The coastal ocean west of Guangdong Province(refers to Yuexi)is characterized as wide and shallow continental shelf,and connected to the Beibu Gulf through the Qiongzhou Strait(as shown in Fig.1).The circulation patte...The coastal ocean west of Guangdong Province(refers to Yuexi)is characterized as wide and shallow continental shelf,and connected to the Beibu Gulf through the Qiongzhou Strait(as shown in Fig.1).The circulation pattern is complicated,controlled by the East Asian monsoon,tides,buoyancy forcing,and topography.In general,the mean cur-rent on the shelf flows southwestward in winter and northeastward in summer,while the coastal current flows always southwestward in summer(Yang et al.,2003;Shu et al.,2018).展开更多
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(anti...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.展开更多
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. Thre...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.展开更多
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 ...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.展开更多
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...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.展开更多
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...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.展开更多
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 bo...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.展开更多
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 s...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.展开更多
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 cyclon...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.展开更多
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 cyclon...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.展开更多
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 in...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.展开更多
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.L...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.展开更多
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 dest...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.展开更多
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 ...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.展开更多
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 ...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.展开更多
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 I...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.展开更多
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,t...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.展开更多
This past year, 2024, is on track to be the warmest year, joining 2023 as the two hottest years on record. With the exceptional heat, weather and climate extremes were common across the world. In particular, 2024 has ...This past year, 2024, is on track to be the warmest year, joining 2023 as the two hottest years on record. With the exceptional heat, weather and climate extremes were common across the world. In particular, 2024 has seen a remarkable run of extreme precipitation events and resulting impacts. Here, we provide an overview of the most notable extreme events of the year, including extreme precipitation and floods, tropical cyclones, and droughts. The characteristics and impacts of these extreme events are summarized, followed by discussion on the physical drivers and the role of global warming.Finally, we also discuss the future prospects in extreme event studies, including impact-based perspectives, challenges in attribution of precipitation extremes, and the existing gap to minimize impacts from climate extremes.展开更多
基金The National Key Research and Development Program of China under contract No.2022YFC3104805the National Natural Science Foundation of China under contract Nos 42276019,42176184,and 42476027+3 种基金the Guangdong Basic and Applied Basic Research Foundation under contract Nos 2024A1515012572 and 2025A1515010741the Innovation Team Plan for Universities in Guangdong Province under contract No.2023KCXTD015the Tropical Ocean Environment in Western Coastal Waters Observation and Research Station of Guangdong Province under contract No.2024B1212040008the Undergraduate Innovation Team Project under contract No.CXTD2019001.
文摘The coastal ocean west of Guangdong Province(refers to Yuexi)is characterized as wide and shallow continental shelf,and connected to the Beibu Gulf through the Qiongzhou Strait(as shown in Fig.1).The circulation pattern is complicated,controlled by the East Asian monsoon,tides,buoyancy forcing,and topography.In general,the mean cur-rent on the shelf flows southwestward in winter and northeastward in summer,while the coastal current flows always southwestward in summer(Yang et al.,2003;Shu et al.,2018).
基金The National Natural Science Foundation of China under contract Nos 41906008,41806039,41806030,42076021,41676010 and 41706205the State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences under contract Nos LTO1902 and LTO1807+9 种基金the Strategic Priority Research Program of Chinese Academy of Sciences under contract No.XDB42000000the Youth Innovation Promotion Association CAS under contract No.2017397the Pearl River S&T Nova Program of Guangzhou under contract No.201806010105the Open Fund of State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of OceanographyMNR under contract No.QNHX2022the Startup Foundation for Introducing Talent of Nanjing University of Information Science&Technology under contract No.2019r049the Startup Foundation for Introducing Talent of Zhejiang Ocean Universitythe National Key Research Programs of China under contract Nos2016YFC1401407 and 2017YFA0604100the National Programme on Global Change and Air-Sea Interaction under contract Nos GASIIPOVAI-03 and GASI-IPOVAI-05the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)under contract No.311020004。
文摘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.
文摘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.
基金The National Key Research and Development Program of China under contract No.2017YFA0604901the National Natural Science Foundation of China under contract Nos 41806005 and 41776183the Public Welfare Technical Applied Research Project of Zhejiang Province of China under contract No.LGF19D060003
文摘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.
基金the National Natural Science Foundation under Grant No.49775263the project of the Tibetan Plateau Experiment(TIPEX)of Atmospheric Science and the 973 Project onheavy rain in China.
文摘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.
基金Project 50425414 supported by the National Outstanding Youth Science Foundation of China
文摘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.
基金the State Key Basic Research Program of China (No. 2012CB214905)Key Program of National Natural Science Foundation of China (No. 500834006)the National Natural Science Foundation of China (No. 50974119) for financial support
文摘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.
基金the National Natural Science Foundation of China (No. 50974119) for the financial support for this project
文摘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.
文摘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.
基金supported by the National Natural Science Foundation of China(Grant No.41975083)。
文摘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.
文摘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.
基金This work is financially supported by Laoshan Laboratory(Grant no.LSKJ202203003)National Natural Science Foundation of China(Grant nos.42276250,41976221)General Project of Natural Science Foundation of Shandong Province(Grant no.ZR2020MD100).
文摘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.
文摘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.
基金Supported by the National Natural Science Foundation of China (21076073)the Shanghai Foundation for Development of Science and Technology (10DZ1201300)Sci-Tech Development Plan of SINOPEC (109070)
文摘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.
文摘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.
文摘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.
基金supported by the National Natural Science Foundation of China (41930972).
文摘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.
基金jointly supported by the National Natural Science Foundation of China (Grant Nos.42422502 and 42275038)the China Meteorological Administration Climate Change Special Program (Grant No.QBZ202306)funded by the Met Office Climate Science for Service Partnership (CSSP) China project under the International Science Partnerships Fund (ISPF)。
文摘This past year, 2024, is on track to be the warmest year, joining 2023 as the two hottest years on record. With the exceptional heat, weather and climate extremes were common across the world. In particular, 2024 has seen a remarkable run of extreme precipitation events and resulting impacts. Here, we provide an overview of the most notable extreme events of the year, including extreme precipitation and floods, tropical cyclones, and droughts. The characteristics and impacts of these extreme events are summarized, followed by discussion on the physical drivers and the role of global warming.Finally, we also discuss the future prospects in extreme event studies, including impact-based perspectives, challenges in attribution of precipitation extremes, and the existing gap to minimize impacts from climate extremes.
