Monitoring water quality of the Southeastern Mediterranean sea using remote sensing

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Reynold Wheeler
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1 Monitoring water quality of the Southeastern Mediterranean sea using remote sensing Tamir Caras The Remote Sensing Laboratory Jacob Blaustein Institutes for Desert Research Ben-Gurion University of the Negev 1

2 Overview Water quality basics and overview Remote sensing of water quality Temporal and spatial dimension Problem solving: chlorophyll and TSS separation VENµS 2

3 Water quality basics and overview Water quality and detecting Pollution Physical Chemical Biological Thermal Sediments (TSS) Dissolved organic matter Algae Sea Surface Temperature (SST) 3 3

4 Sewage ponds - oxidation process 4

5 And anthropogenic pollution 5

6 Remote sensing of water quality Reflectance = Detected energy / Available energy 6

7 Spectral signature of ground features Signatures the foundation of detection Visible Reflected Infrared 7

Chlorophyll and TSS separation Suspended Matter [mgl -1 ] Problem : Suspended matter present in water affects Chl-a* detection erroneously high Chl-a

8 Chlorophyll and TSS separation Suspended Matter [mgl -1 ] Problem : Suspended matter present in water affects Chl-a* detection erroneously high Chl-a detected * Chl-a represents algae that is an indicator of pollution Suspended Matter June 2001 Chlorophyll June 2001 Egypt Israel Egypt Israel Chlorophyll [mgm -3 ] 8

9 Solution: Careful masking high levels of sedimentation Chlorophyll June 2001 After masking sediments: Chlorophyll June 2001 Israel Egypt Chlorophyll [mgm -3 ] Chlorophyll [mgm -3 ] 9

10 Coastal pollution near Tel Aviv Chlorophyll (mg/m 3 ) 2 February 2003 A sewage pipe breaks and raw sewage pores into the sea 10

11 Monitoring an algal event: June

12 Monitoring sedimentation in Haifa port August

13 VENµS - Scientific Applications Land Vegetation Agriculture Digital Elevation Model Atmosphere Water Water quality Inland and coastal water Precision farming Water vapor Aerosol optical thickness Cloud and height 13

VENµS Mission Characteristics Orbit: near polar, sun-synchronic (constant view angle) Altitude: 720 km Inclination: 98.27 Revisit time: two days Swath: 27.56 km Spatial resolution: 5.

14 VENµS Mission Characteristics Orbit: near polar, sun-synchronic (constant view angle) Altitude: 720 km Inclination: Revisit time: two days Swath: km Spatial resolution: 5.3 m Number of spectral bands: 12 (VIS-NIR) Tilting capability: +/-30 across and along track Radiometric resolution: 10 bits Equator crossing time: 10:30 AM, descending mode Mission start/duration: June, 2017, 4.25 years June

15 Spectra of Water Constituents Volume Reflectance Clear Water Null Null Point Point Chl, ug/l SM, mg/l CDOM, mgc/l B1 B3 B2 B4 Clear Water B5 B6 B7 B8 B Wavelength (nm) 15

16 Conclusion Venus may not be the best at any one category but it is the best all-rounder spaceborne sensor to date 16

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19 Remote Sensing of river chlorophyll ote Sensing dissolved carbon in lakes and coast 19

20 Red Sea seasonal climatologies of MODIS Chl-a (mg/m3) and SST ( C). Raitsos DE, Pradhan Y, Brewin RJW, Stenchikov G, Hoteit I (2013) Remote Sensing the Phytoplankton Seasonal Succession of the Red Sea. PLOS ONE 8(6): e

Series of images showing how the digitised plume of a MODIS image relates to a clearer high resolution image and the range of TSS thresholds analysed in this study.

21 Series of images showing how the digitised plume of a MODIS image relates to a clearer high resolution image and the range of TSS thresholds analysed in this study. Evans RD, Murray KL, Field SN, Moore JAY, Shedrawi G, et al. (2012) Digitise This! A Quick and Easy Remote Sensing Method to Monitor the Daily Extent of Dredge Plumes. PLOS ONE 7(12): e

22 Absorption and Scattering Attenuation in Pure Water Maximum Transparency at 470 nm Effective Wavelength = nm 22 22

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25 R 510 > Rule 1 A RS ( xi, yi) 26

26 Rule 1 A R 765 > RS ( xi, yi) 27

27 Rule 2 R R RS RS ( xi, yi) ( xi, yi) >

28 Radiometer vs. Spectrometer Radiometer Point spectrometer Image spectrometer 29

29 Multispectral Camera 6 band 30

30 MS Camera on a Drone 31

31 Other Systems 32

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33 Water Constituents Chlorophyll Sediments Dissolved organic carbon 34

34 Scientific Applications 35 Band Center Land/Vegetation Water quality Atmosphere (nm) Desert lower plants Dissolved organic matter; Turbidity Atmospheric resistance Maximum chlorophyll-a vegetation indices absorption Chlorophyll, other pigments; attenuation Green peak; Vegetation Chlorophyll reference; indices Suspended sediments Chlorophyll absorption; Suspended sediments Detect clouds and cloud edges Atmospheric correction Cloud properties Vegetation indices Digital Elevation Model Suspended sediments Top cloud detection Red edge Chlorophyll absorption Cloud properties Red edge Red edge Red edge Maximum reflectance; Vegetation indices Water vapor reference Water vapor April 27, 2006

Measuring Ocean Color: The Basics

Measuring Ocean Color: The Basics Radiation of energy from the Sun and the Earth s surface. Recall from previous lectures that the Sun (6000 K), radiates energy in three portions of the energy spectrum: