A simulation study of the ensemble-based data assimilation of satellite-borne lidar aerosol observations
A simulation study of the ensemble-based data assimilation of satellite-borne lidar aerosol observations
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DOI：
10.5194/gmdd-5-1877-2012
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发表时间：
2012-07
期刊：
影响因子：
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通讯作者：
T. Sekiyama;T. Tanaka;T. Miyoshi
中科院分区：
文献类型：
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作者：
T. Sekiyama;T. Tanaka;T. Miyoshi
抽象的。通过观测系统模拟实验评估了一个基于四维集合的数据同化系统，其中通过模拟星载激光雷达气溶胶观测来模拟CALIPSO卫星。以东亚地区气溶胶光学厚度（AOT）分布为分析对象，采用基于对象的诊断评价方法（MODE）对该模式进行了为期3个月的验证。因此，该数据同化系统证明了与自由运行的模拟模型相比，能够更好地分析硫酸盐和尘埃气溶胶。例如，平均质心距离（来自真相）在三个月的收集期内的气溶胶羽流从2.15格提高（a 600 km）至1.45个网格（a 400 km），用于硫酸盐气溶胶，（a 750公里）至1.14个网格（a 330公里）用于尘埃气溶胶;的平均面积比在三个月的气溶胶羽流的收集期内，硫酸盐气溶胶从0.49提高到0.76，沙尘气溶胶从0.51提高到0.72。星载激光雷达数据同化成功地改善了气溶胶羽流分析和沙尘排放估计的OSSEs。这些结果提出了很大的可能性，激光雷达数据，其分布是垂直/时间密集，但水平稀疏，再加上一个四维数据同化系统的有益使用。此外，进行了敏感性试验，其结果表明，控制气溶胶变量的自由度可能是有限的，在数据同化，因为在系统中的气象场被约束到天气再分析使用牛顿松弛。气溶胶分析的进一步改进可以通过气溶胶观测与气象观测的同时同化来进行。的OSSE结果强烈表明，使用真实的CALIPSO数据将有一个有益的影响，获得更准确的硫酸盐和粉尘气溶胶分析。此外，使用相同的OSSE技术将使我们能够对将于2015年发射的下一代激光雷达卫星EarthCARE进行事先评估。
Abstract. A four-dimensional ensemble-based data assimilation system was assessed by observing system simulation experiments (OSSEs), in which the CALIPSO satellite was emulated via simulated satellite-borne lidar aerosol observations. Its performance over athree-month period was validated according to the Method for Object-based Diagnostic Evaluation (MODE), using aerosol optical thickness (AOT) distributions in East Asia as the objects of analysis. Consequently, this data assimilation system demonstrated the ability to produce better analyses of sulfate and dust aerosols in comparison to a free-running simulation model. For example, the mean centroid distance (from the truth) over a three-month collection period of aerosol plumes was improved from 2.15 grids (a 600 km) to 1.45 grids (a 400 km) for sulfate aerosols and from 2.59 grids (a 750 km) to 1.14 grids (a 330 km) for dust aerosols; the mean area ratio (to the truth) over a three-month collection period of aerosol plumes was improved from 0.49 to 0.76 for sulfate aerosols and from 0.51 to 0.72 for dust aerosols. The satellite-borne lidar data assimilation successfully improved the aerosol plume analysis and the dust emission estimation in the OSSEs. These results present great possibilities for the beneficial use of lidar data, whose distribution is vertically/temporally dense but horizontally sparse, when coupled with a four-dimensional data assimilation system. In addition, sensitivity tests were conducted, and their results indicated that the degree of freedom to control the aerosol variables was probably limited in the data assimilation because the meteorological field in the system was constrained to weather reanalysis using Newtonian relaxation. Further improvements to the aerosol analysis can be performed through the simultaneous assimilation of aerosol observations with meteorological observations. The OSSE results strongly suggest that the use of real CALIPSO data will have a beneficial effect on obtaining more accurate sulfate and dust aerosol analyses. Furthermore, the use of the same OSSE technique will allow us to perform a prior assessment of the next-generation lidar satellite EarthCARE, which will be launched in 2015.