Uncertainties in Retrieval of Remote Sensing Reflectance from Ocean Color Satellite Observations

Author

Eder I. Herrera Estrella, The Graduate Center, City University of New YorkFollow

Date of Degree

9-2023

Document Type

Dissertation

Degree Name

Ph.D.

Program

Earth & Environmental Sciences

Advisor

Alexander Gilerson

Committee Members

Fred Moshary

Nir Krakauer

Paul DiGiacomo

Robert Foster

Subject Categories

Data Science | Electromagnetics and Photonics | Environmental Monitoring | Oceanography | Other Electrical and Computer Engineering

Keywords

Ocean Color, Atmospheric Correction, Remote Sensing Reflectance, satellites, uncertainty, spatial resolution

Abstract

Ocean Color radiometry uses remote sensing to interpret ocean dynamics by retrieving remote sensing reflectance (𝑅𝑟𝑠) from satellite imagery at different scales and over different time periods. 𝑅𝑟𝑠 spectrum characterizes the ocean color that we observe, and from which we can discern concentrations of chlorophyll, organic and inorganic particles, and carbon fluxes in the ocean and atmosphere. 𝑅𝑟𝑠 is derived from the total radiance at the top of the atmosphere (TOA). However, it only represents up to ten percent of the total signal. Hence, the retrieval of 𝑅𝑟𝑠 from the total radiance at TOA involves the application of atmospheric correction (AC) algorithms, which include accurate modeling of Rayleigh and aerosol scattering, glint, and water variability. Each of these components yields uncertainties in the retrieved value of 𝑅𝑟𝑠, especially in the blue bands. It is important to understand the main sources of uncertainties in 𝑅𝑟𝑠, as uncertainties propagate into the retrieval of water parameters, which in turn inform climate models. In this study, a model was developed that quantifies the uncertainties of the main components in the current AC algorithm and used to analyze holistically the influence of these components on the 𝑅𝑟𝑠 uncertainties spatially and temporally in different water types taking advantage of the spectral differences between the components.

The uncertainties were determined by comparing satellite and in situ data, with the in situ data obtained from the AErosol RObotic NETwork - Ocean Color (AERONET-OC) around the Northern Hemisphere and the Marine Optical BuoY (MOBY), Lanai, Hawaii. The satellite sensor data are from the Visible Infrared Imaging Radiometer Suite (VIIRS) on the S-NPP platform, the Ocean and Land Colour Instruments (OLCI) on Sentinel 3A and 3B, and the Operational Land Imager (OLI) on Landsat 8.

Results showed that the Rayleigh component (molecular scattering and surface effects) is the main source of 𝑅𝑟𝑠 uncertainties for all water types, followed by water variability, which is more influential in coastal areas. The contributions of other components, including aerosol scattering, are usually smaller. In addition, wind speed ranges can influence results, especially in coastal regions. Across spatial scales, water variability played a dominant role in 𝑅𝑟𝑠 uncertainty and increased proportionally to the ground sampling distance.

Recommended Citation

Herrera Estrella, Eder I., "Uncertainties in Retrieval of Remote Sensing Reflectance from Ocean Color Satellite Observations" (2023). CUNY Academic Works.
https://academicworks.cuny.edu/gc_etds/5475