Journal ArticleDOI
Convectively Coupled Equatorial Waves: Analysis of Clouds and Temperature in the Wavenumber–Frequency Domain
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In this article, a wavenumber-frequency spectrum analysis is performed for all longitudes in the domain 158S−158N using a long (;18 years) twice-daily record of satellite-observed outgoing longwave radiation (OLR), a good proxy for deep tropical convection.Abstract:
A wavenumber-frequency spectrum analysis is performed for all longitudes in the domain 158S‐158N using a long (;18 years) twice-daily record of satellite-observed outgoing longwave radiation (OLR), a good proxy for deep tropical convection. The broad nature of the spectrum is red in both zonal wavenumber and frequency. By removing an estimated background spectrum, numerous statistically significant spectral peaks are isolated. Some of the peaks correspond quite well to the dispersion relations of the equatorially trapped wave modes of shallow water theory with implied equivalent depths in the range of 12‐50 m. Cross-spectrum analysis with the satellite-based microwave sounding unit deep-layer temperature data shows that these spectral peaks in the OLR are ‘‘coupled’’ with this dynamical field. The equivalent depths of the convectively coupled waves are shallower than those typical of equatorial waves uncoupled with convection. Such a small equivalent depth is thought to be a result of the interaction between convection and the dynamics. The convectively coupled equatorial waves identified correspond to the Kelvin, n 5 1 equatorial Rossby, mixed Rossby-gravity, n 5 0 eastward inertiogravity, n 5 1 westward inertio-gravity (WIG), and n 5 2 WIG waves. Additionally, the Madden‐Julian oscillation and tropical depression-type disturbances are present in the OLR spectra. These latter two features are unlike the convectively coupled equatorial waves due to their location away from the equatorial wave dispersion curves in the wavenumber-frequency domain. Extraction of the different convectively coupled disturbances in the time‐longitude domain is performed by filtering the OLR dataset for very specific zonal wavenumbers and frequencies. The geographical distribution of the variance of these filtered data gives further evidence that some of the spectral peaks correspond to particular equatorial wave modes. The results have implications for the cumulus parameterization problem, for the excitation of equatorial waves in the lower stratosphere, and for extended-range forecasting in the Tropics.read more
Citations
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Journal ArticleDOI
Differences between Faster versus Slower Components of Convectively Coupled Equatorial Waves
Kazuaki Yasunaga,Brian E. Mapes +1 more
TL;DR: In this paper, the authors describe an analysis of multi-year satellite datasets that subdivide two halves (faster and slower) of the space-time spectral signal peaks corresponding to convectively coupled equatorial waves such as Kelvin and inertia-gravity waves.
Journal ArticleDOI
Response of CO2 and H2O fluxes in a mountainous tropical rainforest in equatorial Indonesia to El Niño events
Alexander Olchev,Andreas Ibrom,Oleg Panferov,Daria Gushchina,H. Kreilein,V. Popov,V. Popov,Pavel Propastin,Tania June,Abdul Rauf,Gode Gravenhorst,Alexander Knohl +11 more
TL;DR: In this article, the possible impact of El Nino-Southern Oscillation (ENSO) events on the main components of CO2 and H2O fluxes between the tropical rainforest and the atmosphere is investigated.
Journal ArticleDOI
Simulation of convectively coupled waves using WRF: a framework for assessing the effects of mesoscales on synoptic scales
Boualem Khouider,Ying Han +1 more
TL;DR: In this paper, the authors presented idealized simulations of convectively coupled equatorial waves (CCWs) using the weather research and forecast model in a horizontally limited domain consisting of a 4,500 km-wide square centered at the equator at moderate horizontal resolution of 10 km.
Journal ArticleDOI
Nonlinear optimal moisture perturbations as excitation of primary MJO events in a hybrid coupled climate model
TL;DR: In this article, the authors developed a new framework of methodology to investigate the nonlinear excitation of primary MJO event, of which the key achievement is the successful implementation of the conditional nonlinear optimal perturbation (CNOP).
References
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Journal ArticleDOI
Observations of the 40-50-day tropical oscillation - a review
Roland A. Madden,Paul R. Julian +1 more
TL;DR: The 40-50-day cyclone oscillation is the result of large-scale circulation cells oriented in the equatorial plane that move eastward from at least the Indian Ocean to the central Pacific as discussed by the authors.
Journal ArticleDOI
TOGA COARE: The Coupled Ocean-Atmosphere Response Experiment.
Peter J. Webster,Roger Lukas +1 more
TL;DR: In this article, the authors present a simulation of the western Pacific warm pool, the region of the warmest sea surface temperature in the open oceans, which coexists with the largest annual precipitation and latent heat release in the atmosphere.