Oscillation of High-Level Cirrus and Heavy Precipitation around Australian Region Tropical Cyclones

Lajoie, Francis; Butterworth, I. J.

doi:10.1175/1520-0493(1984)112<0535:oohlca>2.0.co;2

Cited by 33 publications

(34 citation statements)

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“…No diurnal variations of TC rainfall have been documented using satellite data. On the other hand, our result is similar to those derived from coldest IR T B thresholds (Muramatsu 1983;Lajoie and Butterworth 1984), which are more associated with deep convection. Figure 12 shows 3B42 3-hourly rainfall maps for 1998-2009 global TCs.…”

Section: Diurnal Variations Of Tc Rainfallsupporting

confidence: 90%

A TRMM-Based Tropical Cyclone Cloud and Precipitation Feature Database

Jiang¹,

Liu²,

Zipser³

2011

J. Appl. Meteor. Climatol.

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The Tropical Rainfall Measuring Mission (TRMM) satellite has provided invaluable data for tropical cyclone (TC) research since December 1997. The challenge, however, is how to analyze and efficiently utilize all of the information from several instruments on TRMM that observe the same target. In this study, a tropical cyclone precipitation, cloud, and convective cell feature (TCPF) database has been developed by using observations of the TRMM precipitation radar (PR), Microwave Imager (TMI), Visible and Infrared Scanner (VIRS), Lightning Imaging System (LIS), and the TRMM 3B42 rainfall product. The database is based on an event-based method that analyzes the measurements from multiple sensors. This method condenses the original information of pixel-level measurements into the properties of events, which can significantly increase the efficiency of searching and sorting the observed historical TCs. With both convective and rainfall properties included, the database offers the potential to aid the research aiming to improve both TC intensification and rainfall forecasts. Using the TRMM TCPF database, regional variations of TC convection and diurnal variations of TC rainfall are examined. In terms of absolute number, the northwest Pacific Ocean basin has the deepest and most intense TCPFs according to IR, radar, and 85-GHz microwave measurements. However, the North Atlantic TCPFs appear to have the highest lightning production. Globally, TC rainfall has a maximum at 0430-0730 local solar time (LST) and a minimum around 1930-2230 LST. However, after separating ocean from land, a distinct difference is seen. Over land, the diurnal variation of TC rainfall shows double peaks: one around 0130-0730 LST and the other at 1630-1930 LST. The minimum is at 1030-1330 LST.

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Section: Diurnal Variations Of Tc Rainfallsupporting

confidence: 90%

A TRMM-Based Tropical Cyclone Cloud and Precipitation Feature Database

Jiang¹,

Liu²,

Zipser³

2011

J. Appl. Meteor. Climatol.

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“…Although many other factors may considerably affect the activity of outer spiral rainbands in real TCs (such as radiation, the beta effect, environmental flow, and vertical wind shear), the results from this study provide plausible mechanisms for initiation and evolution of outer spiral rainbands in real TCs. In particular, the quasiperiodic behavior of outer spiral rainbands and the associated storm intensity change coincidentally matches the observed strong quasi-diurnal variation in the horizontal areal extent of the upper-level cirrus canopy (Browner et al 1977;Muramatsu 1983;Lajoie and Butterworth 1984;Hobgood 1986;Kossin 2002) without consideration of radiation or cloud-radiative feedback in the simulation. Therefore, the results from this study may provide an alternative explanation or one of the mechanisms that are responsible for the quasi-diurnal variation in the observed TCs.…”

Section: Conclusion and Discussionsupporting

confidence: 61%

“…Since TCs consist of deep convection in both the eyewall and spiral rainbands, similar diurnal variations could be expected in TCs (Hobgood 1986). Indeed, a number of previous studies have revealed a strong diurnal variation in the horizontal areal extent of the upper-level cirrus canopy (Browner et al 1977;Muramatsu 1983;Lajoie and Butterworth 1984;Kossin 2002). These studies explained the diurnal variation as a result of either the diurnal radiative forcing of eyewall convection (Browner et al 1977;Muramatsu 1983) or the spatial structure of radiatively driven subsidence in the region of the cirrus canopy (Kossin 2002).…”

Section: Introductionmentioning

confidence: 95%

Formation and Quasi-Periodic Behavior of Outer Spiral Rainbands in a Numerically Simulated Tropical Cyclone*

Wang

2012

Journal of the Atmospheric Sciences

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The formation and quasi-periodic behavior of outer spiral rainbands in a tropical cyclone simulated in the cloud-resolving tropical cyclone model version 4 (TCM4) are analyzed. The outer spiral rainbands in the simulation are preferably initiated near the 60-km radius, or roughly about 3 times the radius of maximum wind (RMW). After initiation, they generally propagate radially outward with a mean speed of about 5 m s 21 . They are reinitiated quasi-periodically with a period between 22 and 26 h in the simulation. The inner spiral rainbands, which form within a radius of about 3 times the RMW, are characterized by the convectively coupled vortex Rossby waves (VRWs), but the formation of outer spiral rainbands (i.e., rainbands formed outside a radius of about 3 times the RMW) is much more complicated. It is shown that outer spiral rainbands are triggered by the inner-rainband remnants immediately outside the rapid filamentation zone and inertial instability in the upper troposphere. The preferred radial location of initiation of outer spiral rainbands is understood as a balance between the suppression of deep convection by rapid filamentation and the favorable dynamical and thermodynamic conditions for initiation of deep convection.The quasi-periodic occurrence of outer spiral rainbands is found to be associated with the boundary layer recovery from the effect of convective downdrafts and the consumption of convective available potential energy (CAPE) by convection in the previous outer spiral rainbands. Specifically, once convection is initiated and organized in the form of outer spiral rainbands, it will produce strong downdrafts and consume CAPE. These effects weaken convection near its initiation location. As the rainband propagates outward farther, the boundary layer air near the original location of convection initiation takes about 10 h to recover by extracting energy from the underlying ocean. Convection and thus new outer spiral rainbands will be initiated near a radius of about 3 times the RMW. This will be followed by a similar outward propagation and the subsequent boundary layer recovery, leading to a quasi-periodic occurrence of outer spiral rainbands. In response to the quasi-periodic appearance of outer spiral rainbands, the storm intensity experiences a similar quasi-periodic oscillation with its intensity or intensification rate starting to decrease after about 4 h of the initiation of an outer spiral rainband. The results provide an alternative explanation or one of the mechanisms that are responsible for the quasi-periodic (quasidiurnal) variation in the intensity and in the area of outflow-layer cloud canopy of observed tropical cyclones.

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“…This indicates that the boundary layer recovery was often significantly shorter than the diurnal cycle. Both diurnal and semi-diurnal cycles have been found in the areal extent of the upper level cirrus deck of fully developed tropical cyclones (Browner et al, 1977;Muramatsu, 1983;Lajoie and Butterworth, 1984;Steranka et al, 1984;Kossin, 2002). The results presented here for the early stage of a developing system may be relevant to these previous studies, although the existence of substantial convective downdrafts and cold pools in the core of developing tropical cyclones has not yet been established definitively.…”

Section: Discussionmentioning

confidence: 50%

An examination of two pathways to tropical cyclogenesis occurring in idealized simulations with a cloud-resolving numerical model

Nicholls

Montgomery

2013

Atmos. Chem. Phys.

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Simulations are conducted with a cloud-resolving numerical model to examine the transformation of a weak incipient mid-level cyclonic vortex into a tropical cyclone. Results demonstrate that two distinct pathways are possible and that development along a particular pathway is sensitive to model physics and initial conditions. One pathway involves a steady increase of the surface winds to tropical cyclone strength as the radius of maximum winds gradually decreases. A notable feature of this evolution is the creation of small-scale lower tropospheric cyclonic vorticity anomalies by deep convective towers and subsequent merger and convergence by the low-level secondary circulation. The second pathway also begins with a strengthening low-level circulation, but eventually a significantly stronger mid-level circulation develops. Cyclogenesis occurs subsequently when a small-scale surface concentrated vortex forms abruptly near the center of the larger-scale circulation. The small-scale vortex is warm core throughout the troposphere and results in a fall in local surface pressure of a few millibars. It usually develops rapidly, undergoing a modest growth to form a small tropical cyclone. Many of the simulated systems approach or reach tropical cyclone strength prior to development of a prominent mid-level vortex so that the subsequent formation of a strong small-scale surface concentrated vortex in these cases could be considered intensification rather than genesis.

Experiments are performed to investigate the dependence on the inclusion of the ice phase, radiation, the size and strength of the incipient mid-level vortex, the amount of moisture present in the initial vortex, and the sea surface temperature. Notably, as the sea surface temperature is raised, the likelihood of development along the second pathway is increased. This appears to be related to an increased production of ice. The sensitivity of the pathway taken to model physics and initial conditions revealed by these experiments raise the possibility that the solution to this initial value problem is near a bifurcation point. Future improvements to model parameterizations and more accurate observations of the transformation of disturbances to tropical cyclones should clarify the conditions that favor a particular pathway when starting from a mid-level vortex

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Oscillation of High-Level Cirrus and Heavy Precipitation around Australian Region Tropical Cyclones

Cited by 33 publications

References 0 publications

A TRMM-Based Tropical Cyclone Cloud and Precipitation Feature Database

A TRMM-Based Tropical Cyclone Cloud and Precipitation Feature Database

Formation and Quasi-Periodic Behavior of Outer Spiral Rainbands in a Numerically Simulated Tropical Cyclone*

An examination of two pathways to tropical cyclogenesis occurring in idealized simulations with a cloud-resolving numerical model

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