Moderate Resolution Imaging Spectroradiometer (MODIS) observations of cyanobacteria blooms in Taihu Lake, China
Moderate Resolution Imaging Spectroradiometer (MODIS) observations of cyanobacteria blooms in Taihu Lake, China
复制标题
中国太湖蓝藻水华的中分辨率成像光谱仪 (MODIS) 观测
DOI：
10.1029/2009jc005511
复制
发表时间：
2010-04-01
影响因子：
3.6
通讯作者：
Shang, Shaoling
中科院分区：
文献类型：
--
作者：
Hu, Chuanmin;Lee, Zhongping;Shang, Shaoling
利用中分辨率成像光谱仪（MODIS）的数据，研究了太湖蓝藻（主要是铜绿微囊藻）水华的特征。该方法涉及首先推导出一个浮动藻类指数（FAI）的基础上，中分辨率（250和500米）的MODIS反射率数据在645，859，和1240 nm的臭氧/气体的吸收和瑞利散射效应的校正后，然后客观地确定FAI阈值（-0.004），以分开的水华和非水华沃茨。根据定义，术语“水华”或“漂浮藻类”是指蓝藻在水面上形成漂浮浮渣的水华。9年的MODIS时间序列数据显示了2000年和2008年之间的水华特征（年发生频率，时间和持续时间）。假设25%的面积覆盖率作为衡量的意义，重大的水华事件很少发生在2000年和2004年之间的整个湖泊（不包括东湾）或几个湖段（西北湖，西南湖，和中央湖）。在大多数湖泊段中，从2000-2004年到2006-2008年，每年发生重大水华的频率增加，开始时间更早，持续时间更长。2007年表现出独特的水华特征，由于条件非常有利于水华的发展和增殖。结果表明，长期的水华模式是由营养和气候因素驱动的。连续多年的MODIS FAI数据产品提供了基线信息，以每周监测湖泊的水华状况，这是关键的水质指标之一，并评估其未来的水质趋势。
A novel approach was used with data from the Moderate Resolution Imaging Spectroradiometer (MODIS) to characterize the intense blooms of cyanobacteria (primarily Microcystis aeruginosa) in Taihu Lake, China's third largest freshwater lake. The approach involves first deriving a floating algae index (FAI) based on the medium-resolution (250 and 500 m) MODIS reflectance data at 645, 859, and 1240 nm after correction of the ozone/gaseous absorption and Rayleigh scattering effects and then objectively determining the FAI threshold value (-0.004) to separate the bloom and nonbloom waters. By definition, the term "bloom" or "floating algae" refers to bloom where cyanobacteria form floating scums on the water surface. The 9 year MODIS time series data showed bloom characteristics (annual occurrence frequency, timing, and duration) between 2000 and 2008. Assuming 25% area coverage as a gauge for significance, significant bloom events rarely occurred between 2000 and 2004 for the entire lake (excluding East Bay) or several lake segments (Northwest Lake, Southwest Lake, and Central Lake). In most lake segments, the annual frequency of significant blooms increased from 2000-2004 to 2006-2008, when they started earlier and had a longer duration. The year 2007 showed unique bloom characteristics due to conditions highly favorable for bloom development and proliferation. The results suggest that the long-term bloom patterns are driven by both nutrients and climatic factors. The multiyear series of consistent MODIS FAI data products provide baseline information to monitor the lake's bloom condition, one of the critical water quality indicators, on a weekly basis, as well as to evaluate its future water quality trends.