Graduation Year

2019

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Marine Science

Major Professor

Chuanmin Hu, Ph.D.

Committee Member

Brian B. Barnes, Ph.D.

Committee Member

David F. Naar, Ph.D.

Keywords

DNB, reflectance, remote sensing, sediment front, VIIRS

Abstract

Coastal water turbidity is a key environmental factor that influences the relative clarity of the water, which therefore reduces sunlight penetration. The comprehensive spatial and temporal coverage of remote sensing allows mapping of water turbidity near the coast. Even in locations where time-consuming and expensive conventional turbidity monitoring programs exist, local technological limitations prevent complete coverage. Traditional optical satellite techniques using the visible band also have limitations in monitoring turbidity due to non-optimal observing conditions such as clouds, sun-glint, and thick aerosols. In this study, in order to complement the daytime satellite measurements, I used the data from Visible Infrared Imaging Radiometer Suite Day-Night-Band (VIIRS DNB), which provides 750 m spatial resolution for a wide band (500 – 900 nm) during nighttime imaging. There were two objectives in this study: (1) Determine the contribution that the nighttime DNB data would provide for estimating turbidity, compared to the VIIRS daytime contribution. (2) Quantify turbidity from the nighttime DNB data in the coastal region. In the Northern Gulf of Mexico, the results showed that the mean monthly nighttime DNB data over the two years can contribute 42.9% of the total usable day and night water pixels. The nighttime DNB data can provide 32.5% of total day and night water pixels that can be used to estimate turbidity, within ±4 days of a full moon. The VIIRS nighttime DNB reflectance data showed a poor relationship with daytime estimated turbidity (R2=0.61) with a standard error of 7.4 FNU. The mean relative bias and error were 53.5% and 82.3%. The method used in this study shows promise, but currently still has high uncertainties and errors. Several reasons for these uncertainties and errors were discussed. This study suggests that nighttime DNB data might be useful if uncertainties are reduced through further algorithm development. If so, then during the week of a full moon, nighttime DNB data could be used to calculate nighttime turbidity.

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