Rakesh Kumar Singh

National University of Singapore | NUS · Centre for Remote Imaging, Sensing and Processing (CRISP)

Atmospheric correction of satellite ocean color imagery in sediment-laden and algal bloom waters remains to be a challenging task because of the inefficiency of present methods to accurately assess aerosol radiances in the near-infrared (NIR) bands and extrapolate these into the visible spectrum. This study presents a novel method for estimation an...

Advancing remote sensing into the future to serve the expanding needs of the scientific community requires enhancing current capabilities of space-borne sensors and sustaining ocean color observations for diverse applications. In this study, an extensive set of experimental and space-borne measurements is analyzed for describing the operating chara...

Coastal and open ocean regions throughout the world are now subject to an array of toxic, harmful, or more intense algal blooms with an increasing trend of incidence over large geographical areas due to anthropogenic factors such as pollution and climate shifts. To date, detection capabilities of causative species based on remote sensing data are g...

In the atmospheric correction process of the satellite ocean color data, the removal of the aerosol scattering contribution over the coastal and inland water bodies has been a major challenge with the standard algorithms. In this work, a practical method is proposed based on a combination of NIR and ultraviolet (UV) bands (named as UVNIR-ex) for th...

Climate change has affected the Arctic Ocean (AO) and its marginal seas significantly. The reduction of sea ice in the Arctic region has altered the magnitude of photosynthetically available radiation (PAR) entering the water column, impacting primary productivity. Increasing cloudiness in the atmosphere and rising turbidity in the coastal waters o...

Kelps are a dominant macrophyte group and primary producer in Arctic nearshore waters that provide significant services to the coastal ecosystem. The quantification of these services in the Arctic is constrained, however, by limited estimates of kelp depth extent, which creates uncertainties in the area covered by kelp. Here, we test the environmen...

Through this poster, I introduce my PhD project. During this research we will investigate the marine primary production of the benthic and pelagic. The aim is to create a model enable to retrieve the global primary production at a Pan-Arctic scale using remote sensing.

The retreating sea ice in the coastal Arctic Ocean significantly impacts the nearshore ecosystems. The increasing sediment load in the coastal waters due to increased riverine discharge and waves-driven re-suspension has resulted in increased turbidity in many arctic coastal zones. However, cryospheric, geomorphologic, hydrologic and ocean exposure...

A warmer Arctic with less sea ice will likely improve macroalgae growth conditions, but observational data to support this hypothesis are scarce. In this study, we combined hydroacoustic and video inspections to compare the depth of growth, density and thickness of macroalgae (>10 cm) meadows in two contrasting climate regimes in Svalbard 1) the wa...

Arctic coasts, which feature land-ocean transport of freshwater, sediments, and other terrestrial material, are impacted by climate change, including increased temperatures, melting glaciers, changes in precipitation and runoff. These trends are assumed to affect productivity in fjordic estuaries. However, the spatial extent and temporal variation...

Intertidal vegetation provides important ecological functions, such as food and shelter for wildlife and ecological services with increased coastline protection from erosion. In cold temperate and subarctic environments, the short growing season has a significant impact on the phenological response of the different vegetation types, which must be c...

In most coastal waters, riverine inputs of suspended particulate matter (SPM) and colored dissolved organic matter (CDOM) are the primary optically active constituents. Moderate- and high-resolution satellite optical sensors, such as the Operational Land Imager (OLI) on Landsat-8 and the MultiSpectral Instrument (MSI) on Sentinel-2, offer a synopti...

Melting sea ice over the Arctic Ocean significantly impacts the coastal ecosystem, thereby affecting the Arctic flora and fauna, which has a long-term influence on the coastal communities dependent on them. The substantial reduction in seasonal ice cover over the Arctic Ocean has been ever-changing the coastal ecosystem dynamics, which includes the...

Sea ice in the Arctic Ocean is declining rapidly, leading to a complex set of changes with positive and negative impacts on the coastal ecosystem. The direct response is an increase in photosynthetically active radiation (PAR) penetrating the surface water column with positive impacts on a light-limited system. The reduction in seasonal ice cover o...

In high Arctic fjords, riverine inputs of freshwater and terrestrial particles give rise to turbid plumes in the nearshore zone during melt season and thus act as a major impediment to light availability and primary productivity within the water column. However, the remoteness of Arctic fjords limits our understanding of key drivers of these plumes...

Coastal waters are among the most productive regions in the Arctic (Leu et al. 2015; Smola et al. 2017; Ardyna et al. 2020). In these areas, a strong coupling exists between the sea and the land, and the shallow depths create a tight pelagic-benthic coupling (McGovern et al. 2020). These regions are also critical breeding and foraging grounds for m...

Algae are farmed or foraged to be used directly as food or other industrial applications such as production of biofuels, pharmaceuticals, cosmetics, etc. Floating algae acts as rafts to transport invertebrates, thereby maintaining biodiversity. It also play a potentially significant role in the organic carbon export from the coastal to the deep oce...

Satellite remote sensing offers a unique opportunity to gain insight into seasonally and spatially dynamic processes in Arctic coastal ecosystems. It can be used to estimate key water quality parameters, including suspended particulate matter (SPM) concentration with a higher temporal resolution and synoptic coverage. The present study aims to...

The chlorophyll concentration of a water body is an important proxy for representing the phytoplankton biomass. Its estimation from multi or hyper-spectral remote sensing data in natural waters is generally achieved by using (i) the waveband ratioing in two or more bands in the blue-green or (ii) by using a combination of the radiance peak position...

Despite the capability of Ocean Color Monitor aboard Oceansat-2 satellite to provide frequent, high-spatial resolution, visible and near-infrared images for scientific research on coastal zones and climate data records over the global ocean, the generation of science quality ocean color products from OCM-2 data has been hampered by serious vertical...

The inter-slot radiometric discrepancy (IRD) causes serious inconsistency in geostationary ocean colour imager (GOCI) radiometric products across the neighbouring slots. An accurate IRD correction is essential for generating operational ocean colour products, but it remains a challenging task because of its dynamic variation irrespective of sensor’...

Ocean Color Monitor-2 (OCM-2) on-board Oceansat 2 satellite is a multi-spectral sensor with a spatial resolution of 360×250m. Despite the presence of improved spatial resolution for better ocean color interpretation within coastal zones; differences among the OCM-2 detectors lead to striping artifacts in the along-track direction limiting the ocean...

Removal of the glint effects from satellite imagery for accurate retrieval of water-leaving radiances is a complicated problem since its contribution in the measured signal is dependent on many factors such as viewing geometry, sun elevation and azimuth, illumination conditions, wind speed and direction, and the water refractive index. To simplify...

Estimation of aerosol is a challenging problem in the process of atmospheric correction of ocean color data. Aerosol varies randomly in space, time, and type, increasing the complexity of its estimation with conventional methods. Sunglint amplifies the water signal often leading to saturation of many pixels in some bands and severally contaminating...

The paper “A novel method for estimation of aerosol radiance and its extrapolation in the atmospheric correction of satellite data over optically complex oceanic waters” presents a flowchart having some missing parameters used in the algorithm to obtain the desired water-leaving radiance product. However, all the images and results presented in the...

Removal of the glint effects from satellite imagery for accurate retrieval of water-leaving radiances is a complicated problem since its contribution in the measured signal is dependent on many factors such as viewing geometry, sun elevation and azimuth, illumination conditions, wind speed and direction, and the water refractive index. To simplify...