The TOMCAT global chemical transport model v1.6: description of chemical mechanism and model evaluation
The TOMCAT global chemical transport model v1.6: description of chemical mechanism and model evaluation
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DOI：
10.5194/gmd-10-3025-2017
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发表时间：
2016-08
影响因子：
5.1
通讯作者：
S. Monks;S. Arnold;M. Hollaway;R. Pope;Chris Wilson;W. Feng;K. Emmerson;B. Kerridge;B. Latter;G. Miles;R. Siddans;M. Chipperfield
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文献类型：
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作者：
S. Monks;S. Arnold;M. Hollaway;R. Pope;Chris Wilson;W. Feng;K. Emmerson;B. Kerridge;B. Latter;G. Miles;R. Siddans;M. Chipperfield
抽象的。本文介绍了TOMCAT三维化学输送模式中使用的对流层化学机制方案。目前的方案对碳氢化合物化学的表述比以前在模型中列入的更详细，包括乙烯、丙烯、丁烷、甲苯和单萜烯的排放和氧化。该模型根据一系列表面、气球、飞机和卫星测量进行了评估。该模式能够较好地反映大气中一氧化碳、臭氧、挥发性有机化合物和活性氮的高、低浓度的主要空间和季节特征。然而，在一些物种中发现了模型偏差，其中一些是化学模型中常见的，另一些是Tomcat特有的，值得进一步研究。其中最显著的是：(1)北半球冬季和春季CO为负偏差，南半球(SH)CO全年为正偏差；(2)夏季NHO_3为正偏差，SH冬季为高纬度负偏差；(3)NH冬季C2和C3烷烃和烯烃为负偏差。TOMCAT全球对流层平均羟基(OH)浓度高于从甲基氯仿观测推断的估计值，但与最近模式间比较研究中报告的多模式平均浓度相似或更低。TOMCAT显示的是热带对流层低层的氢氧化物浓度峰值，而不像其他模型显示的是热带对流层高层的峰值浓度。这可能会影响重要痕量气体的寿命和传输，因此需要进一步研究。
Abstract. This paper documents the tropospheric chemical mechanism scheme used in the TOMCAT 3-D chemical transport model. The current scheme includes a more detailed representation of hydrocarbon chemistry than previously included in the model, with the inclusion of the emission and oxidation of ethene, propene, butane, toluene and monoterpenes. The model is evaluated against a range of surface, balloon, aircraft and satellite measurements. The model is generally able to capture the main spatial and seasonal features of high and low concentrations of carbon monoxide (CO), ozone (O3), volatile organic compounds (VOCs) and reactive nitrogen. However, model biases are found in some species, some of which are common to chemistry models and some that are specific to TOMCAT and warrant further investigation. The most notable of these biases are (1) a negative bias in Northern Hemisphere (NH) winter and spring CO and a positive bias in Southern Hemisphere (SH) CO throughout the year, (2) a positive bias in NH O3 in summer and a negative bias at high latitudes during SH winter and (3) a negative bias in NH winter C2 and C3 alkanes and alkenes. TOMCAT global mean tropospheric hydroxyl radical (OH) concentrations are higher than estimates inferred from observations of methyl chloroform but similar to, or lower than, multi-model mean concentrations reported in recent model intercomparison studies. TOMCAT shows peak OH concentrations in the tropical lower troposphere, unlike other models which show peak concentrations in the tropical upper troposphere. This is likely to affect the lifetime and transport of important trace gases and warrants further investigation.