Satellite-based evidence of wavelength-dependent aerosol absorption in biomass burning smoke inferred from Ozone Monitoring Instrument
Satellite-based evidence of wavelength-dependent aerosol absorption in biomass burning smoke inferred from Ozone Monitoring Instrument
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DOI：
10.5194/acp-11-10541-2011
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发表时间：
2011-01-01
影响因子：
6.3
通讯作者：
Torres, O.
中科院分区：
文献类型：
--
作者：
Jethva, H.;Torres, O.
我们提供了基于卫星的证据的光谱依赖性的吸收在生物质燃烧的气溶胶在南美洲使用近紫外线测量臭氧监测仪器（OMI）在2005-2007年。在目前的近紫外OMI气溶胶算法（OMAERUV），它隐含地假设，在碳质气溶胶中的唯一吸收成分是黑碳的折射率的虚部是波长无关的。在这种假设下，OMI导出的气溶胶光学厚度（AOD）被发现是显着高估相比，AERONET在几个站点在强烈的生物质燃烧事件（8月至9月）。影响近紫外气溶胶反演方法的其他众所周知的误差来源并不能解释卫星和地面观测之间观测到的气溶胶光学厚度差异。一些研究表明，在近紫外区域，含碳气溶胶吸收具有很强的光谱依赖性，这表明生物质燃烧产生的气溶胶中存在有机碳。这项工作进行了敏感性分析，审查在卫星遥感中考虑碳质颗粒中存在依赖波长的气溶胶吸收的重要性。结果令人信服地表明，包括光谱依赖的气溶胶吸收的辐射传输计算导致更准确的表征大气中的碳气溶胶的负载。使用一套新的气溶胶模型，假设在近紫外区域（吸收埃指数λ（-2.5）（至-3.0））的波长相关的气溶胶吸收，改善了OMAERUV的检索结果显着减少时，灰色气溶胶假设观测到的AOD偏差。此外，在不确定度范围内（Δ SSA =+/-0.03），新的单次散射反演结果与AERONET的结果吻合较好。新的彩色碳质气溶胶模型也被发现，以再现基于地面的AOD观测的生物质燃烧区域的非洲中部和印度北方。连同证明一个显着的改善，从OMI检索气溶胶特性，本研究强调了更大的灵敏度的近紫外测量的不同光谱的气溶胶吸收。这种能力可以进一步探索用于生物质燃烧气溶胶中的黑碳和有机物的识别。
We provide satellite-based evidence of the spectral dependence of absorption in biomass burning aerosols over South America using near-UV measurements made by the Ozone Monitoring Instrument (OMI) during 2005-2007. In the current near-UV OMI aerosol algorithm (OMAERUV), it is implicitly assumed that the only absorbing component in carbonaceous aerosols is black carbon whose imaginary component of the refractive index is wavelength independent. With this assumption, OMI-derived aerosol optical depth (AOD) is found to be significantly over-estimated compared to that of AERONET at several sites during intense biomass burning events (August-September). Other well-known sources of error affecting the near-UV method of aerosol retrieval do not explain the large observed AOD discrepancies between the satellite and the ground-based observations. A number of studies have revealed strong spectral dependence in carbonaceous aerosol absorption in the near-UV region suggesting the presence of organic carbon in biomass burning generated aerosols. A sensitivity analysis examining the importance of accounting for the presence of wavelength-dependent aerosol absorption in carbonaceous particles in satellite-based remote sensing was carried out in this work. The results convincingly show that the inclusion of spectrally-dependent aerosol absorption in the radiative transfer calculations leads to a more accurate characterization of the atmospheric load of carbonaceous aerosols. The use of a new set of aerosol models assuming wavelength-dependent aerosol absorption in the near-UV region (Absorption Angstrom Exponent lambda(-2.5) (to -3.0)) improved the OMAERUV retrieval results by significantly reducing the AOD bias observed when gray aerosols were assumed. In addition, the new retrieval of single-scattering albedo is in better agreement with those of AERONET within the uncertainties (Delta SSA =+/-0.03). The new colored carbonaceous aerosol model was also found to reproduce the ground-based AOD observations over the biomass burning region of central Africa and northern India. Together with demonstrating a significant improvement in the retrieval of aerosol properties from OMI, the present study highlights the greater sensitivity of the near-UV measurements to the varying spectral aerosol absorption. This capability can be explored further for the use in the identification of the black carbon and organics in the biomass burning aerosols.