A practical method for angular normalization of global MODIS land surface temperature over vegetated surfaces
A practical method for angular normalization of global MODIS land surface temperature over vegetated surfaces
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DOI：
10.1016/j.isprsjprs.2023.04.015
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发表时间：
2023-05
影响因子：
12.7
通讯作者：
Junrui Wang;R. Tang;Yazhen Jiang;Meng Liu;Zhao‐Liang Li
中科院分区：
文献类型：
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作者：
Junrui Wang;R. Tang;Yazhen Jiang;Meng Liu;Zhao‐Liang Li
陆面温度是地表能量平衡中的重要物理量，是区域和全球尺度上陆-气之间热量和水分交换的良好指标。然而，大波段极轨卫星和地球同步卫星遥感的热红外地表温度通常具有角度各向异性，这给地表温度产品在蒸散量估算、城市热环境监测、气候变化研究等领域的应用带来了很大的不确定性。在这项研究中，首次开发了一种实用的角度归一化方法，用于使用MODIS将全球MODIS离底LST校正为植被表面上的最低点2000年至2020年（Terra + Aqua）产品，来自AmeriFlux，FLUXNET和国家青藏高原/第三极环境数据中心（TPDC）的全球213个站点的同步和同位观测，ERA 5-土地再分析数据集。结果表明，角度归一化方法能较好地校正MODIS LST产品的角度各向异性。对213个站点的数据集进行验证，角度归一化模型显示均方根误差（RMSE）为1.57 K，平均偏差误差（MBE）为0 K，决定系数（R2）为0.99。在2020年典型的四天内，通过校正全球MODIS/Terra偏离最低点LST产品与Sentinel-3A最低点LST产品来交叉验证最低点LST（2月26日，6月1日，8月12日和11月16日），角归一化模型给出的RMSE为2.26 K，MBE为-1.20 K，相比之下，当将MODIS离底LST与Sentinel-3A最低LST进行比较时，RMSE为3.01 K，MBE为-2.15 K。全球MODIS/Terra LST的角度各向异性在植被表面的四天的兴趣范围在-1.79到-1.30 K（1%分位数）和3.64到4.37 K（99%分位数）之间，中位数为0.33到0.74 K，平均值为0.46到0.89 K。所建立的角度归一化模型能够对全球范围内的MODIS/Terra和MODIS/Aqua LST产品进行高精度的时间序列业务校正，为进一步应用角度一致性的MODIS LST产品提供基准。
Land surface temperature (LST) is an essential physical quantity in surface energy balance and a good indicator of exchange of heat and water between the land and atmosphere at regional and global scales. However, the thermal-infrared remotely sensed LST from large swath-width polar-orbiting and geostationary satellite sensors is usually subject to the angular anisotropy, bringing great uncertainties in the application of LST products in many fields such as evapotranspiration estimation, urban thermal environment monitoring, and climate change study. In this study, a practical angular normalization method was developed for the first time for correcting global MODIS off-nadir LST to nadir over vegetated surfaces, using MODIS (Terra + Aqua) products from 2000 to 2020, simultaneous and collocated observations at 213 sites worldwide from the AmeriFlux, FLUXNET, and National Tibetan Plateau/Third Pole Environment Data Center (TPDC), and ERA5-Land reanalysis datasets. Results showed that the angular normalization method could well correct the angular anisotropy of MODIS LST products. Validated against datasets at 213 sites, the angular normalization model showed root mean square errors (RMSE) of 1.57 K, mean bias errors (MBE) of 0 K, and coefficient of determination (R2) of 0.99. In the cross-validation of nadir LST by correcting global MODIS/Terra off-nadir LST products against Sentinel-3A nadir LST products over four typical days in 2020 (February 26, June 1, August 12 and November 16), the angular normalization model presented the RMSE of 2.26 K and the MBE of −1.20 K, in contrast to the RMSE of 3.01 K and the MBE of −2.15 K when MODIS off-nadir LST was compared to the Sentinel-3A nadir LST. The angular anisotropy of global MODIS/Terra LST over vegetated surfaces for the four days of interest ranged between −1.79 to −1.30 K (1% quantile) and 3.64 to 4.37 K (99% quantile), with a median of 0.33 to 0.74 K, and a mean of 0.46 to 0.89 K. The developed angular normalization model is a promising approach to operationally correcting all time-series of global MODIS/Terra and MODIS/Aqua LST products with high accuracies, which is significant to provide a benchmark of angle-consistent MODIS LST product for its further application.