A Satellite Study of Tropical Moist Convection and Environmental Variability: A Moisture and Thermal Budget Analysis

Masunaga, Hirohiko

doi:10.1175/jas-d-12-0273.1

Cited by 35 publications

(37 citation statements)

References 62 publications

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“…But to study variability on daily to synoptic timescales a different approach is needed, because most (polar orbiting) satellites sample a given location too infrequently (one exception being the new GPM mission with its three-hourly precipitation rates globally). One approach is to project different polar orbiting satellites onto a composite time axis centered on a rain event, a strategy that has been used in Masunaga (2013) and Masunaga and L'Ecuyer (2014). The result is a statistical time series on hourly and daily timescales, which precedes and follows those rain events.…”

Section: Observationsmentioning

confidence: 99%

Implications of Warm Rain in Shallow Cumulus and Congestus Clouds for Large-Scale Circulations

et al. 2017

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Space-borne observations reveal that 20-40% of marine convective clouds below the freezing level produce rain. In this paper we speculate what the prevalence of warm rain might imply for convection and large-scale circulations over tropical oceans. We present results using a two-column radiative-convective model of hydrostatic, nonlinear flow on a non-rotating sphere, with parameterized convection and radiation, and review ongoing efforts in high-resolution modeling and observations of warm rain. The model experiments investigate the response of convection and circulation to sea surface temperature (SST) gradients between the columns and to changes in a parameter that controls the conversion of cloud condensate to rain. Convection over the cold ocean collapses to a shallow mode with tops near 850 hPa, but a congestus mode with tops near 600 hPa can develop at small SST differences when warm rain formation is more efficient. Here, interactive radiation and the response of the circulation are crucial: along with congestus a deeper moist layer develops, which leads to less low-level radiative cooling, a smaller buoyancy gradient between the columns, and therefore a weaker circulation and less subsidence over the cold ocean. The congestus mode is accompanied with more surface precipitation in the subsiding column and less surface precipitation in the deep convecting column. For the shallow mode over colder oceans, circulations also weaken with more efficient warm rain formation, but only marginally. Here, more warm rain reduces convective tops and the boundary layer depth-similar to Large-Eddy Simulation (LES) studies-which reduces the integrated buoyancy gradient. Elucidating the impact of warm rain can benefit from large-domain high-resolution simulations and observations. Parameterizations of warm rain may be constrained through collocated cloud and rain profiling from ground, and concurrent changes in convection and rain in subsiding and & Louise Nuijens

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Section: Observationsmentioning

confidence: 99%

Implications of Warm Rain in Shallow Cumulus and Congestus Clouds for Large-Scale Circulations

et al. 2017

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“…13a). A rapid development of vertical moisture advection (or moisture convergence) is largely canceled by precipitation during the time of peak convection (Masunaga 2013;Chikira 2014). In the MSE budget, horizontal advection has a comparable magnitude to vertical advection during hours away from t~0.…”

Section: Discussionmentioning

confidence: 99%

“…Under the assumption that SC convergence is determined with QuikSCAT wind, the RHS of equations (1) and (2) can be evaluated solely by satellite measurements currently available (Masunaga 2013). The evolution of moisture and DSE convergences on the LHS thus may be derived as constrained by the set of satellite observations projected onto the composite time axis.…”

Section: Leo Satellite Observationsmentioning

confidence: 99%

“…Taking advantage of such recent technological advances in remote sensing from space, Masunaga (2013) devised a budget analysis scheme that is designed for an exclusive use of satellite data. Masunaga and L'Ecuyer (2014) further advanced this meth-odology to derive large-scale mean vertical velocity.…”

Section: Introductionmentioning

confidence: 99%

“…The strategy of Masunaga (2013) is unique in a few aspects compared with conventional approaches employed for thermodynamic budget analysis. First, it is applied to a large number of satellite snapshots projected onto a composite time axis defined with respect to the timing of convective occurrence (Masunaga 2012a).…”

Section: Introductionmentioning

confidence: 99%

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Assessment of a Satellite-Based Atmospheric Budget Analysis Method Using CINDY2011/DYNAMO/AMIE and TOGA COARE Sounding Array Data

Masunaga

2015

Journal of the Meteorological Society of Japan

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A satellite-based method of moisture and thermal budget analysis is examined in comparison with sounding array observations from Cooperative Indian Ocean experiment on Intraseasonal variability in the Year of 2011 (CINDY2011)/Dynamics of the Madden-Julian Oscillation (MJO) (DYNAMO)/Atmospheric Radiation Measurements (ARM) MJO Investigation Experiment (AMIE) and from the Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment (TOGA COARE). Overall, the satellite analysis is found to quantitatively reproduce the statistical behaviors of large-scale mean vertical motion, moisture convergence, and moist static energy (MSE) convergence as observed from the sounding arrays. However, individual convective events generally do not delineate a systematic evolutionary track but are heavily spread around the ensemble mean of moisture and MSE convergences in composite space.Next, the convective events are broken down into "developing", "off-centered", and "passing-by" classes using geostationary infrared measurements in an attempt to sort irrelevant samples that are not representative of convective dynamics. All the three composite classes show qualitatively similar evolutions except for the amplitude of variability, with genuine developing events being greatest in amplitude and passing-by disturbances being weakest. The spread among individual events is substantially reduced when the convective events immune to strong synoptic-scale influences are isolated and the contribution of horizontal advection is excluded from MSE convergence.

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The cloud population and onset of the Madden‐Julian Oscillation over the Indian Ocean during DYNAMO‐AMIE

2013

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1] Variability of the cloud population in the central equatorial Indian Ocean was observed in the context of the Madden-Julian Oscillation (MJO) during the Dynamics of the Madden-Julian Oscillation (DYNAMO) and Atmospheric Radiation Measurement Madden-Julian Investigation Experiment (AMIE) field campaigns. Radar observations from the polarimetric S-band radar on Addu Atoll in the Maldives characterize the types of convective and stratiform radar echoes and the heights their 20 dBZ contours reach. To gain insight into the relationship between clouds and humidification of the troposphere leading up to and during an active MJO event, the work relates variability of the observed precipitation structure to that of tropospheric humidity and upper level zonal wind. The variability in stratiform precipitation areas dominates variability in the nature of precipitating convection associated with the MJO. Areal coverage of precipitating radar echo, convective echo top height, and tropospheric humidity above 850 hPa rapidly increase over~3-7 days near MJO onset. This rate of increase is substantially faster than the 10-20 days needed for buildup of moisture prior to MJO onset as hypothesized by the "discharge-recharge" hypothesis. Convective echoes become more common during the days prior to MJO onset, and the increased convection occurs before low-tropospheric moistening. The upper troposphere rapidly moistens as the first widespread stratiform region passes over an area. Thus, clouds likely play a role in tropospheric humidification. Whether increased low-tropospheric humidity causes vertical growth of convection has not yet been determined.

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A Satellite Study of Tropical Moist Convection and Environmental Variability: A Moisture and Thermal Budget Analysis

Cited by 35 publications

References 62 publications

Implications of Warm Rain in Shallow Cumulus and Congestus Clouds for Large-Scale Circulations

Implications of Warm Rain in Shallow Cumulus and Congestus Clouds for Large-Scale Circulations

Assessment of a Satellite-Based Atmospheric Budget Analysis Method Using CINDY2011/DYNAMO/AMIE and TOGA COARE Sounding Array Data

The cloud population and onset of the Madden‐Julian Oscillation over the Indian Ocean during DYNAMO‐AMIE

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