Symmetric and Antisymmetric Convection Signals in the Madden–Julian Oscillation. Part I: Basic Modes in Infrared Brightness Temperature

2014 ◽  
Vol 71 (9) ◽  
pp. 3302-3326 ◽  
Author(s):  
Wen-wen Tung ◽  
Dimitrios Giannakis ◽  
Andrew J. Majda
Keyword(s):  
Brightness Temperature ◽  
Diurnal Cycle ◽  
Propagation Speed ◽  
Boreal Winter ◽  
Single Pair ◽  
Madden Julian Oscillation ◽  
Tropical Ocean ◽  
Symmetric Component ◽  
Toga Coare ◽  
Infrared Brightness

Abstract This work studies the significance of north–south asymmetry in convection associated with the 20–90-day Madden–Julian oscillation (MJO) propagating across the equatorial Indo-Pacific warm pool region. Satellite infrared brightness temperature data in the tropical belt for the period 1983–2006 were decomposed into components symmetric and antisymmetric about the equator. Using a recent nonlinear objective method called nonlinear Laplacian spectral analysis, modes of variability were extracted representing symmetric and antisymmetric features of MJO convection signals, along with a plethora of other modes of tropical convective variability spanning diurnal to interannual time scales. The space–time reconstruction of these modes during the 1992/93 Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) period is described in detail. In particular, the boreal winter MJO emerges as a single pair of modes in both symmetric and antisymmetric convection signals. Both signals originate in the Indian Ocean around 60°E. They coexist for all significant MJO events with a varying degree of relative importance, which is affected by ENSO. The symmetric signals tend to be suppressed when crossing the Maritime Continent, while the antisymmetric signals are not as inhibited. Their differences in peak phase and propagation speed suggest fundamental differences in the underlying mechanisms. The multiscale interactions between the diurnal, MJO, and ENSO modes of convection were studied. It was found that the symmetric component of MJO convection appears out of phase with the symmetric component of the diurnal cycle, while the antisymmetric component of MJO convection is in phase with the antisymmetric diurnal cycle. The former relationship likely breaks down during strong El Niño events, and both relationships likely break down during prolonged La Niña events.

scholarly journals Modeling Diurnal and Intraseasonal Variability of the Ocean Mixed Layer

2005 ◽  
Vol 18 (8) ◽  
pp. 1190-1202 ◽  
Author(s):  
D. J. Bernie ◽  
S. J. Woolnough ◽  
J. M. Slingo ◽  
E. Guilyardi
Keyword(s):  
Mixed Layer ◽  
Diurnal Cycle ◽  
Intraseasonal Variability ◽  
Western Pacific ◽  
Madden Julian Oscillation ◽  
Ocean Mixed Layer ◽  
Tropical Ocean ◽  
Toga Coare ◽  
The Impact ◽  
The Western Pacific

Abstract The intraseasonal variability of SST associated with the passage of the Madden–Julian oscillation (MJO) is well documented; yet coupled model integrations generally underpredict the magnitude of this SST variability. Observations from the Improved Meteorological Instrument (IMET) mooring in the western Pacific during the intensive observing period (IOP) of the Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) showed a large diurnal signal in SST that is modulated by the passage of the MJO. In this study, observations from the IOP of the TOGA COARE and a one-dimensional (1D) ocean mixed layer model incorporating the K-Profile Parameterization (KPP) vertical mixing scheme have been used to investigate the rectification of the intraseasonal variability of SST by the diurnal cycle and the implied impact of the absence of a representation of this process on the modeled intraseasonal variability in coupled GCMs. Analysis of the SST observations has shown that the increase of the daily mean SST by the diurnal cycle of SST accounts for about one-third of the magnitude of intraseasonal variability of SST associated with the Madden–Julian oscillation in the western Pacific warm pool. Experiments from the 1D model forced with fluxes at a range of temporal resolutions and with differing vertical resolution of the model have shown that to capture 90% of the diurnal variability of SST, and hence 95% of the intraseasonal variability of SST, requires a 3-h or better temporal resolution of the fluxes and a vertical grid with an upper-layer thickness of the order of 1 m. In addition to the impact of the representation of the diurnal cycle on the intraseasonal variability of SST, the strength of the mixing across the thermocline was found to be enhanced by the proper representation of the nighttime deep mixing in the ocean, implying a possible impact of the diurnal cycle onto the mean climate of the tropical ocean.

scholarly journals Kinematic and Precipitation Characteristics of Convective Systems Observed by Airborne Doppler Radar during the Life Cycle of a Madden–Julian Oscillation in the Indian Ocean

2014 ◽  
Vol 142 (4) ◽  
pp. 1385-1402 ◽  
Author(s):  
Nick Guy ◽  
David P. Jorgensen
Keyword(s):  
Indian Ocean ◽  
Doppler Radar ◽  
Convective System ◽  
Dynamical Structure ◽  
Madden Julian Oscillation ◽  
Tropical Ocean ◽  
Convective Systems ◽  
Toga Coare ◽  
Stratiform Precipitation ◽  
The Indian Ocean

Abstract This study presents characteristics of convective systems observed during the Dynamics of the Madden–Julian oscillation (DYNAMO) experiment by the instrumented NOAA WP-3D aircraft. Nine separate missions, with a focus on observing mesoscale convective systems (MCSs), were executed to obtain data in the active and inactive phase of a Madden–Julian oscillation (MJO) in the Indian Ocean. Doppler radar and in situ thermodynamic data are used to contrast the convective system characteristics during the evolution of the MJO. Isolated convection was prominent during the inactive phases of the MJO, with deepening convection during the onset of the MJO. During the MJO peak, convection and stratiform precipitation became more widespread. A larger population of deep convective elements led to a larger area of stratiform precipitation. As the MJO decayed, convective system top heights increased, though the number of convective systems decreased, eventually transitioning back to isolated convection. A distinct shift of echo top heights and contoured frequency-by-altitude diagram distributions of radar reflectivity and vertical wind speed indicated that some mesoscale characteristics were coupled to the MJO phase. Convective characteristics in the climatological initiation region (Indian Ocean) were also apparent. Comparison to results from the Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) in the western Pacific indicated that DYNAMO MCSs were linearly organized more parallel to the low-level shear and without strong cold pools than in TOGA COARE. Three-dimensional MCS airflow also showed a different dynamical structure, with a lack of the descending rear inflow present in shear perpendicularly organized TOGA COARE MCSs. Weaker, but deeper updrafts were observed in DYNAMO.

A Multiscale Model for the Intraseasonal Impact of the Diurnal Cycle over the Maritime Continent on the Madden–Julian Oscillation

2016 ◽  
Vol 73 (2) ◽  
pp. 579-604 ◽  
Author(s):  
Andrew J. Majda ◽  
Qiu Yang
Keyword(s):  
Diurnal Cycle ◽  
Numerical Models ◽  
Multiscale Model ◽  
Boreal Winter ◽  
Madden Julian Oscillation ◽  
Maritime Continent ◽  
Upper Troposphere ◽  
Planetary Scale ◽  
Baroclinic Modes ◽  
Huge Challenge

Abstract The eastward-propagating Madden–Julian oscillation (MJO) typically exhibits complex behavior during its passage over the Maritime Continent, sometimes slowly propagating eastward and other times stalling and even terminating there with large amounts of rainfall. This is a huge challenge for present-day numerical models to simulate. One possible reason is the inadequate treatment of the diurnal cycle and its scale interaction with the MJO. Here these two components are incorporated into a simple self-consistent multiscale model that includes one model for the intraseasonal impact of the diurnal cycle and another one for the planetary/intraseasonal circulation. The latter model is forced self-consistently by eddy flux divergences of momentum and temperature from a model for the diurnal cycle with two baroclinic modes, which capture the intraseasonal impact of the diurnal cycle. The MJO is modeled as the planetary-scale circulation response to a moving heat source on the synoptic and planetary scales. The results show that the intraseasonal impact of the diurnal cycle during boreal winter tends to strengthen the westerlies (easterlies) in the lower (upper) troposphere in agreement with the observations. In addition, the temperature anomaly induced by the intraseasonal impact of the diurnal cycle can cancel that from the symmetric–asymmetric MJO with convective momentum transfer, yielding stalled or suppressed propagation of the MJO across the Maritime Continent. The simple multiscale model should be useful for the MJO in observations or more complex numerical models.

scholarly journals Embedding a One-column Ocean Model (SIT 1.06) in the Community Atmosphere Model 5.3 (CAM5.3; CAM5–SIT v1.0) to Improve Madden–Julian Oscillation Simulation in Boreal Winter

2021 ◽  
Author(s):  
Yung-Yao Lan ◽  
Huang-Hsiung Hsu ◽  
Wan-Ling Tseng ◽  
Li-Chiang Jiang
Keyword(s):  
Mixed Layer ◽  
Diurnal Cycle ◽  
Ocean Model ◽  
Boreal Winter ◽  
Ocean Temperature ◽  
Vertical Resolution ◽  
Madden Julian Oscillation ◽  
Oceanic Mixed Layer ◽  
Sit Model ◽  
Community Atmosphere Model

Abstract. The effect of the air–sea interaction on the Madden–Julian Oscillation (MJO) was investigated using the one-column ocean model Snow–Ice–Thermocline (SIT 1.06) embedded in the Community Atmosphere Model 5.3 (CAM5.3; hereafter CAM5–SIT v1.0). The SIT model with 41 vertical layers was developed to simulate sea surface temperature (SST) and upper-ocean temperature variations with a high vertical resolution that resolves the cool skin and diurnal warm layer and the upper oceanic mixed layer. A series of 30-year sensitivity experiments were conducted in which various model configurations (e.g., coupled versus uncoupled, vertical resolution and depth of the SIT model, coupling domains, and absence of the diurnal cycle) were considered to evaluate the effect of air–sea coupling on MJO simulation. Most of the CAM5–SIT experiments exhibited higher fidelity than the CAM5-alone experiment in characterizing the basic features of the MJO such as spatiotemporal variability and the eastward propagation in boreal winter. The overall MJO simulation performance of CAM5–SIT benefited from (1) better resolving the fine structure of upper-ocean temperature and therefore the air–sea interaction that resulted in more realistic intraseasonal variability in both SST and atmospheric circulation and (2) the adequate thickness and vertical resolution of the oceanic mixed layer. The sensitivity experiments demonstrated the necessity of coupling the tropical eastern Pacific in addition to the tropical Indian Ocean and the tropical western Pacific. Enhanced MJO could be obtained without considering the diurnal cycle in coupling.

The MJO and Air–Sea Interaction in TOGA COARE and DYNAMO

2015 ◽  
Vol 28 (2) ◽  
pp. 597-622 ◽  
Author(s):  
Simon P. de Szoeke ◽  
James B. Edson ◽  
June R. Marion ◽  
Christopher W. Fairall ◽  
Ludovic Bariteau
Keyword(s):  
Heat Flux ◽  
Surface Wind ◽  
Surface Flux ◽  
Active Phase ◽  
Turbulent Heat ◽  
Madden Julian Oscillation ◽  
Tropical Ocean ◽  
Surface Evaporation ◽  
Toga Coare ◽  
The Mean

Abstract Dynamics of the Madden–Julian Oscillation (DYNAMO) and Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) observations and reanalysis-based surface flux products are used to test theories of atmosphere–ocean interaction that explain the Madden–Julian oscillation (MJO). Negative intraseasonal outgoing longwave radiation, indicating deep convective clouds, is in phase with increased surface wind stress, decreased solar heating, and increased surface turbulent heat flux—mostly evaporation—from the ocean to the atmosphere. Net heat flux cools the upper ocean in the convective phase. Sea surface temperature (SST) warms during the suppressed phase, reaching a maximum before the onset of MJO convection. The timing of convection, surface flux, and SST is consistent from the central Indian Ocean (70°E) to the western Pacific Ocean (160°E). Mean surface evaporation observed in TOGA COARE and DYNAMO (110 W m−2) accounts for about half of the moisture supply for the mean precipitation (210 W m−2 for DYNAMO). Precipitation maxima are an order of magnitude larger than evaporation anomalies, requiring moisture convergence in the mean, and on intraseasonal and daily time scales. Column-integrated moisture increases 2 cm before the convectively active phase over the Research Vessel (R/V) Roger Revelle in DYNAMO, in accordance with MJO moisture recharge theory. Local surface evaporation does not significantly recharge the column water budget before convection. As suggested in moisture mode theories, evaporation increases the moist static energy of the column during convection. Rather than simply discharging moisture from the column, the strongest daily precipitation anomalies in the convectively active phase accompany the increasing column moisture.

scholarly journals Diversity of the Global Teleconnections Associated with the Madden–Julian Oscillation

2021 ◽  
Vol 34 (1) ◽  
pp. 397-414
Author(s):  
Guosen Chen
Keyword(s):  
Rossby Wave ◽  
Potential Vorticity ◽  
Wave Train ◽  
Boreal Winter ◽  
Madden Julian Oscillation ◽  
The Pacific ◽  
Weather And Climate ◽  
Baroclinic Model ◽  
Rossby Wave Train ◽  
Upper Level

AbstractA recent study has revealed that the Madden–Julian oscillation (MJO) during boreal winter exhibits diverse propagation patterns that consist of four archetypes: standing MJO, jumping MJO, slow eastward propagating MJO, and fast eastward propagating MJO. This study has explored the diversity of teleconnection associated with these four MJO groups. The results reveal that each MJO group corresponds to distinct global teleconnections, manifested as diverse upper-tropospheric Rossby wave train patterns. Overall, the teleconnections in the fast and slow MJO are similar to those in the canonical MJO constructed by the real-time multivariate MJO (RMM) indices, while the teleconnections in the jumping and standing MJO generally lose similarities to those in the canonical MJO. The causes of this diversity are investigated using a linearized potential vorticity equation. The various MJO tropical heating patterns in different MJO groups are the main cause of the diverse MJO teleconnections, as they induce assorted upper-level divergent flows that act as Rossby-wave sources through advecting the background potential vorticity. The variation of the Asian jet could affect the teleconnections over the Pacific jet exit region, but it plays an insignificant role in causing the diversity of global teleconnections. The numerical investigation with a linear baroclinic model shows that the teleconnections can be interpreted as linear responses to the MJO’s diabatic heating to various degrees for different MJO groups, with the fast and slow MJO having higher linear skill than the jumping and standing MJO. The results have broad implications in the MJO’s tropical–extratropical interactions and the associated impacts on global weather and climate.

scholarly journals Efficient radiative transfer model for thermal infrared brightness temperature simulation in cloudy atmospheres

2020 ◽  
Vol 28 (18) ◽  
pp. 25730
Author(s):  
Wenwen Li ◽  
Feng Zhang ◽  
Yi-Ning Shi ◽  
Hironobu Iwabuchi ◽  
Mingwei Zhu ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Brightness Temperature ◽  
Thermal Infrared ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Infrared Brightness

scholarly journals Variability of Warm-Season Cloud Episodes over East Asia Based on GMS Infrared Brightness Temperature Observations

2005 ◽  
Vol 133 (6) ◽  
pp. 1478-1500 ◽  
Author(s):  
Chung-Chieh Wang ◽  
George Tai-Jen Chen ◽  
Richard E. Carbone
Keyword(s):  
East Asia ◽  
Brightness Temperature ◽  
Intraseasonal Variability ◽  
Warm Season ◽  
Propagation Speed ◽  
Regional Variability ◽  
Mountain Areas ◽  
Time Space ◽  
Geostationary Meteorological Satellite ◽  
Temperature Observations

Abstract The present study has used the Geostationary Meteorological Satellite (GMS) IR brightness temperature observations to investigate the regional and intraseasonal variability of east Asian warm-season cloud/precipitation episodes (in distance–time space) due to land–sea contrast and latitudinal effects. The data period was May–August 1998–2001, and harmonic analysis was employed as the major tool for analysis. The full domain of study (20°–40°N, 95°–145°E) was divided into northern and southern zones, and into eastern and western sectors, and statistics of episodes in each subregion were derived and compared. For latitudinal effects, episodes were found to be significantly larger in span and duration in northern (30°–40°N) than in southern (20°–30°N) zones. In the northern zone, the propagation characteristics were also stronger and remain evident even in midsummer, while episodes south of 30°N reversed in direction and traveled westward in July and August. For land–sea contrast, the May–August transition over land (western sector, 95°–120°E) was mainly characterized by an increase in diurnal activities, while that over ocean (eastern sector, 120°–145°E) was characterized by decreased overall activities instead. Over the land itself, significant regional variability also existed, with strongest diurnal signals over the eastern Tibetan Plateau near 100°E, and increased diurnal activities over mountain areas in southeastern China since June. Between the two bands, near 107°E, semidiurnal signals were relatively strong and became dominant in June. This double-peaked structure in the diurnal cycle resulted from overlying signals of convection propagating eastward off the plateau with those induced locally in late afternoon, and the phenomenon was more evident in May–June. Over the ocean, on the other hand, both diurnal and semidiurnal waves had small amplitudes, and the regional variability was much weaker. For intraseasonal transition, the number of large episodes was reduced from May through July, as was mean propagation speed. In August, however, some larger events started to reappear over east Asia.

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