scholarly journals Modulation of Tropical Instability Wave Intensity by Equatorial Kelvin Waves

2016 ◽  
Vol 46 (9) ◽  
pp. 2623-2643 ◽  
Author(s):  
R. M. Holmes ◽  
L. N. Thomas
Keyword(s):  
Pacific Ocean ◽  
Kinetic Energy ◽  
Large Scale ◽  
Ocean Model ◽  
Equatorial Pacific ◽  
Kelvin Waves ◽  
Heat Fluxes ◽  
Instability Wave ◽  
Reynolds Stresses ◽  
Equatorial Pacific Ocean

AbstractTropical instability waves (TIWs) and equatorial Kelvin waves are dominant sources of intraseasonal variability in the equatorial Pacific Ocean, and both play important roles in the heat and momentum budgets of the large-scale flow. While individually they have been well studied, little is known about how these two features interact, although satellite observations suggest that TIW propagation speed and amplitude are modulated by Kelvin waves. Here, the influence of Kelvin waves on TIW kinetic energy (TIWKE) is examined using an ensemble set of 1/4° ocean model simulations of the equatorial Pacific Ocean. The results suggest that TIWKE can be significantly modified by 60-day Kelvin waves. To leading order, TIWs derive kinetic energy from the meridional shear and available potential energy of the background zonal currents, while losing TIWKE to friction and the radiation of waves. The passage of Kelvin waves disrupts this balance. Downwelling (upwelling) Kelvin waves induce decay (growth) in TIWKE through modifications to the background currents and the TIWs’ Reynolds stresses. These modulations in TIWKE affect eddy heat fluxes and the downward radiation of waves, with implications for the variability of SST and the energetics of abyssal flows in the eastern equatorial Pacific.

Surface heat fluxes in the Western Equatorial Pacific Ocean

1995 ◽  
Vol 13 (10) ◽  
pp. 1047-1053 ◽  
Author(s):  
N. C. Wells
Keyword(s):  
Heat Flux ◽  
Pacific Ocean ◽  
Latent Heat ◽  
Longwave Radiation ◽  
Surface Heat ◽  
Equatorial Pacific ◽  
Heat Fluxes ◽  
Equatorial Pacific Ocean ◽  
Net Heat Flux ◽  
Western Equatorial Pacific

Abstract. Estimates of the components of the surface heat flux in the Western Equatorial Pacific Ocean are presented for a 22-day period, together with a critical analysis of the errors. It is shown that the errors in latent heat, and solar and longwave radiation fluxes, dominate the net heat flux for this period. It is found that the net heat flux into the ocean over the 22-day period is not significantly different from zero. It is also demonstrated that because of the variability in daily averaged values of solar radiation and the latent heat of evaporation, a large number of independent flux measurements will be required to determine with confidence the climatological net heat flux in this region. The variability of latent fluxes over the 22-day period suggest that climatological estimates based on monthly mean observations may lead to a significant underestimate of the latent heat flux.

scholarly journals Effects of correcting salinity with altimeter measurements in an equatorial Pacific ocean model

2002 ◽  
Vol 107 (C12) ◽  
pp. SRF 2-1-SRF 2-14 ◽  
Author(s):  
Femke C. Vossepoel ◽  
Gerrit Burgers ◽  
Peter Jan van Leeuwen
Keyword(s):  
Pacific Ocean ◽  
Ocean Model ◽  
Equatorial Pacific ◽  
Equatorial Pacific Ocean

scholarly journals Effect of the Variability of Wind Forcing on ENSO Simulation in an OGCM: Case of Canonical and Protracted Event

2021 ◽  
Author(s):  
Anika Arora
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Surface Wind ◽  
Ocean Model ◽  
Equatorial Pacific ◽  
Wind Forcing ◽  
Water Volume ◽  
Equatorial Pacific Ocean ◽  
Warm Water Volume

Abstract This study is an attempt to understand the onset and evolution of canonical El Niño (~ 18–24 months; CE) and protracted El Niño (> greater than 3 years; PE) compared to the normal state (NS) in an ocean model. Indo-Pacific warm pool indicates higher values of SST before the onset of strong canonical El Niño compared to the normal state and protracted El Niño. The ocean model used in the study shows systematic SST bias in the Indo-Pacific Ocean with higher (cooler) values of temperature in western (eastern) Pacific during NS, CE, and PE exhibiting La Niña like conditions. The ocean model exhibits deeper thermocline depth in the western equatorial Pacific Ocean (PO) during PE and CE compared to NS indicating higher values of heat content (warm water volume). Despite the presence of higher warm water volume in the western PO before the onset of El Niño, the difference in the variability of surface wind forcing during the preceding months determines the type of El Niño. The interplay of surface wind forcing among the NS, PE, and CE states without altering the ocean state can modify the subsurface propagation in the equatorial Pacific Ocean. A change in longitudinal extent of upwelling Kelvin waves towards eastern PO along with the change in surface wind forcing decides the fate of El Niño in the eastern Pacific.

Intraseasonal variations of Ocean Heat Content in the tropical Indian and Pacific Ocean

2021 ◽  
Author(s):  
Ashneel Chandra ◽  
Noel Keenlyside ◽  
Lea Svendsen ◽  
Awnesh Singh
Keyword(s):  
Pacific Ocean ◽  
Heat Budget ◽  
Heat Content ◽  
Equatorial Pacific ◽  
Kelvin Waves ◽  
Ocean Heat Content ◽  
Equatorial Pacific Ocean ◽  
Budget Analysis ◽  
The Earth ◽  
The Indian Ocean

<p>The ocean heat content (OHC) is an important thermodynamical parameter in the Earth’s climate system as about 90% of the Earth’s Energy Imbalance (EEI) is stored in the ocean. It is therefore important to understand how this quantity varies on different timescales and how different thermodynamical and dynamical processes affect it. On intraseasonal timescales, there is a two-way interaction between the atmosphere and ocean whereby atmospheric forcing leads to ocean dynamics causing changes in OHC and OHC, in turn, possibly playing a role in affecting the intensity of the Madden-Julian Oscillation (MJO) through air-sea interactions. In this study, we focus on the variations of OHC in the equatorial Indian and Pacific Ocean on intraseasonal timescales. A heat budget analysis for the upper 100 m was performed using HYCOM Reanalysis for the period 2005 – 2015. The simple three-term heat budget comprised of a surface heat flux term <em>(Q),</em> an advection and adiabatic redistribution term <em>(ADV)</em> and finally a residual term <em>(RES)</em> to account for processes not resolved using the reanalysis product. When averaged over the equatorial Pacific Ocean, the heat budget analysis shows that the <em>ADV</em> and <em>RES</em> terms contributed the most to the ocean heat content tendency <em>(OHCT).</em> Zonal wind anomalies are observed to excite intraseasonal Kelvin waves in the equatorial Pacific Ocean. These Kelvin waves are associated with the eastward advection of intraseasonal OHC anomalies from the western Pacific warm pool to the central Pacific. This eastward propagation of intraseasonal OHC anomalies associated with Kelvin waves is seen to contribute to the warming leading to El Niño events such as the 2009 El Niño. In the Indian Ocean, intraseasonal OHC anomalies along the equator were seen to be in phase with the MJO as revealed by the negative intraseasonal outgoing longwave radiation (OLR) anomalies, while the off-equatorial intraseasonal OHC anomalies were seen to be out of phase with the MJO. Off-equatorial intraseasonal OHC anomalies in the Indian Ocean may be a useful parameter to investigate further as it may provide the residual heat energy for air-sea interactions for subsequent MJO events and hence improve subseasonal predictability.</p>

scholarly journals Effect of the Variability of Wind Forcing on ENSO Simulation in an OGCM: Case of Canonical and Protracted Event

2021 ◽  
Author(s):  
Anika Arora
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Surface Wind ◽  
Ocean Model ◽  
Equatorial Pacific ◽  
Wind Forcing ◽  
Water Volume ◽  
Equatorial Pacific Ocean ◽  
Warm Water Volume

Abstract This study is an attempt to understand the onset and evolution of canonical El Niño (~ 18–24 months; CE) and protracted El Niño (> greater than 3 years; PE) compared to the normal state (NS) in an ocean model. Indo-Pacific warm pool indicates higher values of SST before the onset of strong canonical El Niño compared to the normal state and protracted El Niño. The ocean model used in the study shows systematic SST bias in the Indo-Pacific Ocean with higher (cooler) values of temperature in western (eastern) Pacific during NS, CE, and PE exhibiting La Niña like conditions. The ocean model exhibits deeper thermocline depth in the western equatorial Pacific Ocean (PO) during PE and CE compared to NS indicating higher values of heat content (warm water volume). Despite the presence of higher warm water volume in the western PO before the onset of El Niño, the difference in the variability of surface wind forcing during the preceding months determines the type of El Niño. The interplay of surface wind forcing among the NS, PE, and CE states without altering the ocean state can modify the subsurface propagation in the equatorial Pacific Ocean. A change in longitudinal extent of upwelling Kelvin waves towards eastern PO along with the change in surface wind forcing decides the fate of El Niño in the eastern Pacific.

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