Accurate knowledge of mesospheric winds and waves is essential for studying the dynamics and climate in the mesosphere and lower thermosphere(MLT)region.In this study,we conduct a comparative analysis of the mesospher...Accurate knowledge of mesospheric winds and waves is essential for studying the dynamics and climate in the mesosphere and lower thermosphere(MLT)region.In this study,we conduct a comparative analysis of the mesosphere tidal results obtained from two adjacent meteor radars at low latitudes in Kunming,China,from November 2013 to December 2014.These two radars operate at different frequencies of 37.5 MHz and 53.1 MHz,respectively.However,overall good agreement is observed between the two radars in terms of horizontal winds and tide observations.The results show that the dominant tidal waves of the zonal and meridional winds are diurnal and semidiurnal tides.Moreover,we conduct an exhaustive statistical analysis to compare the tidal amplitudes and vertical wavelengths recorded by the dual radar systems,which reveals a high degree of alignment in tidal dynamics.The investigation includes variances and covariances of tidal amplitudes,which demonstrate remarkable consistency across measurements from both radars.This finding highlights clear uniformity in the mesospheric tidal patterns observed at low latitudes by the two neighboring meteor radars.Results of the comparative analysis specifically underscore the significant correlation in vertical wavelength measurements,validating the robustness of radar observations for tidal research.展开更多
Surface-latent heat(LE)and sensible heat(SH)fluxes play a pivotal role in governing hydrological,biological,geochemical,and ecological processes on the land surface in the Tibetan Plateau.However,to accurately assess ...Surface-latent heat(LE)and sensible heat(SH)fluxes play a pivotal role in governing hydrological,biological,geochemical,and ecological processes on the land surface in the Tibetan Plateau.However,to accurately assess and understand the spatial distribution of LE and SH fluxes across different underlying surfaces,it is crucial to verify the validity and reliability of ERA-5,GLDAS,and MODIS data against ground measurements obtained from the Flux Net micrometeorological tower network.This study analyzed the spatial patterns of LE and SH over the Tibetan Plateau using data from ERA-5,GLDAS,and MODIS.The results were compared with ground measurements from Flux Net tower observations on different underlying surfaces,and five statistical parameters(Pearson's r,LR slope,RMSE,MBE,and MAE)were used to validate the data.The results showed that:(1)MODIS LE data and ERA-5 SH data exhibited the closest agreement with ground observations,as indicated by their lowest root mean square error and mean bias area values.(2)The accuracy of ERA-5 SH was the highest in meadows and steppes,while GLDAS SH performed optimally in shrublands.Notably,MODIS LE consistently outperformed the other datasets across all vegetation types.(3)The spatial distribution of LE and SH displayed considerable heterogeneity,contingent upon the specific data sources and underlying surfaces.Notably,there was a contrasting trend between GLDAS and ERA-5,as well as MODIS,in terms of SH distribution in the shrubland.In shrublands and meadows,MODIS SH and LE exhibited more pronounced changes than ERA-5 and GLDAS.Additionally,ERA-5 SH demonstrated the opposite variation in meadow and steppe regions compared to GLDAS and MODIS.展开更多
Using long-term Whole Atmosphere Community Climate Model version 5(WACCM5)simulations initialized with the climatology around the year 2000,we studied the anomalous distribution of planetary wave and gravity wave flux...Using long-term Whole Atmosphere Community Climate Model version 5(WACCM5)simulations initialized with the climatology around the year 2000,we studied the anomalous distribution of planetary wave and gravity wave fluxes during distinct phases of the boreal stratospheric polar vortex(BSPV)and Quasi-Biennial Oscillation(QBO).The contributions of these two types of waves to Brewer-Dobson circulation(BDC)anomalies were further analyzed.The results revealed that under four distinct phases,the northern hemisphere BDC is primarily governed by planetary waves,whereas gravity waves counteract approximately half of the planetary wave influence on the BDC in the upper stratosphere.The QBO regulates the position of the anomaly center within the BDC’s descending branch in the northern hemisphere.In particular,during the westerly phase of the QBO(WQBO),the center of this anomalous descending branch is located in the upper stratosphere,whereas during the easterly phase of the QBO(EQBO),it is located in the lower stratosphere.Southern hemisphere BDC anomalies are regulated more by QBO activity:during the WQBO,it shows synchronous changes with the BDC anomaly in the northern hemisphere,whereas during the EQBO,it exhibits an antiphase relationship with the BDC anomaly in the northern hemisphere.Mesospheric circulation anomalies are predominantly driven by gravity wave activity.The circulation weakens during a weak BSPV and strengthens during a strong BSPV.Additionally,the descending branch anomaly of the northern hemisphere circulation is more pronounced during the WQBO,whereas the ascending branch anomaly of the southern hemisphere circulation is more significant during the EQBO.展开更多
This study investigates the relationship between atmospheric stratification (i.e., static stability given by N^(2)) and the vertical energy transfer of stationary planetary waves, and further illustrates the underlyin...This study investigates the relationship between atmospheric stratification (i.e., static stability given by N^(2)) and the vertical energy transfer of stationary planetary waves, and further illustrates the underlying physical mechanism. Specifically, for the simplified case of constant stratospheric N^(2), the refractive index square of planetary waves has a theoretical tendency to increase first and then decrease with an increased N^(2), whereas the group velocity weakens. Mechanistically, this behavior can be understood as an intensified suppression of vertical isentropic surface displacement caused by meridional heat transport of planetary waves under strong N^(2) conditions. Observational analysis corroborates this finding, demonstrating a reduction in the vertical-propagation velocity of waves with increased N^(2). A linear, quasi- geostrophic, mid-latitude beta-plane model with a constant background westerly wind and a prescribed N^(2) applicable to the stratosphere is used to obtain analytic solutions. In this model, the planetary waves are initiated by steady energy influx from the lower boundary. The analysis indicates that under strong N^(2) conditions, the amplitude of planetary waves can be sufficiently increased by the effective energy convergence due to the slowing vertical energy transfer, resulting in a streamfunction response in this model that contains more energy. For N^(2) with a quasi-linear vertical variation, the results bear a resemblance to the constant case, except that the wave amplitude and oscillating frequency show some vertical variations.展开更多
This study explores the impact of winter sea surface temperature(SST)anomalies in the Southern Indian Ocean on summer precipitation patterns in China,utilizing data from reanalysis sources and Coupled Model Intercompa...This study explores the impact of winter sea surface temperature(SST)anomalies in the Southern Indian Ocean on summer precipitation patterns in China,utilizing data from reanalysis sources and Coupled Model Intercomparison Project Phase 6(CMIP6)models.The results reveal that the Southern Indian Ocean Dipole(SIOD),characterized by contrasting SST anomalies in the northeast and southwest regions,acts as a predictor for Chinese summer precipitation patterns,namely floods in the south and drought in the north.In a positive SIOD event,the southwestern Indian Ocean exhibits warmer SSTs,while the northeastern region remains cooler.A negative SIOD event shows the opposite pattern.During the positive phase of the SIOD,the winter SST distribution strengthens the 850-hPa cross-equatorial airflow,generating a robust low-level westerly jet that enhances water vapor transport to the Bay of Bengal(BoB).These air-sea interactions maintain lower SSTs in the northeastern region,which significantly increase the land-sea temperature contrast in the Northern Hemisphere during spring and summer.This strengthened thermal gradient intensifies the southwest monsoon,establishing a strong convergence zone near the South China Sea and amplifying monsoon-driven precipitation in South China.Additionally,CMIP6 models,such as NorESM2-LM and NorCPM1,which accurately simulate the SIOD pattern,effectively capture the seasonal response of cross-equatorial airflow driven by SST anomalies of Southern Indian Ocean.The result highlights the essential role of cross-equatorial airflow generated by the SIOD in forecasting crossseasonal precipitation patterns.展开更多
The position of the South Asian High(SAH)over the Tibetan Plateau(TP)exhibits significant interannual variability.In this study,the criteria for defining the establishment and withdrawal of the SAH,as well as their ac...The position of the South Asian High(SAH)over the Tibetan Plateau(TP)exhibits significant interannual variability.In this study,the criteria for defining the establishment and withdrawal of the SAH,as well as their activities over the TP,are re-evaluated.The SAH is classified as“established over the TP”when the 1660 dagpm geopotential height contour covers 25%or more of the TP,and“withdrawn from the TP”when this contour covers less than 25%.Statistical analysis shows that,on average,the SAH establishes over the TP by the 4th pentad of May(28th pentad)and withdraws from the TP around the 2nd pentad of October(56th pentad).Over the past 50 years(1974–2023),the SAH has tended to establish over the TP earlier and withdraw later,resulting in a longer duration of control over the TP,with the rate of increase accelerating since 2017.The SAH exhibits a long-term linear trend of an eastward shift during both its establishment and withdrawal phases.The anomalous activity of the SAH over the TP is influenced by atmospheric heat sources.When there is anomalous warming(cooling)of atmospheric heating over the Bay of Bengal and the Indochina Peninsula,the SAH tends to establish and withdraw earlier and further westward(later and further eastward),with the westerly trough located over East Asia(the western part of the TP).展开更多
Using observations and models from phase 6 of the Coupled Model Intercomparison Project(CMIP6),this study analyzes the performance of CMIP6 models in simulating the vertical structure of the Quasi-Biennial Oscillation...Using observations and models from phase 6 of the Coupled Model Intercomparison Project(CMIP6),this study analyzes the performance of CMIP6 models in simulating the vertical structure of the Quasi-Biennial Oscillation(QBO)and its impacts on eastern China surface air temperature(SAT),with empirical orthogonal function(EOF)analysis.The first leading mode(EOF1)of the QBO leads to an overall cooling/warming over eastern China via the QBO’s subtropical path and Holton-Tan effect,while the second leading mode(EOF2)of the QBO tends to cause an east-west dipole of SAT anomalies between eastern and western China due to a strong Holton-Tan effect.Most models with a self-generated QBO can capture both westerly and easterly QBO anomalies in the mid-lower stratosphere in EOF1 and only westerly anomalies in EOF2.The multi-model ensemble mean can reproduce the eastern China SAT anomalies that are statistically significant and related to EOF1-like QBO events.However,the intensity of these anomalies is relatively weaker,attributable to the weak Pacific response to the subtropical effect of the QBO.In contrast,most models fail to induce a strong Holton-Tan effect and a Northern Annular Mode pattern in the polar region during the EOF2-like QBO events,resulting in weak and insignificant eastern China SAT anomalies on average.Overall,the models with a better representation of polar and Pacific responses to the QBO’s vertical structure exhibit a more reasonable eastern China SAT response,although such a response is weaker than observed.展开更多
Geophysical fluid dynamics(GFD)is an interdisciplinary field that studies the large-scale motion of fluids in the natural world.With a wide range of applications such as weather forecasts and climate prediction,GFD em...Geophysical fluid dynamics(GFD)is an interdisciplinary field that studies the large-scale motion of fluids in the natural world.With a wide range of applications such as weather forecasts and climate prediction,GFD employs various research approaches including in-situ observations,satellite measurements,numerical simulations,theoretical analysis,artificial intelligence,and physical model experiments in laboratory.Among these approaches,rotating tank experiments provide a valuable tool for simulating naturally-occurring fluid motions in laboratories.With proportional scaling and proper techniques,scientists can reproduce multi-scale physical processes of stratified fluids in the rotation system,which allows for the simulation of essential characteristics of fluid motions in the atmosphere and oceans.In this review,rotating tanks of various scales in the world are introduced,as these tanks have been actively used to explore fundamental scientific questions in ocean and atmosphere dynamics.To illustrate the GFD experiments,three representative cases are presented to demonstrate the frontier achievements in the the GFD study by using rotating tank experiments:mesoscale eddies in the ocean,convection processes,and plume dynamics.Detailed references for the experimental procedures are provided.Future studies are encouraged to further explore the utilization of rotating tanks with improvements in experimental design and integration of other research methods.This is a promising direction of GFD to help enhance our understanding of the complex nature of fluid motions in the natural world and to address the challenges posed by global environmental changes.展开更多
发展高分辨区域中尺度天气预报模式是改进暴雨落区预报的一个重要途径。区域中尺度模式空间分辨率达到100 m,对当前计算资源提出了严峻挑战。一种可行的解决方案是发展滤除声波的模式替代全弹性模式。滤除声波的模式可以使用较大的时间...发展高分辨区域中尺度天气预报模式是改进暴雨落区预报的一个重要途径。区域中尺度模式空间分辨率达到100 m,对当前计算资源提出了严峻挑战。一种可行的解决方案是发展滤除声波的模式替代全弹性模式。滤除声波的模式可以使用较大的时间步长积分,能显著提高积分效率。作者在2018年利用一种声波滤除理论——假不可压理论,初步在地形追随质量坐标系(η坐标系)下建立了假不可压模式。数值试验表明模式的结果是合理可信的,然而关键问题是没有滤除声波。本文改进了假不可压模式,建立新的假不可压模式干动力框架。新动力框架控制方程的关键改进是使用椭圆方程求解扰动气压,理论上保证了声波的滤除。新动力框架的时间积分方案更简洁,不使用时步分裂算法。对比改进的假不可压模式和WRF(Weather Research and Forecasting)模式的干热泡对流数值试验结果,发现假不可压模式获得了与WRF模式相似的动力场和热力场分布,且模拟的气压扰动时间序列平滑,说明声波已被滤除,相比2018版本的假不可压模式,这是较大的改进。展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 42125402 and 42174183)the National Key Technologies R&D Program of China (Grant No.2022YFF0503703)+2 种基金the B-type Strategic Priority Program of the Chinese Academy of Sciences (Grant No. XDB41000000)the foundation of the National Key Laboratory of Electromagnetic Environment and the Fundamental Research Funds for the Central Universitiesthe Chinese Meridian Project
文摘Accurate knowledge of mesospheric winds and waves is essential for studying the dynamics and climate in the mesosphere and lower thermosphere(MLT)region.In this study,we conduct a comparative analysis of the mesosphere tidal results obtained from two adjacent meteor radars at low latitudes in Kunming,China,from November 2013 to December 2014.These two radars operate at different frequencies of 37.5 MHz and 53.1 MHz,respectively.However,overall good agreement is observed between the two radars in terms of horizontal winds and tide observations.The results show that the dominant tidal waves of the zonal and meridional winds are diurnal and semidiurnal tides.Moreover,we conduct an exhaustive statistical analysis to compare the tidal amplitudes and vertical wavelengths recorded by the dual radar systems,which reveals a high degree of alignment in tidal dynamics.The investigation includes variances and covariances of tidal amplitudes,which demonstrate remarkable consistency across measurements from both radars.This finding highlights clear uniformity in the mesospheric tidal patterns observed at low latitudes by the two neighboring meteor radars.Results of the comparative analysis specifically underscore the significant correlation in vertical wavelength measurements,validating the robustness of radar observations for tidal research.
基金funded by the West Light Scholar of the Chinese Academy of Sciences(xbzg-zdsys-202202)the Natural Science Foundation of Henan(Grant No.232300420165)Integrated Scientific Investigation of the North-South Transitional Zone of China(2017FY100900)。
文摘Surface-latent heat(LE)and sensible heat(SH)fluxes play a pivotal role in governing hydrological,biological,geochemical,and ecological processes on the land surface in the Tibetan Plateau.However,to accurately assess and understand the spatial distribution of LE and SH fluxes across different underlying surfaces,it is crucial to verify the validity and reliability of ERA-5,GLDAS,and MODIS data against ground measurements obtained from the Flux Net micrometeorological tower network.This study analyzed the spatial patterns of LE and SH over the Tibetan Plateau using data from ERA-5,GLDAS,and MODIS.The results were compared with ground measurements from Flux Net tower observations on different underlying surfaces,and five statistical parameters(Pearson's r,LR slope,RMSE,MBE,and MAE)were used to validate the data.The results showed that:(1)MODIS LE data and ERA-5 SH data exhibited the closest agreement with ground observations,as indicated by their lowest root mean square error and mean bias area values.(2)The accuracy of ERA-5 SH was the highest in meadows and steppes,while GLDAS SH performed optimally in shrublands.Notably,MODIS LE consistently outperformed the other datasets across all vegetation types.(3)The spatial distribution of LE and SH displayed considerable heterogeneity,contingent upon the specific data sources and underlying surfaces.Notably,there was a contrasting trend between GLDAS and ERA-5,as well as MODIS,in terms of SH distribution in the shrubland.In shrublands and meadows,MODIS SH and LE exhibited more pronounced changes than ERA-5 and GLDAS.Additionally,ERA-5 SH demonstrated the opposite variation in meadow and steppe regions compared to GLDAS and MODIS.
基金supported by the National Natural Science Foundation of China(Grant Nos.U244221042475072 and 42361144843).
文摘Using long-term Whole Atmosphere Community Climate Model version 5(WACCM5)simulations initialized with the climatology around the year 2000,we studied the anomalous distribution of planetary wave and gravity wave fluxes during distinct phases of the boreal stratospheric polar vortex(BSPV)and Quasi-Biennial Oscillation(QBO).The contributions of these two types of waves to Brewer-Dobson circulation(BDC)anomalies were further analyzed.The results revealed that under four distinct phases,the northern hemisphere BDC is primarily governed by planetary waves,whereas gravity waves counteract approximately half of the planetary wave influence on the BDC in the upper stratosphere.The QBO regulates the position of the anomaly center within the BDC’s descending branch in the northern hemisphere.In particular,during the westerly phase of the QBO(WQBO),the center of this anomalous descending branch is located in the upper stratosphere,whereas during the easterly phase of the QBO(EQBO),it is located in the lower stratosphere.Southern hemisphere BDC anomalies are regulated more by QBO activity:during the WQBO,it shows synchronous changes with the BDC anomaly in the northern hemisphere,whereas during the EQBO,it exhibits an antiphase relationship with the BDC anomaly in the northern hemisphere.Mesospheric circulation anomalies are predominantly driven by gravity wave activity.The circulation weakens during a weak BSPV and strengthens during a strong BSPV.Additionally,the descending branch anomaly of the northern hemisphere circulation is more pronounced during the WQBO,whereas the ascending branch anomaly of the southern hemisphere circulation is more significant during the EQBO.
基金supported by the National Natural Science Foundation of China(Grant No.42261134532,42405059,and U2342212)。
文摘This study investigates the relationship between atmospheric stratification (i.e., static stability given by N^(2)) and the vertical energy transfer of stationary planetary waves, and further illustrates the underlying physical mechanism. Specifically, for the simplified case of constant stratospheric N^(2), the refractive index square of planetary waves has a theoretical tendency to increase first and then decrease with an increased N^(2), whereas the group velocity weakens. Mechanistically, this behavior can be understood as an intensified suppression of vertical isentropic surface displacement caused by meridional heat transport of planetary waves under strong N^(2) conditions. Observational analysis corroborates this finding, demonstrating a reduction in the vertical-propagation velocity of waves with increased N^(2). A linear, quasi- geostrophic, mid-latitude beta-plane model with a constant background westerly wind and a prescribed N^(2) applicable to the stratosphere is used to obtain analytic solutions. In this model, the planetary waves are initiated by steady energy influx from the lower boundary. The analysis indicates that under strong N^(2) conditions, the amplitude of planetary waves can be sufficiently increased by the effective energy convergence due to the slowing vertical energy transfer, resulting in a streamfunction response in this model that contains more energy. For N^(2) with a quasi-linear vertical variation, the results bear a resemblance to the constant case, except that the wave amplitude and oscillating frequency show some vertical variations.
基金Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)National Natural Science Foundation of China(U2442202)+1 种基金Key Innovation Team of China Meteorological Administration“Climate Change Detection and Response”(CMA2022ZD03)National Key Research and Development Program of China(2023YFF0805104)。
文摘This study explores the impact of winter sea surface temperature(SST)anomalies in the Southern Indian Ocean on summer precipitation patterns in China,utilizing data from reanalysis sources and Coupled Model Intercomparison Project Phase 6(CMIP6)models.The results reveal that the Southern Indian Ocean Dipole(SIOD),characterized by contrasting SST anomalies in the northeast and southwest regions,acts as a predictor for Chinese summer precipitation patterns,namely floods in the south and drought in the north.In a positive SIOD event,the southwestern Indian Ocean exhibits warmer SSTs,while the northeastern region remains cooler.A negative SIOD event shows the opposite pattern.During the positive phase of the SIOD,the winter SST distribution strengthens the 850-hPa cross-equatorial airflow,generating a robust low-level westerly jet that enhances water vapor transport to the Bay of Bengal(BoB).These air-sea interactions maintain lower SSTs in the northeastern region,which significantly increase the land-sea temperature contrast in the Northern Hemisphere during spring and summer.This strengthened thermal gradient intensifies the southwest monsoon,establishing a strong convergence zone near the South China Sea and amplifying monsoon-driven precipitation in South China.Additionally,CMIP6 models,such as NorESM2-LM and NorCPM1,which accurately simulate the SIOD pattern,effectively capture the seasonal response of cross-equatorial airflow driven by SST anomalies of Southern Indian Ocean.The result highlights the essential role of cross-equatorial airflow generated by the SIOD in forecasting crossseasonal precipitation patterns.
基金supported by the National Natural Science Foundation of China(Grant Nos.41930972 and 42475015)the Financial Meteorology Scientific and Technological Innovation Group of the China Meteorological Administration(Grant No.CMA2024ZD03).
文摘The position of the South Asian High(SAH)over the Tibetan Plateau(TP)exhibits significant interannual variability.In this study,the criteria for defining the establishment and withdrawal of the SAH,as well as their activities over the TP,are re-evaluated.The SAH is classified as“established over the TP”when the 1660 dagpm geopotential height contour covers 25%or more of the TP,and“withdrawn from the TP”when this contour covers less than 25%.Statistical analysis shows that,on average,the SAH establishes over the TP by the 4th pentad of May(28th pentad)and withdraws from the TP around the 2nd pentad of October(56th pentad).Over the past 50 years(1974–2023),the SAH has tended to establish over the TP earlier and withdraw later,resulting in a longer duration of control over the TP,with the rate of increase accelerating since 2017.The SAH exhibits a long-term linear trend of an eastward shift during both its establishment and withdrawal phases.The anomalous activity of the SAH over the TP is influenced by atmospheric heat sources.When there is anomalous warming(cooling)of atmospheric heating over the Bay of Bengal and the Indochina Peninsula,the SAH tends to establish and withdraw earlier and further westward(later and further eastward),with the westerly trough located over East Asia(the western part of the TP).
基金supported by the National Natural Science Foundation of China(Grant Nos.42120104001,42192563 and 42005010)the Shanghai Sailing Program(Grant No.23YF1401400).
文摘Using observations and models from phase 6 of the Coupled Model Intercomparison Project(CMIP6),this study analyzes the performance of CMIP6 models in simulating the vertical structure of the Quasi-Biennial Oscillation(QBO)and its impacts on eastern China surface air temperature(SAT),with empirical orthogonal function(EOF)analysis.The first leading mode(EOF1)of the QBO leads to an overall cooling/warming over eastern China via the QBO’s subtropical path and Holton-Tan effect,while the second leading mode(EOF2)of the QBO tends to cause an east-west dipole of SAT anomalies between eastern and western China due to a strong Holton-Tan effect.Most models with a self-generated QBO can capture both westerly and easterly QBO anomalies in the mid-lower stratosphere in EOF1 and only westerly anomalies in EOF2.The multi-model ensemble mean can reproduce the eastern China SAT anomalies that are statistically significant and related to EOF1-like QBO events.However,the intensity of these anomalies is relatively weaker,attributable to the weak Pacific response to the subtropical effect of the QBO.In contrast,most models fail to induce a strong Holton-Tan effect and a Northern Annular Mode pattern in the polar region during the EOF2-like QBO events,resulting in weak and insignificant eastern China SAT anomalies on average.Overall,the models with a better representation of polar and Pacific responses to the QBO’s vertical structure exhibit a more reasonable eastern China SAT response,although such a response is weaker than observed.
基金Supported by the National Key Research and Development Program of China(Nos.2017YFA0604100,2016YFC1402004,2017YFC1404200)the Program for Innovation Research and Entrepreneurship Team in Jiangsu Provincethe National Natural Science Foundation of China(Nos.41476022,41490643)。
文摘Geophysical fluid dynamics(GFD)is an interdisciplinary field that studies the large-scale motion of fluids in the natural world.With a wide range of applications such as weather forecasts and climate prediction,GFD employs various research approaches including in-situ observations,satellite measurements,numerical simulations,theoretical analysis,artificial intelligence,and physical model experiments in laboratory.Among these approaches,rotating tank experiments provide a valuable tool for simulating naturally-occurring fluid motions in laboratories.With proportional scaling and proper techniques,scientists can reproduce multi-scale physical processes of stratified fluids in the rotation system,which allows for the simulation of essential characteristics of fluid motions in the atmosphere and oceans.In this review,rotating tanks of various scales in the world are introduced,as these tanks have been actively used to explore fundamental scientific questions in ocean and atmosphere dynamics.To illustrate the GFD experiments,three representative cases are presented to demonstrate the frontier achievements in the the GFD study by using rotating tank experiments:mesoscale eddies in the ocean,convection processes,and plume dynamics.Detailed references for the experimental procedures are provided.Future studies are encouraged to further explore the utilization of rotating tanks with improvements in experimental design and integration of other research methods.This is a promising direction of GFD to help enhance our understanding of the complex nature of fluid motions in the natural world and to address the challenges posed by global environmental changes.
文摘发展高分辨区域中尺度天气预报模式是改进暴雨落区预报的一个重要途径。区域中尺度模式空间分辨率达到100 m,对当前计算资源提出了严峻挑战。一种可行的解决方案是发展滤除声波的模式替代全弹性模式。滤除声波的模式可以使用较大的时间步长积分,能显著提高积分效率。作者在2018年利用一种声波滤除理论——假不可压理论,初步在地形追随质量坐标系(η坐标系)下建立了假不可压模式。数值试验表明模式的结果是合理可信的,然而关键问题是没有滤除声波。本文改进了假不可压模式,建立新的假不可压模式干动力框架。新动力框架控制方程的关键改进是使用椭圆方程求解扰动气压,理论上保证了声波的滤除。新动力框架的时间积分方案更简洁,不使用时步分裂算法。对比改进的假不可压模式和WRF(Weather Research and Forecasting)模式的干热泡对流数值试验结果,发现假不可压模式获得了与WRF模式相似的动力场和热力场分布,且模拟的气压扰动时间序列平滑,说明声波已被滤除,相比2018版本的假不可压模式,这是较大的改进。
