scholarly journals The Relationship between the Interannual Variation of the North Indian Ocean SST Induced by Surface Wind and ENSO during Boreal Summer

2005 ◽  
Vol 18 (12) ◽  
pp. 1942-1956 ◽  
Author(s):  
Motoki Nagura ◽  
Masanori Konda
Keyword(s):  
Indian Ocean ◽  
Interannual Variation ◽  
Temporal Change ◽  
Surface Wind ◽  
North Indian Ocean ◽  
Boreal Summer ◽  
The North ◽  
Second Mode ◽  
Sst Anomaly ◽  
The Relationship

Abstract The relationship between the interannual variation of the surface wind in the north Indian Ocean (0°–30°N, 30°–100°E) and El Niño–Southern Oscillation (ENSO) during boreal summer is investigated. The association of the surface wind with the sea surface temperature (SST) in the north Indian Ocean is evaluated. The NCEP–NCAR reanalysis, NOAA outgoing longwave radiation (OLR), and Reynolds SST data are used. The June–August mean of the surface wind anomaly over the north Indian Ocean is decomposed by EOF analysis, and two dominant modes are extracted. The first (second) mode shows the corresponding variation with the ENSO events maturing in the subsequent (previous) winter. The first mode has a large amplitude during the 1990s, while the amplitude of the second mode is large mainly during the 1980s. Such contrast of the amplitude of the two modes results in the temporal change of the surface wind–ENSO relationships between the two decades. The temporal characteristics of the first and second modes are consistent with those of convective variability in the eastern Indian Ocean and the Philippine Sea, respectively. The local thermal forcings associated with these two contrastive modes are compared with the time change of the SST anomaly. The thermal forcings are evaluated in terms of the latent heat flux and the Ekman heat transport. The thermal forcing of the first mode is consistent with a meridionally antisymmetric pattern of the SST anomaly during the 1990s, while that of the second mode is correlated with the basinwide SST anomaly during the 1980s. This result suggests that the temporal change is also found in the north Indian Ocean SST anomaly.

Delayed impact of Indian Ocean warming on the East Asian surface temperature variation in boreal summer

2021 ◽  
pp. 1-40
Author(s):  
Sunyong Kim ◽  
Jong-Seong Kug
Keyword(s):  
Indian Ocean ◽  
Surface Temperature ◽  
East Asian ◽  
Negative Relationship ◽  
North Indian Ocean ◽  
Ocean Warming ◽  
Boreal Summer ◽  
Indian Ocean Warming ◽  
Sst Anomaly ◽  
The Relationship

AbstractA significant negative relationship is found between the summer mean North Indian Ocean sea surface temperature (SST) and East Asian surface temperature anomalies. However, the relationship is distinctively different for each month and shows a time-lagged relation rather than a simultaneous one. The North Indian Ocean warming in June is responsible for significant cold anomalies over the Korea-Japan region that peak in July, exhibiting a 1-month leading role. The SST increase is closely associated with enhanced convective activity in the region in June, but the relationship between SST and resultant precipitation is substantially weakened afterward. This dependency of the precipitation sensitivity to SST anomaly is related to the climatological evolution of SST. The relatively low background SST due to the strengthening of southwesterly monsoons in the late summer can weaken the sensitivity of the precipitation to SST anomaly, yet the background SST in June is strong enough to maintain an increased sensitivity of precipitation. Thus, the Indian Ocean warming in June effectively drives atmospheric Kelvin waves that propagate into the equatorial western Pacific. In the western North Pacific (WNP), the resultant Kelvin wave-induced Ekman divergence triggers suppressed convection and anticyclonic anomalies. The WNP suppressed convection and anticyclonic anomalies move slowly northeastward until they are located near 20°N through the local air-sea interaction, and act as a source of the Pacific-Japan teleconnection. This teleconnection pathway brings clod surface anomalies to the Korea-Japan region due to the cyclonic circulation that causes the radiative and horizontal advection.

scholarly journals Use of scatterometer based surface vorticity fields in forecasting genesis of tropical cyclones over the north Indian Ocean

MAUSAM ◽  
2021 ◽  
Vol 62 (1) ◽  
pp. 61-72
Author(s):  
O. P. SINGH ◽  
HARVIR SINGH
Keyword(s):  
Indian Ocean ◽  
Tropical Cyclones ◽  
Lead Time ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
North Indian Ocean ◽  
The North ◽  
Peak Intensity ◽  
Ocean Surface Wind ◽  
Vorticity Anomaly

. Utilizing surface vorticity fields computed with the ocean surface wind speed and direction dataobtained from QuikSCAT, a study has been undertaken to investigate the increase in surface vorticity during the genesisphase of tropical cyclones over the north Indian Ocean. Six named tropical cyclones; Agni, Hibaru, Mala, Akash, Nargisand Phyan which formed over the region during 2004-2009 have been selected for this purpose. It has been found thatthere was a steep rise in scatterometer based surface vorticity before the formation of a cyclone in the cyclogenesisregion. The peak surface vorticity in the genesis region was observed on the day of intensification of the vortex to thedepression stage or a day earlier. However, the rising trend in the genesis region begins a few days before the formationof the system. Thus, the surface vorticity fields derived on the basis of scatterometer data can provide predictiveindication of the genesis of tropical cyclones over the Bay of Bengal and Arabian Sea with a lead time of 2-3 days. Usingthis technique it is possible to increase the lead time of pre-cyclone watch period over the north Indian Ocean. No relationship was found between the peak surface vorticity anomaly during the genesis phase and the surfacevorticity anomaly at the time of peak intensity of the system during its life cycle. In other words, the peak surfacevorticity anomaly during genesis phase does not provide any indication of future maximum intensity of the cyclone.

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.

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