The impact of observation nudging on simulated meteorology and ozone concentrations during DISCOVER-AQ 2013 Texas campaign
The impact of observation nudging on simulated meteorology and ozone concentrations during DISCOVER-AQ 2013 Texas campaign
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DOI：
10.5194/acpd-15-27357-2015
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发表时间：
2015-10
影响因子：
6.3
通讯作者：
X. Li;Yunsoo Choi;B. Czader;Hyun Cheol Kim;B. Lefer;S. Pan
中科院分区：
文献类型：
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作者：
X. Li;Yunsoo Choi;B. Czader;Hyun Cheol Kim;B. Lefer;S. Pan
摘要。准确的气象场是建立正确的化学输运模型的必要条件。观测推动和客观分析通常被认为是改善气象模拟的一种低成本和有效的技术。然而，观测助推对化学的气象影响尚未得到很好的表征。本研究使用天气研究与预报（WRF）和社区多尺度空气质量（CMAQ）模型，分析了2013年从空气质量相关的柱状和垂直分辨率观测中获取地表条件信息（discovery - aq）德克萨斯州活动期间，观测推动对模拟气象和臭氧浓度的影响。结果表明，观测参数和模拟参数之间的相关性得到了改善。例如，当使用观测推力时，地表温度的一致性指数（IOA）提高了约9%，地表纬向风（U-WIND）和经向风（V-WIND）的一致性指数（IOA）提高了6 - 11%。对一次冷锋事件的分析表明，在锋面通过过程中，轻推改善了风转变的时间。观测推力也减少了行星边界层高度预测的模式偏差。此外，CMAQ模拟的地表臭氧的IOA在模拟期间提高了6%。9月25日的高臭氧事件是在休斯顿发生的一个前沿臭氧事件。休斯顿航道附近的小尺度晨风转移加上清晨较高的高空臭氧可能是造成当天臭氧超标的原因。虽然观测推动并没有重现当天的风向变化，也未能重现观测到的高臭氧，但对地面和飞机数据的分析发现，观测推动有助于模型产生更好的臭氧预测。在事件发生期间的2小时内，在敏感情况下，明显更好的风明显改善了臭氧。在此期间，臭氧的平均IOA从略高于0.4增加到接近0.7。进一步的工作是提高微推力重现局部气象事件的能力，如停滞和风逆转，这可以提高化学输送模型预测高臭氧事件的能力。
Abstract. Accurate meteorological fields are imperative for correct chemical transport modeling. Observation nudging, along with objective analysis, is generally considered a low-cost and effective technique to improve meteorological simulations. However, the meteorological impact of observation nudging on chemistry has not been well characterized. This study involved two simulations to analyze the impact of observation nudging on simulated meteorology and ozone concentrations during the 2013 Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) Texas campaign period, using the Weather Research and Forecasting (WRF) and Community Multiscale Air Quality (CMAQ) models. The results showed improved correlations between observed and simulated parameters. For example, the index of agreement (IOA) improved by about 9 % for surface temperature and 6–11 % for surface zonal (U-WIND) and meridional (V-WIND) winds when observation nudging was employed. Analysis of a cold front event indicated that nudging improved the timing of wind transition during the front passage. Observation nudging also reduced the model biases for the planetary boundary layer height predictions. Additionally, the IOA for CMAQ simulated surface ozone improved by 6 % during the simulation period. The high-ozone episode on 25 September was a post-front ozone event in Houston. The small-scale morning wind shifts near the Houston Ship Channel combined with higher aloft ozone early morning likely caused the day's ozone exceedance. While observation nudging did not recreate the wind shifts on that day and failed to reproduce the observed high ozone, analyses of surface and aircraft data found that observation nudging helped the model yield improved ozone predictions. In a 2 h period during the event, substantially better winds in the sensitivity case noticeably improved the ozone. The average IOA for ozone in the period increased from just over 0.4 to near 0.7. Further work on improving the capability of nudging to reproduce local meteorological events such as stagnations and wind reversals could enhance a chemical transport model's skill for predicting high-ozone events.