The Ross-Amundsen sector is experiencing an accelerating warming trend and a more intensive advective influx of marine air streams.As a result,massive surface melting events of the ice shelf are occurring more frequen...The Ross-Amundsen sector is experiencing an accelerating warming trend and a more intensive advective influx of marine air streams.As a result,massive surface melting events of the ice shelf are occurring more frequently,which puts the West Antarctica Ice Sheet at greater risk of degradation.This study shows the connection between surface melting and the prominent intrusion of warm and humid air flows from lower latitudes.By applying the Climate Feedback-Response Analysis Method(CFRAM),the temporal surge of the downward longwave(LW)fluxes over the surface of the Ross Ice Shelf(RIS)and adjacent regions are identified for four historically massive RIS surface melting events.The melting events are decomposed to identify which physical mechanisms are the main contributors.We found that intrusions of warm and humid airflow from lower latitudes are conducive to warm air temperature and water vapor anomalies,as well as cloud development.These changes exert a combined impact on the abnormal enhancement of the downward LW surface radiative fluxes,significantly contributing to surface warming and the resultant massive melting of ice.展开更多
Typhoon Hato (2017) went through a rapid intensification (RI) process before making landfall in Zhuhai,Guangdong Province, as the observational data shows. Within 24 hours, its minimum sea level pressure deepened by35...Typhoon Hato (2017) went through a rapid intensification (RI) process before making landfall in Zhuhai,Guangdong Province, as the observational data shows. Within 24 hours, its minimum sea level pressure deepened by35hPa and its maximum sustained wind speed increased by 20m s-1. According to satellite observations, Hato encountered a large area of warm water and two warm core rings before the RI process, and the average sea surface temperature cooling (SSTC) induced by Hato was only around 0.73℃. Air-sea coupled simulations were implemented to investigate the specific impact of the warm water on its RI process. The results showed that the warm water played an important role by facilitating the RI process by around 20%. Sea surface temperature budget analysis showed that the SSTC induced by mixing mechanism was not obvious due to the warm water. Besides, the cold advection hardly caused any SSTC, either. Therefore, the SSTC induced by Hato was much weaker compared with that in general cases. The negative feedback between ocean and Hato was restrained and abundant heat and moisture were sufficiently supplied to Hato. The warm water helped heat flux increase by around 20%, too. Therefore, the warm water influenced the structure and the intensity of Hato. Although there might be other factors that also participated in the RI process, this study focused on air-sea interaction in tropical cyclone forecast and discussed the impact of warm water on the intensity and structure of a tropical cyclone.展开更多
Based on the air-sea interface heat fluxes and related meteorological variables datasets recently released by Objectively Analyzed Air-Sea Fluxes(OA Flux) Project of Woods Hole Oceanographic Institution,as well as the...Based on the air-sea interface heat fluxes and related meteorological variables datasets recently released by Objectively Analyzed Air-Sea Fluxes(OA Flux) Project of Woods Hole Oceanographic Institution,as well as the outgoing longwave radiation and surface wind datasets from National Oceanic and Atmospheric Administration,the seasonal dependence of local air-sea interaction over the tropical western Pacific warm pool(referred to the region(1o-6oN,144o-154oE)) is revealed and the probable impacts of remote forcing on the air-sea interaction are examined.The results indicated the dominance of oceanic forcing with the significant impact of ENSO in March and that of atmospheric feedback without notable influence of remote forcing in June.While the interannual variability of sea surface temperature anomaly(SSTA) is larger than that of SSTA tendency when oceanic forcing is dominant,the opposite is true when atmospheric feedback is dominant.The magnitude of the oceanic forcing of the atmosphere tends to decrease in March with the occurrence of ENSO,though ENSO has little influence on the atmospheric feedback to the ocean in June.The local air-sea interaction is substantially the same before and after the removal of the effect of Indian Oceanic Dipole.The reduction of shortwave radiation fluxes into the western Pacific warm pool,due to the enhanced overlaying convection in March associated with ENSO,leads to the decline of SST tendency that will weaken the oceanic forcing of the atmosphere.展开更多
Nitric oxide(NO)is one of the most crucial products in the plasma-based nitrogen fixation process.In this work,in situ measurements were performed for quantifying the NO synthesis spatially in a warm air glow discharg...Nitric oxide(NO)is one of the most crucial products in the plasma-based nitrogen fixation process.In this work,in situ measurements were performed for quantifying the NO synthesis spatially in a warm air glow discharge,through the method of Mid-infrared quantum cascade laser absorption spectroscopy(QCL-AS).Two ro-vibrational transitions at 1900.076 cm^(-1) and 1900.517 cm^(-1) of the ground-state NO(X)were probed sensitively by the help of the wavelength modulation spectroscopy(WMS)approach to increase the signal/noise(S/N)level.The results show a decline trend of NO synthesis rate along the discharge channel from the cathode to the anode.However,from the point of energy efficiency,the cathode region is of significantly low energy efficiency of NO production.Severe disproportionality was found for the high energy consumption but low NO production in the region of cathode area,compared to that in the positive column zone.Further analysis demonstrates the high energy cost of NO production in the cathode region,is ascribed to the extremely high reduced electric field E/N therein not selectively preferable for the processes of vibrational excitation or dissociation of N_(2) and O_(2) molecules.This drags down the overall energy efficiency of NO synthesis by this typical warm air glow discharge,particularly for the ones with short electrode gaps.Limitations of further improving the energy cost of NO synthesis by variations of the discharge operation conditions,such as discharge current or airflow rate,imply other effective manners able to tune the energy delivery selectively to the NO formation process,are sorely needed.展开更多
Hurricane Michael was intensifying as it made landfall devastating areas of the Florida Panhandle including the small town of Mexico Beach.The structure of the hurricane is examined using radar wind data made availabl...Hurricane Michael was intensifying as it made landfall devastating areas of the Florida Panhandle including the small town of Mexico Beach.The structure of the hurricane is examined using radar wind data made available from aircraft reconnaissance missions.This showed a dominant warm air advection configuration(winds turning in direction in an anticyclonic fashion with height)around the core of the hurricane.Conventional radiosonde data was also used to study the warm air advection environment east of a deep layered tough system which Michael moved into and which appeared to favour such strong intensification.The structure of this deep trough is also examined and compared with a situation where Hurricane Dennis in 2005 weakened as it approached the coast in much the same region.It appears that the thermal structure of the upper trough at low to middle levels is critical to whether the hurricane intensifies or weakens with the presence of strong cold air advection associated with weakening.展开更多
Based on oceanic and atmospheric parameters retrieved by satellite remote sensing using a neural network method, air-sea heat fluxes over the western Pacific warm pool area were calculated with the advanced the advanc...Based on oceanic and atmospheric parameters retrieved by satellite remote sensing using a neural network method, air-sea heat fluxes over the western Pacific warm pool area were calculated with the advanced the advanced Coupled Ocean-Atmosphere Response Experiment 3.0 (COARE3.0) bulk algorithm method. Then, the average annual and interannual characteristics of these fluxes were analyzed. The rela- tionship between the fluxes and the South China Sea (SCS) summer monsoon onset is highlighted. The results indicate that these fluxes have clear temporal and spatial characteristics. The sensible heat flux is at its maximum in the Kuroshio area, while the latent heat flux is at its maximum in the North Equatorial Current and Kuroshio area. The distribution of average annual air-sea heat fluxes shows that both sensible and latent heat fluxes are maximized in winter and minimized in summer. The air-sea heat fluxes have obvious interannual variations. Correlation analysis indicates a close lag-correlation between air-sea heat fluxes in the western Pacific warm pool area and at the SCS summer monsoon onset. The lagcorrelation can therefore predict the SCS summer monsoon onset, providing a reference for the study of precipitation related to the monsoon.展开更多
An extensive search has been carried out to find all major flood and very heavy rainfall events in Victoria since 1876 when Southern Oscillation(SOI)data became available.The synoptic weather patterns were analysed an...An extensive search has been carried out to find all major flood and very heavy rainfall events in Victoria since 1876 when Southern Oscillation(SOI)data became available.The synoptic weather patterns were analysed and of the 319 events studied,121 events were found to be East Coast Lows(ECLs)and 82 were other types of low-pressure systems.Tropical influences also played a large role with 105 events being associated with tropical air advecting down to Victoria into weather systems.Examples are presented of all the major synoptic patterns identified.The SOI was found to be an important climate driver with positive SOIs being associated with many events over the 144 years studied.The 1976 Climate Shift and its influence on significant Victorian rainfall events is studied and negative SOI monthly values were shown to dominate following the Shift.However,one of the most active periods in 144 years of Victorian heavy rain occurred after the shift with a sustained period of positive SOI events from 2007 to 2014.Therefore,it is critical for forecasting future Victorian heavy rainfall is to understand if sequences of these positive SOI events continue like those preceding the Shift.Possible relationships between the Shift and Global Temperature rises are also explored.Upper wind data available from some of the heaviest rainfall events showed the presence of anticyclonic turning of the winds between 850hPa and 500hPa levels which has been found to be linked with extreme rainfall around the Globe.展开更多
Arctic amplification in the context of global warming has received considerable attention,and mechanisms such as ice-albedo feedback and extratropical cyclone activity have been proposed to explain such abnormal warmi...Arctic amplification in the context of global warming has received considerable attention,and mechanisms such as ice-albedo feedback and extratropical cyclone activity have been proposed to explain such abnormal warming.Since 2000,several short-term episodes of significant temperature rise have been observed in the Arctic;however,long-duration warming events in the central Arctic are less common and lack comprehensive research.Previous studies identified that amplified Rossbywaves could connect Arctic warming with extreme weather events in mid-latitude regions,and thus the recent increase in the frequency of mid-latitude extreme weather is also a subject of intensive research.With consideration of temperature anomalies,this study defined a continuous warming process as a warming event and selected strong warming events based on duration.Analysis of National Centers for Environmental Prediction Reanalysis-2 surface air temperature data found that nine strong warming events occurred during 2000-2019,which could be categorized into three types based on the area of warming.This study also investigated the relation between strong warming events and sea ice concentration reduction,sudden stratospheric warming,and extratropical cyclone activities.After full consideration and comparison,we believe that strong warming events in the central Arctic are induced primarily by continuous transport of warm air from mid-latitude ocean areas.展开更多
The oceanic warm pool （OWP） defined by sea surface temperature （SST） is known as the ＂heat reservoir＂ in the ocean. The warmest portion in the ocean mirrors the fact that the wettest region with the largest accu...The oceanic warm pool （OWP） defined by sea surface temperature （SST） is known as the ＂heat reservoir＂ in the ocean. The warmest portion in the ocean mirrors the fact that the wettest region with the largest accumulation of water vapor （WV） in the atmosphere, termed atmospheric wet pool （AWP）, should be identified because of the well-known Clausius-Clapeyron relationship between SST and WV. In this study, we used 14-year simultaneous observations of WV and SST from January 1988 to December 2001 to define the AWP and investigate its coupling and co-variations with the OWE The joint examination of the area variations, centroid locations, and zonal migrations of the AWP and OWP lead to a number of interesting findings. The results hopefully can contribute to our understanding of the air-sea interaction in general and characterization of E1 Nifio/La Nifia events in particular.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 42075028 and 42222502)the Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (Grant SML2021SP302)
文摘The Ross-Amundsen sector is experiencing an accelerating warming trend and a more intensive advective influx of marine air streams.As a result,massive surface melting events of the ice shelf are occurring more frequently,which puts the West Antarctica Ice Sheet at greater risk of degradation.This study shows the connection between surface melting and the prominent intrusion of warm and humid air flows from lower latitudes.By applying the Climate Feedback-Response Analysis Method(CFRAM),the temporal surge of the downward longwave(LW)fluxes over the surface of the Ross Ice Shelf(RIS)and adjacent regions are identified for four historically massive RIS surface melting events.The melting events are decomposed to identify which physical mechanisms are the main contributors.We found that intrusions of warm and humid airflow from lower latitudes are conducive to warm air temperature and water vapor anomalies,as well as cloud development.These changes exert a combined impact on the abnormal enhancement of the downward LW surface radiative fluxes,significantly contributing to surface warming and the resultant massive melting of ice.
基金National Basic R&D Project(973 Program)of China(2015CB452805)National Natural Science Foundation of China(61827901)+3 种基金National Key R&D Program of China(2017YFC1501602)Open Research Program of the State Key Laboratory of Severe Weather(2019LASW-A08)Basic Research Fund of CAMS(2016Z003,2018Y013)Program of the National Satellite Meteorological Centre(FY3(02P)-MAS-1803)。
文摘Typhoon Hato (2017) went through a rapid intensification (RI) process before making landfall in Zhuhai,Guangdong Province, as the observational data shows. Within 24 hours, its minimum sea level pressure deepened by35hPa and its maximum sustained wind speed increased by 20m s-1. According to satellite observations, Hato encountered a large area of warm water and two warm core rings before the RI process, and the average sea surface temperature cooling (SSTC) induced by Hato was only around 0.73℃. Air-sea coupled simulations were implemented to investigate the specific impact of the warm water on its RI process. The results showed that the warm water played an important role by facilitating the RI process by around 20%. Sea surface temperature budget analysis showed that the SSTC induced by mixing mechanism was not obvious due to the warm water. Besides, the cold advection hardly caused any SSTC, either. Therefore, the SSTC induced by Hato was much weaker compared with that in general cases. The negative feedback between ocean and Hato was restrained and abundant heat and moisture were sufficiently supplied to Hato. The warm water helped heat flux increase by around 20%, too. Therefore, the warm water influenced the structure and the intensity of Hato. Although there might be other factors that also participated in the RI process, this study focused on air-sea interaction in tropical cyclone forecast and discussed the impact of warm water on the intensity and structure of a tropical cyclone.
基金Fundamental Research Funds for the Central Universities(WK2080000037)Natural Science Foundation of Anhui Province(1208085QD75)Open Fund of the Key Laboratory of Ocean Circulation and Waves from Chinese Academy of Sciences(KLOCAW1204)
文摘Based on the air-sea interface heat fluxes and related meteorological variables datasets recently released by Objectively Analyzed Air-Sea Fluxes(OA Flux) Project of Woods Hole Oceanographic Institution,as well as the outgoing longwave radiation and surface wind datasets from National Oceanic and Atmospheric Administration,the seasonal dependence of local air-sea interaction over the tropical western Pacific warm pool(referred to the region(1o-6oN,144o-154oE)) is revealed and the probable impacts of remote forcing on the air-sea interaction are examined.The results indicated the dominance of oceanic forcing with the significant impact of ENSO in March and that of atmospheric feedback without notable influence of remote forcing in June.While the interannual variability of sea surface temperature anomaly(SSTA) is larger than that of SSTA tendency when oceanic forcing is dominant,the opposite is true when atmospheric feedback is dominant.The magnitude of the oceanic forcing of the atmosphere tends to decrease in March with the occurrence of ENSO,though ENSO has little influence on the atmospheric feedback to the ocean in June.The local air-sea interaction is substantially the same before and after the removal of the effect of Indian Oceanic Dipole.The reduction of shortwave radiation fluxes into the western Pacific warm pool,due to the enhanced overlaying convection in March associated with ENSO,leads to the decline of SST tendency that will weaken the oceanic forcing of the atmosphere.
基金partly supported by National Natural Science Foundation of China(Nos.11975061,52111530088)the Technology Innovation and Application Development Project of Chongqing(No.cstc2019jscx-msxm X0041)+1 种基金the Construction Committee Project of Chongqing(No.2018-1-3-6)the Fundamental Research Funds for the Central Universities(No.2019CDQYDQ034)。
文摘Nitric oxide(NO)is one of the most crucial products in the plasma-based nitrogen fixation process.In this work,in situ measurements were performed for quantifying the NO synthesis spatially in a warm air glow discharge,through the method of Mid-infrared quantum cascade laser absorption spectroscopy(QCL-AS).Two ro-vibrational transitions at 1900.076 cm^(-1) and 1900.517 cm^(-1) of the ground-state NO(X)were probed sensitively by the help of the wavelength modulation spectroscopy(WMS)approach to increase the signal/noise(S/N)level.The results show a decline trend of NO synthesis rate along the discharge channel from the cathode to the anode.However,from the point of energy efficiency,the cathode region is of significantly low energy efficiency of NO production.Severe disproportionality was found for the high energy consumption but low NO production in the region of cathode area,compared to that in the positive column zone.Further analysis demonstrates the high energy cost of NO production in the cathode region,is ascribed to the extremely high reduced electric field E/N therein not selectively preferable for the processes of vibrational excitation or dissociation of N_(2) and O_(2) molecules.This drags down the overall energy efficiency of NO synthesis by this typical warm air glow discharge,particularly for the ones with short electrode gaps.Limitations of further improving the energy cost of NO synthesis by variations of the discharge operation conditions,such as discharge current or airflow rate,imply other effective manners able to tune the energy delivery selectively to the NO formation process,are sorely needed.
文摘Hurricane Michael was intensifying as it made landfall devastating areas of the Florida Panhandle including the small town of Mexico Beach.The structure of the hurricane is examined using radar wind data made available from aircraft reconnaissance missions.This showed a dominant warm air advection configuration(winds turning in direction in an anticyclonic fashion with height)around the core of the hurricane.Conventional radiosonde data was also used to study the warm air advection environment east of a deep layered tough system which Michael moved into and which appeared to favour such strong intensification.The structure of this deep trough is also examined and compared with a situation where Hurricane Dennis in 2005 weakened as it approached the coast in much the same region.It appears that the thermal structure of the upper trough at low to middle levels is critical to whether the hurricane intensifies or weakens with the presence of strong cold air advection associated with weakening.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Science(KZCX2-YW-Q11-02)the National Basic Research Program of China (2012CB417402)
文摘Based on oceanic and atmospheric parameters retrieved by satellite remote sensing using a neural network method, air-sea heat fluxes over the western Pacific warm pool area were calculated with the advanced the advanced Coupled Ocean-Atmosphere Response Experiment 3.0 (COARE3.0) bulk algorithm method. Then, the average annual and interannual characteristics of these fluxes were analyzed. The rela- tionship between the fluxes and the South China Sea (SCS) summer monsoon onset is highlighted. The results indicate that these fluxes have clear temporal and spatial characteristics. The sensible heat flux is at its maximum in the Kuroshio area, while the latent heat flux is at its maximum in the North Equatorial Current and Kuroshio area. The distribution of average annual air-sea heat fluxes shows that both sensible and latent heat fluxes are maximized in winter and minimized in summer. The air-sea heat fluxes have obvious interannual variations. Correlation analysis indicates a close lag-correlation between air-sea heat fluxes in the western Pacific warm pool area and at the SCS summer monsoon onset. The lagcorrelation can therefore predict the SCS summer monsoon onset, providing a reference for the study of precipitation related to the monsoon.
文摘An extensive search has been carried out to find all major flood and very heavy rainfall events in Victoria since 1876 when Southern Oscillation(SOI)data became available.The synoptic weather patterns were analysed and of the 319 events studied,121 events were found to be East Coast Lows(ECLs)and 82 were other types of low-pressure systems.Tropical influences also played a large role with 105 events being associated with tropical air advecting down to Victoria into weather systems.Examples are presented of all the major synoptic patterns identified.The SOI was found to be an important climate driver with positive SOIs being associated with many events over the 144 years studied.The 1976 Climate Shift and its influence on significant Victorian rainfall events is studied and negative SOI monthly values were shown to dominate following the Shift.However,one of the most active periods in 144 years of Victorian heavy rain occurred after the shift with a sustained period of positive SOI events from 2007 to 2014.Therefore,it is critical for forecasting future Victorian heavy rainfall is to understand if sequences of these positive SOI events continue like those preceding the Shift.Possible relationships between the Shift and Global Temperature rises are also explored.Upper wind data available from some of the heaviest rainfall events showed the presence of anticyclonic turning of the winds between 850hPa and 500hPa levels which has been found to be linked with extreme rainfall around the Globe.
基金the Chinese Natural Science Foundation(Grant nos.,41941012 and 41976022)the Major Scientific and Technological Innovation Projects of Shandong Province(Grant no.,2018SDKJ0104-1)。
文摘Arctic amplification in the context of global warming has received considerable attention,and mechanisms such as ice-albedo feedback and extratropical cyclone activity have been proposed to explain such abnormal warming.Since 2000,several short-term episodes of significant temperature rise have been observed in the Arctic;however,long-duration warming events in the central Arctic are less common and lack comprehensive research.Previous studies identified that amplified Rossbywaves could connect Arctic warming with extreme weather events in mid-latitude regions,and thus the recent increase in the frequency of mid-latitude extreme weather is also a subject of intensive research.With consideration of temperature anomalies,this study defined a continuous warming process as a warming event and selected strong warming events based on duration.Analysis of National Centers for Environmental Prediction Reanalysis-2 surface air temperature data found that nine strong warming events occurred during 2000-2019,which could be categorized into three types based on the area of warming.This study also investigated the relation between strong warming events and sea ice concentration reduction,sudden stratospheric warming,and extratropical cyclone activities.After full consideration and comparison,we believe that strong warming events in the central Arctic are induced primarily by continuous transport of warm air from mid-latitude ocean areas.
基金Supported by the National Natural Science Foundation of China under projects (Nos.40730530,40675016,40706056)
文摘The oceanic warm pool （OWP） defined by sea surface temperature （SST） is known as the ＂heat reservoir＂ in the ocean. The warmest portion in the ocean mirrors the fact that the wettest region with the largest accumulation of water vapor （WV） in the atmosphere, termed atmospheric wet pool （AWP）, should be identified because of the well-known Clausius-Clapeyron relationship between SST and WV. In this study, we used 14-year simultaneous observations of WV and SST from January 1988 to December 2001 to define the AWP and investigate its coupling and co-variations with the OWE The joint examination of the area variations, centroid locations, and zonal migrations of the AWP and OWP lead to a number of interesting findings. The results hopefully can contribute to our understanding of the air-sea interaction in general and characterization of E1 Nifio/La Nifia events in particular.
