Tracking Pulses of the Madden–Julian Oscillation

Yoneyama, Kunio; Zhang, Chidong; Long, Charles

doi:10.1175/bams-d-12-00157.1

Cited by 372 publications

(476 citation statements)

References 66 publications

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“…(hereafter PH13) used scanning precipitation radar data obtained during the Dynamics of the Madden-Julian Oscillation (DYNAMO) [Yoneyama et al, 2013] campaign to conclude that observed convection transitions from a shallower mode during convectively suppressed periods to a deeper mode during active MJO periods in 3-7 days. That time scale is consistent with DYNAMO sounding network data analyzed by Johnson and Ciesielski [2013] and Ruppert and Johnson [2015].…”

Section: Introductionmentioning

confidence: 99%

Evolution of precipitation and convective echo top heights observed by TRMM radar over the Indian Ocean during DYNAMO

Powell

Houze

2015

JGR Atmospheres

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Radar data from the Tropical Rainfall Measuring Mission show the evolution of echo tops of convective elements over the Indian Ocean and Maritime Continent during the Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign of 2011-2012. Echo top heights exhibited a bimodal distribution wherein cumulonimbi of moderate height constituted a "congestus mode" while vertically extensive cumulonimbus made up a "deep mode." An intraseasonal time scale dominated variability in these modes from October to January over much of the Indian Ocean. Over the Maritime Continent, there was no clear intraseasonal signal in convective echo top heights. Where the intraseasonal oscillation was detected, radar echoes evolved from being dominated by the congestus mode to being characterized by more deep mode convection on time scales of less than 1 week. The areal coverage of congestus echoes began to increase 2-8 days prior to the rise in area of deep echoes. These satellite-derived results confirm that the time scale for convective deepening seen at individual DYNAMO observational sites is consistent with that of convection on the large scale over the Indian Ocean. Intraseasonal variability of zonal wind, temperature, and humidity as depicted by reanalysis is also consistent with that derived from rawinsonde observations during DYNAMO. Thus, the gradual buildup of convection as depicted by recent versions of the "discharge-recharge" hypothesis does not accurately describe evolutions of convection prior to MJO events observed during DYNAMO, although cloud moistening processes may still be relevant on time scales of 1 week or less.

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Section: Introductionmentioning

confidence: 99%

Evolution of precipitation and convective echo top heights observed by TRMM radar over the Indian Ocean during DYNAMO

Powell

Houze

2015

JGR Atmospheres

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“…Accordingly, a thorough understanding of key processes involved in the MJO initiation in the Indian Ocean is crucial for the improvement of climate model simulations and prediction. The Cooperative Indian Ocean experiment on intraseasonal variability (CINDY)/Dynamics of the MJO (DYNAMO) international field program was thus designed to collect in situ observations over the Indian Ocean to advance our understanding of the MJO initiation processes and to improve MJO prediction [5]. One of the primary targets of the field campaign is the role of air-sea interaction in MJO initiation, and thus oceanic processes are of the great importance because they are fundamental in determining sea surface temperature (SST).…”

Section: Introductionmentioning

confidence: 99%

Large-Scale Oceanic Variability Associated with the Madden-Julian Oscillation during the CINDY/DYNAMO Field Campaign from Satellite Observations

et al. 2013

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During the CINDY/DYNAMO field campaign (fall/winter 2011), intensive measurements of the upper ocean, including an array of several surface moorings and ship observations for the area around 75°E-80°E, Equator-10°S, were conducted. In this study, large-scale upper ocean variations surrounding the intensive array during the field campaign are described based on the analysis of satellite-derived data. Surface currents, sea surface height (SSH), sea surface salinity (SSS), surface winds and sea surface temperature (SST) during the CINDY/DYNAMO field campaign derived from satellite observations are analyzed. During the intensive observation period, three active episodes of large-scale convection associated with the Madden-Julian Oscillation (MJO) propagated eastward across the tropical Indian Ocean. Surface westerly winds near the equator were particularly strong during the events in late November and late December, exceeding 10 m/s. These westerlies generated strong eastward jets (>1 m/s) on the equator. Significant remote ocean responses to the equatorial westerlies were observed in both Northern and Southern Hemispheres in the central and eastern Indian Oceans. The anomalous SSH associated with strong eastward jets propagated eastward as an equatorial Kelvin wave and generated OPEN ACCESSRemote Sens. 2013, 5 2073 intense downwelling near the eastern boundary. The anomalous positive SSH then partly propagated westward around 4°S as a reflected equatorial Rossby wave, and it significantly influenced the upper ocean structure in the Seychelles-Chagos thermocline ridge about two months after the last MJO event during the field campaign. For the first time, it is demonstrated that subseasonal SSS variations in the central Indian Ocean can be monitored by Aquarius measurements based on the comparison with in situ observations at three locations. Subseasonal SSS variability in the central Indian Ocean observed by RAMA buoys is explained by large-scale water exchanges between the Arabian Sea and Bay of Bengal through the zonal current variation near the equator.

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“…Because of its broad impact on global weather, an understanding and accurate prediction of the MJO are important for potential improvements in extended-range forecasts (Gottschalck et al 2010;Vitart and Molteni 2010;Straub 2013). An international observation project, Cooperative Indian Ocean experiment on intraseasonal variability in the year 2011 (CINDY2011)/Dynamics of the Madden-Julian Oscillation (DYNAMO), was conducted over the Indian Ocean in 2011−2012 (Yoneyama et al 2013). The goal of the project was to improve our understanding of the onset mechanism and dynamics of the MJO and our ability to simulate and forecast the MJO in models.…”

Section: Introductionmentioning

confidence: 99%

Forecast Skill of Madden-Julian Oscillation Events in a Global Nonhydrostatic Model during the CINDY2011/DYNAMO Observation Period

Nasuno

2013

SOLA

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Near real-time week-long forecasts of Madden-Julian Oscillation (MJO) events using a regionally stretched global nonhydrostatic model were executed for the intensive observation period of the Cooperative Indian Ocean experiment on intraseasonal variability in the year 2011 (CINDY2011)/Dynamics of the MaddenJulian Oscillation (DYNAMO) field program. Forecast skill was validated using a real-time multivariate MJO (RMM) index and the forecast skill scores. The scores indicated a dependency on the initial MJO amplitude and phase. The errors were smaller in forecasts initialized in the active period of the MJO. A tendency for over-amplification (under-amplification) in forecasts initialized at phases 2−6 (7−8, 1) and earlier (delayed) phase propagation in the forecasts initialized at phases 1−3 (5−6) was identified. This was related to systematic positive biases in RMM1 and RMM2. The RMM1 error dominated in wind fields without significant contributions from convection. The RMM2 error grew in both convection and wind anomalies after the 5-day lead time, causing reduction in the MJO skill score. These results suggest that improvement in the basic model fields, i.e., large-scale circulations and a link between convection and dynamics, should extend the predictability of MJO in this framework.(Citation: Nasuno, T., 2013: Forecast skill of Madden-Julian Oscillation events in a global nonhydrostatic model during the CINDY2011/DYNAMO observation period. SOLA, 9, 69−73,

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Tracking Pulses of the Madden–Julian Oscillation

Cited by 372 publications

References 66 publications

Evolution of precipitation and convective echo top heights observed by TRMM radar over the Indian Ocean during DYNAMO

Evolution of precipitation and convective echo top heights observed by TRMM radar over the Indian Ocean during DYNAMO

Large-Scale Oceanic Variability Associated with the Madden-Julian Oscillation during the CINDY/DYNAMO Field Campaign from Satellite Observations

Forecast Skill of Madden-Julian Oscillation Events in a Global Nonhydrostatic Model during the CINDY2011/DYNAMO Observation Period

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