Characterization of an eastern U.S. severe air pollution episode using WRF/Chem
Characterization of an eastern U.S. severe air pollution episode using WRF/Chem
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DOI：
10.1029/2010jd015054
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发表时间：
2011-09
影响因子：
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通讯作者：
E. Yegorova;D. Allen;C. Loughner;K. Pickering;R. Dickerson
中科院分区：
文献类型：
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作者：
E. Yegorova;D. Allen;C. Loughner;K. Pickering;R. Dickerson
[1]2007年7月8日至11日，美国东部经历了一次严重的热浪和烟雾事件，最高温度接近38摄氏度，最大8小时平均臭氧混合比为125 ppbv。我们使用在线化学的天气研究和预报模式(WRF/CHEM和RADM2)通过观测和数值模拟来检查这一事件。模式很好地模拟了这次严重雾霾事件的总体特征--由冷锋通过而终止的大范围高压、弱风和重污染。WRF/Chem对空气质量较差的地区(通常是东北部)的臭氧最大值低估了5-8 ppbv，但在臭氧含量较低的地区(通常是东南部)高估了最大值16 ppbv。模拟的马里兰州贝尔茨维尔上空的臭氧垂直廓线与臭氧探空仪的测量结果吻合得很好，但模式边界层在7月9日太深，这是导致该地区偏低的原因之一。NOx化学在RADM2中的表现可能导致对NOx寿命的低估，并可能是东北污染最严重地区臭氧偏置较低的部分原因。为了模拟夜间多相NOY损失的最大影响，我们将N2O5非均相水解反应速率常数设置为零。这增加了臭氧浓度最高区域以外的平均偏差，但大大改善了大部分区域的臭氧和NOY，特别是在雾霾笼罩的地区，如农村、尖峰地区。
[1] On 8–11 July 2007 the eastern United States experienced a severe heat wave and smog event with maximum temperatures approaching 38°C and maximum 8 h average ozone mixing ratios of 125 ppbv. We examine this episode with observations and numerical simulations using the Weather Research and Forecasting model with online chemistry (WRF/Chem with RADM2). The general features of this severe smog event–a broad area of high pressure, weak winds and heavy pollution, terminated by the passage of a cold front–were well simulated by the model. WRF/Chem underpredicted O3 maxima by 5–8 ppbv where air quality was poor, usually in the northeast, but overpredicted maxima by up to 16 ppbv where ozone amounts were low, usually in the southeast. Simulated O3 vertical profiles over Beltsville, Maryland, showed good agreement with ozonesonde measurements, but the model boundary layer was too deep on 9 July, contributing to the low bias over this region. The representation of NOx chemistry in RADM2 may lead to an underestimation of NOx lifetime and is likely partially responsible for low O3 biases in the most polluted area in the northeast. To simulate the maximum effect of nighttime multiphase NOy loss, we set the N2O5 heterogeneous hydrolysis reaction rate constant to zero. This increased the mean bias outside the area of highest ozone concentration but substantially improved O3 and NOy over most of the domain, especially in smoggy areas such as the rural, Pinnacles site.