A comparison between above-water surface and subsurface spectral reflectances collected over inland waters

Abstract

A comparison between above-water surface and subsurface spectral reflectances collected over inland waters Asif M. Bhatti Kochi University of Technology, Japan, asifmumtaz.bhatti@kochi-tech.ac.jp Donald RundquistUniversity of drundquist1@unl.edu John SchallesCreighton University, jfsaqua@creighton.edu Luis RamirezUniversity of Nebraska-Lincoln, luisermz@yahoo.com Seigo NasuKochi University of Technology, Japan Bhatti, Asif M.; Rundquist, Donald; Schalles, John; Ramirez, Luis; and Nasu, Seigo, "A comparison between above-water surface and subsurface spectral reflectances collected over inland waters" (2009 AbstractThe objective of the research was to undertake a quantitative comparison of spectral-reflectance measurements made slightly above the surface of water bodies with the measurements made slightly below the surface. The study is focused on three rivers; two in Georgia, USA and one in Japan. As expected, the differences in reflectance are not constant and vary with the wavelength. The contribution of surface-reflection effects to the surface reflectance measured slightly above the water is both pronounced and highly variable, but although they do alter the magnitude of the upwelling signal, they do not change the general shape of the spectral profiles. The correction of surface-reflection effects by assuming a proportionality factor (ρ) is not considered to be efficient for inland fresh water bodies. For in situ spectroscopy, the recommended approach is to measure upwelling radiance slightly below the water's surface as a means of minimizing extraneous noise. Researchers should be aware of the potential for diminishing the validity of findings because of measurement errors.

Spectral reflectance is a reliable water-quality estimator for small, highly turbid wetlands

“…Chipman et al (2009) andOlmanson et al (2011) showed that all water bodies of 0.04 km 2 and larger are suitable for monitoring with this moderate resolution. However, their radiometric resolution and signal-to-noise ratio are not designed for a very low signal emanating from these waters (Arst 2003).…”

Critical Metadata for Spectroscopy Field Campaigns

“…Underwater campaigns can vary in terms of the application of the data being investigated and the protocol necessary to capture the required data. Targets can include seagrass, macro-algae, corals and sponges and spectral measurements may be taken above surface or below surface: opinions differ on how inclusive a metadataset must be to document environmental and target properties [4,23]. The unique complexities of measuring targets and controlling influencing variables in a marine environment can be understood best by the scientists with in-field expertise.…”

Analysis of Cross-Seasonal Spectral Response from Kettle Holes: Application of Remote Sensing Techniques for Chlorophyll Estimation

“…Therefore, integration of field spectrometry data for interpretation of the remote sensing images is an essential component in the classification of small shallow water bodies. Future research in the field of spectrometry can be focused on subsurface measurement and influence of fluorescence on the water leaving signal [5,39]. Precise understanding of the light attenuation under shallow waters can lead to detail interpretation of upwelling radiance.…”

“…Additionally, it can be applied in the field by portable spectrometers [4]. Field spectroscopy has an important role in environmental science in which it allows to characterize the object being observed with in situ measurements [5]. With proper equipment and methodology, spectrometry can be conducted under a variety of conditions [6].…”