Effects of Cumulus Convection on the vorticity Field in the Tropics

Chu, Jan-Hwa; Yanai, Michio; Sui, Chung‐Hsiung

doi:10.2151/jmsj1965.59.4_535

Cited by 15 publications

(8 citation statements)

References 57 publications

(24 reference statements)

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“…As described in the literature (e.g. Reed and Johnson, 1974; Chu et al , 1981), regions with significant convective activity show an apparent source of cyclonic vorticity in the upper troposphere and an apparent sink near the surface, suggesting a vertical transport of vorticity by convective processes.…”

Section: Methodsmentioning

confidence: 99%

Structure and evolution of subtropical cyclone Anita as evaluated by heat and vorticity budgets

Dutra

Rocha

Lee

et al. 2017

Quart J Royal Meteoro Soc

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This article explores the evolution of subtropical cyclone Anita, which occurred near the east coast of Brazil (∼19°S–37°W) in March 2010. Thermodynamic and dynamic processes during Anita's life cycle are investigated using the heat and vorticity budget equations. The cyclone developed with hybrid characteristics and moved anomalously to the southwest, where it coupled with an upper‐level cut‐off low during the mature phase. This coupling was the main dynamical mechanism for further cyclone deepening. Anita then remained quasi‐stationary at about 30°S–47°W for 2 days, due to an upper‐level dipole pattern, which prevented earlier displacement of the upper‐level low counterpart. When the dipole pattern dissipated, the cyclone moved southeast and underwent extratropical transition whilst merging with a midlatitude frontal cyclone. Diabatic heating and horizontal temperature advection are found to be essential for subtropical development. During extratropical transition, instead it is diabatic cooling together with adiabatic cooling and warm‐air advection that act as the main mechanisms to influence the local temperature tendencies at low levels. Low‐level cyclonic tendencies were mostly due to convergent flow and the residual vorticity partially destroyed the vorticity tendencies produced by the divergence term. Moreover, in regions and levels where convection could explain some of the vorticity tendencies, it is found that apparent sinks of cyclonic vorticity were related to negative vorticity due to divergence (i.e. convergent flow), whilst apparent sources were related to positive vorticity due to divergence (i.e. divergent flow).

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Section: Methodsmentioning

confidence: 99%

Structure and evolution of subtropical cyclone Anita as evaluated by heat and vorticity budgets

Dutra

Rocha

Lee

et al. 2017

Quart J Royal Meteoro Soc

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show abstract

“…Earlier studies (HOLOPAINEN and OORT, 1981;CHU et al, 1981) revealed that the horizontal transport and the production terms (stretching and tipping) are signi®cant in the vorticity budget.…”

Section: Vorticity Budgetmentioning

confidence: 99%

“…The budget terms show that the horizontal transportation of vorticity is eectively balanced in the monsoon region by the production of vorticity through sub-grid scale processes such as cumulus convection. Earlier studies (WILLIAMS and GREY, 1973;REED and JOHNSON, 1974;CHU et al, 1981) have delineated that the cumulus convection in the tropics could generate a large apparent source of positive vorticity.…”

Section: Vorticity Budgetmentioning

confidence: 99%

The Energetics of Asian Summer Monsoon

Rao¹

2001

Pure appl. geophys.

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Ð In this paper, we examine the large-scale balances of kinetic energy, vorticity, angular momentum, heat and moisture over the Asian summer monsoon region. The ®ve year (1986±1990) uninitialized daily analyses for the summer season comprising June, July and August (JJA), produced at the European Centre for Medium Range Weather Forecasts (ECMWF) under the aegis of Tropical Ocean and Global Atmosphere (TOGA) have been considered to carry out the study.The following features characterize the Asian summer monsoon domain. It acts as the source of kinetic energy as well as vorticity, and sink of heat and moisture. Kinetic energy and vorticity are produced in the monsoon region and transported horizontally. On the contrary, heat and moisture are transported into the monsoon region. The zonal and meridional components of adiabatic generation of kinetic energy contribute to the production of kinetic energy over the Arabian Sea and Bay of Bengal, respectively. The horizontal advection of relative vorticity is balanced by sub-grid scale generation. The angular momentum generated due to pressure torque (east-west pressure gradient) is balanced by the¯ux convergence of omega momentum. Further, the angular momentum budget delineates that¯ux convergence of relative momentum is necessary to maintain the surface westerlies against the friction. The horizontal convergence of heat and moisture facilitates enhancement of diabatic heating, and also leads to the formation of diabatic heat sources, which are crucial to sustain the summer monsoon circulation.

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“…Some studies (HOLOPAINEN and OORT;CHU et al, 1981) reveal that the horizontal transport and the production term (stretching and tipping) are significant in the vorticity budget. The geographical distributions of vertically integrated vorticity budget terms are presented in Figure 8.…”

Section: Vorticity Budgetmentioning

confidence: 99%

A Study of Mean Winter Circulation Characteristics and Energetics over Southeastern Asia

Dimri

2007

Pure appl. geophys.

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A mean climatology is studied to examine atmospheric circulation characteristics to assess the wintertime (December, January, February and March -DJFM) synoptic weather system affecting northern India. The main objective is to study the mean circulation and mean energetics distribution pertaining to the winter season, which are embedded with an eastward moving synoptic weather system in westerlies, called Western Disturbances (WDs). Forty years of uninitialized daily re-analysis data of the National Center for Environmental Prediction -National Center for Atmospheric Research (NCEP-NCAR, henceafter NCEP), U.S. has been considered for this study. Winter circulations are considered over the domain 15°S-45°N and 30°E-120°E. This domain is considered particularly to illustrate the impact of wintertime synoptic weather system Western Disturbances (WDs), which travel towards the east over the western Himalayas during winter and yield an enormous amount of precipitation in the form of snow. Large-scale balances of kinetic energy, vorticity, angular momentum, heat and moisture budget terms are analyzed. The main findings of the study show that strong rising motion in the extratropical region brings a significant amount of precipitation over the region of study. Also, horizontal flux of kinetic energy converges in the tropical region and diverges over the extratropical region. It is seen that both the zonal and meridional component of kinetic energy contributes to the production of kinetic energy in the upper troposphere. Vorticity budget shows that wintertime circulation over the western Himalayas is characterized by a negative generation of vorticity. The relative and planetary vorticity advection contributes to the horizontal transport of vorticity. The moisture flux transported into the region shows that in the middle tropospheric levels moisture undergoes phase transformation due to turbulent exchange and hence releases latent heat.

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Effects of Cumulus Convection on the vorticity Field in the Tropics

Cited by 15 publications

References 57 publications

Structure and evolution of subtropical cyclone Anita as evaluated by heat and vorticity budgets

Structure and evolution of subtropical cyclone Anita as evaluated by heat and vorticity budgets

The Energetics of Asian Summer Monsoon

A Study of Mean Winter Circulation Characteristics and Energetics over Southeastern Asia

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