Radar observations of MJO and Kelvin wave interactions during DYNAMO/CINDY2011/AMIE

DePasquale, A. M.; Schumacher, Courtney; Rapp, A. D.

doi:10.1002/2013jd021031

Cited by 22 publications

(31 citation statements)

References 48 publications

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“…Additional details of how the SMART‐R rainfall product was produced are given in DePasquale et al . []. The estimated uncertainty in 3 h domain‐averaged SMART‐R rainfall increases with rain rate but is generally <10% (Weixin Xu 2016, personal communication).…”

Section: Data and Proceduresmentioning

confidence: 99%

Relationships between radiation, clouds, and convection during DYNAMO

Ciesielski

Johnson

Jiang³

et al. 2017

JGR Atmospheres

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The relationships between radiation, clouds, and convection on an intraseasonal time scale are examined with data taken during the Dynamics of the Madden‐Julian Oscillation (MJO) field campaign. Specifically, column‐net, as well as vertical profiles of radiative heating rates, computed over Gan Island in the central Indian Ocean (IO) are used along with an objective analysis of large‐scale fields to examine three MJO events that occurred during the 3 month period (October to December 2011) over this region. Longwave (LW) and shortwave radiative heating rates exhibit tilted structures, reflecting radiative effects associated with the prevalence of shallow cumulus during the dry, suppressed MJO phase followed by increasing deep convection leading into the active phase. As the convection builds going into the MJO active phase, there are increasingly top‐heavy anomalous radiative heating rates while the column‐net radiative cooling rate progressively decreases. Temporal fluctuations in the cloud radiative forcing, being quite sensitive to changes in high cloudiness, are dominated by LW effects with an intraseasonal variation of ~0.4–0.6 K/d. While both the water vapor and cloud fields are inextricably linked, it appears that the tilted radiative structures are more related to water vapor effects. The intraseasonal variation of column‐net radiative heating enhances the convective signal in the mean by ~20% with a minimum in this enhancement ~10 days prior to peak MJO rainfall and maximum ~7 days after. This suggests that as MJO convective envelope weakens over the central IO, cloud‐radiative feedbacks help maintain the mature MJO as it moves eastward.

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Section: Data and Proceduresmentioning

confidence: 99%

Relationships between radiation, clouds, and convection during DYNAMO

Ciesielski

Johnson

Jiang³

et al. 2017

JGR Atmospheres

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“…During the DYNAMO field campaign [ Yoneyama et al , ] three MJO events were intensively studied [ DePasquale et al , ; Gottschalck et al , ; Johnson and Ciesielski , ; Kent et al , ]. The November 2011 MJO was associated with two sequential atmospheric Kelvin waves.…”

Section: The Dynamo Field Project: Case Study Of Sequential Cckwsmentioning

confidence: 99%

“…Nine of these events were associated with the active phase of the MJO, while seven developed during the suppressed phase [ Gottschalck et al , ]. Radar observations were used to analyze the difference in structure and intensity of the CCKWs during the suppressed and active phases of the MJO in DYNAMO [ DePasquale et al , ]. In the active phase, the waves were more intense with higher moisture and more clouds, possibly impacting the radiative effects of the wave.…”

Section: Introductionmentioning

confidence: 99%

Impact of atmospheric convectively coupled equatorial Kelvin waves on upper ocean variability

Baranowski

Flatau²,

Flatau

et al. 2016

JGR Atmospheres

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Convectively coupled Kelvin waves (CCKWs) are atmospheric weather systems that propagate eastward along the equatorial wave guide with phase speeds between 11 and 14 m s À1 . They are an important constituent of the convective envelope of the Madden-Julian oscillation (MJO), for which ocean-atmosphere interactions play a vital role. Hence, ocean-atmosphere interactions within CCKWs may be important for MJO development and prediction and for tropical climate, in general. Although the atmospheric structure of CCKWs has been well studied, their impact on the underlying ocean is unknown. In this paper, the ocean-atmosphere interactions in CCKWs are investigated by a case study from November 2011 during the CINDY/DYNAMO field experiment, using in situ oceanographic measurements from an ocean glider. The analysis is then extended to a 15 year period using precipitation data from the Tropical Rainfall Measuring Mission and surface fluxes from the TropFlux analysis. A methodology is developed to calculate trajectories of CCKWs. CCKW events are strongly controlled by the MJO, with twice as many CCKWs observed during the convectively active phase of the MJO compared to the suppressed phase. Coherent ocean-atmosphere interaction is observed during the passage of a CCKW, which lasts approximately 4 days at any given longitude. Surface wind speed and latent heat flux are enhanced, leading to a transient suppression of the diurnal cycle of sea surface temperature (SST) and a sustained decrease in bulk SST of 0.1°C. Given that a typical composite mean MJO SST anomaly is of the order of 0.3°C, and more than one CCKW can occur during the active phase of a single MJO event, the oceanographic impact of CCKWs is of major importance to the MJO cycle.

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“…Investigations of high-frequency disturbances utilizing the CINDY2011/DYNAMO field observation data have been undertaken (e.g., JC13; Zuluaga and Houze 2013;DePasquale et al 2014). By analyzing radar data, DePasquale et al (2014) discussed the roles of convectively coupled Kelvin waves in deep moistening during the developing phase of the MJO events. JC13 reported that westward-moving 2-day disturbances were pronounced in MJO1, whereas 4-5-day disturbances were more frequent in MJO2.…”

Section: B Roles Of High-frequency Disturbancesmentioning

confidence: 99%

Moistening Processes before the Convective Initiation of Madden–Julian Oscillation Events during the CINDY2011/DYNAMO Period

Nasuno

Kikuchi

2015

Monthly Weather Review

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Convective initiation processes in the Madden-Julian oscillation (MJO) events that occurred during the Cooperative Indian Ocean Experiment on Intraseasonal Variability in the Year 2011 (CINDY2011)/ Dynamics of the Madden-Julian Oscillation (DYNAMO) intensive observation period (IOP) were investigated. Two episodes that were initiated in mid-October (MJO1) and mid-November (MJO2) 2011 were analyzed using European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis and satellite data. Moisture budgets in the equatorial Indian Ocean (IO) domain (108S-108N, 608-908E) were analyzed in detail by separating each variable into basic-state (.80 day), intraseasonal (20-80 day), and high-frequency (,20 day) variations. The quality of the ECMWF reanalysis was also evaluated against the sounding data collected during the field campaign.In both MJO events, the increase in precipitable water started 8-9 days prior to the convective initiation. Moisture advection decomposition revealed that advection of basic moisture by intraseasonal easterly anomalies and of intraseasonal moisture anomalies by the basic zonal wind were pronounced in these two events. The nonlinear high-frequency terms in the meridional moisture advection were the same order of magnitude as the primary term in the middle troposphere, implying systematic upscale transport of moisture. As a possible mechanism of the acceleration of easterly anomalies, amplification of off-equatorial Rossby wave trains that intruded into the equatorial zone was detected during the preconditioning periods in both MJO events.

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Radar observations of MJO and Kelvin wave interactions during DYNAMO/CINDY2011/AMIE

Cited by 22 publications

References 48 publications

Relationships between radiation, clouds, and convection during DYNAMO

Relationships between radiation, clouds, and convection during DYNAMO

Impact of atmospheric convectively coupled equatorial Kelvin waves on upper ocean variability

Moistening Processes before the Convective Initiation of Madden–Julian Oscillation Events during the CINDY2011/DYNAMO Period

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