Convective vertical velocity and cloud internal vertical structure: An A‐Train perspective

Luo, Zhengzhao Johnny; Jeyaratnam, Jeyavinoth; Iwasaki, S.; Takahashi, H.; Anderson, Ricardo

doi:10.1002/2013gl058922

Cited by 35 publications

(27 citation statements)

References 25 publications

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“…These contrasts in CFTD between land and oceanic deep convective cores are very similar to that between strong and weak convection (sorted by vertical velocity) as reported in Luo et al . []. Hence, CloudSat CPR observations suggest that land convection generates more intense cores than the oceanic counterpart, consistent with direct measurements from cloud‐penetrating aircraft [e.g., LeMone and Zipser , ; Lucas et al ., ] and inference made from analyzing TRMM precipitation radar data [ Liu and Zipser , ; Zipser et al ., ].…”

Section: Regional Variationsmentioning

confidence: 99%

Level of neutral buoyancy, deep convective outflow, and convective core: New perspectives based on 5 years of CloudSat data

2017

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This paper is the follow on to a previous publication by the authors, which investigated the relationship between the level of neutral buoyancy (LNB) determined from the ambient sounding and the actual outflow levels using mainly CloudSat observations. The goal of the current study is to provide a more complete characterization of LNB, deep convective outflow, and convective core, and the relationship among them, as well as the dependence on environmental parameters and convective system size. A proxy is introduced to estimate convective entrainment, namely, the difference between the LNB (based on the ambient sounding) and the actual outflow height. The principal findings are as follows: (1) Deep convection over the Warm Pool has larger entrainment rates and smaller convective cores than the counterpart over the two tropical land regions (Africa and Amazonia), lending observational support to a long‐standing assumption in convection models concerning the negative relationship between the two parameters. (2) The differences in internal vertical structure of convection between the two tropical land regions and the Warm Pool suggest that deep convection over the two tropical land regions contains more intense cores. (3) Deep convective outflow occurs at a higher level when the midtroposphere is more humid and the convective system size is smaller. The convective system size dependence is postulated to be related to convective lifecycle, highlighting the importance of cloud life stage information in interpretation of snapshot measurements by satellite. Finally, implications of the study to global modeling are discussed.

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Section: Regional Variationsmentioning

confidence: 99%

Level of neutral buoyancy, deep convective outflow, and convective core: New perspectives based on 5 years of CloudSat data

2017

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“…Luo et al (2014) use time-differenced infrared brightness temperatures to relate cloud top vertical velocities to convective mass transport and precipitation efficiency, two central physical characteristics linking the causes and effects of convective aggregation. They demonstrate that stronger updrafts correlate with higher precipitation echo-tops, increased convective mass fluxes, and heavier rainfall throughout the tropics.…”

Section: Spaceborne Cloud Radar Approachesmentioning

confidence: 99%

Observing Convective Aggregation

et al. 2017

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Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of 123Surv Geophys (2017) 38:1199-1236 https://doi.org/10.1007/s10712-017-9419-1 model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a groundbased observational network.

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“…In this case, the horizontal wind speed is smaller, but the fast cloud evolution is the major issue. Luo et al (2014) and Schumacher et al (2015) reported that tropical DCCs located at altitude between 6 and 8 km typically have an updraft velocity about 2-4 m s −1 . According to this analysis, the comparisons are restricted to | t| < 500 s for the cirrus case, while for the DCC case the threshold is tightened to | t| < 300 s.…”

Section: Data Filtermentioning

confidence: 99%

Comparing airborne and satellite retrievals of cloud optical thickness and particle effective radius using a spectral radiance ratio technique: two case studies for cirrus and deep convective clouds

et al. 2018

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Abstract. Solar radiation reflected by cirrus and deep convective clouds (DCCs) was measured by the Spectral Modular Airborne Radiation Measurement System (SMART) installed on the German High Altitude and Long Range Research Aircraft (HALO) during the Mid-Latitude Cirrus (ML-CIRRUS) and the Aerosol, Cloud, Precipitation, and Radiation Interaction and Dynamic of Convective Clouds System -Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modelling and to the Global Precipitation Measurement (ACRIDICON-CHUVA) campaigns. On particular flights, HALO performed measurements closely collocated with overpasses of the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite. A cirrus cloud located above liquid water clouds and a DCC topped by an anvil cirrus are analyzed in this paper. Based on the nadir spectral upward radiance measured above the two clouds, the optical thickness τ and particle effective radius r eff of the cirrus and DCC are retrieved using a radiance ratio technique, which considers the cloud thermodynamic phase, the vertical profile of cloud microphysical properties, the presence of multilayer clouds, and the heterogeneity of the surface albedo. For the cirrus case, the comparison of τ and r eff retrieved on the basis of SMART and MODIS measurements yields a normalized mean absolute deviation of up to 1.2 % for τ and 2.1 % for r eff . For the DCC case, deviations of up to 3.6 % for τ and 6.2 % for r eff are obtained. The larger deviations in the DCC case are mainly attributed to the fast cloud evolution and three-dimensional (3-D) radiative effects. Measurements of spectral upward radiance at near-infrared wavelengths are employed to investigate the vertical profile of r eff in the cirrus. The retrieved values of r eff are compared with corresponding in situ measurements using a vertical weighting method. Compared to the MODIS observations, measurements of SMART provide more information on the vertical distribution of particle sizes, which allow reconstructing the profile of r eff close to the cloud top. The comparison between retrieved and in situ r eff yields a normalized mean absolute deviation, which ranges between 1.5 and 10.3 %, and a robust correlation coefficient of 0.82.

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Convective vertical velocity and cloud internal vertical structure: An A‐Train perspective

Cited by 35 publications

References 25 publications

Level of neutral buoyancy, deep convective outflow, and convective core: New perspectives based on 5 years of CloudSat data

Level of neutral buoyancy, deep convective outflow, and convective core: New perspectives based on 5 years of CloudSat data

Observing Convective Aggregation

Comparing airborne and satellite retrievals of cloud optical thickness and particle effective radius using a spectral radiance ratio technique: two case studies for cirrus and deep convective clouds

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