Can MODIS Land Reflectance Products be Used for Estuarine and Inland Waters?
Can MODIS Land Reflectance Products be Used for Estuarine and Inland Waters?
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DOI：
10.1029/2017wr021607
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发表时间：
2018-05-01
影响因子：
5.4
通讯作者：
Li, Junsheng
中科院分区：
文献类型：
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作者：
Feng, Lian;Hu, Chuanmin;Li, Junsheng
虽然是为陆地表面设计的，但MODIS Aqua表面反射率数据产品（MYD 09，在这项工作中称为R_Land）也用于水的应用。然而，迄今为止，它们在这些应用中的不确定性和普遍适用性很少有文献记载。在这项研究中，两个地区的R_Land产品根据原位测量结果和MODIS海洋小组使用专门为水应用设计的大气校正方案（即基于近红外（NIR）波段的默认大气校正方法）得出的反射率产品，对2002年7月至2015年12月期间（切萨皮克湾和太湖）的大气进行了评估（表示为R_NIR，可从NASA获得的数据产品）和基于短波红外（SWIR）波段的替代大气校正方法（表示为R_SWIR，不可从NASA获得但需要用户定制处理的数据产品）。结果表明，R_Land（645）和R_Land（645/555）在切萨皮克湾和太湖的日空间分布，季节性和长期趋势方面具有较高的精度。灵敏度测试还显示，当数据在空间上按7 x 7像素和时间上按32天合并时，R_Land（645/555）中的数据质量有所改善。当数据仅被及时分箱以最小化R_Land每日图像中的斑块噪声时，还可以针对R_Land（645）获得改进的数据质量。考虑到大多数用户没有能力处理低水平数据以获得R_SWIR，并且标准NASA R_NIR产品通常缺乏对内陆沃茨的覆盖，因为它们针对全球海洋而不是内陆沃茨进行了优化，本研究为在没有定制R_NIR或R_的情况下广泛使用的R_Land产品在内陆和河口水应用中的适用性提供了通用指南适用于本地区域的短波红外数据产品。
Although designed for land surfaces, MODIS Aqua surface reflectance data products (MYD09, termed as R_Land in this work) have also been used for water applications. Yet to date their uncertainties and general suitability in such applications have rarely been documented. In this study, R_Land products of two regions (Chesapeake Bay and Taihu Lake) between July 2002 and December 2015 are evaluated against in situ measurements and against reflectance products derived by the MODIS Ocean Team using atmospheric correction schemes specifically designed for water applications, namely the default atmospheric correction method based on the near-infrared (NIR) bands (denoted as R_NIR, data products available from NASA) and alternative atmospheric correction method based on the shortwave-infrared (SWIR) bands (denoted as R_SWIR, data products not available from NASA but require customized processing by the user), respectively. Results suggest high accuracy in R_Land(645) and R_Land(645/555) for both Chesapeake Bay and Taihu Lake in terms of daily spatial distributions, seasonality, and long-term trends. A sensitivity test also shows improved data quality in R_Land(645/555) when data are binned by 7 x 7 pixels in space and 32 days in time. Improved data quality can also be obtained for R_Land(645) when data are only binned in time to minimize the patchiness noise in R_Land daily images. Given the fact that most users do not have the capacity to process low-level data to obtain R_SWIR and the standard NASA R_NIR products often lack coverage over inland waters because they are optimized for global oceans instead of inland waters, this study provides a general guide on the applicability of the widely available R_Land products in inland and estuarine water applications in the absence of customized R_NIR or R_SWIR data products for local regions.