Long-term distribution patterns of remotely sensed water quality parameters in Chesapeake Bay
Long-term distribution patterns of remotely sensed water quality parameters in Chesapeake Bay
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DOI：
10.1016/j.ecss.2013.05.004
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发表时间：
2013-08
影响因子：
2.8
通讯作者：
C. Le;Chuanmin Hu;Jennifer P. Cannizzaro;H. Duan
中科院分区：
文献类型：
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作者：
C. Le;Chuanmin Hu;Jennifer P. Cannizzaro;H. Duan
切萨皮克湾是美国最大的河口之一，需要对其水质进行长期监测和评估，以了解趋势和事件，从而支持管理决策。在过去十年中，通过卫星对海洋、沿海和河口沃茨的海洋颜色测量，在开发用于估算两个关键水质参数的遥感算法方面取得了重大进展，这两个参数是叶绿素a浓度（Chla，mg m−3）和490 nm处的漫射光衰减系数（Kd（490），m−1）。然而，推导出一个强大的Chla数据产品的切萨皮克湾仍然是一个挑战，因为它的复杂的光学特性。本文采用一种新的算法（基于红绿遥感反射率（Rrs（λ））比值的红绿叶绿素指数（RGCI）），对海洋观测宽视场传感器（SeaWiFS）和中分辨率成像光谱仪（MODIS）数据进行了验证，并建立了14年（1997年9月至2011年12月）的叶绿素环境数据记录（EDR）。新方法显示出比传统蓝绿Rrs（λ）频带比算法（例如，OC4，OC3M），与MODIS（平均相对误差= 40.9%，平均比值= 1.09）和SeaWiFS（MRE = 45.8%，平均比值= 1.09）的性能一致，Chla的范围在1至50 mg m−3之间。异常和ESTA分析显示，强烈的空间梯度，季节性和气候驱动的年际变化，基于卫星的叶绿素EDR。这些变化与基于卫星的Kd（490）EDR高度相关，导致水质决策矩阵（WQDM）的发展，并为该河口正在进行的营养盐减少管理计划提供支持。
Chesapeake Bay is the largest and one of the most productive estuaries in the U.S., where long-term monitoring and assessment of its water quality are necessary to understand trends and events in order to support management decisions. Significant progress has been made during the past decade in developing remote sensing algorithms for estimating two key water quality parameters, chlorophyll-a concentration (Chla, mg m−3) and diffuse light attenuation coefficient at 490 nm (Kd(490), m−1), from satellite ocean color measurements in oceanic, coastal, and estuarine waters. Yet deriving a robust Chla data product for Chesapeake Bay still remains a challenge because of its complex optical properties. Here, a recently developed algorithm approach (Red–Green Chlorophyll Index or RGCI, based on red–green remote-sensing reflectance (Rrs (λ)) ratios) was tested, validated, and applied to Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS) data to establish a 14-year (September 1997 to December 2011) Chla Environmental Data Record (EDR). The new approach showed significant improvement over the traditional blue–green Rrs (λ) band-ratio algorithms (e.g., OC4, OC3M), with consistent performance for MODIS (mean relative error = 40.9%, mean ratio = 1.09) and SeaWiFS (MRE = 45.8%, mean ratio = 1.09) for Chla ranging between 1 and 50 mg m−3. Anomaly and EOF analyses revealed strong spatial gradients, seasonality, and climate-driven inter-annual changes in the satellite-based Chla EDR. These changes were highly correlated with satellite-based Kd(490) EDR, leading to the development of a Water Quality Decision Matrix (WQDM) and providing support to on-going nutrient reduction management programs for this estuary.