Response of a high-resolution ocean circulation model to winds from different sources in simulating summer monsoon freshening in the North Bay of Bengal: A case study
“…3 a depicts the prevailing strong cLCSs all along the east coast of India during November. Thus, it further indicates that the cLCSs can also be used to understand the seasonal transport patterns of freshwater plumes in the coastal regions of BoB 74 , 75 . Figure 3 ( a ) Climatological LCSs for the November month (The colour bar in the figure represents the variation of climatological attraction strengths in lncρ) ( b ) November Climatological SSS (Sea Surface Salinity) over the Bay of Bengal for the period of 2015-present.…”
Lagrangian Coherent Structures (LCS) are the hidden fluid flow skeletons that provide meaningful information about the Lagrangian circulation. In this study, we computed the monthly climatological LCSs (cLCS) maps utilizing 24 years (1994–2017) of HYbrid Coordinate Ocean Model (HYCOM) currents and ECMWF re-analysis winds in the Bay of Bengal (BoB). The seasonal reversal of winds and associated reversal of currents makes the BoB dynamic. Therefore, we primarily aim to reveal the cLCSs associated with seasonal monsoon currents and mesoscale (eddies) processes over BoB. The simulated cLCS were augmented with the complex empirical orthogonal functions to confirm the dominant lagrangian transport pattern features better. The constructed cLCS patterns show a seasonal accumulation zone and the transport pattern of freshwater plumes along the coastal region of the BoB. We further validated with the satellite imagery of real-time oil spill dispersion and modelled oil spill trajectories that match well with the LCS patterns. In addition, the application of cLCSs to study the transport of hypothetical oil spills occurring at one of the active oil exploration sites (Krishna-Godavari basin) was described. Thus, demonstrated the accumulation zones in the BoB and confirmed that the persistent monthly cLCS maps are reasonably performing well for the trajectory prediction of pollutants such as oil spills. These maps will help to initiate mitigation measures in case of any occurrence of oil spills in the future.
“…3 a depicts the prevailing strong cLCSs all along the east coast of India during November. Thus, it further indicates that the cLCSs can also be used to understand the seasonal transport patterns of freshwater plumes in the coastal regions of BoB 74 , 75 . Figure 3 ( a ) Climatological LCSs for the November month (The colour bar in the figure represents the variation of climatological attraction strengths in lncρ) ( b ) November Climatological SSS (Sea Surface Salinity) over the Bay of Bengal for the period of 2015-present.…”
Lagrangian Coherent Structures (LCS) are the hidden fluid flow skeletons that provide meaningful information about the Lagrangian circulation. In this study, we computed the monthly climatological LCSs (cLCS) maps utilizing 24 years (1994–2017) of HYbrid Coordinate Ocean Model (HYCOM) currents and ECMWF re-analysis winds in the Bay of Bengal (BoB). The seasonal reversal of winds and associated reversal of currents makes the BoB dynamic. Therefore, we primarily aim to reveal the cLCSs associated with seasonal monsoon currents and mesoscale (eddies) processes over BoB. The simulated cLCS were augmented with the complex empirical orthogonal functions to confirm the dominant lagrangian transport pattern features better. The constructed cLCS patterns show a seasonal accumulation zone and the transport pattern of freshwater plumes along the coastal region of the BoB. We further validated with the satellite imagery of real-time oil spill dispersion and modelled oil spill trajectories that match well with the LCS patterns. In addition, the application of cLCSs to study the transport of hypothetical oil spills occurring at one of the active oil exploration sites (Krishna-Godavari basin) was described. Thus, demonstrated the accumulation zones in the BoB and confirmed that the persistent monthly cLCS maps are reasonably performing well for the trajectory prediction of pollutants such as oil spills. These maps will help to initiate mitigation measures in case of any occurrence of oil spills in the future.
“…Ratheesh et al. (2020) used SCATSat‐1 winds on the simulation of mesoscale and submesoscale variability of Ekman pumping for the BoB. Availability of the scatterometer winds in near real‐time is one of the advantages of using in the ocean model simulations.…”
Section: Introductionmentioning
confidence: 99%
“…Recently, Scatterometer Satellite-1 (SCAT-Sat-1), launched by the Indian Space Research Organization (ISRO) on September 26, 2016, operates from sun-synchronous polar orbit with Ku-band frequency and provides the winds data over the oceanic regions. Ratheesh et al (2020) used SCATSat-1 winds on the simulation of mesoscale and submesoscale variability of Ekman pumping for the BoB. Availability of the scatterometer winds in near real-time is one of the advantages of using in the ocean model simulations.…”
are the dominant modes of intraseasonal oscillation (ISO) in the tropical ocean. These processes are described by the 30-90 days fluctuations of low-level winds and convection over the Indian Ocean (IO) and propagating from the equator to the southeast Asian region. Strong intraseasonal variability of sea surface temperature (SST) during MISO events in the tropical IO is well established and modulated by air-sea interactions, which is confirmed by both observational studies (Duvel & Vialard, 2007;Sengupta & Ravichandran, 2001) as well as modeling studies (Achuthavarier & Krishnamurthy, 2011;Fu et al., 2002). Additionally, mixed layer depth (MLD), barrier layer thickness (BLT), and salinity stratification influence the amplitude of SST in intraseasonal variability (Li et al., 2017). Strong intraseasonal SST variability is associated with shallower MLD (Sengupta Abstract The performance of a new scatterometer SCATSat-1 winds with TropFlux on simulating the upper oceanic processes is analyzed over the northern Indian Ocean (IO) using Regional Ocean Modeling System (ROMS). The nutrient, phytoplankton, zooplankton, and detritus (NPZD) ecosystem model are included for studying the postcyclonic responses on biophysical parameters during three cyclones of different intensities (Maarutha, Mora, and Ockhi) in 2017. The SCATSat-1 (TropFlux) winds showed that skill scores are higher than 0.85 (0.66), and RMSEs are less than 0.48 (1.96) m s −1 with RAMA and OMNI buoy observations. Two SCATSat-1 wind experiments, one with 1/4° (SS-E) and other regridded wind to 1° (SSR-E), are compared with the simulation by TropFlux air-sea fluxes available at 1° (TF-E). Seasonal variability of simulated oceanic parameters in SS-E and SSR-E showed marginal improvement than TF-E as compared with observations. However, SSHA variability associated with downwelling Kelvin waves along the Bay of Bengal coast and southward east India coastal current (EICC) during postmonsoon is better simulated in SCATSat-1 experiments. All experiments showed observed intraseasonal oscillations (30-90 days) with higher variability in thermocline than upper layers at RAMA locations over the equator. On western (eastern) equatorial IO, the signals are stronger during boreal winter (premonsoon) and summer (monsoon). Drop in temperature up to 2.5°C during cyclonic events is reasonably better captured in SS-E and SSR-E than TF-E due to better accuracy in SCATSat-1 winds. During cyclones, surface chlorophyll attained a peak after 5-10 days of cyclone passage in SCATSat-1 winds experiments and satellite observations. Plain Language Summary Wind plays an important role in driving the surface circulation of the ocean. Therefore, winds with reasonable accuracy are required to simulate the ocean processes at different timescales through numerical modeling. The ocean simulations are useful for studying oceanic processes and air-sea interaction. The study evaluated the performance of a scatterometer wind and a reanalysis wind. The validations with satellite and in situ observat...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
