赤潮水体水质遥感参数时空变化分析

Temporal Variation Analysis on Remote Sensing Parameters of Water Quality in Red Tide Water

以福建厦门附近海域2011年7月发生的一次赤潮为例,利用赤潮发生前后多时相的MODIS数据,分析叶绿素a浓度(Chl-a)、海水表面温度(SST)及波段光谱信息(Rrs比值、nLw比值)等水体特征参数在赤潮发生前后的时空变化规律。通过基于时间序列的异常图与历史资料对比后发现:赤潮水体Chl-a、SST、Rrs比值、nLw比值大于非赤潮水体,赤潮水体在赤潮发生时变化明显,有明显拐点。Chl-a赤潮发生前基本没有变化,赤潮发生时急剧升高,赤潮退去后平稳下降;SST变化平稳;Rrs比值、nLw比值在赤潮严重时有极大值。赤潮发生前后水质参数的时间变化特征可为赤潮监测预报提供参考。

By using temporal MODIS data before and after the red tide occurred in Xiamen,Fujian July,2011,we analyzed temporal variation of red tide characteristics such as chlorophyll a concentration(Chl-a),sea surface temperature(SST)and the spectral information of wave bands(the ratio of Rrsand nLw).Compared the abnormal areas of water in time-series with historical data,we find Chl-a,SST,the ratio of Rrsand nLw in red tide water are bigger than non-red tide water,red tide water changed significantly when red tide happens,with a clear inflection point.Chl-a remained relatively unchanged before red tide,increased rapidly in red tide and steadily declined after red tide;SST changed smoothly during red tide;the ratio of Rrsand nLw had maximums when severe red tide occurred.The temporal variation of water quality parameters before and after red tide can provide a reference for red tide monitoring and forecasting.