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
An All-Season Real-Time Multivariate MJO Index: Development of an Index for Monitoring and Prediction
TL;DR: A seasonally independent index for monitoring the Madden-Julian oscillation (MJO) is described in this paper, which is based on a pair of empirical orthogonal functions (EOFs) of the combined fields of near-equatorially averaged 850-hPa zonal wind, 200-hpa zonal winds, and satellite-observed outgoing longwave radiation (OLR) data.
Journal ArticleDOI
Madden‐Julian Oscillation
TL;DR: The Madden-Julian Oscillation (MJO) is the dominant component of the intraseasonal (30-90 days) variability in the tropical atmosphere as mentioned in this paper, which consists of large-scale coupled patterns in atmospheric circulation and deep convection with coherent signals in many other variables, all propagating eastward slowly through the portion of the Indian and Pacific oceans where the sea surface is warm.
Journal ArticleDOI
The quasi-biennial oscillation
Mark P. Baldwin,Lesley J. Gray,Timothy J. Dunkerton,Kevin Hamilton,Peter H. Haynes,William J. Randel,James R. Holton,M. J. Alexander,Isamu Hirota,Takeshi Horinouchi,Dylan B. A. Jones,J. S. Kinnersley,C. Marquardt,Kaoru Sato,M. Takahashi +14 more
TL;DR: The quasi-biennial oscillation (QBO) as discussed by the authors dominates the variability of the equatorial stratosphere (∼16-50 km) and is easily seen as downward propagating easterly and westerly wind regimes, with a variable period averaging approximately 28 months.
Journal ArticleDOI
Improved Climate Simulation by MIROC5: Mean States, Variability, and Climate Sensitivity
Masahiro Watanabe,Tatsuo Suzuki,Ryouta O'ishi,Yoshiki Komuro,Shingo Watanabe,Seita Emori,Seita Emori,Seita Emori,Toshihiko Takemura,Minoru Chikira,Tomoo Ogura,Miho Sekiguchi,Kumiko Takata,Dai Yamazaki,Tokuta Yokohata,Toru Nozawa,Hiroyasu Hasumi,Hiroaki Tatebe,Masahide Kimoto +18 more
TL;DR: A new version of the atmosphere-ocean general circulation model cooperatively produced by the Japanese research community, known as the Model for Interdisciplinary Research on Climate (MIROC), has recently been developed.
Book
Atmospheric and Oceanic Fluid Dynamics: Fundamentals and Large-Scale Circulation
TL;DR: A comprehensive unified treatment of atmospheric and oceanic fluid dynamics is provided in this paper, including rotation and stratification, vorticity, scaling and approximations, and wave-mean flow interactions and turbulence.
References
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Journal ArticleDOI
The Structure and Annual Variation of Antisymmetric Fluctuations of Tropical Convection and Their Association with Rossby-Gravity Waves.
Harry H. Hendon,Brant Liebmann +1 more
TL;DR: In this paper, the authors explored the signature of 4-5-day-period Rossby-gravity waves in the tropical convection field across the Indian and Pacific oceans and found that the convergence/divergence field of these waves in lower troposphere is anticipated to produce an antisymmetric fluctuation in tropical convections.
Journal ArticleDOI
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TL;DR: In this paper, a signal in the equatorial troposphere of the Eastern Pacific is detected, first in historical meteorological observations and then in more recent data, and a first baroclinic mode vertical structure is identified with this signal in separate analyses based on linear theory and complex empirical orthogonal functions.
Journal ArticleDOI
The Structure of Super Cloud Clusters Observed in 1-20 June 1986 and their Relationship to Easterly Waves
Journal ArticleDOI
The Global Climate of December 1992–February 1993. Part II: Large-Scale Variability across the Tropical Western Pacific during TOGA COARE
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Book ChapterDOI
Equilibrium Vs. Activation Control of Large-Scale Variations of Tropical Deep Convection
TL;DR: In this article, the authors highlight the distinction between processes which supply moisture or available energy over the depth of the convecting layer (equilibrium control), versus inhibition and initiation processes at low levels (activation control).