水体叶绿素a含量的遥感反演是监测水体光学特性、评价水体污染的一个重要指标。本文以FY-3A/MERSI和AQUA/MODIS遥感影像为数据源,结合水体实测的叶绿素a含量,利用两类反射率模型,研究星载数据遥感反演叶绿素a的可行性。研究表明:基于FY-3A/MERSI和AQUA/MODIS可见光-近红外通道的光谱反演模型(Rλ1-1-Rλ2-1)×Rλ3和Rλ1-1×Rλ3在太湖水体叶绿素a含量反演方面取得了较高的精度。基于MERISI通道的模型反演相关系数R2分别在0.60和0.72左右,基于MODIS通道的模型反演相关系数R2分别在0.55和0.65左右。通过比较分析,决定叶绿素a含量反演精度的主要因素包括两个方面,一是通道位置,即蓝波段和近红外波段是叶绿素a反演的敏感波段;其次,卫星空间分辨率,即较高的空间地面分辨率改善了混合像元。因此,MERSI比MODIS对应模型获得了较高的叶绿素a反演精度。这一结果将有助于FY-3A/MERSI遥感数据在环境监测和水体污染领域的进一步研究,为国产卫星的应用提供一定的参考。
韩秀珍, 郑伟, 刘诚, 安思颖
. 基于MERSI和MODIS的太湖水体叶绿素a含量反演[J]. 地理研究, 2011
, 30(2)
: 291
-300
.
DOI: 10.11821/yj2011020009
The Chlorophyll-a (Chl-a) concentrations in water are of great importance to the monitoring of water quality and ecosystem balance. Remote sensing offers a convenient and systematical tool for the observations of water at a long time scale. In this paper, we present a study of Chl-a estimation using the reflectance models (MOD3: Rλ1-1-Rλ2-1)×Rλ3and MOD2:Rλ1-1×Rλ3) derived from the Medium Resolution Spectral Image (MERSI) onboard the newly launched FY-3A satellite and the Moderate Imaging Spectroradiometer (MODIS) onboard the AQUA platforms. Validation studies demonstrated that both models provided reliable estimates of Chl-a concentrations with determination coefficients R2 of 0.72~0.79 (MOD2) and 0.52~0.76 (MOD3) for MERSI standard band settings. This accuracy is slightly better than that of the MODIS results with R2 of 0.65~0.69 and 0.43~0.70 for MOD2 and MOD3, respectively. Comparison analysis between models and sensors indicated that the blue and near infrared wave ranges are of potential for Chl-a estimation. Besides, the higher spatial resolution of MERSI (250m) may explain the better performance for both models compared to that of MODIS. This research will be helpful for the development of future Chl-a estimation models using the satellite observations.
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