In-Situ Measurement of Diffuse Attenuation Coefficient and Its Relationship With Water Constituent and Depth Estimation of Shallow Waters by Remote Sensing Technique

Abstract

Abstract. Diffuse attenuation coefficient, Kd(λ), has an empirical relationship with water depth, thus potentially to be used to estimate the depth of the water based on the light penetration in the water column. The aim of this research is to assess the relationship of diffuse attenuation coefficient with the water constituent and its relationship to estimate the depth of shallow waters of Air Island, Panggang Island and Karang Lebar lagoons and to compare the result of depth estimation from Kd model and derived from Landsat 8 imagery. The measurement of Kd(λ) was carried out using hyperspectral spectroradiometer TriOS-RAMSES with range 320 -950 nm. The relationship between measurement Kd(λ) on study site with the water constituent was the occurrence of absorption by chlorophyll-a concentration at the blue and green spectral wavelength. Depth estimation using band ratio from Kd(λ) occurred at 442,96 nm and 654,59 nm, which had better relationship with the depth from in-situ measurement compared to the estimation based on Landsat 8 band ratio. Depth estimated based on Kd(λ) ratio and in-situ measurement are not significantly different statistically.Depth estimated based on Kd(λ) ratio and in-situ measurement are not significantly different statistically. However, depth estimation based on Kd(λ) ratio was inconsistent due to the bottom albedo reflection because the Kd(λ) measurement was carried out in shallow waters. Estimation of water depth based on Kd(λ) ratio had better results compared to the Landsat 8 band ratio.

Use of Digital Images as a Low-Cost System to Estimate Surface Optical Parameters in the Ocean

“…The methods traditionally used for in situ monitoring to estimate optical parameters involve the use of specialized instrumentation, which can be relatively complex and expensive [ 63 , 66 , 67 , 84 , 85 , 86 , 87 , 88 , 89 , 90 ]. In addition, these methods involve a slow analytical process, making them ineffective to obtain a large-scale view of the study area in a short time [ 48 , 90 ].…”

“…Taking into account these advantages, using the model generated for the Jerlov scale (Equation (27)), as an example, would help to classify water types in a quick and efficient way, since the equipment currently used to define water types based on this scale require specialized knowledge for their use. This is the case of hyperspectral irradiometers [ 87 ] or spectrophotometers (for calculating inherent optical properties) if the criteria of Solonenko and Mobley [ 67 ] are followed, as in the cruises used to build the database used in the present study. Likewise, approaches such as that proposed by Mallick et al [ 89 ], where K d values are derived from satellite images, may be considered for estimating the Jerlov scale.…”

Estimation of diffuse coefficient attenuation (Kd 490) using sentinel 2A in Panggang Island and its Surrounding Water

“…The absorption and scattering are the limiting factors in detecting objects at the bottom and water column. So knowledge about the value of diffuse attenuation coefficient (Kd) is needed to determine and improve the detection accuracy [2]. The field-based methods to monitor water quality, especially attenuation coefficient, are costly and hard to allow adequate spatial and temporal analysis [2].…”

“…So knowledge about the value of diffuse attenuation coefficient (Kd) is needed to determine and improve the detection accuracy [2]. The field-based methods to monitor water quality, especially attenuation coefficient, are costly and hard to allow adequate spatial and temporal analysis [2]. We need the time series data for spatial and temporal analysis, which is evenly distributed in the research area.…”

“…Landsat 8 OLI satellite imagery has been used to estimate the diffuse attenuation coefficient (Kd 490) in Panggang Island and its surrounding waters [2]. Landsat 8 satellite carries sensors with a medium spatial resolution of 30 m and has a 185 km swath.…”