Coherent intraseasonal oscillations of ocean and atmosphere during the Asian Summer Monsoon

Sengupta, Debasis; Goswami, B. N.; Senan, Retish

doi:10.1029/2001gl013587

Cited by 231 publications

(166 citation statements)

References 21 publications

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“…The observed SST-precipitation quadrature phase relationship on intraseasonal timescales (Shinoda et al 1998;Senguta et al 2001) has suggested that interactive air-sea coupling represents an important process for MJO dynamics (Wang and Xie 1998). On the one hand, the (Senguta et al 2001;Waliser et al 2003), oceanic mixed-layer entrainment (Fu et al 2003;Saji et al 2006), and horizontal advection (Han et al 2007).…”

Section: Discussionmentioning

confidence: 99%

“…On the one hand, the (Senguta et al 2001;Waliser et al 2003), oceanic mixed-layer entrainment (Fu et al 2003;Saji et al 2006), and horizontal advection (Han et al 2007). On the other hand, the resultant intraseasonal SST anomaly feeds back to organize MJO convection and associated circulations through enhancing boundary-layer convergence (Wang and Xie 1998;Waliser et al 1999) and surface evaporation (Fu et al 2008).…”

Section: Discussionmentioning

confidence: 99%

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Multi-model MJO forecasting during DYNAMO/CINDY period

Lee

Hsu

et al. 2013

Clim Dyn

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The present study assesses the forecast skill of the Madden-Julian Oscillation (MJO) observed during the period of DYNAMO (Dynamics of the MJO)/CINDY (Cooperative Indian Ocean Experiment on Intraseasonal Variability in Year 2011) field campaign in the GFS (NCEP Global Forecast System), CFSv2 (NCEP Climate Forecast System version 2) and UH (University of Hawaii) models, and revealed their strength and weakness in forecasting initiation and propagation of the MJO. Overall, the models forecast better the successive MJO which follows the preceding event than that with no preceding event (primary MJO). The common modeling problems include too slow eastward propagation, the Maritime Continent barrier and weak intensity. The forecasting skills of MJO major modes reach 13, 25 and 28 days, respectively, in the GFS atmosphere-only model, the CFSv2 and UH coupled models. An equal-weighted multi-model ensemble with the CFSv2 and UH models reaches 36 days. Air-sea coupling plays an important role for initiation and propagation of the MJO and largely accounts for the skill difference between the GFS and CFSv2. A series of forecasting experiments by forcing UH model with persistent, forecasted and observed daily SST further demonstrate that: (1) air-sea coupling extends MJO skill by about 1 week; (2) atmosphere-only forecasts driven by forecasted daily SST have a similar skill as the coupled forecasts, which suggests that if the high-resolution GFS is forced with CFSv2 forecasted daily SST, its forecast skill can be much higher than its current level as forced with persistent SST; (3) atmosphere-only forecasts driven by observed daily SST reaches beyond 40 days. It is also found that the MJO-TC (Tropical Cyclone) interactions have been much better represented in the UH and CFSv2 models than that in the GFS model. Both the CFSv2 and UH coupled models reasonably well capture the development of westerly wind bursts associated with November 2011 MJO and the cyclogenesis of TC05A in the Indian Ocean with a lead time of 2 weeks. However, the high-resolution GFS atmosphere-only model fails to reproduce the November MJO and the genesis of TC05A at 2 weeks' lead. This result highlights the necessity to get MJO right in order to ensure skillful extended-range TC forecasting.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Multi-model MJO forecasting during DYNAMO/CINDY period

Lee

Hsu

et al. 2013

Clim Dyn

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“…These anomalies, in turn, generate further SST change through diabatic heating across the sea surface and generation of oceanic waves. A possibility of such air-sea interactions in the warm pool region has been reported for phenomena at intraseasonal timescale [Zhang and McPhaden, 2000;Shinoda and Hendon, 2001;Sengupta et al, 2001b;Saji et al, 2006;Han et al, 2007] and for interannual variations, such as the Indian Ocean dipole mode event [Saji et al, 1999;Webster et al, 1999;Murtugudde et al, 2000].…”

Section: Introductionmentioning

confidence: 99%

“…As responses to such significant ISV in the atmosphere, upper-ocean variability is also expected to have large variability at the intraseasonal time-scale. For example, Sengupta et al [2001b], Saji et al [2006], and Han et al [2007] demonstrate the possibility of the air-sea interaction in the eastern Indian Ocean at the intraseasonal timescale by analyzing observed and simulated data. Recent studies also reveal that multiscale air-sea interactions between intraseasonal and interannual variations are important processes in this key region [Rao and Yamagata, 2004;Shinoda and Han, 2005] as well as in the western tropical Pacific.…”

Section: Introductionmentioning

confidence: 99%

Intraseasonal meridional current variability in the eastern equatorial Indian Ocean

et al. 2008

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[1] Intraseasonal variability in meridional current in the eastern equatorial Indian Ocean is investigated by use of results from a high-resolution ocean general circulation model. Both the simulated and observed meridional current variability demonstrate energy peaks in two distinct time-scales; one in the biweekly (6-8 d) period above the thermocline and the other in lower frequency band (20-70 d) within the subsurface layer. In addition, the intraseasonal current variability can be seen even in the deep ocean at 2000 m and 4000 m depths. Composite analysis of the biweekly current field demonstrates that the horizontal structure is consistent with the one for the Mixed Rossby-gravity wave, with the phase speed and wavelength close to theoretical values of the Mixed Rossby-gravity wave at 15-d period. This meridional current variability shows large coherence with the local meridional wind stress, suggesting the upper-ocean responses to the local wind-forcing. A part of the energy of the biweekly variability penetrates into the deeper layer along the raypath of the 15-d Mixed Rossby-gravity wave, causing the intraseasonal variability observed in the current meter data at 4000 m depth. On the other hand, the lower frequency intraseasonal variability in the subsurface layer is also captured in the model simulation forced by climatological winds. Large barotropic energy conversion rate appears during boreal autumn and early winter in a region southeast of Sri Lanka, suggesting importance of instability due to the seasonally changing current systems to generate mesoscale eddy-like disturbances that result in the subsurface meridional current variability.

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“…The southern tropical Indian Ocean (STIO) features remarkable intraseasonal sea surface temperature (SST) variability as a result of ocean-atmosphere interaction between SST and strong atmospheric intraseasonal oscillations (ISOs) [1][2][3][4]. The eastward propagating Madden-Julian Oscillation (MJO), one of the most well-known ISOs, can affect the Indian Monsoon [5] and global climate [6,7] significantly.…”

Section: Introductionmentioning

confidence: 99%

The 30–50-Day Intraseasonal Oscillation of SST and Precipitation in the South Tropical Indian Ocean

Liang

Zhang

et al. 2018

Atmosphere

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Abstract:The Sea Surface Temperature (SST) in the South Tropical Indian Ocean (STIO) displays significant intraseasonal oscillation (ISO) in two regions. A striking 30-50-day ISO found over the east of thermocline ridge (Region A, 80-90 • E, 6-12 • S), as identified by the Empirical Mode Decomposition (EMD) method, is distinguished from the SST signature over the thermocline ridge (Region B, 52.5-65 • E, 6-13 • S). The 30-50-day ISO of SST in the Region A is active in March-May (MAM) and suppressed in September-November (SON). Meanwhile, a 30-50-day ISO of precipitation correlates with the SST over the Region A. SST leads precipitation by 10 days, implying a pronounced ocean-atmosphere interaction at the intraseasonal timescale, especially the oceanic feedback to the atmosphere during Madden-Julian Oscillation (MJO) events. Analysis on mechanism of the ISO manifests heat fluxes are critical to the development of the intraseasonal SST variability. The local thermocline in Region A, as the shallowest in MAM and the thickest in SON, is likely to modulate the strength of ISO and contribute to its sustainability. It suggests that thermocline plays a more important role in Region A than in Region B, leading to the difference between the two regions.

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Coherent intraseasonal oscillations of ocean and atmosphere during the Asian Summer Monsoon

Abstract: Abstract.The space-time evolution of the ocean and atmosphere associated with 1998-2000 monsoon intraseasonal oscillations (ISO) in the Indian Ocean and west Pacific is studied using validated sea surface temperature (

Cited by 231 publications

References 21 publications

Multi-model MJO forecasting during DYNAMO/CINDY period

Multi-model MJO forecasting during DYNAMO/CINDY period

Intraseasonal meridional current variability in the eastern equatorial Indian Ocean

The 30–50-Day Intraseasonal Oscillation of SST and Precipitation in the South Tropical Indian Ocean

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