Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T The use of in situ, laboratory and airborne measurements to estimate the chlorophyll-a concentration in the St. Lawrence River Yushan Zhu Vodacek Anthony Michael Twiss Center for Imaging Science Digital Imaging and Remote Sensing Lab Rochester Institute of Technology 04/05/2006

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T Outline In situ measurements: HOBI Labs HydroRad- 4(RIT), bbe FluoroProbe 2 (Clarkson University)In situ measurements: HOBI Labs HydroRad- 4(RIT), bbe FluoroProbe 2 (Clarkson University) Field collected water sample was analyzed in lab by spectrophotometer (Cary 500)Field collected water sample was analyzed in lab by spectrophotometer (Cary 500) Airborne image was taken at the same time by MISIAirborne image was taken at the same time by MISI SummarySummary Further studiesFurther studies

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T Study Area – St. Lawrence River Block section of St. Lawrence north of Wilson Hill Island: 44° to 44° ° to 75°06.873Block section of St. Lawrence north of Wilson Hill Island: 44° to 44° ° to 75° Time: July 21, 2005Time: July 21, 2005 Yellow points: HydroRad-4Yellow points: HydroRad-4 Red points: bbe fluoroprobeRed points: bbe fluoroprobe

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T MISI image after MNF

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T HydroRad-4 HydroRad-4 is a versatile system for in-situ radiometric measurements constructed from four Ocean Optics spectrometer 2048 pixels ; wavelength from: 350nm~700nm; spectral resolution 3.0nm The four sensors are used as two pairs This method of deployment was effective for determine the scalar irradiance, net irradiance, and average cosine Approximately total absorption can also be derived using Gershun’s equation

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T HydroRad-4 A B C D 1+cos - collector

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T Example of measurements by HydroRad-4

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T bbe FluoroProbe 2 (Clarkson University) Highly sensitive measuring instrument for in situ chlorophyll analysisHighly sensitive measuring instrument for in situ chlorophyll analysis Algae differentiation uses 5 LEDs for fluorescence excitation. (450, 525, 570, 590, 610nm)Algae differentiation uses 5 LEDs for fluorescence excitation. (450, 525, 570, 590, 610nm) Give the concentration for different type of algae: green algae, bluegreen algae, diatoms, and cryptophytaGive the concentration for different type of algae: green algae, bluegreen algae, diatoms, and cryptophyta

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T Laboratory measured parameters from water samples The field collected water samples were analyzed in lab to get following results The field collected water samples were analyzed in lab to get following results 1.Total Suspended Solids (TSS) 2.Colored Dissolved Organic Matter absorption (CDOM) 3.Particle and pigment absorption

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T TSS TSS: 1L water sample filter through GF/F glass- fiber filter (0.2 µm); weight the difference of GF/F filterTSS: 1L water sample filter through GF/F glass- fiber filter (0.2 µm); weight the difference of GF/F filter TSS Station Pre Weight after filtering Differencetss(g/m3)

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T Cary spectrometer Absorption can be measured by Cary 500Absorption can be measured by Cary 500 Typical of high performance laboratory spectrometers range from UV to NIRTypical of high performance laboratory spectrometers range from UV to NIR It has a dual-beam design: The instrument alternately measures the spectral radiance from a reference material and from the sample material of interestIt has a dual-beam design: The instrument alternately measures the spectral radiance from a reference material and from the sample material of interest The instrument uses a common light source, monochromators, and detector for both beams. A chopper wheel controls which beam the detector is viewing during the measurement cycleThe instrument uses a common light source, monochromators, and detector for both beams. A chopper wheel controls which beam the detector is viewing during the measurement cycle The spectral transmission of a material can be determined by the two measured beamsThe spectral transmission of a material can be determined by the two measured beams

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T CDOM absorption Use two 10cm length cuvettes, one with pure water and the other with filtered sample water through GF/F and membrane (0.2um) filter. When the same light beam penetrated two cell, the difference tells the CDOM absorption Use two 10cm length cuvettes, one with pure water and the other with filtered sample water through GF/F and membrane (0.2um) filter. When the same light beam penetrated two cell, the difference tells the CDOM absorption

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T Particle and pigment absorption A pair of filters is used: one is wetted with pure water as a reference; the other is filtered with sample water. The difference of the two filters can tell the optical density of concentrated culturesA pair of filters is used: one is wetted with pure water as a reference; the other is filtered with sample water. The difference of the two filters can tell the optical density of concentrated cultures After the sample filter is washed by MeOH, the pigment will extracted out and the difference now is only about particle absorptionAfter the sample filter is washed by MeOH, the pigment will extracted out and the difference now is only about particle absorption Absorption spectra measured for aquatic particles concentrated onto glass-fiber filters require a correction for increase in path length caused by multiple scattering in the glass-fiber filterAbsorption spectra measured for aquatic particles concentrated onto glass-fiber filters require a correction for increase in path length caused by multiple scattering in the glass-fiber filter

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T Particle and pigment absorption

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T Compare the results of in situ and laboratory measurements The absorption obtained from in situ measurements (HydroRad – 4) can tell the information about the CHL concentration well

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T Modular Imaging Spectrometer Instrument - MISI MISI is designed by Digital Imaging and Remote Sensing Group at RITMISI is designed by Digital Imaging and Remote Sensing Group at RIT Line scanner: scanner mirror spinning to project the image of the detector along a line on the ground perpendicular to the aircraft ground trackLine scanner: scanner mirror spinning to project the image of the detector along a line on the ground perpendicular to the aircraft ground track High spatial resolution: 1.0 m GIFOV at 1km of altitudeHigh spatial resolution: 1.0 m GIFOV at 1km of altitude High spectral resolution: two separate 36- channel spectrometers to cover the spectrum from 440nm to 1020nm in 10nm spectral bands.High spectral resolution: two separate 36- channel spectrometers to cover the spectrum from 440nm to 1020nm in 10nm spectral bands. Procedure: Raw Data -> oversampling correction, roll compensation -> glint remove -> spectral, radiometric calibration -> atmosphere calibrationProcedure: Raw Data -> oversampling correction, roll compensation -> glint remove -> spectral, radiometric calibration -> atmosphere calibration

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T MISI Images (before and after deglint) The reflection of solar radiation on non-flat water surfaces is a serious problem for the image.The reflection of solar radiation on non-flat water surfaces is a serious problem for the image. The wave and glint patterns can clearly see from the left imageThe wave and glint patterns can clearly see from the left image In order to eliminate most of the glint patterns, deglint algorithm is appliedIn order to eliminate most of the glint patterns, deglint algorithm is applied After deglint, the image is more smooth, eliminate most of the information from sun glint, and get more information about water itselfAfter deglint, the image is more smooth, eliminate most of the information from sun glint, and get more information about water itself

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T Sun glint remove algorithm Since water is relatively opaque to NIR wavelength, which mean it has maximum absorption and minimal water leaving radianceSince water is relatively opaque to NIR wavelength, which mean it has maximum absorption and minimal water leaving radiance The amount of sun glint in the visible bands is linearly related to the brightness in the NIR band because the real index of refraction is nearly equal for NIR and visible wavelengthThe amount of sun glint in the visible bands is linearly related to the brightness in the NIR band because the real index of refraction is nearly equal for NIR and visible wavelength The amount of light reflected from the water surface in the NIR is good indicator of the amount of light that will be reflected in visible wavelengthsThe amount of light reflected from the water surface in the NIR is good indicator of the amount of light that will be reflected in visible wavelengths Regions of the image are selected where a range of sun glint is evidentRegions of the image are selected where a range of sun glint is evident Algorithm by J.D.HedleyAlgorithm by J.D.Hedley

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T Different TSS, CDOM, CHL concentration simulated by HydroLight Hydrolight: radiative transfer numerical model that computes radiance distributions and derived quantities for natural water bodies.Hydrolight: radiative transfer numerical model that computes radiance distributions and derived quantities for natural water bodies. The Chl-a has strong absorption of blue light between 400nm and 500nm and red light at approximately 680nmThe Chl-a has strong absorption of blue light between 400nm and 500nm and red light at approximately 680nm

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T Summary The apparent and inherent optical properties of the St. Lawrence river were obtained using in situ and laboratory measurementsThe apparent and inherent optical properties of the St. Lawrence river were obtained using in situ and laboratory measurements The average concentrations of Chl-a and TSS are 1ug/l and 1mg/l. CDOM absorption is only about 0.1 at 440nmThe average concentrations of Chl-a and TSS are 1ug/l and 1mg/l. CDOM absorption is only about 0.1 at 440nm Chl-a concentration can’t be mapped by airborne image for now because of the less variance of Chl-a, TSS, and CDOMChl-a concentration can’t be mapped by airborne image for now because of the less variance of Chl-a, TSS, and CDOM

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T Further studies Continue field studies in this summer, more measurements will be done for different water samples which have more concentration ranges for Chl, TSS, and CDOMContinue field studies in this summer, more measurements will be done for different water samples which have more concentration ranges for Chl, TSS, and CDOM Suitable Chl concentration estimation algorithms for coastal and inland waters need to develop using MISI dataSuitable Chl concentration estimation algorithms for coastal and inland waters need to develop using MISI data Then algal growth model output can be compared with these chlorophyll map derived from MISI to validate and calibrate the models.Then algal growth model output can be compared with these chlorophyll map derived from MISI to validate and calibrate the models.

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T ?