Global and regional trends of aerosol optical depth over land and ocean using SeaWiFS measurements from 1997 to 2010
Global and regional trends of aerosol optical depth over land and ocean using SeaWiFS measurements from 1997 to 2010
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DOI：
10.5194/acp-12-8037-2012
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发表时间：
2012-01-01
影响因子：
6.3
通讯作者：
Holben, B. N.
中科院分区：
文献类型：
--
作者：
Hsu, N. C.;Gautam, R.;Holben, B. N.
传感器标定和卫星反演算法在从卫星数据准确确定长期趋势的能力中起着重要作用。由于其辐射校准具有前所未有的准确性和长期稳定性，SeaWiFS测量在传感器校准方面表现出最小的不确定性。在这项研究中，我们利用这一良好的校准设置的测量应用新开发的气溶胶光学厚度（AOD）反演算法在陆地和海洋调查AOD的分布，并确定新兴的模式和趋势，在全球和区域气溶胶加载在其13年的使命。我们的气候指标（如ENSO）和AOD之间的相关性分析表明，撒哈拉沙漠的灰尘出口以及热带地区的生物质燃烧活动，与大规模的反馈有很强的关系。结果还表明，1998 - 2010年全球海洋平均气溶胶光学厚度呈弱正趋势，与MODIS观测结果相当，但与AVHRR观测结果在重叠年份符号相反。在区域尺度上，不同的地区与自然和人为气溶胶排放和运输的不同趋势。例如，在阿拉伯半岛发现了大的上升趋势，这表明在整个区域以及在顺风海洋区域，灰尘排放和输送过程的季节性周期加强。相比之下，在沙漠/干旱的撒哈拉地区以及在北大西洋上空的相关尘埃外流中观察到负中性趋势。此外，我们发现美国东部和欧洲的趋势下降，而中国和印度等经济快速发展的国家的趋势上升。总的来说，这些结果与地面AERONET测量的结果是一致的。
Both sensor calibration and satellite retrieval algorithm play an important role in the ability to determine accurately long-term trends from satellite data. Owing to the unprecedented accuracy and long-term stability of its radiometric calibration, SeaWiFS measurements exhibit minimal uncertainty with respect to sensor calibration. In this study, we take advantage of this well-calibrated set of measurements by applying a newly-developed aerosol optical depth (AOD) retrieval algorithm over land and ocean to investigate the distribution of AOD, and to identify emerging patterns and trends in global and regional aerosol loading during its 13-yr mission. Our correlation analysis between climatic indices (such as ENSO) and AOD suggests strong relationships for Saharan dust export as well as biomass-burning activity in the tropics, associated with large-scale feedbacks. The results also indicate that the averaged AOD trend over global ocean is weakly positive from 1998 to 2010 and comparable to that observed by MODIS but opposite in sign to that observed by AVHRR during overlapping years. On regional scales, distinct tendencies are found for different regions associated with natural and anthropogenic aerosol emission and transport. For example, large upward trends are found over the Arabian Peninsula that indicate a strengthening of the seasonal cycle of dust emission and transport processes over the whole region as well as over downwind oceanic regions. In contrast, a negative-neutral tendency is observed over the desert/arid Saharan region as well as in the associated dust outflow over the north Atlantic. Additionally, we found de-creasing trends over the eastern US and Europe, and increasing trends over countries such as China and India that are experiencing rapid economic development. In general, these results are consistent with those derived from ground-based AERONET measurements.