾大桥隧道（CBBT）的TOLNet激光雷达观测数据进行比较时，在海拔400至2000米之间，LaRC的中位数差异为 - 6%至8%，CBBT为±7%。这表明，对于本案例研究，GEOS - CF能够在地表至2000米海拔的小尺度上模拟地表臭氧日变化周期和垂直臭氧剖面。在次区域尺度上评估全球化学模型模拟将有助于空气质量科学家理解复杂地表地形变化内小空间和时间尺度上发生的复杂过程，模拟夜间化学和沉降，以及利用全球化学传输模拟来支持区域和次区域实地考察的潜力。
