基于Landsat数据的洱海蓝藻动态变化监测

The Dynamic Monitoring of Erhai Cyanobacteria Based on Landsat Data

近年来,位于云南省境内的洱海湖区蓝藻水华现象频发引起了人们的关注。叶绿素a是水体初级生产力的重要指标,可以有效反映浮游植物生物量状况及其变化趋势。本文选取了蓝藻水华易爆发期（2009年5月~11月）洱海湖区Landsat TM/ETM＋数据,在对图像进行了辐射定标、大气校正、条带修复等预处理的基础上,运用41.57×（TM3＋TM4）-0.697波段组合模型对其进行叶绿素a浓度反演,反演结果表明,洱海湖区叶绿素a含量逐渐升高,在10月份达到了峰值,11月开始下降。各时相叶绿素a浓度反演结果与实际采样分析结果基本一致,验证了利用Landsat TM/ETM＋数据进行洱海湖区叶绿素a浓度动态监测的有效性。该方法具有周期短、信息丰富、现势性强、成本低等优势,值得进一步推广。

In recent years,algal bloom occurring in Erhai frequently attracts wide attention. The chlorophyll-a concentration,which can effectively reflect the status of phytoplankton biomass and its change trend,is an important parameter for evaluating primary productivity of the water. Using the Landsat TM/ETM＋ remote sensing images when cyanobacteria bloom erupted（from May to November in 2009）,after preprocessing like radiometric calibration,atmospheric correction and destriping on the images,the chlorophyll-a concentration was quantitatively inversed by the band combination of 41.57＊（TM3＋TM4）-0.697.The results showed that chlorophyll-a concentration in Erhai Lake increased gradually and reached the highest value in October,then decreased in November. Chlorophyll-a concentrations in each phase inversion result are consistent with the actual results of sampling and analysis that demonstrates the effectiveness of the use of Landsat TM/ETM＋ data on dynamic monitoring chlorophyll-a concentration of Erhai Lake. This method is worthy of further promotion with short period,rich information,high actuality and low cost.