Simulations of column-averaged CO2 and CH4 using the NIES TM with a hybrid sigma-isentropic (σ-θ) vertical coordinate
Simulations of column-averaged CO2 and CH4 using the NIES TM with a hybrid sigma-isentropic (σ-θ) vertical coordinate
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DOI：
10.5194/acp-13-1713-2013
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发表时间：
2013-01-01
影响因子：
6.3
通讯作者：
Wunch, D.
中科院分区：
文献类型：
--
作者：
Belikov, D. A.;Maksyutov, S.;Wunch, D.
我们已经开发了一个改进版本的国家环境研究所（NIES）的三维化学传输模型（TM）设计的准确的示踪剂传输模拟在平流层中，使用混合σ-等熵（σ-θ）垂直坐标，采用地形跟踪和等熵部分切换顺利对流层顶周围。空气上升速率来自有效加热速率，用于模拟网格等熵部分（350 K以上）的垂直运动，并对其进行了调整，以适应平流层空气的观测年龄。使用NIES TM进行了多年模拟，以评估垂直剖面和干空气柱平均摩尔分数的CO2和CH 4。与2000-2007年在三陆（日本）的气球观测结果的比较表明，在对流层上部和平流层下部的示踪剂输送模拟的精度类似于5%的CH 4和SF6，和类似于1%的CO2相比，所观察到的体积混合比。利用地面高分辨率傅里叶变换光谱仪（FTS）在全球碳柱观测网络（TCCON）12个站点的观测数据，对模拟的大气中二氧化碳（XCO 2）和甲烷（XCH 4）的柱平均干空气摩尔分数进行了评估。（比亚韦斯托克、不莱梅、达尔文、加米施、伊扎纳、拉蒙、兰黛、奥尔良、公园福尔斯、索丹基拉、筑波和卧龙岗）。比较结果表明，该模型能够再现TCCON观测到的场地相关季节性周期，XCO 2和XCH 4的相关系数通常分别为0.8-0.9和0.4-0.8，平均模型偏差为+/- 0.2%和+/-0.5%，不包括索丹基拉，该模型捕获示踪剂总柱摩尔分数的能力是强烈依赖于该模型的能力，以重现在行星边界层（PBL）中的示踪剂浓度的季节性变化。我们发现一个显着的差异，该模型的能力，再现近地表浓度在位于一些距离多个排放源和高排放量发挥显着的作用，示踪剂的预算。与苏尔古特（西西伯利亚）湿地甲烷排放量高的地区的飞机观测结果进行比较，显示出PBL和自由对流层中模型性能的对比。因此，PBL是模拟示踪剂总柱摩尔分数的另一个关键区域。
We have developed an improved version of the National Institute for Environmental Studies (NIES) three-dimensional chemical transport model (TM) designed for accurate tracer transport simulations in the stratosphere, using a hybrid sigma-isentropic (sigma-theta) vertical coordinate that employs both terrain-following and isentropic parts switched smoothly around the tropopause. The air-ascending rate was derived from the effective heating rate and was used to simulate vertical motion in the isentropic part of the grid (above level 350 K), which was adjusted to fit to the observed age of the air in the stratosphere. Multi-annual simulations were conducted using the NIES TM to evaluate vertical profiles and dry-air column-averaged mole fractions of CO2 and CH4. Comparisons with balloon-borne observations over Sanriku (Japan) in 2000-2007 revealed that the tracer transport simulations in the upper troposphere and lower stratosphere are performed with accuracies of similar to 5% for CH4 and SF6, and similar to 1% for CO2 compared with the observed volume-mixing ratios. The simulated column-averaged dry air mole fractions of atmospheric carbon dioxide (XCO2) and methane (XCH4) were evaluated against daily ground-based high-resolution Fourier Transform Spectrometer (FTS) observations measured at twelve sites of the Total Carbon Column Observing Network (TCCON) (Bialystok, Bremen, Darwin, Garmisch, Izana, Lamont, Lauder, Orleans, Park Falls, Sodankyla, Tsukuba, and Wollongong) between January 2009 and January 2011. The comparison shows the model's ability to reproduce the site-dependent seasonal cycles as observed by TCCON, with correlation coefficients typically on the order 0.8-0.9 and 0.4-0.8 for XCO2 and XCH4, respectively, and mean model biases of +/- 0.2% and +/- 0.5%, excluding Sodankyla, where strong biases are found. The ability of the model to capture the tracer total column mole fractions is strongly dependent on the model's ability to reproduce seasonal variations in tracer concentrations in the planetary boundary layer (PBL). We found a marked difference in the model's ability to reproduce near-surface concentrations at sites located some distance from multiple emission sources and where high emissions play a notable role in the tracer's budget. Comparisons with aircraft observations over Surgut (West Siberia), in an area with high emissions of methane from wetlands, show contrasting model performance in the PBL and in the free troposphere. Thus, the PBL is another critical region for simulating the tracer total column mole fractions.