Using 250-M Surface Reflectance MODIS Aqua/Terra Product to Estimate Turbidity in a Macro-Tidal Harbour: Darwin Harbour, Australia

Abstract

Turbidity is an indicator of the quality of water and usually exhibits variability associated with changing hydrodynamic conditions, which can be reflected in the sediment dynamics in coastal regions. Darwin Harbour is a typical macro-tidal, well mixed, and complex environment influenced by industries, human activities, and natural factors-including winds, currents, river discharges, waves, and tides. As a case study, hydrodynamics and sediment dynamics in Darwin Harbour are investigated using moderate resolution imaging spectroradiometer (MODIS) measurements. This study focuses on understanding the variability of turbidity, mechanisms that control the variations of turbidity and analyzing field data to determine the main factors that influence the sediment dynamics in Darwin Harbour. The results of this study illustrate the seasonal turbidity variation is mainly influenced by the wind waves. The dredging campaigns in 2013 and 2014 wet seasons contributed to the rise of turbidity in Darwin Harbour. The action of tidal currents appears to be the dominant factor controlling the turbidity pattern in a spring-neap cycle and the turbidity intra-tidal variation. In addition, the turbidity maximum zone (TMZ) near Charles Point is formed by the tidal current convergence based on the results of current modelling.

Impacts of reduced deposition of atmospheric nitrogen on coastal marine eco-system during substantial shift in human activities in the twenty-first century

“…For modeling coastal water quality in terms of turbidity, we have used a Semi-Analytic Sediment Model (SASM), which was already applied to MODIS Aqua observations (Dorji et al 2016). Recently SASM model has used by (Yang et al 2018) using MODIS Terra observations and found that this model performed better than other linear and exponential models (Dorji and Fearns 2017). Algorithms of the SASM model used in the present study are explained as following (Eq.…”

“…Ozone Monitoring Instrument (OMI) (Latif et al 2021) and Sentinel-5 Precursor Tropospheric Monitoring Instrument (TROPOMI) were recently missioned to map air pollution worldwide. Surface Reflectance data from MODIS onboard Aqua/Terra sensors at 250 m resolution and daily temporal scale provide a better understanding of the coastal marine water quality (Yang et al 2018). Herein, the effects of ongoing restricted anthropogenic activities on the atmospheric NO 2 are investigated based on real-time observations from the OMI satellite by comparing NO 2 in 2020 with the average of past years (2015 À 2019).…”

Total Suspended Matter Distribution in the Hooghly River Estuary and the Sundarbans: A Remote Sensing Approach

“…TSM retrieval was carried out using 645 nm (Red) data after applying geo-referencing and atmospheric corrections as suggested by [8], [21], [22]. This data is highly useful for studying turbid coastal waters as the measurements in these bands do not saturate in turbid waters [23], [24].…”

“…Various TSM retrieval algorithms were developed using the relation between MODIS reflectance measurements and in-situ observations for different regions of the world [3], [8], [30] - [33]. In the study region, TSM retrieval algorithm was developed based on MODIS single band reflectance in the red region (λ = 645nm) and the available in-situ observations through regression based best-curve fit method and is given as follows:…”

“…The availability of observations from Moderate resolution Imaging Spectroradiometer (MODIS) remote sensing platform has provided a unique opportunity to monitor the sediment dynamics for more than a decade and half continuously [4]. Several researchers used these data products for estimation of TSM concentration in different estuaries across the global oceans [5] - [8]. All of these studies primarily focussed to analyse the distribution of TSM concentration or turbidity in the coastal and estuarine regions dominated by river discharges utilizing MODIS surface reflectances and in-situ observations through development of regional suspended sediment retrieval algorithms.…”