STUDY ON KINETIC ENERGY BUDGET OF A TYPHOON——THE CONVERSION BETWEEN KINETIC ENERGIES OF DIVERGENT WINDS AND NON-DIVERGENT WINDS

This paper is the Part Ⅱ of studying the budget of kinetic energy of the typhoon No. 7507, with the emphasis on the conversion between the kinetic energy of the divergent winds and that of the non-divergent winds, and its relationship to the heating field. The main findings have been brought out as follows.

The Dynamical Effects of Divergent Wind on the Intraseasonal variabinty of the East Asian Circulation

In this paper, the dynamical effeCts of divergent wind on the intraseasonal variability of atmospheric circulationover East Asia are analyzed by using the function of Rossby-wave source and the energy exchanging function between divergent component and rotahonal component of the flow.The results analyzed from the observed data show that the advection of voracity by divergent wind caused by theheating due to the monsoon rainfall in the south to the Yangals River and the strong convective activities around thePhilippines may play an important role in the northward jump of westerly jet stream during the seasonal transitionfrom sprillg circulation to summer circulahon over East Asia. Due to the northward movement of the advechon ofvorticity by the divergent willd, the energy transformation from divergent component into rotational component canbe caused over the Yellow River basin and Northwest China and will cause the intensification of the zonal flow there.Thus, the jet stream abruptly shifts northward to North China.Moreover, the analysed results also show that the advection of vorticity by divergent wind caused by the heatingdue to the strong convective activities around the Philippines also plays an important role in the intraseasonal variability of the circulation over East Asia during the seasonal transition from summer to winter. With the southward'movement of the advection of vorticity by the divergent wind, the energy transformation from divergent componentinto rotational comPOnent can be caused over East Asia, espeially over the Yangtze-Huaihe River basin. Therefore,the jet stream gradually moves southward from North China to the YangtZe River basin.

THE FORCING OF ANOMALOUS DIVERGENT WIND AND TRANSIENT VORTICITY FLUXES TO THE ANOMALY OF STATIONARY WAVES

The forcing of anomalous divergent wind and transient vorticity fluxes to the anomaly of stationary waves of DJF (December—January—February) 1982/1983 is studied.The results show that the anomaly of the transient vorticity flux convergence tends to cancel or dissipate the anomaly of the vorticity sources generated by divergent wind.The stationary wave anomalies are maintained by both of these forcings.It is also found that,for the DJF 1982/1983 case,both of the vorticity source anomaly over the tropical and equatorial eastern Pacific and that over the midlatitude North Pacific are important to maintain the atmospheric circulation anomaly over the Pacific/North America region.

Energetics characteristics accounting for the low-level wind’s rapid enhancement associated with an extreme explosive extratropical cyclone over the western North Pacific Ocean

During mid-January 2011,a rarely seen twin-extratropical-cyclone event appeared over the western North Pacific Ocean.One of the twin cyclones developed into an extreme explosive extratropical cyclone(EEC),which was comparable to the intensity of a typhoon.Rotational and divergent wind kinetic energy(KE)analyses were applied to understand the low-level wind’s rapid enhancement associated with the cyclone.It was found that:(i)the total wind KE associated with the EEC showed a remarkable enhancement in the lower troposphere during the cyclone’s maximum development stage,with the maximum/minimum wind acceleration appearing in the southeastern/northwestern quadrant of the EEC;(ii)the rotational wind KE experienced an obvious increase,which corresponded to the total wind KE enhancement,whereas the divergent wind KE,which was much smaller than the rotational wind,mainly featured a decreasing trend;(iii)the rotational wind KE enhancement showed variational features consistent with the horizontal enlargement and upward stretching of the EEC;(iv)the nonorthogonal wind KE enhanced the total wind KE in regions with strong rotational wind,which resulted in the maximum lower-tropospheric maximum wind,whereas in regions with strong divergent wind it mainly reduced the total wind KE;(v)the northward transport of total wind KE and the rotational wind KE production due to the work done by pressure gradient force were dominant factors for the enhancement of winds associated with the EEC,particularly in its southeastern section.In contrast,an overall conversion from rotational wind KE to divergent wind KE decelerated the rotational wind enhancement.

Intensity Evolution of Zonal Shear Line over the Tibetan Plateau in Summer:A Perspective of Divergent and Rotational Kinetic Energies

Based on the ERA5 reanalysis datasets during 1980-2019,a total of eleven zonal shear lines(ZSLs)that caused heavy precipitation and lasted more than 60 hours over the Tibetan Plateau in summer are selected for composite analysis.By decomposing the kinetic energy(K)near the ZSL into divergent and rotational kinetic energies(K_(D)and K_(R))and the kinetic energy of interaction between the divergent wind and the rotational wind(K_(R)D),the influence of the rotational and divergent winds on the evolution of the ZSL intensity is investigated from the perspective of K_(D)and K_(R).The main results are as follows.The ZSL is a comprehensive reflection of rotation and convergence.The intensity evolution of ZSL is essentially synchronized with those of K,K_(R),and K_(RD)but lags behind K_(D)by about three hours.The enhancement of K is mainly contributed by K_(R),which is governed by the conversion from K_(D)to K_(R).Furthermore,the increase in the conversion from K_(D)to K_(R)is controlled by the geostrophic effect term Af,which is determined by the joint enhancement of the zonal rotational and meridional divergent wind components(u_(R)and v_(D)).Therefore,the joint enhancement of u_(R)and v_(D)controls the increase of the ZSL intensity,leading to increased precipitation.

On the Variation of Divergent Flow： An Eddy-flux Form Equation Based on the Quasi-geostrophic Balance and Its Application

Based on basic equations in isobaric coordinates and the quasi-geostrophic balance,an eddy-flux form budget equation of the divergent wind has been derived. This newly derived budget equation has evident physical significance. It can show the intensity of a weather system,the variation of its flow pattern,and the feedback effects from smaller-scale systems(eddy flows). The usefulness of this new budget equation is examined by calculating budgets for the strong divergent-wind centers associated with the South Asian high,and the strong divergence centers over the Tibetan Plateau,during summer(June–August) 2010. The results indicate that the South Asian high significantly interacts with eddy flows. Compared with effects from the mean flow(background circulation),the eddy flows’ feedback influences are of greater importance in determining the flow pattern of the South Asian high. Although the positive divergence centers over the Tibetan Plateau intensify through different mechanisms,certain similarities are also obvious. First,the effects from mean flow are dominant in the rapid intensification process of the positive divergence center. Second,an intense offsetting mechanism exists between the effects associated with the eddy flows’ horizontal component and the effects related to the eddy flows’ convection activities,which weakens the total effects of the eddy flows significantly. Finally,compared with the effects associated with the convection activities of the mean flow,the accumulated effects of the eddy flows’ convection activities may be more favorable for the enhancement of the positive-divergence centers.

Multivariate Objective Analysis of Wind and Height Fields in the Tropics

The commollly used objective analysis scheme(Scheme-A) for the analysis Of wind and geopotential height smoothen the divergent component of the wind which is rather important in the tropics,specifically over convective regions.To overcome this deficiellcy, a new analysis SCheme in which divergent component is included in the statistical model of the wind forecast errors,has been proposed by Daley(1985).Following this scheme,a new set of correlahon functions of forecast errors for the indian region during monsoon season which are suitable for analysing the tropical wind are obtained.This analysis scheme(Scheme--B) as well as Scheme-A were used to make analyses for the period from 4 July to & July 1979(12 GMT) at 850,700 and 200 hpa levels over an area bounded by l.875'N to 39.375'N and 41.250'E to 108.750'E and subsequently divergent component,velocity potential are computed for both schemes.Results from both these schemes show that in the monsoon depression region the velocity potential and divergence have increased in the later case(Scheme-B).This suggests that the divergent component has been enhanced in Scheme-B and that the objechve of this study is realized to some extent.

Modified Mackenzie Equation and CVOA Algorithm Reduces Delay in UASN

In Underwater Acoustic Sensor Network(UASN),routing and propagation delay is affected in each node by various water column environmental factors such as temperature,salinity,depth,gases,divergent and rotational wind.High sound velocity increases the transmission rate of the packets and the high dissolved gases in the water increases the sound velocity.High dissolved gases and sound velocity environment in the water column provides high transmission rates among UASN nodes.In this paper,the Modified Mackenzie Sound equation calculates the sound velocity in each node for energy-efficient routing.Golden Ratio Optimization Method(GROM)and Gaussian Process Regression(GPR)predicts propagation delay of each node in UASN using temperature,salinity,depth,dissolved gases dataset.Dissolved gases,rotational and divergent winds,and stress plays a major problem in UASN,which increases propagation delay and energy consumption.Predicted values from GPR and GROM leads to node selection and Corona Virus Optimization Algorithm(CVOA)routing is performed on the selected nodes.The proposed GPR-CVOA and GROM-CVOA algorithm solves the problem of propagation delay and consumes less energy in nodes,based on appropriate tolerant delays in transmitting packets among nodes during high rotational and divergent winds.From simulation results,CVOA Algorithm performs better than traditional DF and LION algorithms.

MAINTENANCE MECHANISMS OF THE STATIONARY WAVE ANOMALY TELECONNECTION PATTERNS IN THE UPPER TROPOSPHERE

The spatial structure and temporal variations of the stationary wave anomalies in the upper troposphere during the Northern Hemisphere winter are studied with the ECMWF data of 1980— 1988 and PCA(principal component analysis)method.The vorticity source anomalies of the main teleconnection patterns are analyzed,and their roles in the maintenance of the stationary wave anomaly teleconnection patterns are investigated with the harotropic model.The results show that the anomalies of transient vorticity flux convergences tend to cancel the anomaly of vorticity sources generated by divergent winds.The stationary wave anomaly patterns caused by divergent wind anomalies only are very different from observations.However,if the anomalous transient vorticity flux convergences are also included in the vorticity sources,the simulated patterns will be greatly improved.