Diurnal Cloud and Circulation Changes in Simulated Tropical Cyclones

Ruppert, James H.; O’Neill, Morgan

doi:10.1029/2018gl081302

Cited by 33 publications

(53 citation statements)

References 49 publications

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“…Due to their ring-like nature, one of the Dunion et al (2014) hypotheses for diurnal pulse propagation was that they might be governed by gravity waves dynamics, perhaps initiated from enhanced deep convection in the inner core. A gravity wave interpretation of diurnal pulses has also been suggested in recent research (Navarro et al 2017;O'Neill et al 2017;Ruppert and O'Neill 2019;Evans and Nolan 2019), with calculated gravity wave phase speeds similar to the diurnal pulse propagation speed of 5-10 m s 21 found in Dunion et al (2014) and 8-14 m s 21 found in Ditchek et al (2019). Fig.…”

Section: ) Propagation Speedsupporting

confidence: 74%

Electrically Active Tropical Cyclone Diurnal Pulses in the Atlantic Basin

Ditchek

Corbosiero

Fovell

et al. 2019

Monthly Weather Review

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While the frequency and structure of Atlantic basin tropical cyclone diurnal cooling and warming pulses have recently been explored, how often diurnal pulses are associated with deep convection was left unanswered. Here, storm-relative, GridSat-B1, 6-h IR brightness temperature difference fields were supplemented with World Wide Lightning Location Network (WWLLN) data to answer that question. Electrically active, long-lived cooling and warming pulses were defined objectively by determining critical thresholds for the lightning flash density, areal coverage, and longevity within each pulse. Pulses with lightning occurred 61% of the time, with persistently electrically active pulses (≥9 h, ACT) occurring on 38% of pulse days and quasi–electrically active pulses (3–6 h, QUASI) occurring on 23% of pulse days. Electrically inactive pulses (<3 h, INACT) occurred 39% of the time. ACT pulse days had more pulses located right-of-shear, the preferred quadrant for outer-rainband lightning activity, and were associated with more favorable environmental conditions than INACT pulse days. Cooling pulses were more likely to occur in lower-shear environments while warming pulses were more likely to occur in high-shear environments. Finally, while the propagation speeds of ACT and INACT cooling pulses and ACT warming pulses did lend support to the recent gravity wave and tropical squall-line explanations of diurnal pulses, the INACT warming pulses did not and should be studied further.

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Section: ) Propagation Speedsupporting

confidence: 74%

Electrically Active Tropical Cyclone Diurnal Pulses in the Atlantic Basin

Ditchek

Corbosiero

Fovell

et al. 2019

Monthly Weather Review

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“…The findings of this study support both of these hypotheses and emphasize that the upward motion in organized tropical deep convective systems is characterized by a bimodal diurnal cycle upward motion peaks nocturnally in the lower-midtroposphere and peaks in the afternoon in the upper troposphere. Such an evolution manifests in the ITCZ (Ciesielski et al, 2018), mesoscale convective clusters (Ruppert & Hohenegger, 2018), and tropical cyclones (Navarro & Hakim, 2016;Ruppert & O'Neill, 2019).…”

Section: Discussionmentioning

confidence: 99%

The Two Diurnal Modes of Tropical Upward Motion

Ruppert

Klocke

2019

Geophysical Research Letters

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This study describes a new mechanism governing the diurnal variation of vertical motion in tropical oceanic heavy rainfall zones, such as the intertropical convergence zone. In such regions, the diurnal heating of widespread anvil clouds due to shortwave radiative absorption enhances upward motion in these upper layers in the afternoon. This radiatively driven ascent promotes an afternoon maximum of anvil clouds, indicating a diurnal cloud‐radiative feedback. The opposite occurs at nighttime: While rainfall exhibits a dominant peak at night‐early morning, the boundary layer rooted upward motion and latent heating tied to this peak are forced to be more bottom heavy by the nighttime anomalous radiative cooling at upper levels. This mechanism therefore favors the stratiform top‐heavy heating mode during daytime and suppresses it nocturnally. These diurnal circulation signatures arise from microphysical‐radiative feedbacks that manifest on the scales of organized deep convection, which may ultimately impact the daily mean radiation budget.

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“…Analyses of a 10 year data set of stormcentered infrared satellite images suggested that the TC diurnal cycle may be tied to hurricane dynamics, structure and intensity change (Dunion et al, 2014). Numerical studies have also confirmed the diurnal cycle of TC structure at both the genesis (Melhauser & Zhang, 2014) and mature stages (Ruppert & O'Neill, 2019;Tang & Zhang, 2016) with attention to how radiation affects the structure and diurnal cycle of TCs. O'Neill et al (2017) investigated the possible mechanisms that are responsible for the diurnal pulsing of clouds near the TC outflow layer and found diurnal waves that have characteristics of internal gravity waves forced by heating in the TC inner core.…”

Section: Introductionmentioning

confidence: 93%

In Situ Observations of the Diurnal Variation in the Boundary Layer of Mature Hurricanes

Zhang

Dunion

Nolan

2020

Geophysical Research Letters

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Recent studies have suggested that the structure of tropical cyclones (TCs), especially the upper‐level clouds as indicated by satellite infrared brightness temperatures and precipitation, fluctuates with the diurnal cycle. The diurnal cycle of the low‐level structure, including the boundary layer, has not yet been investigated with observations. This study analyzes data from 2242 GPS dropsondes collected in mature hurricanes to investigate the diurnal variation of the mean boundary layer structure. A composite analysis is conducted to compare the kinematic and thermodynamic structure during nighttime (0–6 local time) vs in the afternoon (12–18 local time). The composites show that much stronger inflow occurs during nighttime and the moist entropy is also larger than that in the daytime. Grouping the dropsonde data into 6‐h time windows relative to the local time shows a clear diurnal signal of boundary layer inflow. The amplitude of the diurnal signal is largest at a radius of 250–500 km.

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Diurnal Cloud and Circulation Changes in Simulated Tropical Cyclones

Cited by 33 publications

References 49 publications

Electrically Active Tropical Cyclone Diurnal Pulses in the Atlantic Basin

Electrically Active Tropical Cyclone Diurnal Pulses in the Atlantic Basin

The Two Diurnal Modes of Tropical Upward Motion

In Situ Observations of the Diurnal Variation in the Boundary Layer of Mature Hurricanes

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