Vertical distribution and radiative effects of mineral dust and biomass burning aerosol over West Africa during DABEX
Vertical distribution and radiative effects of mineral dust and biomass burning aerosol over West Africa during DABEX
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DOI：
10.1029/2008jd009848
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发表时间：
2008-12
影响因子：
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通讯作者：
B. Johnson;B. Heese;S. McFarlane;P. Chazette;A. Jones;N. Bellouin
中科院分区：
文献类型：
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作者：
B. Johnson;B. Heese;S. McFarlane;P. Chazette;A. Jones;N. Bellouin
[1] 本文介绍了在沙尘和生物质燃烧气溶胶实验（DABEX）/非洲季风多学科分析旱季特别观测期零（AMMA - SOP0）期间西非气溶胶消光系数垂直分布的测量结果。英国FAAM飞机的原位飞行测量结果已与两部地基激光雷达（POLIS和ARM MPL）以及一架超轻型飞机上的机载激光雷达进行了比较。一般来说，在低海拔（最高达2千米）观测到矿物沙尘，在2 - 5千米海拔观测到生物质燃烧气溶胶和沙尘的混合物。该研究揭示了在对飞机和地面测量结果进行相互比较时与空间和时间变异性相关的困难。对许多廓线取平均值为评估与原位采样仪器以及激光雷达比反演相关的一致性误差和偏差提供了一种更好的方法。短波辐射传输计算以及使用HadGEM2 - A气候模型进行的3年模拟表明，生物质燃烧气溶胶的辐射效应在一定程度上对气溶胶的垂直分布敏感。特别是，当模型中包含观测到的低空沙尘层时，生物质燃烧气溶胶对太阳辐射的吸收增加了10%。我们得出结论，这种吸收增强是由沙尘将太阳辐射反射到生物质燃烧气溶胶层中导致的。这一结果说明，人为吸收性气溶胶的辐射强迫可能对自然气溶胶种类的存在敏感。
[1] This paper presents measurements of the vertical distribution of aerosol extinction coefficient over West Africa during the Dust and Biomass-burning Aerosol Experiment (DABEX)/African Monsoon Multidisciplinary Analysis dry season Special Observing Period Zero (AMMA-SOP0). In situ aircraft measurements from the UK FAAM aircraft have been compared with two ground-based lidars (POLIS and ARM MPL) and an airborne lidar on an ultralight aircraft. In general, mineral dust was observed at low altitudes (up to 2 km), and a mixture of biomass burning aerosol and dust was observed at altitudes of 2–5 km. The study exposes difficulties associated with spatial and temporal variability when intercomparing aircraft and ground measurements. Averaging over many profiles provided a better means of assessing consistent errors and biases associated with in situ sampling instruments and retrievals of lidar ratios. Shortwave radiative transfer calculations and a 3-year simulation with the HadGEM2-A climate model show that the radiative effect of biomass burning aerosol was somewhat sensitive to the vertical distribution of aerosol. In particular, when the observed low-level dust layer was included in the model, the absorption of solar radiation by the biomass burning aerosols increased by 10%. We conclude that this absorption enhancement was caused by the dust reflecting solar radiation up into the biomass burning aerosol layer. This result illustrates that the radiative forcing of anthropogenic absorbing aerosol can be sensitive to the presence of natural aerosol species.