Three-dimensional properties of mesoscale cyclonic warm-core and anticyclonic cold-core eddies in the South China Sea

In general,a mesoscale cyclonic(anticyclonic)eddy has a colder(warmer)core,and it is considered as a cold(warm)eddy.However,recently research found that there are a number of"abnormal"mesoscale cyclonic(anticyclonic)eddies associated with warm(cold)cores in the South China Sea(SCS).These"abnormal"eddies pose a challenge to previous works on eddy detection,characteristic analysis,eddy-induced heat and salt transports,and even on mesoscale eddy dynamics.Based on a 9-year(2000–2008)numerical modelling data,the cyclonic warm-core eddies(CWEs)and anticyclonic cold-core eddies(ACEs)in the SCS are analyzed.This study found that the highest incidence area of the"abnormal"eddies is the northwest of Luzon Strait.In terms of the eddy snapshot counting method,8620 CWEs and 9879 ACEs are detected,accounting for 14.6%and 15.8%of the total eddy number,respectively.The size of the"abnormal"eddies is usually smaller than that of the"normal"eddies,with the radius only around 50 km.In the generation time aspect,they usually appear within the 0.1–0.3 interval in the normalized eddy lifespan.The survival time of CWEs(ACEs)occupies 16.3%(17.1%)of the total eddy lifespan.Based on two case studies,the intrusion of Kuroshio warm water is considered as a key mechanism for the generation of these"abnormal"eddies near the northeastern SCS.

Detection of cyclonic eddy generated by looping tropical cyclone in the northern South China Sea: a case study

A case study on the cyclonic eddy generated by the tropical cyclone looping over the northern South China Sea (NSCS) is presented, using TOPEX/POSEIDON altimeter data and AVHRR sea surface temperature (SST) data. Three cases relating to the tropical cyclone events (Typhoon Kai-Tak in July 2000, Tropical Storm Russ in June 1994 and Tropical Storm Maria in August-September 2000) over the NSCS have been analyzed. For each looping tropical cyclone case, the cyclonic eddy with an obvious sea level depression appears in the sea area where the tropical cyclone takes a loop form, and lasts for about 2 weeks with a slight variation in location. The cold core with the SST difference greater than 2℃against its surrounding areas is also observed by the satellite-derived SST data.

A Preliminary Study of the Dynamics of Eastward Shifting Cyclonic Vortices

The dynamics of eastward shifting cyclonic vortices are investigated in terms of a barotropic primitive equation model, and six experiments are performed. Both the interaction of a cyclonic vortex with vorticity lumps and the interaction of the vortex with the shearing basic flow may induce the strengthening of the vortex in a short period, however, the vortex intensity still shows a general decreasing tendency over the whole integration time period. The interaction among the shearing basic flow, cyclonic vortex, and multiple vorticity lumps can change the tendency. The merging of the cyclonic vortex with vorticity lumps in the shearing basic flow of positive vorticity is directly responsible for the maintenance and development of the cyclonic vortex.

Wave parameters retrieval for dual-polarization C-band synthetic aperture radar using a theoretical-based algorithm under cyclonic conditions

Theoretical-based ocean wave retrieval algorithms are applied by inverting a synthetic aperture radar(SAR)intensity spectrum into a wave spectrum, that has been developed based on a SAR wave mapping mechanism. In our previous studies, it was shown that the wave retrieval algorithm, named the parameterized first-guess spectrum method(PFSM), works for C-band and X-band SAR at low to moderate sea states. In this work, we investigate the performance of the PFSM algorithm when it is applied for dual-polarization c-band sentinel-1(S-1) SAR acquired in extra wide-swath(EW) and interferometric wide-swath(IW) mode under cyclonic conditions.Strong winds are retrieved from six vertical-horizontal(VH) polarization S-1 SAR images using the c-band crosspolarization coupled-parameters ocean(C-3 PO) model and then wave parameters are obtained from the image at the vertical-vertical(VV) polarization channel. significant wave height(SWH) and mean wave period(MWP) are compared with simulations from the WAVEWATCH-III(WW3) model. The validation shows a 0.69 m root mean square error(RMSE) of SWH with a –0.01 m bias and a 0.62 s RMSE of MWP with a –0.17 s bias. Although the PFSM algorithm relies on a good quality SAR spectrum, this study confirms the applicability for wave retrieval from an S-1 SAR image. Moreover, it is found that the retrieved results have less accuracy on the right sector of cyclone eyes where swell directly affects strong wind-sea, while the PFSM algorithm works well on the left and rear sectors of cyclone eyes where the interaction of wind-sea and swell is relatively poor.

Particle Residence Time in Column Flotation Based on Cyclonic Separation

The cyclonic static micro-bubble column flotation (FCSMC) is an effective separation device for fine particle treatment. The high mineralization rate and short flotation time of this equipment can be attributed to its unique cyclonic force field. It also has been observed that the presence of a cyclonic force field leads to a lower bottom separation size limit and a reduction of unselective entrainment. The collection zone of the column is considered to consist of two parts,a column separation zone and a cyclonic zone. Total recovery of the collection zone was developed. For our study,we analyzed the particle movement in the cyclonic zone. Particle residence time equations for the cyclonic zone were de-rived by force analysis. Results obtained in this study provide a theoretical foundation for the design and scale-up of the FCSMC.

Velocity distribution of the flow field in the cyclonic zone of cyclone-static micro-bubble flotation column

Laboratory experiments have been conducted to study the flow field in a cyclone static micro-bubble flotation column. The method of Particle Image Velocimetry (PIV) was used. The flow field velocity distribution in both cross section and longitudinal section within cyclonic zone was studied for different circulating volumes. The cross sectional vortex was also analyzed. The results show that in cross section as the circulating volume increases from 0.187 to 0.350 m 3 /h, the flow velocity ranges from 0 to 0.68 m/s. The flow field is mainly a non-vortex potential flow that forms a free vortex without outside energy input. In the cyclonic region the vortex deviates from the center of the flotation column because a single tangential opening introduces circulating fluid into the column. The tangential component of the velocity plays a defining role in the cross section. In the longitudinal section the velocity ranges from 0 to 0.08 m/s. The flow velocity increases as does the circulating volume. Advantageous mineral separation conditions arise from the combined effects of cyclonic flow in cross and longitudinal section.

Cyclonic separation process intensification oil removal based on microbubble flotation

The cyclonic-static microbubble flotation column has dual effects including the cyclonic separation and floatation separation with the characteristics of the small lower limit of the effective separation size, short separation time, large handling capacity, and low operation cost. It shows significant advantages in the oily wastewater treatment field, especially the polymer flooding oily wastewater treatment aspect. In this paper, the cyclonic separation function mechanism of the cyclonic-static microbubble flotation column was studied, the impact of the parameters including the feeding rate, aeration rate, circulating pressure, and underflow split ratio on the cyclonic separation efficiency was investigated, and the cyclonic separation efficiency model was established as well. In addition, by applying the Doppler Laser Velocimeter (LDV) and Fluent simulation software, the test and simulation to the single-phase flow velocity field of the cyclonic separation section of the cyclonic-static microbubble flotation column were carried out, and the velocity distribution rule of the cyclonic separation section was analyzed under the singlephase flow conditions.

Investigation on the Sediment Characteristics of the Electrostatic Cyclonic Precipitator

In order to find out the relationship between the sediment characteristics and collecting efficiency of the electrostatic cyclonic precipitator, an online study for the sediment characteristics of electrostatic cyclonic precipitator had been done with Kompton back scatter method, with the collecting efficiency tested at the same time. And the relationship between the sediment characteristics and the collecting efficiency was gotten. The sediment thickness increased with time extended and the concentration increased when the inlet velocity was fixed. The collecting efficiency increased with the inlet velocity increased, but dropped with the concentration increased. When the concentration and inlet velocity were fixed, the collecting efficiency drop a little with the increase of sediment thickness. The sediment would decrease the corona current in the collecting filed, which would make the electrostatic effect fall, then made the collecting efficiency drop a little.

Response of extreme precipitation to increasing extratropical cyclonic vortex frequency

Since the 2000 s,extratropical extremes have been more frequent,which are closely related to anomalies of planetary-scale and synoptic-scale systems.This study focuses on a key synoptic system,the extratropical cyclonic vortex(ECV)over land,to investigate its relations with extreme precipitation.It was found that ECVs have been more active post-2000,which has induced more extreme precipitation,and such variation is projected to persist along with increasing temperature within 1.5℃of global warming.An enhanced quasi-stationary vortex(QSV)primarily contributes to the ECV,rather than inactive synoptic-scale transient eddies(STEs).Inactive STEs respond to a decline in baroclinicity due to the tendency of the homogeneous temperature gradient.However,such conditions are helpful to widening the westerly jet belt,favoring strong dynamic processes of quasi-resonant amplification and interaction of STEs with the quasi-stationary wave,and the result favors an increasing frequency and persistence of QSVs,contributing to extreme precipitation.

Short－term Climatic Fluctuations in North Atlantic Oscillation and Frequency of Cyclonic Disturbances over North Indian Ocean and Northwest Pacific

A relationship between mean sea level pressure gradient between Azores High (AH) and Icelandic Low (IL) hereafter called North Atlantic Oscillation Index (NAOI) and the frequency of cyclonic disturbances over North indianOcean is investigated using 98 years of date (1891-1988). The analysis is carried out on monthly, seasonel, annual anddecadal scales. Similar studies are also done for North West Pacific ocean cyclonic disturbances. It is nohced that thenumber of cyclonic disturbances over North indian Ocean during monsoon season (June-September) as well as onannual scale is significantly correlated with NAOI. However for pre (April-May) and post (October-November-December) monsoon seasons frequency of cyclonic disturbances do not bear similar relationship with NAOI. Thestudy also shows that decadal scale variability of cyclonic disturbances during the summer monsoon over North Indian Ocean has a remarkable correspondence with the decadal variability of NAOI.

Arctic summertime anticyclonic circulation mode and its influence on substantial sea ice depletion:a review

The summertime anticyclonic circulation mode(SACM)is related to recent substantial loss of sea ice in the Arctic.This review outlines the potential causes of the SACM and considers its influence on sea ice depletion.Local triggers(i.e.,sea ice loss and sea surface temperature(SST)variation)and spatiotemporal teleconnections(i.e.,extratropical cyclone intrusion,tropical and mid-latitude SST anomalies,and winter atmospheric circulation preconditions)are discussed.The influence of the SACM on the dramatic loss of sea ice is emphasized through inspection of relevant dynamic(i.e.,Ekman drift and export)and thermodynamic(i.e.,moisture content,cloudiness,and associated changes in radiation)mechanisms.Moreover,the motivation for investigation of the underlying physical mechanisms of the SACM in response to the recent substantial sea ice depletionis also clarified through an attempt to better understand the shifting ice-atmosphere interaction in the Arctic during summer.Therecord low extent of sea ice in September 2012 could be reset in the near future if the SACM-like scenario continues to exist during summer in the Arctic troposphere.

Frequency of Cyclonic Disturbances and Changing Productivity Patterns in the North Indian Ocean Region: A Study Using Sea Surface Temperature and Ocean Colour Data

In recent years we are observing devastating cyclones like Nargis, Gonu, Sidr, Liala, Phet etc in the North Indian Ocean associated with heavy rains, thunderstorm, high tide and intense winds that caused shocking destructions in the coastal areas. As these are originating over the Ocean and propagating towards land, they also change physical property as well as biological structure of the Ocean. In recent years, several attempts were made to associate tropical cyclone trends with climate change resulting from green house warming. The studies have indicated an increase in intense cyclones in the Arabian Sea. Time series analysis of ocean colour data have revealed rapid and profound change in the productivity pattern over the last few years in the Arabian Sea that appears to be related to the warming trends being experienced over the Asian subcontinent. In view of the above, a study was carried out to examine the frequency of cyclonic disturbances in the Arabian Sea and the Bay of Bengal and its effect in modulating the productivity patterns. Data on the monthly and annual occurrences of tropical cyclones in the Bay of Bengal and the Arabian Sea were collected from 1908 to 2007 from SAARC Meteorological Research Centre and Indian Meteorological Department. Sea surface temperature (SST) from NOAA-AVHRR and phytoplankton biomass indexed as chlorophyll-a concentration from Sea WiFs for ten years (1998-2007) were used to study the physical and biological effects of cyclonic events in the Arabian Sea (AS) and the Bay of Bengal (BOB). Analysis of the monthly and annual occurrences of tropical cyclone reveals an increasing trend of cyclonic disturbances in the AS whereas there is a decreasing trend in the BOB in the last decade (1998-2007). SST analysis indicates decrease in monthly average SST by 1.5℃ to 1.75℃ in the AS and 1.5℃ to 1.25℃ in the BOB in the pre-monsoon season. Phytoplankton biomass was observed to increase by a factor of two after the passage of cyclone. Results of the ten year analysis and comparison with the climatology showed that frequent occurrence of cyclonic events that cause short term-nutrient enrichment of upper-stratified ocean resulting in enhanced biological productivity and perturbations in the otherwise stable and seasonally-varying ecological structure of the North Indian Ocean.

Cyclonic Separation Technology:Researches and Developments

Centered on thetechniques and industrial applications of the reinforced cyclonic separation process, its principles and mechanism for separation ot ions, molecules and their aggregates using polyalsperse aroplets are discussed generally; the characteristics and influential factors of fish-hook phenomenon of the grade efficiency curve in cyclonic separation for both gas and liquid are analyzed; and the influence of shear force on particle be- havior （or that of particle swarm） is also summarized. A novel idea for cyclonic separation is presented here： enhancing the cyclonic seoaration process of ions, molecules and their aggregates with monodisperse microspheres and their surface grafting, rearranging the distribution of particles by size using centrifugal field, reinforcing the cyclonic separation performance with orderly arranged particle swarm. Also the investigation of the shortcut flow, recirculation flow, the asymmetric structure and non-linear characteristics of the cyclonic flow field with a com-bined method of Volumetric 3-component Velocimetry （V3V） and Phase-Doppler Particle Anemometer （PDPA） are elaborated. It is recommended to develop new systems for the separation of heterogeneous phases with cyclonic technology, in accordance with the capture and reuse of CO2, methanol to olefins （MTO） process, coal transfer, andthe exploitation of oil shale.

Joint Manifestations of PDO （Pacific Decadal Oscillation） and Negative AMO （Atlantic Multidecadal Oscillation） Phases in Winter Cyclonic Activity

The AMO （Atlantic Multidecadal Oscillation） and PDO （Pacific Decadal Oscillation） were considered as the main indicators of decadal-multidecadal variations of global climate system. Joint and separate AMO and PDO manifestations in the winter cyclonic activity on the global and regional scales for the Northern Hemisphere and Mediterranean and Black Sea were studied. Composite schemes of typical displacement of cyclonic active zones in Northern Hemisphere for two combinations of AMO and PDO phases are proposed.

BEHAVIOR OF JET SUCKING CYCLONIC ULTRAMICRON CLASSIFIER

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Numerical Modeling of the Initial Formation of Cyclonic Vortices at Tropical Latitudes

To investigate the initial formation of large-scale vortices at tropical latitudes a regional non-hydrostatic mathematical model of the wind system of the lower atmosphere, developed earlier in the Polar Geophysical Institute, is utilized. Three-dimensional distributions of the atmospheric parameters in the height range from 0 to 15 km over a limited region of the Earth’s surface are produced by the utilized model. Simulations are performed for the case when the limited three-dimensional simulation domain is intersected by an intertropical convergence zone in the west-east direction. Simulation results indicated that the origin of two convexities in the north direction in the configuration of the intertropical convergence zone can lead to the formation of three distinct tropical cyclones during the period of about four days.

Comparative analysis of the rapid intensification of two super cyclonic storms in the Arabian Sea

A comparative analysis of the rapid intensification(RI)of super cyclonic storms Chapala(2015)and Kyarr(2019)in the Arabian Sea is conducted using the North Indian Ocean tropical cyclone data,microwave sounding images,the NOAA OISST data and the ERA5 reanalysis data.Results show that the subtropical westerly jet stream and the Southern Hemisphere anticyclonic circulation led to the formation of an obvious double-channel outflow from the northern and southern sides of the two storm centers,and the substantial inflow appeared at the eastern boundary layer of both storms.These promoted the vertical ascent motion and release of the latent heat of condensation.A warm sea surface is a necessary but not dominant factor for the RI of cyclonic storms in the Arabian Sea.During the RI of Chapala and Kyarr,the deep vertical wind shear was less than 10 m s-1;moreover,the mid-level humidity conditions favored the RI of the two cyclonic storms.Chapala had a single warm core,whereas Kyarr had double warm cores in the vertical direction.The impacts of the latent heat of fusion is more obvious for Chapala,and the potential vorticity in its inner core increases from 4.4 PVU to 8.8 PVU,whereas the potential vorticity and vorticity in the inner core of Kyarr do not change significantly.Microwave detection images show that both Chapala and Kyarr were accompanied by the formation of eyewalls during the RI phase,and the radius of maximum wind decreased and the maximum wind speed increased during the eyewall-thinning process.Both Chapala and Kyarr passed through a positive anomaly region of maximum potential intensity during the RI phase,which increases the possibility to develop to higher intensity after genesis.

Simulation of Tropical Cyclogenesis in Association with Large-Scale Cyclonic Circulation over the Western North Pacific

The aim of this study is to examine the difference in tropical cyclone （TC） formation in different cyclonic circulation locations using a mesoscale model on a beta plane. A weak initial vortex is imposed at different positions in a cyclonic circulation. Numerical experiments indicate that the tropical disturbances located in the center and northeastern parts of the cyclonic circulation are favorable to TC formation, while those located in the south of the cyclonic circulation are unfavorable. Since the asymmetric circulation induced by the beta effect peaks in the northeastern quadrant of the vortex, when the initial vortex is placed in the southern part of the cyclonic circulation, the vortex begins to develop in the south due to the effect of the westerly wind of the cyclonic circulation. The westerly wind of the cyclonic circulation gradually decreases and the vortex is contributed mainly by the beta effect afterwards. Thus, establishment of the convection circulation-moisture positive feedback is delayed, unfavorable to TC rapid development. On the contrary, when the initial vortex is placed in the northern part of the cyclonic circulation, the superposition of the beta gyres and easterly wind of the cyclonic circulation induces stronger wavenumber-1 wind in the northeastern part of the vortex. The greater asymmetric wind is closely associated with the symmetric wind through energy conversion, thus accelerating a positive feedback and facilitating vortex development into a stronger TC. Meanwhile, when the initial vortex is placed in the center and eastern parts of the cyclonic circulation, the vortex develops a little slower than when it is placed in the northern part, but stronger than when placed in the southern part.

ANALYSIS OF THE CYCLONIC VORTEX AND EVALUATION OF THE PERFORMANCE OF THE RADAR INTEGRATED NOWCASTING SYSTEM(RAINS) DURING THE HEAVY RAINFALL EPISODE WHICH CAUSED FLOODING IN PENANG, MALAYSIA ON 5 NOVEMBER 2017

Even though Malaysia is relatively safe from the direct path of tropical cyclones nevertheless the passage of such systems over the neighbouring seas and their tail effect present a unique challenge for forecasters. In rare situations, tropical cyclones had made landfall on Malaysian shores such as Typhoon Vamei in 2001 and Tropical Storm Greg in 1996. Hence it is vital to forecast the severity of the heavy rainfall events associated with low pressure systems to assist the disaster management agencies in decision making. Towards this endeavour, the Malaysian Meteorological Department(MMD) utilises a nowcasting system called Radar Integrated Nowcasting System(RaINS) which uses a combination of radar data and Numerical Weather Prediction(NWP) data. RaINS was adapted from SWIRLS(Short-range Warning of Intense Rainstorms in Localised Systems) developed by the Hong Kong Observatory(HKO) and operationalised in MMD in August 2017. This paper studies the cyclonic vortex and synoptic features during the heavy rainfall event that caused major flooding in Penang, Malaysia on 5 November 2017. This paper also investigates the performance of RaINS in predicting the rain cloud distribution and intensity during that event. It is found that RaINS is capable of forecasting the rain cloud distribution and intensity reasonably well in the very short-term period of 1-3 hours. The forecasts are verified by comparing the RaINS forecast data with observed radar echo.

EVOLUTION OF THERMODYNAMIC STRUCTURES DURING RAPID GROWTH AND DECAY OF EXTREMELY SEVERE CYCLONIC STORM CHAPALA(2015)

The structure and evolution of inner-core convective bursts and their differences associated with rapid intensification(RI) and rapid decay(RD) of tropical cyclone CHAPALA are examined. The inception of RI was associated with substantial increase of convective heating and its vertical extent in the inner core. Increase in diabatic heating was of the order of 12-21 oC, particularly in the middle and upper troposphere. Latent heat release produced a diabatically generated potential vorticity(PV) in vertical column. The immediate cause of RI was a significant increase of moisture flux from surface to 500 h Pa. This was accomplished primarily by updrafts of the order of 6-12 Pa s-1, representing the strong vertical motion distribution inside the warm core convective zone. The episode of deep convective bursts transpired during the period of RI. The evolving flow became highly symmetric and dominated by deep convective axisymmetric vortex structures. The RD coincided with the significant weakening in updraft of moisture flux consequently decrease of diabatic heating in the middle and upper troposphere and dissipation of upper and lower PV.