Algal blooms in lakes have become a common global environmental problem.Nowadays,remote sensing is widely used to monitor algal blooms in lakes due to the macroscopic,fast,real-time characteristics.However,it is often difficult to distinguish between algal blooms and aquatic vegetation due to their similar spectral characteristics.In this paper,we used modified vegetation presence fre-quency index(VPF)based on Moderate-resolution Imaging Spectroradiometer(MODIS)imagery to distinguish algal blooms from aquatic vegetation,and analyzed the spatial and temporal variations of algal blooms and aquatic vegetation from a phenological per-spective for five large natural lakes with frequent algal bloom outbreaks in China from 2019 to 2020.We simplified the VPF method to make it with a higher spatial transferability so that it could be applied to other lakes in different climatic zones.Through accuracy valid-ation,we found that the modified VPF method can effectively distinguish between algal blooms and aquatic vegetation,and the results vary from lake to lake.The highest accuracy of 97％was achieved in Hulun Lake,where the frequency of algal outbreaks is low and the extent of aquatic vegetation is stable,while the lowest accuracy of 76％was achieved in Dianchi Lake,which is rainy in summer and the lake is small.Analyses suggests that the time period when algal blooms occur most frequently might not coincide with that when they have the largest area.However,in most cases these two are close in terms of time period.The modified VPF method has a broad scope of application,is easy to implement,and has a high practical value.Furthermore,the method could be established using only a small amount of measured data,which is useful for water quality monitoring on large spatial scales.

PU Jing;SONG Kaishan;LIU Ge;WEN Zhidan;FANG Chong;HOU Junbing;LV Yunfeng

College of Geographical Sciences,Changchun Normal University,Changchun 130032,China;Northeast Institute of Geography and Agro ecology,Chinese Academy of Science,Changchun 130102,China

中国地理科学（英文版）

[1]PU Jing;SONG Kaishan;LIU Ge;WEN Zhidan;FANG Chong;HOU Junbing;LV Yunfeng-.Differentiation of Algal Blooms and Aquatic Vegetation in Chinese Lakes Using Modified Vegetation Presence Frequency Index Method)[J].中国地理科学（英文版）,2022(05):792-807

Hulun,Dianchi

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