Satellite Multispectral Compositional Mapping of Lake Blooms
Dr. Robert K. Vincent Dept. of GeologyBowling Green State University firstname.lastname@example.org
Besides the lone thermal infrared band, LANDSAT TM has6 reflected sunlight spectral bands in the 0.4-2.5 µmwavelength region with 30-m spatial resolution (each pixelcovers about 1/5th of an acre), yielding these advantagesover human observations from boats or docks:◦ TM data can make observations as dense as 5 observations (or measurements if a tested algorithm exists) per acre over an entire body of water for most lakes (3 frames required for all of Lake Erie).◦ TM data can observe what humans cannot see, because 3 of its 6 spectral bands are outside the visible light wavelength range.◦ TM looks ±3° from straight down (nadir), reducing surface (specular or glint) reflection in calm water.◦ TM data can be downloaded to the company’s computer within 24 hours of overpass (every 16 days for one LANDSAT and every 8 days for 2 LANDSATs), and the entire lake can be processed in a few hours.Blue Water Satellite, Inc. has licensed 7 (one more being added)algorithms for which BGSU has applied for patents thus far.
LBPC (Low Bloom Phycocyanin Content)◦ Maps low blooms of cyanobacteria in water in the 2-17 µm/L (ppb) range, with rms error = 3.1 ppb◦ Can map cyanobacteria blooms before they can be identified by a human observer in a boat on the water (helps early mitigation)HBPC (High Bloom Phycocyanin Content◦ Maps high blooms of cyanobacteria in water in the 2-64 m/L (ppb) range, with SE= 7.2 ppbMC (Microcystin Content)◦ Maps toxin Microcystin in high blooms of cyanobacteria in water in 2-63 m/L (ppb) range, and it has been correct on 45 of 47 water samples from 2 dates of collection, as to whether MC was above or below the World Health Organization sporting lake advisory limit of 20 m/L (ppb)
Microcystin Toxin Measured in Water Samples Vs. HBPC3RAT Algorithm (LANDSAT TM) Estimate of PC on 25 Sept 2008 70 y = 0.514x - 17.133 60 R² = 0.8606Microcystin Content ((g/L) 50 40 30 Microcystin 20 Linear (Microcystin) 10 0 0 20 40 60 80 100 120 140 160 -10 -20 HBPC Algorithm Results for PC Content (g/L)
Red 90-150 µg/LOrange 80- 89 g/LYellow 60- 79 g/LBlue-Gr. 45- 59 g/LBlue 1 - 44 g/L (in water)D. Blue 0 (neg. numbers on land)
LRTP (Low-Range Total Phosphate in Water)◦ Maps the amount of total phosphate in water in range 9-100 µg/L (ppb); accuracy ±5 ppb from 9-33 ppbHRTP (High-Range Total Phosphate in Water)◦ Maps the amount of total phosphate in water in the range 100-700 g/L (ppb); rms error = 69 ppbTPL (Total Phosphate on Land)◦ Maps the amount of total phosphorous on/in bare soil in range 550-2500 mg/kg (ppm) with SE=531 ppm
Fig. 5. Image showing the total P concentration (mg/kg) in surface soil samples of F34 (left side of the image) andF11 (right side of the image) fields displayed as red (high P content) to Turquoise (low P content) obtained byapplying the P spectral ratio model to the LANDSAT 5 frame of May 20, 2005 which was used for developing themodel. Field near Oregon, OH; field on left had Class B sewage sludge injected hours earlier.
Tested algorithms pertaining tocyanobacterial blooms currently exist thatemploy LANDSAT TM data for mapping:◦ Pigment content in surface waters (phycocyanin)◦ Toxin content in surface waters (Microcystin)◦ Nutrient content in surface waters (T. Phosphate)◦ Nutrient content on bare soil (T. Phosphate)◦ Others (Total Sulfate content in surface waters; Copper and Sulfur contents in bare soils)It is time to use satellite monitoring forcyanobacterial blooms in lakes and streams.