scholarly journals Simulation of north India Ocean circulation Using a simple barotropic model and Some sensitivity studies

MAUSAM ◽  
2021 ◽  
Vol 43 (4) ◽  
pp. 353-360
Author(s):  
S. K. BEHERA ◽  
H. J. SAWANT ◽  
P. S. SALVEKAR
Keyword(s):  
Indian Ocean ◽  
Wind Stress ◽  
Ocean Circulation ◽  
North Indian Ocean ◽  
North India ◽  
Wind Stress Curl ◽  
Meridional Component ◽  
Barotropic Model ◽  
The North ◽  
Sensitivity Studies

A non-divergent barotropic model has been formulated on the basis of splitting up method and used to study the circulation in the north Indian Ocean (1-26° N, 4~-99° E). The circulation was simulated for summer and winter seasons separately. It IS found that the model simulated the summer and winter calculation satisfactorily. It is also found that the meridional component of wind stress IS dominant over the zonal component in shaping the Somali current. Some sensitivity studies were also carried out and the results indicate the importance of wind stress curl.

scholarly journals Annual Sea Level Changes on the North American Northeast Coast: Influence of Local Winds and Barotropic Motions

2016 ◽  
Vol 29 (13) ◽  
pp. 4801-4816 ◽  
Author(s):  
Christopher G. Piecuch ◽  
Sönke Dangendorf ◽  
Rui M. Ponte ◽  
Marta Marcos
Keyword(s):  
Sea Level ◽  
Wind Stress ◽  
Ocean Circulation ◽  
Tide Gauge ◽  
Sea Level Changes ◽  
Tide Gauge Records ◽  
Barotropic Model ◽  
The North ◽  
Ocean Reanalyses ◽  
Coastal Sea

Abstract Understanding the relationship between coastal sea level and the variable ocean circulation is crucial for interpreting tide gauge records and projecting sea level rise. In this study, annual sea level records (adjusted for the inverted barometer effect) from tide gauges along the North American northeast coast over 1980–2010 are compared to a set of data-assimilating ocean reanalysis products as well as a global barotropic model solution forced with wind stress and barometric pressure. Correspondence between models and data depends strongly on model and location. At sites north of Cape Hatteras, the barotropic model shows as much (if not more) skill than ocean reanalyses, explaining about 50% of the variance in the adjusted annual tide gauge sea level records. Additional numerical experiments show that annual sea level changes along this coast from the barotropic model are driven by local wind stress over the continental shelf and slope. This result is interpreted in the light of a simple dynamic framework, wherein bottom friction balances surface wind stress in the alongshore direction and geostrophy holds in the across-shore direction. Results highlight the importance of barotropic dynamics on coastal sea level changes on interannual and decadal time scales; they also have implications for diagnosing the uncertainties in current ocean reanalyses, using tide gauge records to infer past changes in ocean circulation, and identifying the physical mechanisms responsible for projected future regional sea level rise.

scholarly journals Stochastic Forcing of the North Atlantic Wind-Driven Ocean Circulation. Part II: An Analysis of the Dynamical Ocean Response Using Generalized Stability Theory

2006 ◽  
Vol 36 (3) ◽  
pp. 316-334 ◽  
Author(s):  
Kettyah C. Chhak ◽  
Andrew M. Moore ◽  
Ralph F. Milliff ◽  
Grant Branstator ◽  
William R. Holland ◽  
...  
Keyword(s):  
Wind Stress ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Boundary Region ◽  
Western Boundary ◽  
Transient Growth ◽  
Wind Stress Curl ◽  
Stochastic Forcing ◽  
The North ◽  
The North Atlantic

Abstract As discussed in Part I of this study, the magnitude of the stochastic component of wind stress forcing is comparable to that of the seasonal cycle and thus will likely have a significant influence on the ocean circulation. By forcing a quasigeostrophic model of the North Atlantic Ocean circulation with stochastic wind stress curl data from the NCAR CCM3, it was found in Part I that much of the stochastically induced variability in the ocean circulation is confined to the western boundary region and some major topographic features even though the stochastic forcing is basinwide. This can be attributed to effects of bathymetry and vorticity gradients in the basic state on the system eigenmodes. Using generalized stability theory (GST), it was found in Part I that transient growth due to the linear interference of nonnormal eigenmodes enhances the stochastically induced variance. In the present study, the GST analysis of Part I is extended and it is found that the patterns of wind stress curl that are most effective for inducing variability in the model have their largest projection on the most nonnormal eigenmodes of the system. These eigenmodes are confined primarily to the western boundary region and are composed of long Rossby wave packets that are Doppler shifted by the Gulf Stream to have eastward group velocity. Linear interference of these eigenmodes yields transient growth of stochastically induced perturbations, and it is this process that maintains the variance of the stochastically induced circulations. Analysis of the large-scale circulation also reveals that the system possesses a large number of degrees of freedom, which has significant implications for ocean prediction. Sensitivity studies show that the results and conclusions of this study are insensitive and robust to variations in model parameters and model configuration.

scholarly journals Monthly-mean wind stress along the coast of the north Indian Ocean

1985 ◽  
Vol 94 (2) ◽  
pp. 129-137 ◽  
Author(s):  
Satish R Shetye ◽  
S Satheesh Chandra Shenoi ◽  
M K Antony ◽  
V Krishna Kumar
Keyword(s):  
Indian Ocean ◽  
Wind Stress ◽  
North Indian Ocean ◽  
The North

scholarly journals Design of Wave Glider Optimal Parameters Suitable for the Northwest Pacific Ocean, the North Indian Ocean, and the South China Sea

2021 ◽  
Vol 9 (4) ◽  
pp. 408
Author(s):  
Xi Chen ◽  
Mei Hong ◽  
Shiqi Wu ◽  
Kefeng Liu ◽  
Kefeng Mao
Keyword(s):  
Indian Ocean ◽  
South China Sea ◽  
South China ◽  
North Indian Ocean ◽  
Northwest Pacific ◽  
Northwest Pacific Ocean ◽  
The North ◽  
Wave Element ◽  
Wave Glider ◽  
The Northwest Pacific Ocean

To study the optimal design of Wave Glider parameters in the wave environment of the Northwest Pacific Ocean, the North Indian Ocean, and the South China Sea, the average velocity of a Wave Glider was taken as the evaluation criterion. Wave reanalysis data from ERA5 were used to classify the mean wave height and period into five types by the K-means clustering method. In addition, a dynamic model was used to simulate the influence of umbilical length, airfoil, and maximum limited angle on the velocity of the Wave Glider under the five types of wave element. The force of the wings was simulated using FLUENT as the model input. The simulation results show that (1) 7 m is the most suitable umbilical length; (2) a smaller relative thickness should be selected in perfect conditions; and (3) for the first type of wave element, 15° is the best choice for the maximum limited angle, and 20° is preferred for the second, third, and fourth types, while 25° is preferred for the fifth type.

Extended Prediction of North Indian Ocean Tropical Cyclones

2012 ◽  
Vol 27 (3) ◽  
pp. 757-769 ◽  
Author(s):  
James I. Belanger ◽  
Peter J. Webster ◽  
Judith A. Curry ◽  
Mark T. Jelinek
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
Tropical Cyclones ◽  
North Indian Ocean ◽  
Ensemble Prediction ◽  
Tropical Cyclone Genesis ◽  
Lead Times ◽  
Prediction System ◽  
Ensemble Prediction System ◽  
The North

Abstract This analysis examines the predictability of several key forecasting parameters using the ECMWF Variable Ensemble Prediction System (VarEPS) for tropical cyclones (TCs) in the North Indian Ocean (NIO) including tropical cyclone genesis, pregenesis and postgenesis track and intensity projections, and regional outlooks of tropical cyclone activity for the Arabian Sea and the Bay of Bengal. Based on the evaluation period from 2007 to 2010, the VarEPS TC genesis forecasts demonstrate low false-alarm rates and moderate to high probabilities of detection for lead times of 1–7 days. In addition, VarEPS pregenesis track forecasts on average perform better than VarEPS postgenesis forecasts through 120 h and feature a total track error growth of 41 n mi day−1. VarEPS provides superior postgenesis track forecasts for lead times greater than 12 h compared to other models, including the Met Office global model (UKMET), the Navy Operational Global Atmospheric Prediction System (NOGAPS), and the Global Forecasting System (GFS), and slightly lower track errors than the Joint Typhoon Warning Center. This paper concludes with a discussion of how VarEPS can provide much of this extended predictability within a probabilistic framework for the region.

scholarly journals Effect of tropical cyclones on the Stratosphere-Troposphere Exchange observed using satellite observations over north Indian Ocean

2016 ◽  
Author(s):  
M. Venkat Ratnam ◽  
S. Ravindra Babu ◽  
S. S. Das ◽  
Ghouse Basha ◽  
B. V. Krishnamurthy ◽  
...  
Keyword(s):  
Water Vapor ◽  
Indian Ocean ◽  
Tropical Cyclones ◽  
Lower Stratosphere ◽  
North Indian Ocean ◽  
Satellite Observations ◽  
Upper Troposphere ◽  
North West ◽  
The North ◽  
The Impact

Abstract. Tropical cyclones play an important role in modifying the tropopause structure and dynamics as well as stratosphere-troposphere exchange (STE) process in the Upper Troposphere and Lower Stratosphere (UTLS) region. In the present study, the impact of cyclones that occurred over the North Indian Ocean during 2007–2013 on the STE process is quantified using satellite observations. Tropopause characteristics during cyclones are obtained from the Global Positioning System (GPS) Radio Occultation (RO) measurements and ozone and water vapor concentrations in UTLS region are obtained from Aura-Microwave Limb Sounder (MLS) satellite observations. The effect of cyclones on the tropopause parameters is observed to be more prominent within 500 km from the centre of cyclone. In our earlier study we have observed decrease (increase) in the tropopause altitude (temperature) up to 0.6 km (3 K) and the convective outflow level increased up to 2 km. This change leads to a total increase in the tropical tropopause layer (TTL) thickness of 3 km within the 500 km from the centre of cyclone. Interestingly, an enhancement in the ozone mixing ratio in the upper troposphere is clearly noticed within 500 km from cyclone centre whereas the enhancement in the water vapor in the lower stratosphere is more significant on south-east side extending from 500–1000 km away from the cyclone centre. We estimated the cross-tropopause mass flux for different intensities of cyclones and found that the mean flux from stratosphere to troposphere for cyclonic stroms is 0.05 ± 0.29 × 10−3 kg m−2 and for very severe cyclonic stroms it is 0.5 ± 1.07 × 10−3 kg m−2. More downward flux is noticed in the north-west and south-west side of the cyclone centre. These results indicate that the cyclones have significant impact in effecting the tropopause structure, ozone and water vapour budget and consequentially the STE in the UTLS region.

scholarly journals Seasonal Nature and Trends of Tropical Cyclone Frequency and Intensity over the North Indian Ocean

2020 ◽  
Vol 15 (3) ◽  
pp. 526-534
Author(s):  
Abhisek Pal ◽  
Soumendu Chatterjee
Keyword(s):  
Time Series ◽  
Tropical Cyclone ◽  
Indian Ocean ◽  
Monsoon Season ◽  
North Indian Ocean ◽  
Post Monsoon ◽  
The North ◽  
Increasing Trend ◽  
Post Monsoon Season ◽  
Cyclone Frequency

Tropical cyclone (TC) genesis over the North Indian Ocean (NIO) region showed significant amount of both spatial and temporal variability.It was observed that the TC genesis was significantly suppressed during the monsoon (June-September) compared to pre-monsoon (March-May) and post-monsoon (October-December) season specifically in terms of severe cyclonic storms (SCS) frequency. The Bay of Bengal (BoB) was characterized by higher TC frequency but lower intensity compared to the Arabian Sea (AS). It was also observed that the TC genesis locations were shifted significantly seasonally.The movement of the TCs also portrayed some significant seasonal differences. The pre-monsoon and post-monsoon season was responsible for generating TCs with higher values of accumulated cyclone energy (ACE) compared to the monsoon. The time series of TC frequency showed a statistically significant decreasing trend whereas the time series of ACE showed astatistically significant increasing trend over the NIO.

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