Oscillations & Dipoles
Earth's ocean and atmosphere interact in countless ways. A striking example is the El Niño Southern Oscillation (ENSO). "El Niño" is widely recognized but what is the "Southern Oscillation"? It's the coupled system where neither the ocean nor the atmosphere is clearly the dominant driving force.
ENSO is just one of many such oscillations that occur naturally over different times and regions. Each varies among three phases; for example, a neutral ENSO means normal conditions, while El Niño and La Niña are warming and cooling phases, respectively.
El Niño conditions were first documented in the year 1525. The Indian Ocean Dipole (IOD), however, has only been recognized for about two decades. Better understanding the IOD's impact on weather – including the monsoon of South Asia - is crucial. This is a challenge because ocean-atmosphere oscillations and dipoles are erratic in strength, timing, and notoriously difficult to predict.
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- Chacko, N. and Jayaram, C. (2021). Response of the Bay of Bengal to super cyclone Amphan examined using synergistic satellite and in-situ observations, Oceanologia, doi: 10.1016/j.oceano.2021.09.006.
- Mandal, A., Chaudhary, A., Agarwal, N., and Sharma, R. (2021). Sub-Surface Ocean Structure from Satellite Surface Observations in the North Indian Ocean, Marine Geodesy, doi: 10.1080/01490419.2021.1974132.
- Nyadjro, E. (2021). Impacts of the 2019 Strong IOD and Monsoon Events on Indian Ocean Sea Surface Salinity, Remote Sens. Earth Syst. Sci., doi: 10.1007/s41976-021-00054-1.
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- Lekha, J.S., Lucas, A., Sukhatme, J., Joseph, J., Ravichandran, M., Kumar, N. S., Farrar, J.T., and Sengupta, D. (2020). Quasi-Biweekly Mode of the Asian Summer Monsoon Revealed in Bay of Bengal Surface Observations, J. Geophys. Res. Oceans, 125(12), e2020JC016271, doi: 10.1029/2020JC016271.
- Yi, D., Melnichenko, O., Hacker, P., and Potemra, J. (2020). Remote Sensing of Sea Surface Salinity Variability in the South China Sea, J. Geophys. Res. Oceans, 125(12), e2020JC016827, doi: 10.1029/2020JC016827.
- Greaser, S., Subrahmanyam, B., Trott, C., and Roman-Stork, H. (2020). Interactions Between Mesoscale Eddies and Synoptic Oscillations in the Bay of Bengal During the Strong Monsoon of 2019, J. Geophys. Res. Oceans, 125(10), e2020JC016772, doi: 10.1029/2020JC016772.
- Hackert, E., Kovach, R.M., Molod, A., Vernieres, G., Borovikov, A., Marshak, J., and Chang, Y. (2020). Satellite Sea Surface Salinity Observations Impact on El Niño/Southern Oscillation Predictions: Case Studies From the NASA GEOS Seasonal Forecast System, J. Geophys. Res.-Oceans, 125(4), doi: 10.1029/2019JC015788.
- Molod, A., Hackert, E., Akella, S., Andrews, L., Arnold, N., Barahona, D., Borovikov, A., Cullather, R., Chang, Y., and Kovach, R. (2020). An Introduction to the NASA GMAO Coupled Atmosphere-Ocean System - GEOS-S2S Version 3, NASA Technical Reports Server, GSFC-E-DAA-TN78568, 22 p.
- Roman‐Stork, H., Subrahmanyam, B., and Trott, C. (2020). Monitoring Intraseasonal Oscillations in the Indian Ocean Using Satellite Observations, J. Geophys. Res. Oceans, 125(2), e2019JC015891, doi: 10.1029/2019JC015891.
- Merryfield, W. et al. (2020). Current and Emerging Developments in Subseasonal to Decadal Prediction, Bull. Amer. Meteorol. Soc., doi: 10.1175/BAMS-D-19-0037.1.
- Roman-Stork, H., Subrahmanyam, B., and Murty, V. (2020). The Role of Salinity in the Southeastern Arabian Sea in Determining Monsoon Onset and Strength, J. Geophys. Res.-Oceans, 125(1), e2019JC015592, doi: 10.1029/2019JC015592.
- Zedler, S., Powell, B., Qiu, B., and Rudnick, D. (2019). Energy Transfer in the Western Tropical Pacific, Oceanography, 32(4), 136–145, doi: 10.5670/oceanog.2019.419.
- Trott, C.B., Subrahmanyam, B., Roman-Stork, H.L., Murty, V.S.N., and Gnanaseelan, C. (2019). Variability of Intraseasonal Oscillations and Synoptic Signals in Sea Surface Salinity in the Bay of Bengal, J. Climate, 32 (20), 6703-6728, doi: 10.1175/JCLI-D-19-0178.1.
- Hu, S., Zhang, Y., Feng, M., Du, Y., Sprintall, J., Wang, F., Hu, D., Xie, Q., and Chai, F. (2019). Interannual to Decadal Variability of Upper-Ocean Salinity in the Southern Indian Ocean and the Role of the Indonesian Throughflow, J. Climate, 32 (19), 6403-6421, doi: 10.1175/JCLI-D-19-0056.1.
- Zhu, J. and Kumar, A. (2019). Role of Sea Surface Salinity Feedback in MJO Predictability: A Study with CFSv2, J. Climate, 32, 5745-5759, doi: 10.1175/JCLI-D-18-0755.1.
- Shoup, C.G., Subrahmanyam, B., and Roman-Stork, H.L. (2019). Madden-Julian Oscillation-Induced Sea Surface Salinity Variability as Detected in Satellite-Derived Salinity, Geophys. Res. Lett., 46 (16), 9748-9756, doi: 10.1029/2019GL083694.
- Roman-Stork, H.L., Subrahmanyam, B., and Murty, V.S.N. (2019). Quasi-biweekly Oscillations in the Bay of Bengal in Observations and Model Simulations, Deep-Sea Res. Pt. II, 168, 104609, doi: 10.1016/j.dsr2.2019.06.017.
- Hackert, E.C., Kovach, R.M., Busalacchi, A.J., and Ballabrera-Poy, J. (2019). Impact of Aquarius and SMAP Satellite Sea Surface Salinity Observations on Coupled El Niño/Southern Oscillation Forecasts, J. Geophys. Res.-Oceans, 124 (7), 4546-4556, doi: 10.1029/2019JC015130.
- Trott, C. (2019). Upper Ocean Dynamics and Mixing in the Arabian Sea During Monsoons, Thesis (Ph.D.).
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- Sharma, N. (2018). Salinity from SMAP Radiometer can Monitor El Niño, J. Marine Syst., 187, 141-145, doi: 10.1016/j.jmarsys.2018.07.008.
- Subrahmanyam, B., Trott, C.B., and Murty, V.S.N. (2018). Detection of Intraseasonal Oscillations in SMAP Salinity in the Bay of Bengal, Geophys. Res. Lett., 45 (14), 7057-7065, doi: 10.1029/2018gl078662.
- Kohler, J., Serra, N., Bryan, F.M., Johnson, B.K., and Stammer, D. (2018). Mechanisms of Mixed-Layer Salinity Seasonal Variability in the Indian Ocean, J. Geophys. Res.-Oceans, 123 (1), 466-496, doi: 10.1002/2017JC013640.
- Fournier, S., Vialard, J., Lengaigne, M., Lee, T., Gierach, M.M., and Chaitanya, A.V.S. (2017). Modulation of the Ganges-Brahmaputra River Plume by the Indian Ocean Dipole and Eddies Inferred From Satellite Observations, J. Geophys. Res.-Oceans, 122 (12), 9591-9604, doi: 10.1002/2016JC011662.
- Burns, J.M., Subrahmanyam, B., and Murty, V.S.N. (2017). On the Dynamics of the Sri Lanka Dome in the Bay of Bengal, J. Geophys. Res.-Oceans, 122 (9), 7737-7750, doi: 10.1002/2017JC012986.
El Niño/Southern Oscillation (ENSO) has far reaching global climatic impacts and extending useful ENSO forecasts would have great societal benefit. However, one key variable that has yet to be fully exploited within coupled forecast systems is accurate estimation of near‐surface ocean salinity. Satellite sea surface salinity (SSS), combined with temperature, help to improve estimates of ocean density changes and associated near‐surface mixing. In this study, the authors assess the impact of satellite SSS observations for improving near‐surface dynamics within ocean reanalyses and how these initializations impact dynamical ENSO forecasts using NASA's coupled forecast system.
Hackert, E., Kovach, R.M., Molod, A., Vernieres, G., Borovikov, A., Marshak, J., and Chang, Y. (2020). Read the full paper.
Intraseasonal oscillations (ISOs) in the Indian Ocean play a significant role in determining the active (wet) and break (dry) cycles of the southwest monsoon rainfall. In this study, we use satellite‐derived precipitation, sea level anomalies, sea surface salinity, sea surface temperature, and surface winds to monitor the 30‐90‐day, 10‐20‐day, and 3‐7‐day ISOs, and how they influence local dynamics.
Roman‐Stork, H., Subrahmanyam, B., and Trott, C. (2020). Read the full paper.
As a dominant source of tropical variability, the Madden‐Julian oscillation (MJO) influences the ocean in many ways. One approach to observe the atmosphere‐ocean relationship is by examining sea surface salinity (SSS) due to direct freshening by MJO precipitation. The convectively enhanced (suppressed) phase of the MJO is associated with negative (positive) SSS anomalies that propagate eastward along the equatorial Indian and Pacific oceans. In this study, primary MJO events are identified, and their SSS signatures are compared for the first time across multiple satellite salinity products from 2010 to 2017.
Shoup, C.G., Subrahmanyam, B., and Roman-Stork, H.L. (2019). Read the full paper.
- What is El Nino?
- El Niño Theme Page
- El Niño/La Niña Observations
- El Niño
- El Niño & La Niña (El Niño-Southern Oscillation)
- El Niño & Other Oscillations
- NASA Stories
- Latest El Niño/La Niña Watch Data
- What Is the MJO, and Why Do We Care?
- How NASA Sees El Niño Effects From Space
- El Niño Affects More than 60 Million People
- NASA Examines Global Impacts of the 2015 El Niño
- 2015-2016 El Niño Triggered Disease Outbreaks Across Globe
- El Niño Fueled Rains Swamp South America
- El Niño Disrupts the Marine Food Web
- NASA Examines El Niño's Impact on Ocean's Food Source
- Severe 2015 Indonesian Fire Season Linked to El Niño Drought
- NASA Study Adds a Pinch of Salt to El Niño Models
- GEOS Sub-seasonal / Seasonal Project
- Meet ENSO's neighbor, the Indian Ocean Dipole
- Indian Ocean Dipole: What Is It and Why Is It Linked to Floods and Bushfires?
- The Indian Ocean Dipole – the Unsung Driver of Climatic Variability in East Africa
- Indian Ocean Dipole - Outlook
- Spate of Cyclones in the North Indian Ocean
- Indian Ocean Influences on Australian Climate
- Fire in Western Australia
- Unusual Monsoon Season Causes Flooding in India
- Smoke Blankets Borneo
- Food Shortages in the Greater Horn of Africa