Bridging between SeaWiFS and MODIS for continuity of chlorophyll-a concentration assessments off Southeastern China
Bridging between SeaWiFS and MODIS for continuity of chlorophyll-a concentration assessments off Southeastern China
复制标题
DOI：
10.1016/j.rse.2006.02.015
复制
发表时间：
2006-06
影响因子：
13.5
通讯作者：
Caiyun Zhang;Chuanmin Hu;S. Shang;F. Muller‐Karger;Yan Li;M. Dai;Bangqin Huang;X. Ning;H. Hong
中科院分区：
文献类型：
--
作者：
Caiyun Zhang;Chuanmin Hu;S. Shang;F. Muller‐Karger;Yan Li;M. Dai;Bangqin Huang;X. Ning;H. Hong
台湾海峡 (TWS) 和南海 (SCS) 的叶绿素 a (Chl) 浓度是利用 MODIS/Aqua 和 SeaWiFS 仪器收集的卫星数据时间序列进行估算的，并通过 2004 年冬季和夏季进行的 3 次巡航的现场测量进行了验证。对于 0.1 至 10mg m−3 之间的 Chl，SeaWiFS 和 MODIS 与现场数据非常吻合。浑浊的沿海水域的误差大于近海水域，但对数尺度的总体 RMS（均方根）误差在 0.35 以内。对于公海和大多数浅海 (<30 m) 沿海地区，百分比 RMS 误差要大得多，在 60% 到 170% 之间变化。然而，这两个卫星数据集都不存在大的系统误差或显着偏差，并且这些数字与其他全球海洋的数据相当，并且没有明显大于算法“噪声”（对数尺度的 RMS 误差为 0.22）。此外，SeaWiFS 和 MODIS 显示 2002 年 7 月至 2004 年 10 月之间相似的空间和时间模式，以及在 0.1 至 4mg m−3 之间的叶绿素浓度几乎相同。几个分区月平均叶绿素的两个数据集之间的RMS差值一般<11%和<0.05（对数变换后）。对于每个单独的月份，整个研究区域（分辨率为 6-9×105 卫星像素）的两个数据集的统计数据（均值、众数、中位数）非常相似，RMS 差异通常在 30% 到 40% 之间以及 0.10 到 0.15 之间（对数变换后），没有发现显着偏差。因此，在最终没有 SeaWiFS 的情况下，可以仅使用 MODIS 等一个传感器来继续时间序列。需要进一步研究改进遥感算法在浑浊沿海水域的应用。
Chlorophyll-a (Chl) concentration in the Taiwan Strait (TWS) and in the South China Sea (SCS) was estimated using time series of satellite data collected with the MODIS/Aqua and SeaWiFS instruments, and validated with in situ measurements from three cruises conducted in winter and summer 2004. For Chl between 0.1 and 10mg m−3, both SeaWiFS and MODIS agreed well with in situ data. Errors for turbid coastal waters were larger than for offshore waters but the overall RMS (root mean square) error in log scale was within 0.35. The percentage RMS error was much larger, varying between 60% and 170% for open ocean and most of the shallow (<30 m), coastal regions. However, there was no large systematic error or significant bias in either satellite data set, and these numbers were comparable to those for other global oceans and not significantly larger than the algorithm “noise” (0.22 in RMS error in log scale). Further, SeaWiFS and MODIS showed similar spatial and temporal patterns between July 2002 and October 2004, as well as nearly identical concentrations for Chl between 0.1 and 4mg m−3. RMS difference between the two data sets of monthly mean Chl for several sub-regions was generally <11% and <0.05 (after logarithmic transformation). For each individual month, the statistics (mean, mode, median) of the two data sets for the entire study region (6–9×105satellite pixels at ∼1km resolution) were very similar, with RMS differences typically between 30% and 40% and between 0.10 and 0.15 (after logarithmic transformation), where no significant bias was found. Therefore, it would be possible to continue the time series using only one sensor such as MODIS, in the eventual absence of SeaWiFS. Further research is needed to improve the remote sensing algorithms for application in turbid coastal waters.