Thermal infrared dust optical depth and coarse-mode effective diameter over oceans retrieved from collocated MODIS and CALIOP observations
Thermal infrared dust optical depth and coarse-mode effective diameter over oceans retrieved from collocated MODIS and CALIOP observations
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DOI：
10.5194/acp-23-8271-2023
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发表时间：
2023-07
影响因子：
6.3
通讯作者：
Jianyu Zheng;Zhibo Zhang;Hongbin Yu;A. Garnier;Qianqian Song;Chenxi Wang;Claudia Di Biagio;J. Kok;Y. Derimian;C. Ryder
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文献类型：
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作者：
Jianyu Zheng;Zhibo Zhang;Hongbin Yu;A. Garnier;Qianqian Song;Chenxi Wang;Claudia Di Biagio;J. Kok;Y. Derimian;C. Ryder
抽象。在这项研究中，我们开发了一种新的算法的基础上并置的中分辨率成像光谱仪（MODIS）的热红外（TIR）观测和灰尘垂直廓线的云-气溶胶激光雷达与正交偏振（CALIOP），同时反演灰尘气溶胶光学厚度在10 µm（DAOD 10 µm）和粗模灰尘有效直径（Deff）在全球海洋。通过比较灰尘对数正态体积粒径分布（PSD）检索Deff与现场测量的灰尘PSD从气溶胶特性-灰尘（AER-D），撒哈拉矿物粉尘实验（SAMUM-2），撒哈拉气溶胶远程传输和气溶胶-云相互作用实验（SALTRACE）现场活动通过案例研究的准确性进行评估。首先通过与从我们先前研究的组合成像红外辐射仪（IIR）和CALIOP观测中检索到的并置DAOD 10.6 µm进行比较，对新的DAOD 10 µm检索进行评估（Zheng et al.，2022年）。两个DAOD反演的像素到像素的比较表明，一个很好的协议（R <0.7）和显着减少（<50%）的检索不确定性，主要是由于更好的约束尘埃大小。在气候学比较中，基于我们的组合MODIS和CALIOP方法的季节和区域（2 μ m ×5 μ m）平均DAOD 10 µm反演与三个沙尘传输区域（即，北大西洋（NA; R=0.9）、印度洋（IO; R=0.8）和北太平洋（NP; R=0.7））。使用2013年至2017年的新检索，我们对全球海洋上的粗模式尘埃Deff进行了气候学分析。我们发现IO和NP上的粉尘Deff比NA上的粉尘Deff小20%。在夏季NA期间，我们发现从15到35 W，Deff>5 µm的检索数量减少了50%，并且在整个加勒比海（90 W），从35 W到4.4 µm的Deff平均值呈稳定趋势。在春季的NP上，从150到180 ° E，只有0.5%的Deff>5 µm的检索像素被发现，而在整个NP东部，平均Deff保持稳定在4.0 µm。据我们所知，这项研究是第一个检索DAOD和粗模式尘埃粒子大小在全球海洋多年。该反演数据集为评估模式中尘埃长波辐射效应和粗模尘埃粒子尺寸提供了有见地的信息。
Abstract. In this study, we developed a novel algorithm based on the collocated Moderate Resolution Imaging Spectroradiometer (MODIS) thermal infrared (TIR) observations and dust vertical profiles from the Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) to simultaneously retrieve dust aerosol optical depth at 10 µm (DAOD10 µm) and the coarse-mode dust effective diameter (Deff) over global oceans. The accuracy of the Deff retrieval is assessed by comparing the dust lognormal volume particle size distribution (PSD) corresponding to retrieved Deff with the in situ-measured dust PSDs from the AERosol Properties – Dust (AER-D), Saharan Mineral Dust Experiment (SAMUM-2), and Saharan Aerosol Long-Range Transport and Aerosol–Cloud-Interaction Experiment (SALTRACE) field campaigns through case studies. The new DAOD10 µm retrievals were evaluated first through comparisons with the collocated DAOD10.6 µm retrieved from the combined Imaging Infrared Radiometer (IIR) and CALIOP observations from our previous study (Zheng et al., 2022). The pixel-to-pixel comparison of the two DAOD retrievals indicates a good agreement (R∼0.7) and a significant reduction in (∼50 %) retrieval uncertainties largely thanks to the better constraint on dust size. In a climatological comparison, the seasonal and regional (2∘×5∘) mean DAOD10 µm retrievals based on our combined MODIS and CALIOP method are in good agreement with the two independent Infrared Atmospheric Sounding Interferometer (IASI) products over three dust transport regions (i.e., North Atlantic (NA; R=0.9), Indian Ocean (IO; R=0.8) and North Pacific (NP; R=0.7)). Using the new retrievals from 2013 to 2017, we performed a climatological analysis of coarse-mode dust Deff over global oceans. We found that dust Deff over IO and NP is up to 20 % smaller than that over NA. Over NA in summer, we found a ∼50 % reduction in the number of retrievals with Deff>5 µm from 15 to 35∘ W and a stable trend of Deff average at 4.4 µm from 35∘ W throughout the Caribbean Sea (90∘ W). Over NP in spring, only ∼5 % of retrieved pixels with Deff>5 µm are found from 150 to 180∘ E, while the mean Deff remains stable at 4.0 µm throughout eastern NP. To the best of our knowledge, this study is the first to retrieve both DAOD and coarse-mode dust particle size over global oceans for multiple years. This retrieval dataset provides insightful information for evaluating dust longwave radiative effects and coarse-mode dust particle size in models.