Sensing an Intense Phytoplankton Bloom in the Western Taiwan Strait from Radiometric Measurements on a UAV

Shaoling Shang; Zhongping Lee; Gong Lin; Chuanmin Hu; Lianghai Shi; Yongnian Zhang; Xueding Li; Jingyu Wu; Jing Yan

doi:10.1016/j.rse.2017.05.036

Sensing an Intense Phytoplankton Bloom in the Western Taiwan Strait from Radiometric Measurements on a UAV

Shaoling Shang, Zhongping Lee, Gong Lin, Chuanmin Hu, Lianghai Shi, Yongnian Zhang, Xueding Li, Jingyu Wu, Jing Yan

College of Marine Science

Research output: Contribution to journal › Article › peer-review

Abstract

Rapid assessment of <a title="Learn more about Algal Bloom from ScienceDirect's AI-generated Topic Pages"> algal blooms </a> in bays and <a title="Learn more about Estuary from ScienceDirect's AI-generated Topic Pages"> estuaries </a> has been difficult due to lack of timely shipboard measurements and lack of <a title="Learn more about Spatial Resolution from ScienceDirect's AI-generated Topic Pages"> spatial resolution </a> from current ocean color satellites. Airborne measurements may fill the gap, yet they are often hindered by the high cost and difficulty in deployment. Here we demonstrate the capacity of a low-cost, <a title="Learn more about Low Altitude from ScienceDirect's AI-generated Topic Pages"> low-altitude </a> <a title="Learn more about Pilotless Aircraft from ScienceDirect's AI-generated Topic Pages"> unmanned aerial vehicle </a> (UAV) in assessing an intense <a title="Learn more about Phytoplankton from ScienceDirect's AI-generated Topic Pages"> phytoplankton </a> ( Phaeocystis globosa ) bloom (chlorophyll concentrations ranged from 7.3 to 45.6 mg/m 3 ) in Weitou Bay in the western Taiwan Strait. The UAV was equipped with a hyperspectral sensor to measure the water color with a footprint of 5 m at every 30 m distance along the flight track. A novel approach was developed to obtain <a title="Learn more about Remote Sensing from ScienceDirect's AI-generated Topic Pages"> remote sensing </a> reflectance ( R rs ) from the UAV at-sensor radiometric measurements. Compared with concurrent and co-located field measured R rs (14 stations in total), the UAV-derived R rs showed reasonable agreement with root mean square difference ranging 0.0028–0.0043 sr − 1 (relative difference ~ 20–32%) of such turbid waters for the six <a title="Learn more about MODIS from ScienceDirect's AI-generated Topic Pages"> MODIS </a> bands (412–667 nm). The magnitude of the bloom was further evaluated from the UAV-derived R rs . For the bloom waters, the estimated surface chlorophyll a concentration ( Chl ) ranged 6–98 mg/m 3 , which is 3–50 times of the Chl under normal conditions. This effort demonstrates for the first time a successful retrieval of both water color ( i.e. , R rs ) and Chl in a <a title="Learn more about Nearshore Environment from ScienceDirect's AI-generated Topic Pages"> nearshore environment </a> from UAV hyperspectral measurements, which advocates the use of UAVs for rapid assessment of water quality, especially for nearshore or difficult-to-reach waters, due to its flexibility, low cost, <a title="Learn more about High Spatial Resolution from ScienceDirect's AI-generated Topic Pages"> high spatial resolution </a> , and sound accuracy.

Original language	American English
Journal	Remote Sensing of Environment
Volume	198
DOIs	https://doi.org/10.1016/j.rse.2017.05.036
State	Published - Jan 1 2017

Keywords

Unmanned aerial vehicle
Remote sensing reflectance
Phytoplankton bloom

Disciplines

Life Sciences

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10.1016/j.rse.2017.05.036License: CC BY

https://doi.org/10.1016/j.rse.2017.05.036

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title = "Sensing an Intense Phytoplankton Bloom in the Western Taiwan Strait from Radiometric Measurements on a UAV",

abstract = " Rapid assessment of algal blooms in bays and estuaries has been difficult due to lack of timely shipboard measurements and lack of spatial resolution from current ocean color satellites. Airborne measurements may fill the gap, yet they are often hindered by the high cost and difficulty in deployment. Here we demonstrate the capacity of a low-cost, low-altitude unmanned aerial vehicle (UAV) in assessing an intense phytoplankton ( Phaeocystis globosa ) bloom (chlorophyll concentrations ranged from 7.3 to 45.6 mg/m 3 ) in Weitou Bay in the western Taiwan Strait. The UAV was equipped with a hyperspectral sensor to measure the water color with a footprint of 5 m at every 30 m distance along the flight track. A novel approach was developed to obtain remote sensing reflectance ( R rs ) from the UAV at-sensor radiometric measurements. Compared with concurrent and co-located field measured R rs (14 stations in total), the UAV-derived R rs showed reasonable agreement with root mean square difference ranging 0.0028–0.0043 sr − 1 (relative difference ~ 20–32%) of such turbid waters for the six MODIS bands (412–667 nm). The magnitude of the bloom was further evaluated from the UAV-derived R rs . For the bloom waters, the estimated surface chlorophyll a concentration ( Chl ) ranged 6–98 mg/m 3 , which is 3–50 times of the Chl under normal conditions. This effort demonstrates for the first time a successful retrieval of both water color ( i.e. , R rs ) and Chl in a nearshore environment from UAV hyperspectral measurements, which advocates the use of UAVs for rapid assessment of water quality, especially for nearshore or difficult-to-reach waters, due to its flexibility, low cost, high spatial resolution , and sound accuracy. ",

keywords = "Unmanned aerial vehicle, Remote sensing reflectance, Phytoplankton bloom",

author = "Shaoling Shang and Zhongping Lee and Gong Lin and Chuanmin Hu and Lianghai Shi and Yongnian Zhang and Xueding Li and Jingyu Wu and Jing Yan",

year = "2017",

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doi = "10.1016/j.rse.2017.05.036",

language = "American English",

volume = "198",

journal = "Remote Sensing of Environment",

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T1 - Sensing an Intense Phytoplankton Bloom in the Western Taiwan Strait from Radiometric Measurements on a UAV

AU - Shang, Shaoling

AU - Lee, Zhongping

AU - Lin, Gong

AU - Hu, Chuanmin

AU - Shi, Lianghai

AU - Zhang, Yongnian

AU - Li, Xueding

AU - Wu, Jingyu

AU - Yan, Jing

PY - 2017/1/1

Y1 - 2017/1/1

N2 - Rapid assessment of algal blooms in bays and estuaries has been difficult due to lack of timely shipboard measurements and lack of spatial resolution from current ocean color satellites. Airborne measurements may fill the gap, yet they are often hindered by the high cost and difficulty in deployment. Here we demonstrate the capacity of a low-cost, low-altitude unmanned aerial vehicle (UAV) in assessing an intense phytoplankton ( Phaeocystis globosa ) bloom (chlorophyll concentrations ranged from 7.3 to 45.6 mg/m 3 ) in Weitou Bay in the western Taiwan Strait. The UAV was equipped with a hyperspectral sensor to measure the water color with a footprint of 5 m at every 30 m distance along the flight track. A novel approach was developed to obtain remote sensing reflectance ( R rs ) from the UAV at-sensor radiometric measurements. Compared with concurrent and co-located field measured R rs (14 stations in total), the UAV-derived R rs showed reasonable agreement with root mean square difference ranging 0.0028–0.0043 sr − 1 (relative difference ~ 20–32%) of such turbid waters for the six MODIS bands (412–667 nm). The magnitude of the bloom was further evaluated from the UAV-derived R rs . For the bloom waters, the estimated surface chlorophyll a concentration ( Chl ) ranged 6–98 mg/m 3 , which is 3–50 times of the Chl under normal conditions. This effort demonstrates for the first time a successful retrieval of both water color ( i.e. , R rs ) and Chl in a nearshore environment from UAV hyperspectral measurements, which advocates the use of UAVs for rapid assessment of water quality, especially for nearshore or difficult-to-reach waters, due to its flexibility, low cost, high spatial resolution , and sound accuracy.

AB - Rapid assessment of algal blooms in bays and estuaries has been difficult due to lack of timely shipboard measurements and lack of spatial resolution from current ocean color satellites. Airborne measurements may fill the gap, yet they are often hindered by the high cost and difficulty in deployment. Here we demonstrate the capacity of a low-cost, low-altitude unmanned aerial vehicle (UAV) in assessing an intense phytoplankton ( Phaeocystis globosa ) bloom (chlorophyll concentrations ranged from 7.3 to 45.6 mg/m 3 ) in Weitou Bay in the western Taiwan Strait. The UAV was equipped with a hyperspectral sensor to measure the water color with a footprint of 5 m at every 30 m distance along the flight track. A novel approach was developed to obtain remote sensing reflectance ( R rs ) from the UAV at-sensor radiometric measurements. Compared with concurrent and co-located field measured R rs (14 stations in total), the UAV-derived R rs showed reasonable agreement with root mean square difference ranging 0.0028–0.0043 sr − 1 (relative difference ~ 20–32%) of such turbid waters for the six MODIS bands (412–667 nm). The magnitude of the bloom was further evaluated from the UAV-derived R rs . For the bloom waters, the estimated surface chlorophyll a concentration ( Chl ) ranged 6–98 mg/m 3 , which is 3–50 times of the Chl under normal conditions. This effort demonstrates for the first time a successful retrieval of both water color ( i.e. , R rs ) and Chl in a nearshore environment from UAV hyperspectral measurements, which advocates the use of UAVs for rapid assessment of water quality, especially for nearshore or difficult-to-reach waters, due to its flexibility, low cost, high spatial resolution , and sound accuracy.

KW - Unmanned aerial vehicle

KW - Remote sensing reflectance

KW - Phytoplankton bloom

UR - https://digitalcommons.usf.edu/msc_facpub/1972

UR - https://doi.org/10.1016/j.rse.2017.05.036

U2 - 10.1016/j.rse.2017.05.036

DO - 10.1016/j.rse.2017.05.036

M3 - Article

VL - 198

JO - Remote Sensing of Environment

JF - Remote Sensing of Environment

ER -

Sensing an Intense Phytoplankton Bloom in the Western Taiwan Strait from Radiometric Measurements on a UAV

Abstract

Keywords

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