![]() Variations in the mass-specific absorptionĬoefficient of mineral particles suspended in water. In the future, we would like to provide the user with the option to share the data they collected by uploading it to an online database directlyīabin, M., Stramski, D. A MatLab function to read in HydroColor data and images can be found here (note that this function is for the HydroColor v1.2 text file). Longitude, date, time, sun zenith, sun azimuth, device zenith, deviceĪzimuth, exposure values, remote sensing reflectance, turbidity, suspended particulate matter concentration, and the backscattering coefficient. The data saved to the file contains: latitude, Text file that can be downloaded from the device (found in HydroColor'sĭocuments folder). 2012).Īt the end of each measurement, additional information is written to a A 1:1 relationship was used to convert turbidity (NTU) to suspended particulate matter (g m -3) (Neukermans et al. The green line is the least squares fit to the TSM-R rs(Red) data from Nechad et al. ![]() The averageĪ p* (mass-specific absorption) of the particles wasĠ.009 m 2 g -1, which is consistant with Babin and Stramski 2004. The average b bp* (mass-specific backscattering) of the particles was 0.01 m 2 g -1, which is consistant with Neukermans et al. Fitting the model provided the average mass specific optical characteristics of the the particles encountered at the various study sites. The red line is the result of fitting the oceanic radiance model from Gordon et al. The right plot shows a close up of the low turbidity values.Įrror bars display the standard error (when available). HydroColor R rs in the red channel as function of water Therefore, HydroColor's calculation of turbidity is valid for manyĭifferent environments and works across platforms. (sunny, cloudy), and platforms (iPhone 5, iPhone 4, iPod Touch). The data set in figureĥ spans many different environments (ocean, river, estuary), conditions The HydroColor reflectance in the red increases with turbidity in mannorĬonsistant with remote sensing theory (figure 5). HydroColor was calibrated to measure turbidity by collecting HydroColorĭata in parallel with a Hach portable turbidity meter. Outliers were likely caused by changing sky conditions during a HydroColor measurement. Boxed data points are outliers identified by falling more than 3.5 standard deviations from the regression model. Least squares linear regression, the dashed line shows the one to one The spectral sensitivities in figure 1 as weights. Using the Water Insight Spectrometer (WISP). Goddjin-Murphy, 2009).Ĭomparison of HydroColor R rs with R rs measured (chlorophyllĪlgorithm is still being developed, however, proof of concept hasĪlready been shown: L. Particulate matter, and the backscattering coefficient. Remote sensing reflectance values along with turbidity, suspended HydroColor will save each of the three images and display the Three satisfactory images, the user can select to analyze and save theĭata. ThisĮnsures the image is either taken at 40° (for the water image) or Inclinometer display should be aligned with the two green triangles. ![]() Images 135° from the azimuth angle of the sun. This insures the user takes both the sky and water The North arrow of the compass inįigure 3 should be aligned with one of the green tick marks beforeĬapturing an image. Location, HydroColor directs the user to the correct angles where sun HydroColor takes advantage of the internal GPS, compass, gyroscope, andĬlock to compute the position of the sun in the sky. Images are used to calculate the remote sensing reflectance. Reflectance and by providing an estimate of water turbidity.Įxample of the three images collected by a HydroColor user. ![]() Taken this a step further by using a more robust method to measure The use of a pocket camera (Nikon Coolpix) to estimate chlorophyll concentration forīoth water quality and plant research has been demonstrated (L. With high concentrations of such dissolved materials appear black). Intensity of light emanating form water (indeed some lakes in Maine Dissolved substances, such as plant extract (or tea)Ībsorb light while negligibly scattering and hence decrease the Hence can be diagnosed by ratios of radiance at different wavelengths Particles containing pigments, suchĪs phytoplankton, modulate the color emanating from the water, and Hence, allĮlse being equal, an increase in turbidity will increase the intensity Inversely proportional to the water absorption coefficient. Radiation, is proportional to the water backscattering coefficient and The light emanating from the water, when normalized by the incoming The idea behind HydroColor ( Apple App Store, Google Play Store, Facebook Page) is similar to that of Ocean Color satellites:
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