Water quality analysis from hyperspectral observations

• Grant number: 22/01107-2
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Effective date (Start): June 01, 2022
• Effective date (End): November 30, 2022
• Field of knowledge: Physical Sciences and Mathematics - Geosciences
• Principal Investigator: Cláudio Clemente Faria Barbosa
• Grantee: Thainara Munhoz Alexandre de Lima
• Supervisor: Claudia Giardino
• Host Institution: Instituto Nacional de Pesquisas Espaciais (INPE). Ministério da Ciência, Tecnologia e Inovações (Brasil). São José dos Campos , SP, Brazil
• Research place: Institute for Electromagnetic Sensing of the Environment, Milano (IREA-CNR), Italy
• Associated to the scholarship: 21/02714-7 - Cyanobacteria mapping in Promissão reservoir by hybrid algorithms and images from OLCI/Sentinel-3 sensor, BP.MS

Abstract

In recent decades, with increasing population growth and climate change, biogeochemical processes in aquatic environments have been negatively affected in terms of water quality. In this context, remote sensing emerges as an important tool in monitoring these ecosystems, where through bio-optical algorithms, information about water quality parameters can be derived. Despite its wide use, the high spatiotemporal variations in the optical properties of Brazilian aquatic systems, bring challenges to the use of multispectral sensing. Multispectral systems commonly collect data in three to six spectral bands in a single observation from the visible and near-infrared region of the electromagnetic spectrum. This type of spectral categorization ends up masking the specific absorption features of many optical constituents, limiting the application of multispectral sensors. Over the past decade, advances in sensor technology have been overcoming this limitation, with the development of hyperspectral sensor technologies, which allows for an almost continuous spectral characterization of targets across the spectrum. With regard to the application of hyperspectral data in aquatic environments, greater attention must be taken due to the low radiometric signal that comes from water bodies. This makes these environments require sensors that have accurate radiometric characteristics. In this context, the PRISMA hyperspectral mission, launched in 2019, has shown promising results in estimating water quality parameters in continental water bodies. With a spectral resolution of 237 bands, the satellite allows a better estimate of absorption features of aquatic optical components, such as the pigment phycocyanin, which has a specific absorption peak at 620nm. In order to better assess the applicability of PRISMA mission in Brazilian waters, the BEPE research aims to analyze the estimation of water quality parameters from PRISMA imagery, comparing with in situ measurements and multispectral sensors. (AU)