Water- Sensors

Question 1

What is alternative to satellite oceanography?

Answer 1

• Ocean full of sensors and buoys, sensors on all ships

- Long time to make same number of measurements from a ship as satellite

Question 2

What is the Best way to get ocean measurements?

Answer 2

Satellite imagery and direct ocean sampling together

Question 3

How to get from reflectance to chlorophyll concentration

Answer 3

• Ratio of B and G bands
• Similar to simple ratio for vegetation
• Chl = f (Blue reflectance/Green reflectance)
• More G and Less B = high chl
• Low ratio result = high chl
• Tune eqn for different waters b/c of turbidity etc.

Question 4

SeaWiFS

Answer 4

Sea-Viewing Wide-Field-of-View Sensor

• 1997
• 1 x 1 km, 2800km
• Daily data acquisition
• OrbView-2
• Main driver for chl-a detection
• 1st platform of this kind

Question 5

What is penalty for high spatial resolution?

Answer 5

• Low temporal resolution and frequency for recording data

- Temporal is better for oceanography time series and wide open ocean

Question 6

What is best for measuring substrate? Platforms?

Answer 6

• High spatial resolution

- SPOT, WorldView

Question 7

What is best for measuring ocean productivity? Platforms?

Answer 7

• Low spatial resolution, high not necessary
• High temporal resolution
• MODIS-Aqua, Sentinal Series (measures daily)

Question 8

What are the Band utilities for wavelength ranges for SeaWiFS?

Answer 8

• 402-422nm ID yellow substances (blue absorption)
• 433-453nm Chl conc’n
• 480-500nm Increased chl sensitivity
• 500-520 chl conc’n
• 545-565nm Gelbstoffe (yellow substance)
• 660-680nm chl conc’n
• > 700nm Surface veg, land-water interface, atm correction

Question 9

WorldView 3 (WV3)

Answer 9

• 2m spatial res

Question 10

MODIS

Answer 10

• Moderate Resolution Imaging Spectroradiometer
• Onboard NASA’s EOS satellites
• Spatial res of 250m (2 bands), 500m (5 bands), 1000m (29 bands)
• Many bands in B,G, and R
• Launched May 2002

Question 11

What is necessary for an oceanographic satellite platform?

Answer 11

• High temporal res for time series

- Bands in proper locations, i.e. B and G (for ratio to approximate chl a)

Question 12

ENVISAT

Answer 12

MERIS, Medium Resolution Imaging Spectrometer

• 300m res
• 1150km swath
• every 3 days
• Newer is Sentinal 3

Question 13

Coccolithofores

Answer 13

• Turned Salish Sea milky green
• Not seen in area before
• Mostly found in open ocean
• Time-series (high temporal res) useful b/c data collected everyday
• Bloom could be tracked

Question 14

Sentinel 3

Answer 14

• Newest ocean platform
• 300m res
• 1.5day temporal res
• European Space Agency
• Launched June 2016
• Best but still in validation stage
• OLCI bands similar to MODIS but has better spectral resolution over more wavelengths

Question 15

Best land based platforms?

Answer 15

• Landsat, ASTER

Question 16

Human eye has difficulty separating which wavelengths and why?

Answer 16

• Difficulty separating G and R

- B/c they overlap

Question 17

Why is chl-a closer to land and coasts?

Answer 17

• Nutrients coming from rivers

- Wind mixing can also bring up nutrients from bottom

Question 18

Why is knowing about phytoplankton blooms and timing important?

Answer 18

• Peak phyto to peak zoo to salmon fry
• Salmon use zoo to get fat for migration (fatter = less (predation)
• Bloom timing needs to be concurrent w/ salmon exiting river