Effect of remote sensing spatial resolution on interpreting tower-based flux observations
Effect of remote sensing spatial resolution on interpreting tower-based flux observations
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DOI：
10.1016/j.rse.2006.11.032
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发表时间：
2006-05
影响因子：
13.5
通讯作者：
Fuqin Li;W. Kustas;Martha C. Anderson;J. Prueger;R. Scott
中科院分区：
文献类型：
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作者：
Fuqin Li;W. Kustas;Martha C. Anderson;J. Prueger;R. Scott
基于卫星的表面能量平衡模型和异质景观上基于塔的通量测量之间的验证比较可能会受到遥感输入的空间分辨率的强烈影响。在本文中，开发了一个使用热和可见/近红外遥感数据的双源能量平衡模型，并将其应用于 2004 年在亚利桑那州南部进行的土壤湿度实验 (SMEX04) 期间收集的陆地卫星图像。使用二维通量足迹算法，将建模的表面通量与 SMEX04 研究区域三个地点的塔测量值进行比较：两个高地地点和一个河岸地点。评估了像素分辨率对评估地表模型性能和解释这些异质区域地表通量空间变化的影响。检查了三个陆地卫星场景，一个代表旱季，另外两个代表相对潮湿的季风季节。该模型在三个分辨率尺度下运行：即 Landsat 可见光/近红外波段分辨率 (30 m)、Landsat 5 热波段分辨率 (120 m) 和 960 m（名义上是近最低点处的 MODIS 热分辨率）。三个塔位点的模拟通量和测量通量之间的比较显示，在 30 m 和 120 m 分辨率（影响塔测量的源区域（∼100 m）的像素尺度）上具有良好的一致性。在 960 米处，一致性相对较差，特别是对于潜热通量而言，这是由于地表条件的亚像素异质性超过了塔占地面积。因此，在这种特定景观中，1 公里分辨率的热数据对于评估地表模型与塔通量相比的内在准确性没有用处。此外，在这种分辨率下，景观中重要的空间模式会丢失。目前，在 Landsat 5 和 ASTER 发生故障后，还没有明确的计划支持常规全球覆盖范围低于 700 m 的高分辨率热数据。对于基于热的地表模型在异质景观上的应用和验证来说，这将是一个严重的问题。
Validation comparisons between satellite-based surface energy balance models and tower-based flux measurements over heterogeneous landscapes can be strongly influenced by the spatial resolution of the remote sensing inputs. In this paper, a two-source energy balance model developed to use thermal and visible /near-infrared remotely sensed data is applied to Landsat imagery collected during the 2004 Soil Moisture Experiment (SMEX04) conducted in southern Arizona. Using a two dimensional flux-footprint algorithm, modeled surface fluxes are compared to tower measurements at three locations in the SMEX04 study area: two upland sites, and one riparian site. The effect of pixel resolution on evaluating the performance of the land surface model and interpreting spatial variations of land surface fluxes over these heterogeneous areas is evaluated. Three Landsat scenes were examined, one representing the dry season and the other two representing the relatively wet monsoon season. The model was run at three resolution scales: namely the Landsat visible/near-infrared band resolution (30 m), the Landsat 5 thermal band resolution (120 m), and 960 m, which is nominally the MODIS thermal resolution at near-nadir. Comparisons between modeled and measured fluxes at the three tower sites showed good agreement at the 30 m and 120 m resolutions — pixel scales at which the source area influencing the tower measurement (∼100 m) is reasonably resolved. At 960 m, the agreement is relatively poor, especially for the latent heat flux, due to sub-pixel heterogeneity in land surface conditions at scales exceeding the tower footprint. Therefore in this particular landscape, thermal data at 1-km resolution are not useful in assessing the intrinsic accuracy of the land-surface model in comparison with tower fluxes. Furthermore, important spatial patterns in the landscape are lost at this resolution. Currently, there are no definite plans supporting high resolution thermal data with regular global coverage below ∼700 m after Landsat 5 and ASTER fail. This will be a serious problem for the application and validation of thermal-based land-surface models over heterogeneous landscapes.