Correlating chlorophyll movement with wind speed and direction using satellite imagery: A case study of Devils Lake, North Dakota

Estimating the locations of high concentrations of Chlorophyll-a (Chl-a) is essential for accurate analysis of Harmful Algal Blooms (HABs). This paper focused on identifying the locations of higher concentrations of Chl-a in Devils Lake, North Dakota via satellite images by applying different segmentation techniques. The segmentation evaluation metrics indicate that Random Forest (RF) yielded better accuracy than other methods. The segmented images were validated with ground-sampled Chlorophyll data (location matching) and provided a matching percentage of 88.14% on August 08, 2023. The centroids of the contours from the segmented images acquired between 2017 and 2021 were analyzed to study the shift of chlorophyll against the average wind direction. The results indicate that there was a positive correlation of Chl-a against the wind direction. The wind velocity for the same periods was compared against the percentage change of the total area of Chl-a concentration. The results proved that the days having wind velocity greater than 3 m/s had a decrease in the area of Chl-a concentration.

Automated summary

This paper investigates the locations of high concentrations of Chlorophyll-a (Chl-a) in Devils Lake, North Dakota using satellite images and ground-sampled data. The study reveals a positive correlation between Chl-a and wind direction, as well as a decrease in Chl-a concentration area on days with wind velocity greater than 3 m/s. Random Forest method shows higher accuracy in image segmentation compared to other methods.