Intraseasonal Variations in the Upper Equatorial Pacific Ocean prior to and during the 1997–98 El Niño

Kutsuwada, Kunio; McPhaden, Michael J.

doi:10.1175/1520-0485(2002)032<1133:ivitue>2.0.co;2

Cited by 45 publications

(41 citation statements)

References 51 publications

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“…Intraseasonal (30-90 days) Kelvin waves in the Pacific have received considerable attention (Enfield 1987;McPhaden and Taft 1988;Johnson 1993;Johnson and McPhaden 1993;Kessler et al 1995;Kessler and McPhaden 1995;Hendon et al 1998;Kutsuwada and McPhaden 2002;Zang et al 2002;Cravatte et al 2003;Roundy and Kiladis 2006) and thus provide a useful point of reference for examination of the meridional sea level structure. These waves are forced in the western and central Pacific by intraseasonal variations in the zonal wind stress that are associated with the MaddenJulian oscillation (MJO), but the dominant period of the Kelvin waves, as measured by thermocline depth spectra, is about 70 days, whereas the dominant period for zonal wind stress variations associated with the MJO is 40-50 days (Kessler et al 1995;Hendon et al 1998).…”

Section: A the Kelvin Wavementioning

confidence: 99%

“…2) are consistent with the previous studies showing more power at 50-90 day periods than at 30-50 day periods. There are few, if any, detailed accounts of the meridional structure of these prominent intraseasonal Kelvin waves, but Kutsuwada and McPhaden (2002) and Cravatte et al (2003) have tangentially addressed the meridional structure in attempting to determine the wave speed by fitting observed sea level variability at these periods to the wave-speed-dependent Gaussian profile of the classical theory.…”

Section: A the Kelvin Wavementioning

confidence: 99%

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Observations of the Dispersion Characteristics and Meridional Sea Level Structure of Equatorial Waves in the Pacific Ocean

Farrar

2008

Journal of Physical Oceanography

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Spectral techniques applied to altimetry data are used to examine the dispersion relation and meridional sea level structure of wavelike variability with periods of about 20 to 200 days in the equatorial Pacific Ocean. Zonal wavenumber-frequency power spectra of sea surface height, when averaged over about 7°S-7°N, exhibit spectral peaks near the theoretical dispersion curves of first baroclinic-mode equatorial Kelvin and Rossby waves. There are distinct, statistically significant ridges of power near the first and second meridional-mode Rossby wave dispersion curves. Sea level variability near the theoretical Kelvin wave and first meridional-mode Rossby wave dispersion curves is dominantly (but not perfectly) symmetric about the equator, while variability near the theoretical second meridional-mode Rossby wave dispersion curve is dominantly antisymmetric. These results are qualitatively consistent with expectations from classical or shear-modified theories of equatorial waves.The meridional structures of these modes resemble the meridional modes of equatorial wave theory, but there are some robust features of the meridional profiles that were not anticipated. The meridional sea level structure in the intraseasonal Kelvin wave band closely resembles the theoretically expected Gaussian profile, but sea level variability coherent with that at the equator is detected as far away as 11.75°S, possibly as a result of the forced nature of these Kelvin waves. Both first and second meridional-mode Rossby waves have larger amplitude in the Northern Hemisphere. The meridional sea level structure of tropical instability waves closely resembles that predicted by Lyman et al. using a model linearized about a realistic equatorial zonal current system.

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Section: A the Kelvin Wavementioning

confidence: 99%

Section: A the Kelvin Wavementioning

confidence: 99%

Observations of the Dispersion Characteristics and Meridional Sea Level Structure of Equatorial Waves in the Pacific Ocean

Farrar

2008

Journal of Physical Oceanography

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“…These Kelvin waves can then be instrumental in triggering El Niño events (McPhaden 1999(McPhaden , 2002Kessler and Kleeman 2000;Kutsuwada and McPhaden 2002;Zhang and Gottschalk 2002;Seo and Xue 2005). These analyses were mainly carried out using data from the TOGA-TAO array of moored buoys, that cover the equatorial Pacific, and measure temperature down to 500 m. Until recently, there were no deeper temperature data suitable for such large-scale analysis of intraseasonal variability, and no suitable salinity data at any depth, except from single isolated buoys (Cronin and McPhaden 1998).…”

Section: Introductionmentioning

confidence: 99%

Ocean temperature and salinity components of the Madden–Julian oscillation observed by Argo floats

2009

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New diagnostics of the Madden-Julian oscillation (MJO) cycle in ocean temperature and, for the first time, salinity are presented. The MJO composites are based on 4 years of gridded Argo float data from [2003][2004][2005][2006], and extend from the surface to 1400 m depth in the tropical Indian and Pacific Oceans. The MJO surface salinity anomalies are consistent with precipitation minus evaporation fluxes in the Indian Ocean, and with anomalous zonal advection in the Pacific. The Argo sea surface temperature and thermocline depth anomalies are consistent with previous studies using other data sets. The near-surface density changes due to salinity are comparable to, and partially offset, those due to temperature, emphasising the importance of including salinity as well as temperature changes in mixedlayer modelling of tropical intraseasonal processes. The MJO-forced equatorial Kelvin wave that propagates along the thermocline in the Pacific extends down into the deep ocean, to at least 1400 m. Coherent, statistically significant, MJO temperature and salinity anomalies are also present in the deep Indian Ocean.

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“…The MJO may be linked to a change of upper zonal wind in the tropical Atlantic associated with the NAO. The MJO is also considered a significant aspect of ENSO through its forcing of the equatorial ocean (e.g., Kutsuwada and McPhaden 2002). At the synoptic scale, energy originating at high latitudes, in upper-level westerly flow in the Pacific and Atlantic storm tracks, propagates into the tropics through Rossby wave dispersion.…”

Section: Tropical Convection and Its Two-way Interaction With The Glomentioning

confidence: 99%

Collaboration of the Weather and Climate Communities to Advance Subseasonal-to-Seasonal Prediction

Brunet

Shapiro

Hoskins

et al. 2010

Bull. Amer. Meteor. Soc.

188

131

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| iv) Utilization of subseasonal and seasonal predictions for social and economic benefits.These are particularly promising areas of research that will greatly accelerate realizing the common goals of WWRP and WCRP and in turn any Earthsystem prediction initiative that would embrace our research (Nobre 2010;Shapiro et al. 2010;Shukla et al. 2010). The advance of predictive skill of weather/ climate EPSs, promoted by the first of the four areas of collaboration, will depend crucially on progress in the other three areas. These are the most pressing issues to solve before achieving optimal utilization of EPSs and their applications. Because they lie at the intersection of weather and climate, these research priorities require the multidisciplinary, collaborative approach promoted by an Earth-system prediction initiative. SEAMLESS WEATHER/CLIMATE EPSS.A fundamental principle of seamless prediction is that the Earth system 1 exhibits a wide range of dynamical, physical, biological, and chemical interactions involving spatial and temporal variability continuously spanning all weather/climate scales. The traditional boundaries between weather and climate are artificial (Shapiro et al. 2010).As explained in Hurrell et al. (2009), for example, the slowly varying planetary-scale circulation preconditions the environment for the "fast acting" microscale and mesoscale processes of daily highimpact weather and regional climate. As an example, there is evidence that natural climate variations, such as ENSO and the North Atlantic Oscillation (NAO)/ northern annular mode, significantly alter the intensity, track, and frequency of extratropical and tropical cyclones and also affect decadal variability in tropical cyclones and the multidecadal drought in the Sahel region. Conversely, small-scale processes have significant upscale effects on large-scale circulation and on the interactions among the components of the global climate system.The challenge facing our scientific community is to improve the prediction of the spatial-temporal continuum of the interactions among weather, climate, and the Earth system. The most important aspect of the challenge is the chaotic nature of weather and climate predictability that needs to be characterized with probabilistic information.EPSs are widely used for weather and environmental (e.g., hydrological) prediction by operational services. Ensemble forecasts offer not only an estimate of the most probable future state of a system, but also a range of possible outcomes. Assessing how climate subseasonal-to-seasonal variations may alter the frequencies, intensities, and locations of highimpact events is a high priority for decision making. Many users are risk averse-more concerned with the probability of high-impact events than with the most probable future mean state. This makes the AFFILIATIONS: brunet-meteorological research division, environment Canada, dorval, Quebec, Canada; Shapiro-national Center for atmospheric research, boulder, Colorado, and Geophysical institute, university of berge...

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Intraseasonal Variations in the Upper Equatorial Pacific Ocean prior to and during the 1997–98 El Niño

Cited by 45 publications

References 51 publications

Observations of the Dispersion Characteristics and Meridional Sea Level Structure of Equatorial Waves in the Pacific Ocean

Observations of the Dispersion Characteristics and Meridional Sea Level Structure of Equatorial Waves in the Pacific Ocean

Ocean temperature and salinity components of the Madden–Julian oscillation observed by Argo floats

Collaboration of the Weather and Climate Communities to Advance Subseasonal-to-Seasonal Prediction

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