NOPR Collection:

Observation and modeling approach in acoustic propagation in the shallow waters of southwest Bay of Bengal

2021-03-31T09:14:56Z

Title: Observation and modeling approach in acoustic propagation in the shallow waters of southwest Bay of Bengal Authors: Noufal, K K; Latha, G; Ramesh, R Abstract: The primary focus of the work was to estimate propagation loss and provide a quantitative estimate in transmission loss using sound propagation modeling in shallow waters of south west Bay of Bengal and also to validate the results with field measurements. KRAKEN normal mode sound propagation for a range independent environment in the frequency range of 850-1050 Hz was used for the simulation. The water depth was taken as 20 m. Transmission loss is estimated at four different ranges for a source at 10 m depth by using the essential acoustic input parameters. To validate results obtained through modeling, an experiment was conducted to measure transmission loss directly in an environment that closely matched with the model. The results of transmission loss estimated using the model was compared with the field measurements at short ranges. Page(s): 177-186

Metrics for the assessment of quantity and quality of the data by Argo floats

2021-03-31T09:13:06Z

Title: Metrics for the assessment of quantity and quality of the data by Argo floats Authors: Satish, R U V N; Bhaskar, T V S Udaya Abstract: Observing system or research initiative's foundation lies on reliable in situ data from sensors, which accurately tell about various key parameters that are being measured. Argo floats had brought huge amount of ocean observational in-situ data which is widely used from analysis to modelling. Present work describes a metrics for analyzing performance of sensors on Argo floats which can be used to assess the performance of float or set of floats as a whole. A set of new metrics like Total Data Return, Quality Data Returned and Quality Data Expected are proposed including the well-known Half-Life Period utilizing all of the Argo profile data. From the analysis, temperature and sensors performance is found to be more than 80 % and average Half-Life is found to be 1065 days. These metrics provide the overall performance of the floats, and can also be applied to other similar floats deployed by other countries as well as sensors fitted on other oceanic platforms. Page(s): 187-192

Wave attenuation by coastal heterospecific vegetation - modeling of synthetic plant meadows by Response Surface Methodology (RSM)

2021-03-31T09:11:33Z

Title: Wave attenuation by coastal heterospecific vegetation - modeling of synthetic plant meadows by Response Surface Methodology (RSM) Authors: Hemavathi, S; Manjula, R Abstract: Knowing the interactions between wave and aquatic vegetation is becoming increasingly important because of the phenomenon of plant-induced wave attenuation for the development of sustainable coastal management systems. Many of the wave-vegetation interaction studies focus on monotypic coastal plant meadows, while coastal plant meadows are typically heterospecific in nature, and the work on heterospecific plant meadows is still very limited. This research aims therefore to explain the heterospecific vegetation-wave interactions using a three-level four-factor surface response methodology (RSM) using controlled laboratory wave flume conditions. Heterospecific seagrass species, Cymodocea serrulata is physically simulated using synthetic plant mimics to establish a relationship between wave attenuation (E%) and four direct control factors, i.e. wave period (T), water depth (h), bed roughness factor (f) and plant density (N), using an empirical model. The model developed was evaluated using the methodology of variance analysis (ANOVA) and analyzed for the key and interaction effects of the parameters studied. The findings showed that both individually and in combination, all the parameters considered are significantly successful on E%. All model-based findings were compared with a new collection of experimental data, and validation tests were carried out. Page(s): 193-202

Texture and mineralogy of beach sediments of Chavara and Manavalakurichi, South India - A comparative analysis

2021-03-31T09:07:54Z

Title: Texture and mineralogy of beach sediments of Chavara and Manavalakurichi, South India - A comparative analysis Authors: Gayathri, G S; Sundararajan, M; Rejith, R G; Sreela, S R; Silambarasan, S; Pruthiviraj, N Abstract: Chavara and Manavalakurichi are the two important areas with heavy mineral deposits in India. Surface samples were collected from five locations, each from Chavara and Manavalakurichi, and were analyzed for their textural parameters and mineralogy. Sediments from both regions are characteristically fine and medium sand. Chavara (CH) sands are moderately well sorted, whereas Manavalakurichi (MK) sands are moderately sorted to moderately well sorted sediments. Linear discriminate functions (LDF) calculated using the textural parameters show deposition environments of aeolian and shallow marine. Ilmenite predominantly exists along with other heavy minerals such as zircon, sillimanite, rutile, monazite, leucoxene, and garnet. The heavy minerals show an increasing trend towards, but its grain size becomes finer and well sorted. The berm and upper foreshore regions shows high concentration of heavy minerals. Page(s): 203-211