Seasonal Behaviour of Mesoscale Eddy Trajectories in the North Indian Ocean Based on Satellite Altimetry

Pednekar, S.M.

doi:10.4236/ijg.2022.132006

Cited by 3 publications

(2 citation statements)

References 44 publications

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“…The former was based on the widely used deterministic approach, while the latter was based on the new stochastic-deterministic methodology and was significantly faster, by a factor of about 100. The models were set up to study the Lakshadweep Sea, which is known for its dramatic seasonal change of general circulation and intensive mesoscale dynamics, in particular around the southern tip of India [45]. The Lakshadweep Sea is an important source of food supply for India, Sri Lanka and the Maldives [46], and the efficiency of fishery is reliant on the smaller scale phenomena such as variations in the coastal current and upwellings.…”

Section: Discussionmentioning

confidence: 99%

A Comparison of Stochastic and Deterministic Downscaling in Eddy Resolving Ocean Modelling: The Lakshadweep Sea Case Study

Shapiro

González-Ondina

Salim

et al. 2023

JMSE

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This study compares the skills of two numerical models at the same horizontal resolution but based on different principles in representing meso- and sub-mesoscale ocean features. The first model, titled LD20-NEMO, was based on solving primitive equations of ocean dynamics. The second model, titled LD20-SDD, used a newer stochastic–deterministic downscaling (SDD) method. Both models had 1/20° resolution, the same meteo forcing, and used outputs from a data assimilating global model at 1/12° resolution available from Copernicus Marine Service (CMEMS). The LD20 models did not assimilate observational data but were physically aware of observations via the parent model. The LD20-NEMO only used a 2D set of data from CMEMS as the lateral boundary conditions. The LD20-SDD consumed the full 3D set of data from CMEMS and exploited the stochastic properties of these data to generate the downscaled field variables at higher resolution than the parent model. The skills of the three models were assessed against remotely sensed and in situ observations for the four-year period 2015–2018. The models showed similar skills in reproducing temperature and salinity, however the SDD version performed slightly better than the NEMO, and was more computationally efficient by a large margin.

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Section: Discussionmentioning

confidence: 99%

A Comparison of Stochastic and Deterministic Downscaling in Eddy Resolving Ocean Modelling: The Lakshadweep Sea Case Study

Shapiro

González-Ondina

Salim

et al. 2023

JMSE

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“…Still, the interactions between eddies and cyclones remain unknown. Eddies in the Mediterranean are ∼0.4–160 km in diameter (Stuhlmacher & Gade, 2020), which is considerably smaller than those of other ocean basins (the diameter of an eddy in the North Indian Ocean is ∼60–600 km; Pednekar, 2022). Cyclones have a maximum diameter of about 1,000 km, in contrast to synoptic North Atlantic systems, which have an expected maximum radius of 2,000–4,000 km.…”

Section: Introductionmentioning

confidence: 99%

Effects of Mesoscale Eddies on the Intensity of Cyclones in the Mediterranean Sea

2023

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The Mediterranean Sea is a relatively small basin with complex, unique topography and has long been considered a hot spot for cyclones. This sea is also characterized by intense mesoscale eddy activity. Although eddies are known to play important roles in cyclones in other regions, their effects on Mediterranean cyclones have not received much research attention. Here, we analyzed how warm‐core eddies (WCEs) and cold‐core eddies (CCEs) interact with Mediterranean cyclones. We considered eight Mediterranean cyclones: four that passed over WCEs and four that passed over CCEs. In general, we observed sudden drops in Mean Sea level (MSL) pressure and increased wind speeds over the WCEs and increased MSL pressure and decreased wind speeds above the CCEs. The temperature of the mixed layer decreased after a cyclone passed over an eddy, but this occurred to a lesser extent for CCEs. In contrast, mixed‐layer salinity decreased in the case of WCEs and increased in the case of CCEs. Larger amounts of precipitation were observed over WCEs, as compared to CCEs. The amount of precipitation associated with a WCE seemed to depend on the area and intensity of the eddy; larger, more intense eddies were associated with larger amounts of precipitation. Also, higher latent and sensible heat fluxes were observed over WCEs, as compared to CCEs, which could be responsible for the sudden increases in cyclone intensity. Interestingly, only one persistent WCE was found in the winter; whereas no persistent CCEs were found in the summer, calling for further case‐by‐case detailed investigation.

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Influence of mesoscale sea‐surface temperature structures on the Mediterranean cyclone Ianos in convection‐permitting simulations: Contributions of surface warming and cold wakes

Mishra,

Jangir,

Strobach

2024

Quart J Royal Meteoro Soc

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This study examined the influence of mesoscale sea‐surface temperature (SST) structures and warming on the tropical‐like cyclone Ianos. The controlling mechanisms were investigated using a set of sensitivity experiments with the non‐hydrostatic weather research and forecasting model. A simulation forced by a high‐resolution SST field from the mesoscale eddy‐resolving HYCOM reanalysis (CTRLH) performed better than a simulation forced by a coarse‐resolution SST field from Optimum Interpolation Sea Surface Temperature (OISST) in terms of precipitation, wind intensity, and landfall location. The suppression of mesoscale SST variability affected the cyclone's intensity, its path, and associated processes. This effect depends on the nature of the anomalies (cold/warm). The suppression of mesoscale SST forcing intensified wind and precipitation in the presence of cold anomalies, leading to a northwestward shift of the storm's path during its mature phase. The magnitude of these changes varied with the scale of smoothing (mesoscale SST). Compared to the CTRLH simulation, a simulation in which a 60‐km smoothing filter was applied to the SST field resulted in a cyclone centered slightly to the west (or delayed by 3–6 hr), which was further shifted to the west (or delayed) when the smoothing filter was increased to 150 km. The intensification of wind and precipitation may be associated with the reduction in the storm's cold wake, which would lead to enhanced turbulent fluxes and increased atmospheric water vapor. These results highlight the role of small‐scale air–sea interaction processes that could have a strong impact on Mediterranean cyclones' path and intensity.

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Seasonal Behaviour of Mesoscale Eddy Trajectories in the North Indian Ocean Based on Satellite Altimetry

Cited by 3 publications

References 44 publications

A Comparison of Stochastic and Deterministic Downscaling in Eddy Resolving Ocean Modelling: The Lakshadweep Sea Case Study

A Comparison of Stochastic and Deterministic Downscaling in Eddy Resolving Ocean Modelling: The Lakshadweep Sea Case Study

Effects of Mesoscale Eddies on the Intensity of Cyclones in the Mediterranean Sea

Influence of mesoscale sea‐surface temperature structures on the Mediterranean cyclone Ianos in convection‐permitting simulations: Contributions of surface warming and cold wakes

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