Ranjit Sarangi - Academia.edu (original) (raw)

Papers by Ranjit Sarangi

IEEE Transactions on Geoscience and Remote Sensing

Dust particles make up almost all of the atmospheric phosphorus, which accounts for 82% of the to... more Dust particles make up almost all of the atmospheric phosphorus, which accounts for 82% of the total phosphorus in the world. Phosphorus (P) is an important nutrient for terrestrial ecosystems, playing a critical role in influencing primary productivity and hence ecosystem dynamics. The deposition of airborne dust, particularly from arid and semi-arid regions, has been recognized as a significant source of phosphorus input in distant ecosystems. The study area, the Banni Plains, is a semi-arid ecosystem with a unique geological history, that has suffered from degradation due to varied natural and anthropogenic reasons. It is located in arid tract of western India (23º 19' to 23º52' N latitude and 68º 56' to 70º32' E longitude).Soil samples were collected from 10*10 km grid locations in the grassland before, after 48 hours, and 20 days after a cyclonic storm, Biporjoy, which hit the region in June, 2023. Statistical analyses (Shapiro-Wilk normality and Kruskalwallis H...

Research Square (Research Square), Oct 12, 2022

In situ sampling and analysis for water quality and bio-optical parameters carried out in the nor... more In situ sampling and analysis for water quality and bio-optical parameters carried out in the northeast Arabian Sea, in Diu and Daman coastal waters during February and August 2021. The in situ sampled water analysed to estimate chlorophyll, nutrients, Particulate Organic Carbon (POC) in the study area. The bio-optical parameters, normalized water leaving radiance (L wn) and remote sensing re ectance (R rs) retrieved with the operation of underwater hyperspectral radiometer (Satlantic/Wetlabs inc.). The main objective of the work was to develop POC algorithm using in situ radiometer derived R rs for selected wavelengths in visible regions and linking the band ratios to in situ POC data. In Diu, total 11 stations data collected and produced POC range (44-608 mg m − 3). These 11 points POC data correlated with R rs band ratios using 2nd order polynomial function and indicated coe cient of determination (R 2 values 0.37, 0.34 and 0.13). This correlation was also made using 3rd order polynomial t and indicated R 2 values 0.41, 0.42 and 0.26. The same datasets were observed with 3-Dimensional correlation between R rs (490/555), R rs (443/555), R rs (510/555) and POC using linear, paraboloid, gaussian and Lorentzian function t, which showed improved R 2 values ranging 0.34 to 0.66. The data from Daman added to Diu data (total 18 points), which resulted with further better correlation (R 2 = 0.75, RMSE = 9.12) with higher range of POC upto 2600 mg/m 3. The Modis-Aqua satellite derived POC data for our in situ stations for the sampling dates ranged 392-411 mg m − 3 as compared to our in situ data range 44-608 mg m − 3. Out of these different POC algorithms inter-comparison and satellite data, it is observed mandatory to have regional POC algorithms with su cient in situ data points.

Thalassas: an International Journal of Marine Sciences, Mar 28, 2023

Journal of the Indian Society of Remote Sensing

Thalassas: An International Journal of Marine Sciences

A spatial and temporal variation of sea surface salinity (SSS) is vital to understand the dynamic... more A spatial and temporal variation of sea surface salinity (SSS) is vital to understand the dynamics of the seasonal and inter-annual changes in the marine environment. In the present study, Soil Moisture Active-Passive (SMAP) derived daily SSS product and Moderate Resolution Imaging Spectroradiometer (MODIS-Aqua) remote sensing reflectance (Rrs) based SSS images (Algorithm by Qing et al, 2013), applied in the coastal and offshore region of the Bay of Bengal (BoB). SMAP data validation with in situ data (offshore and coastal water, 10 and 15 points) showed good correlation at offshore water and less correlation at coastal water (R2 = 0.707/0.499, SEE = ± 0.291/±0.546, MNB = -0.0029/-0.0089 and RMSE = ± 0.092/±0.139) respectively. Similarly, MODIS-Aqua Rrs derived salinity data validated with in-situ SSS and observed the correlation as follows with R2 = 0.908/0.891, SEE = ± 2.395/±1.512, MNB = 0.0718/0.0361, RMSE = ± 0.760/±0.316 in offshore and coastal water respectively during April ...

tsunami on ocean-surface chlorophyll concentration using MODIS-Aqua data

Geocarto International, 2021

NASA’s Suomi National Polar-orbiting Partnership (NPP), Visible Infra-red Imaging Radiometer Suit... more NASA’s Suomi National Polar-orbiting Partnership (NPP), Visible Infra-red Imaging Radiometer Suite (VIIRS) data utilized to detect night time lights (NTL) radiances and fishing boat pixels using VI...

Journal of Earth System Science, 2021

Abstract The phytoplankton variability and ocean productivity have been studied with the retrieva... more Abstract The phytoplankton variability and ocean productivity have been studied with the retrieval of chlorophyll concentration (CC) from various satellite ocean colour missions. The phytoplankton distribution is related to ocean processes and physical parameters such as temperature, wind speed, currents, etc., at regional and global scales. In the current study, the phytoplankton productivity has been observed in the southeast Arabian Sea during southwest (SW, June–September) and northeast (NE, October–December) monsoon seasons using merged chlorophyll product datasets during the years 2017 and 2018. There has been an observation of high chlorophyll concentration (~5.0 mg m −3 ) in the southeast Arabian Sea (southern tip of India) during SW monsoon and less in NE monsoons (~1.0 mg m −3 ). The spread in CC has been observed maximum during July–September. High anomaly of CC was observed along north-eastern Arabian Sea during northeast monsoon months of 2017 due to the very severe cyclonic storm Ockhi. Similarly, during August 2018, high chlorophyll concentration was observed (18.8 mg m −3 ) in south-eastern tip as a result of heavy rainfall and discharge of nutrient rich riverine water. The sea surface temperature (Modis-Aqua SST) has been observed to be cooler (26–27°C) in the SE Arabian Sea coastal waters during July–August as compared to warmer (28–30°C) surrounding waters. During the SW monsoon (June–August), the wind speed has been observed to be of high magnitude (~10 m/s), which was not evident during September. The alongshore (north-westerly) wind has been observed during July–September in the near coastal water that causes coastal to offshore moving Ekman mass transport (EMT). Similarly, the alongshore (north-easterly) wind has been observed during December in the southern tip of India and off Sri Lankan west coast. The strong zonal EMT (–1500 to –500 kg/m/s) has been observed in the southeast Arabian Sea during July–September 2017 and 2018 which is weak to moderate (> –500 kg/m/s) in NE monsoon months. Statistical analysis has been made between SST, wind speed and CC which shows significant correlation coefficient ( r > 0.6, p < 0.001). Hence, the present study confers that the alongshore wind and high wind speed regions are favourable to upwelling events and have been responsible for cooling of SST resulting in high productivity zones in the southeast Arabian Sea, which is important from the point of view of marine fishery and ecosystem assessment. Research Highlights During August 2018, high anomaly of chlorophyll concentration (CC) was observed (18.8 mg m –3 ) in south-eastern tip as a result of heavy rainfall, flood and discharge of nutrient rich riverine water from Kerala. Very severe cyclonic storm Ockhi results in high CC (2 mg m –3 ) in north-eastern Arabian Sea during December 2017. High magnitude of north-westerly wind (~ 7 m/s) in the southwest monsoon months (July–September) favours the upwelling event in south-eastern Arabian Sea. Single and multiple correlation analysis confirms the manifestation of low SST due to high magnitude of north-westerly winds for the enhancement in CC with significant correlation coefficient ( r > 0.6, p < 0.001).

Observation made to study the aerosol pattern retrieved from the 865nm central wavelength band of... more Observation made to study the aerosol pattern retrieved from the 865nm central wavelength band of Indian Remote Sensing satellite, IRS-P4 OCM (Oceansat-1) images. Aerosol concentration found higher during December (Northeast monsoon) over Bay of Bengal off Sundarbans with distinct plume. The aerosol optical depth (AOD) ranged 0.20.85 in the image of December 24, 2002. Decreasing-trend observed towards offshore with AOD ~0.45. To understand its link with biological productivity, the ocean surface chlorophyll retrieved from seasonal datasets during April, June, October and December 2002. December has shown very high chlorophyll >2.0mg/m, compared to other seasonal-months with aerosol plume from west to east, towards offshore. High wind speed (~6-8m/sec) and its direction played the role to move the aerosol towards offshore. Similar aerosol plumes observed during December 2003 and 2004.

Oceanologia, 2021

Abstract An intense bloom of Asterionellopsis glacialis (Family: Flagilariaceae; Class: Bacillari... more Abstract An intense bloom of Asterionellopsis glacialis (Family: Flagilariaceae; Class: Bacillariophyceae; Phylum: Ochrophyta) was observed in the near-shore waters at Kalpakkam, Tamil Nadu. Proliferation was supported by the favorable temperature, salinity, and nutrient levels in the coastal waters prevailing in the post-northeast monsoon period. BIOENV analysis and PCA confirmed salinity and nitrate as the key environmental factors responsible for the A. glacialis abundance. Cluster analysis further supported the distinct state of coastal water during the bloom with respect to physicochemical properties. The bloom period was floristically and faunistically richer than the pre- and post-bloom periods. The cluster and nMDS analysis confirmed the effects of bloom on plankton dynamics in the near-shore waters at Kalpakkam. The dominance of meroplankters especially, Cirripedia nauplii and Bivalvia larvae over Copepoda during the peak bloom period, was a significant result of the study. PCA ordination plot for the quantitative aspects of phytoplankton and zooplankton groups further supported the above observation. Among Copepoda, Cyclopoida and Poecilostomatoida (mostly carnivorous) exceeded the Calanoida (mostly herbivorous) during the peak bloom period unlike the reverse trend observed during other periods. Fish eggs and larvae were available in substantial numbers during the bloom which indicated their proliferation in the presence of the blooming diatom standing stock as the food material.

Regional Studies in Marine Science, 2021

Abstract To investigate the cruise samples among 14 stations, it was observed that high nutrients... more Abstract To investigate the cruise samples among 14 stations, it was observed that high nutrients concentration and phytoplankton abundance in stations 13 and 12 pose challenges to related ocean processes and physical parameters such as sea surface temperature (SST), wind action, currents, etc., in the Arabian Sea. Based on this, analysis and interpretation were carried out to compute the Ekman mass transport using satellite-derived wind stress curl and wind speed. Our results showed the upwelling, high nutrient fluxes, and chlorophyll-a bloom was observed in station 13 (8.426 μ M) and station 12 (7.196 μ M) with favorable sea surface temperature and wind condition. Our results revealed that the upwelling within these offshore stations 13 and 12 is much greater than in the surrounding regions. The phytoplankton density maxima were around 1874 cell L−1 and 1864 cell L−1 in stations 13 and 12 respectively. Totally 100 species of phytoplankton identified in the present study belonging to three different classes, 68 species of diatoms (Bacillariophyceae), 24 species of dinoflagellates (Dinophyceae), and 8 species of blue–green (Cyanophyceae). Throughout the cruise, the occurrence of the most dominant species was observed from class Bacillariophyceae. The phytoplankton diversity index, species richness, and evenness ranged from 2.13 to 3.79, 1.24 to 6.56, and 0.63 to 0.97 respectively. The observed highest value of chlorophyll-a and nutrients in station 13 was due to the high species composition observed during the cruise. The datasets were analyzed with a statistical approach using Canonical correspondence analysis (CCA) to find out the relationship between phytoplankton and physico-chemical parameters. The CCA results inferred that SST, salinity, nutrients have a higher influence on phytoplankton abundance. The correlation revealed chemical parameters such as nitrite, nitrate, silicate, IP, DO and ammonia showed significant positive correlations with biological productivity of chlorophyll-a concentrations and negative correlations with salinity and sea surface temperature along with Ekman mass transport.

Journal of Operational Oceanography, 2019

ABSTRACT A new conceptual framework, based on ocean bio-physical observations from different sate... more ABSTRACT A new conceptual framework, based on ocean bio-physical observations from different satellites, has been proposed to track fishing ground parameters to identify Potential Fishing Zones (PFZ) in the Bay of Bengal (BoB). The proposed technique also attempts to provide a short-term forecast based on feature propagation, even under cloudy conditions. The current study has been carried out to understand the link between possible fish catch availability and satellite-derived parameters such as chlorophyll concentration, sea surface temperature, sea-level anomaly, ocean surface currents and wind vectors. Net Ekman transport obtained from the upfront and downfront components of the wind relative to the frontal direction provides valuable information on the forecast of PFZ regions and its possible shift. Comparison of the identified PFZs with limited in situ fish catch data proves that the suggested approach holds the promise in improved monitoring of possible fish catch locations. The study provides a novel approach for the monitoring and short-term forecasting of PFZ even for cloud-contaminated regions by using all possible ocean information from space-based platforms.

Russian Journal of Marine Biology, 2019

An investigation was carried out at eleven different transect points from 0 to 10 km in the coast... more An investigation was carried out at eleven different transect points from 0 to 10 km in the coastal waters of Chandipur, Bay of Bengal (between 21°27′10.4″ N and 87°04′9.02″ E to 21°21′46.54″ N and 87°07′29.41″ E) during winter, summer and monsoon on hydrography and plankton diversity. Productivity in Chandipur coastal water was found to be higher during winter compared to summer and monsoon season. Chlorophyll concentration was 0.32 ± 0.35 mg/m3 in winter, 3.17 ± 0.12 mg/m3 in summer and 2.51 ± 0.16 mg/m3 in monsoon, respectively. Similarly, the average phytoplankton cell count for winter, summer and monsoon season was observed to be 26 618 ± 13 529 cell/L, 14 136 ± 8258 cell/L and 6909 ± 3769 cell/L. Nutrient ratio (N : Si : P) ranged between 5 : 0.1 : 1 to 30 : 0.2 : 1. Two-way ANOVA test (p ≤ 0.001) was tested and showed significant variation in the phytoplankton distribution. A total of 70 phytoplankton species belonging to 36 genera were identified, and Chandipur coastal water was found to be dominated by diatom species. Silicate concentration was comparatively low which could be attributed to the presence of diatoms in coastal water. Species diversity was observed to be maximum in winter (47 species) followed by summer (46 species) and monsoon (35 species) season.

International Journal of Remote Sensing, 2017

ABSTRACT The present study was carried out to find the variability of chlorophyll-a (chl-a) conce... more ABSTRACT The present study was carried out to find the variability of chlorophyll-a (chl-a) concentration, sea surface temperature (SST), and sea surface height anomalies (SSHa) during 2003–2014, covering the Bay of Bengal (BoB) and Arabian Sea (AS) waters. These parameters were linked with El Niño, La Niña, and Indian Ocean Dipole (IOD) years. The observed results during 2003–2014 were evaluated and it was found that the monthly mean value for 12-year data ranged as follows: chl-a (0.11–0.46 mg m−3), SST (27–31 °C), and SSHa (−0.2 to 20 cm). The annual mean range of chl-a for 12-year data was 0.1–0.23 mg m−3, the SST range was 27–28 °C, and the SSHa range was 2.14–13.91 cm. It has been observed that with the SST range of 27–28 °C and the SSHa range of 7–9 cm, the chl-a concentration enhanced to 0.20–0.23 mg m−3. With a higher SST range of 28–29 °C and with a positive SSHa range of 11–14 cm, the chl-a concentration appeared to be low (0.17–0.18 mgm−3). During normal years, SSHa was positive with the >5 to <10 cm range during the months of April–June, which coincided with an increase in SST, >2 to <4 °C. During the normal years, SSHa (>−0.2 to <−10 cm) was observed to be negative during October–December, with a decrease in SST (<3 °C) observed. The high monthly mean chl-a concentration (>0.3 to <0.5 mg m−3) was noticed during December–February in the BoB and AS. Compared to the BoB chl-a range (<0.4 mg m−3), a high chl-a concentration was observed in AS (>0.4 mg m−3). However, during the phenomenon years, the study area had experienced low chl-a (<0.2 mg m−3), high SST (>5 °C), and more positive SSHa (>10 to <20 cm) during January–March and October–December in AS and BoB. The present study infers that a positive IOD leads to low chl-a concentration (<2 mg m−3) and low primary productivity in AS. El Niño caused the down-welling process, it results in a low chl-a concentration (<1 mg m−3) in BoB and AS. La Niña caused the upwelling process, and it results in a high chl-a concentration (>2.0 mg m−3) in BoB and AS. In the recent past years (2003–2014), the intensity and frequency of El Niño, La Niña, and IOD have been increasing, evidenced with few studies, and have impacts on the Indian Ocean climate. Therefore, the influences of the relative changes of these phenomena on the BoB and AS need to be understood for productivity assessment and ocean state monitoring.