scholarly journals Multiscale Temporal Mean Features of Perturbation Kinetic Energy and Its Budget in the Tropics: Review and Computation

2016 ◽  
Vol 56 ◽  
pp. 8.1-8.23
Author(s):  
Baode Chen ◽  
Wen-wen Tung ◽  
Michio Yanai
Keyword(s):  
Indian Ocean ◽  
Kinetic Energy ◽  
Energy Flux ◽  
Eastern Pacific ◽  
Multiple Time Scales ◽  
Convective Heating ◽  
Multiple Time ◽  
Tropical Regions ◽  
Synoptic Variability ◽  
The Indian Ocean

Abstract The authors examined the maintenance mechanisms of perturbation kinetic energy (PKE) in the tropical regions for multiple time scales by computing and analyzing its budget equation. The emphasis has been placed on the mean features of synoptic and subseasonal variabilities using a 33-yr dataset. From analysis of the contributions from u-wind and υ-wind components, the PKE maximum in the Indian Ocean is attributed less to synoptic variability and more to intraseasonal variability in which the Madden–Julian oscillation (MJO) dominates; however, there is strong evidence of seasonal variability affiliated with the Asian monsoon systems. The ones in the eastern Pacific and Atlantic Oceans are closely related to both intraseasonal and synoptic variability that result from the strong MJO and the relatively large amplitude of equatorial waves. The maintenance of the PKE budget mainly depends on the structure of time mean horizontal flows, the location of convection, and the transport of PKE from the extratropics. In the regions with strong convective activities, such as the eastern Indian Ocean to the western Pacific, the production of PKE occurs between 700 and 200 hPa at the expense of perturbation available potential energy (PAPE), which is generated by convective heating. This gain in PKE is largely offset by divergence of the geopotential component of vertical energy flux; that is, it is redistributed to the upper- and lower-atmospheric layers by the pressure field. Strong PKE generation through the horizontal convergence of the extratropical energy flux takes place in the upper troposphere over the eastern Pacific and Atlantic Ocean, and is largely balanced by a PKE loss due to barotropic conversion, which is determined solely by the sign of longitudinal stretching deformation. However, over the Indian Ocean, there is a net PKE loss due to divergence of energy flux, which is compensated by PKE gain through the shear generation.

scholarly journals Physical Mechanisms for the Maintenance of GCM-Simulated Madden–Julian Oscillation over the Indian Ocean and Pacific

2011 ◽  
Vol 24 (10) ◽  
pp. 2469-2482 ◽  
Author(s):  
Liping Deng ◽  
Xiaoqing Wu
Keyword(s):  
Indian Ocean ◽  
Energy Flux ◽  
Wave Energy ◽  
Western Pacific ◽  
Eastern Pacific ◽  
Convective Heating ◽  
Trigger Condition ◽  
Wave Energy Flux ◽  
The Indian Ocean ◽  
Central Eastern

Abstract The kinetic energy budget is conducted to analyze the physical processes responsible for the improved Madden–Julian oscillation (MJO) simulated by the Iowa State University general circulation models (ISUGCMs). The modified deep convection scheme that includes the revised convection closure, convection trigger condition, and convective momentum transport (CMT) enhances the equatorial (10°S–10°N) MJO-related perturbation kinetic energy (PKE) in the upper troposphere and leads to a more robust and coherent eastward-propagating MJO signal. In the MJO source region, the Indian Ocean (45°–120°E), the upper-tropospheric MJO PKE is maintained by the vertical convergence of wave energy flux and the barotropic conversion through the horizontal shear of mean flow. In the convectively active region, the western Pacific (120°E–180°), the upper-tropospheric MJO PKE is supported by the convergence of horizontal and vertical wave energy fluxes. Over the central-eastern Pacific (180°–120°W), where convection is suppressed, the upper-tropospheric MJO PKE is mainly due to the horizontal convergence of wave energy flux. The deep convection trigger condition produces stronger convective heating that enhances the perturbation available potential energy (PAPE) production and the upward wave energy fluxes and leads to the increased MJO PKE over the Indian Ocean and western Pacific. The trigger condition also enhances the MJO PKE over the central-eastern Pacific through the increased convergence of meridional wave energy flux from the subtropical latitudes of both hemispheres. The revised convection closure affects the response of mean zonal wind shear to the convective heating over the Indian Ocean and leads to the enhanced upper-tropospheric MJO PKE through the barotropic conversion. The stronger eastward wave energy flux due to the increase of convective heating over the Indian Ocean and western Pacific by the revised closure is favorable to the eastward propagation of MJO and the convergence of horizontal wave energy flux over the central-eastern Pacific. The convection-induced momentum tendency tends to decelerate the upper-tropospheric wind, which results in a negative work to the PKE budget in the upper troposphere. However, the convection momentum tendency accelerates the westerly wind below 800 hPa over the western Pacific, which is partially responsible for the improved MJO simulation.

Time-dependent treatment of scattering: potential referenced and kinetic energy referenced modified Cayley approaches to atom–diatom collisions and time-scale separations

1992 ◽  
Vol 70 (2) ◽  
pp. 686-692
Author(s):  
Omar A.Sharafeddin ◽  
Donald J. Kouri ◽  
David K. Hoffman
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Time Scales ◽  
Quantum Dynamics ◽  
Time Dependent ◽  
Multiple Time Scales ◽  
Binding Potential ◽  
Multiple Time ◽  
General Reference ◽  
Cayley Transformation

The time-dependent Lippmann–Schwinger equation describing atom–diatom collisions is expressed in terms of a general reference Hamiltonian, Hr, whose dynamics are easily solved in one representation, and a corresponding disturbance Hamiltonian, Hd, whose dynamics are easily solved in a different representation. The wavefunction at time t + τ t is then expressed in terms of its value at a previous time t by means of a simple quadrature approximation. The resulting expression for ψ(t + τ) has a form similar to that occurring in earlier numerical unitary solutions to the time-dependent Schrodinger equation via a Cayley transformation. The structure of the new equations is made explicit for (a) the choice where Hr is taken to be the kinetic energy and Hd is the potential energy and (b) the choice where Hr is taken to be the potential energy and Hd is the kinetic energy. In addition, we also deal with several alternatives for treating the binding potential of the diatom. Several alternatives for choosing representations are then explored for reducing the equations to a form amenable to computation. The short time structure of the equations is discussed in terms of a multiple time-scales analysis. Keywords: molecular collisions, multiple time scales, quantum dynamics.

Bulinus on Aldabra and the subfamily Bulininae in the Indian Ocean area

1971 ◽  
Vol 260 (836) ◽  
pp. 299-313 ◽  
Keyword(s):  
Indian Ocean ◽  
Western Indian Ocean ◽  
Starch Gel Electrophoresis ◽  
Intermediate Hosts ◽  
Tropical Regions ◽  
Ocean Area ◽  
Freshwater Molluscs ◽  
Mitotic Metaphase Chromosome ◽  
Morphological Criteria ◽  
The Indian Ocean

The molluscan family Planorbidae is widely distributed throughout the temperate and tropical regions of the world. The subfamily Bulininae includes two genera only, Bulinus which is confined to the Ethiopian zoogeographical region, the Mediterranean area, the Middle East and some islands in the Western Indian Ocean, and Indoplanorbis which is common throughout India and Southeast Asia and also occurs on Socotra. These snails have been the subject of particularly intense study because of their importance as intermediate hosts for blood-flukes of the genus Schistosoma parasitic in man and domestic animals. The presence of a species of Bulinus on Aldabra is interesting because of the relative rarity of freshwater molluscs on atolls and also because it has served as a focus for drawing together the results of recent investigations into the distribution, relationships and intermediate host capacity of bulinids in the Indian Ocean area. This area has presented a number of problems in the interpretation of patterns of schistosomiasis transmission and most of these problems stem from misunderstandings about the taxonomy of the host snails and their parasites. Many of the misunderstandings have arisen from the paucity and unreliable nature of morphological criteria for taxonomic studies in basommatophoran snails and these have now been supplemented by cytogenetic, biochemical and immunological information. The methods used include paper chromatography of bodysurface mucus (Wright 1964), electrophoresis of egg proteins on cellulose acetate (Wright & Ross 1965, 1966), starch-gel electrophoresis of digestive-gland enzymes (Wright, File & Ross 1966; Wright & File 1968), Ouchterlony plate gel diffusion and agar-gel immuno-electrophoresis of egg proteins using antisera prepared in rabbits, and colcimid blocking of mitotic metaphase chromosome figures in developing embryos.

Generation and seasonal variability of eddy kinetic energy in the central Indian Ocean

2021 ◽  
Author(s):  
Georgy I. Shapiro ◽  
Jose Maria Gonzalez-Ondina
Keyword(s):  
Indian Ocean ◽  
Kinetic Energy ◽  
Seasonal Variability ◽  
Open Ocean ◽  
Eddy Kinetic Energy ◽  
Horizontal Shear ◽  
Data Set ◽  
Central Indian Ocean ◽  
The Indian Ocean ◽  
Meso Scale

<p>The breakthrough in our knowledge of ocean eddies came with the results of the POLYGON-67 experiment in the central Indian Ocean carried out in January-April 1967 (see Koshlyakov et al, 2016). It was the first direct and unambiguous observation that proved an earlier hypothesis by V. B. Shtockman of the existence of mesoscale eddies in open ocean, not only next to strong jet-stream currents. Now it is well known that the currents in open ocean are almost everywhere dominated by meso-scale eddies also known as synoptic eddies (Robinson, 1983). POLYGON-67 experiment covered a rectangle bounded by 10-15°N and 63-66.5°E. The purpose of this work is to analyse the seasonal variability of meso-scale eddy activity in the area covered by POLYGON-67 using a modern and comprehensive data set produced by an operational data assimilation model over a period from 1998 to 2017.</p><p>The 20-year long eddy resolving reanalysis of velocity fields in the Indian Ocean allows the study of seasonal variability, dynamics and generating mechanisms of eddy kinetic energy (EKE) in the tropical Indian Ocean, including the area covered by the original survey of POLYGON-67. In contrast to some other areas of the World Ocean, the EKE seasonality shows two maxima, the large one in April and the secondary one in October. The main mechanism of EKE generation is the barotropic instability which is evidenced by high correlation between EKE and enstrophy of large-scale currents, representing the strength of horizontal shear. It is found that the main contributor to the EKE variability within POLYGON-67 area is the advection of EKE across the boundaries during January-October, while the local generation has a comparable magnitude during August-December. The direction and strength of surface currents is consistent with the monsoon wind pattern in the area.</p><p>References</p><p>Koshlyakov, M.N., Morozov, E.G., and Neiman, V.G., 2016. Historical findings of the Russian physical oceanographers in the Indian Ocean. Geoscience Letters, 3:19; doi:10.1186/s40562-016-0051-6</p><p>Robinson, A.R. (Ed), 1983. Eddies in Marine Science. Springer, ISBN 978-3-642-69003-7, 612p.</p>

scholarly journals Characteristics of the Near-Surface Currents in the Indian Ocean as Deduced from Satellite-Tracked Surface Drifters. Part I: Pseudo-Eulerian Statistics

2015 ◽  
Vol 45 (2) ◽  
pp. 441-458 ◽  
Author(s):  
Shiqiu Peng ◽  
Yu-Kun Qian ◽  
Rick Lumpkin ◽  
Yan Du ◽  
Dongxiao Wang ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Kinetic Energy ◽  
Eastern Coast ◽  
Western Boundary ◽  
Surface Currents ◽  
Mean Velocity ◽  
Near Surface ◽  
The Indian Ocean ◽  
Central Eastern ◽  
Surface Drifters

AbstractUsing the 1985–2013 record of near-surface currents from satellite-tracked drifters, the pseudo-Eulerian statistics of the near-surface circulation in the Indian Ocean (IO) are analyzed. It is found that the distributions of the current velocities and mean kinetic energy (MKE) in the IO are extremely inhomogeneous in space and nonstationary in time. The most energetic regions with climatologic mean velocity over 50 cm s−1 and MKE over 500 cm2 s−2 are found off the eastern coast of Somalia (with maxima of over 100 cm s−1 and 1500 cm2 s−2) and the equatorial IO, associated with the strong, annually reversing Somalia Current and the twice-a-year eastward equatorial jets. High eddy kinetic energy (EKE) is found in regions of the equatorial IO, western boundary currents, and Agulhas Return Current, with a maximum of over 3000 cm2 s−2 off the eastern coast of Somalia. The lowest EKE (<500 cm2 s−2) occurs in the south subtropical gyre between 30° and 40°S and the central-eastern Arabian Sea. Annual and semiannual variability is a significant fraction of the total EKE off the eastern coast of Somalia and in the central-eastern equatorial IO. In general, both the MKE and EKE estimated in the present study are qualitatively in agreement with, but quantitatively larger than, estimates from previous studies. These pseudo-Eulerian MKE and EKE fields, based on the most extensive drifter dataset to date, are the most precise in situ estimates to date and can be used to validate satellite and numerical results.

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