Temperature trends in the upper stratosphere are investigated using satellite measurements from Stratospheric Sounding Unit(SSU)outputs and simulations from chemistry-climate models(CCMs)and the Coupled Model Intercom...Temperature trends in the upper stratosphere are investigated using satellite measurements from Stratospheric Sounding Unit(SSU)outputs and simulations from chemistry-climate models(CCMs)and the Coupled Model Intercomparison Project Phase 6(CMIP6).Observational evidence shows a lack of cooling in the Antarctic,in contrast to strong cooling at other latitudes,during austral winter over 1979-97.Analysis of CCM simulations for a longer period of1961-97 also shows a significant contrast in the upper stratospheric temperature trends between the Antarctic and lower latitudes.Results from two sets of model integrations with fixed ozone-depleting substances(ODSs)and fixed greenhouse gases(GHGs)at their 1960 levels suggest that the ODSs have made a major contribution to the lack of cooling in the Antarctic upper stratosphere.Results from CMIP6 simulations with prescribed GHGs and ozone confirm that changes in the dynamical processes associated with observed ozone depletion are largely responsible for the lack of cooling in the Antarctic upper stratosphere.The lack of cooling is found to be dynamically induced through increased upward wave activity into the upper stratosphere,which is attributed mainly to ODSs forcing.Specifically,the radiative cooling caused by the ozone depletion results in a stronger meridional temperature gradient between middle and high latitudes in the upper stratosphere,allowing more planetary waves propagating upward to warm the Antarctic upper stratosphere.These findings improve our understanding of the chemistry-climate coupling in the southern upper stratosphere.展开更多
On the basis of the EOF analysis of global geopotential height anomaly (GHA) field at 10 hPa level, the arctic oscillation (AO) and the means antarctic oscillation (AAO) can be detected more obviously at the upper lev...On the basis of the EOF analysis of global geopotential height anomaly (GHA) field at 10 hPa level, the arctic oscillation (AO) and the means antarctic oscillation (AAO) can be detected more obviously at the upper level of atmosphere than the AO or the AAO in surface layer. Unlike the hemisphere pattern of the AO and the AAO in the surface lager given by previous authors, the AO or the AAO in the stratosphere has its global features. The zonal oscillations-the Southern Oscillation (SO) and the north oscillation (NO) in atmospheric surface layer become less clear in the upper air. The first mode (AO mode, abbreviated to AOM hereafter) and the second mode (AAO mode, abbreviated to AAOM hereafter) respectively have 41.47% and 27.04% of the total variance contribution. The cumulative variance contribution of the first two modes reaches 68.51%. These two modes are the main components for the interdecadal or decadal oscillation in the stratosphere. In addition, there still exist two kinds of oscillation patterns with less probability, namely, the symmetric pattern at mid-high latitudes in the Southern Hemisphere and the asymmetric pattern. Spectral analysis shows that the AOM and the AAOM all have a spectral peak for 22 a period, being consistent with the periodic variations of the solar magnetic field, and a peak for 11 a period, being consistent with the period of the numbers of sunspots. Step filter analysis shows that the influencing factor for the upper atmospheric oscillation is the solar activity. The fluctuation of the solar magnetic field is the more influencing factor than the variation of the sunspot number.展开更多
To enhance the controllability of stratosphere airship,a vectored electric propulsion system is used.By using the Lagrangian method,a kinetic model of the vectored electric propulsion system is established and validat...To enhance the controllability of stratosphere airship,a vectored electric propulsion system is used.By using the Lagrangian method,a kinetic model of the vectored electric propulsion system is established and validated through ground tests.The fake gyroscopic torque is first proposed,which the vector mechanism should overcome besides the inertial torque and the gravitational torque.The fake gyroscopic torque is caused by the difference between inertial moments about two principal inertial axes of the propeller in the rotating plane,appears only when the propeller is rotating and is proportional with the rotation speed.It is a sinusoidal pulse,with a frequency that is twice of the rotation speed.Considering the fake gyroscope torque pulse and aerodynamic efficiency,three blade propeller is recommended for the vectored propulsion system used for stratosphere airship.展开更多
Utilizing three different sets of reanalysis data,this study examines the long-and short-lived observed positive North Atlantic Oscillation(NAO)events(referred to as NAO+_LE and NAO+_SE)and long-and short-lived observ...Utilizing three different sets of reanalysis data,this study examines the long-and short-lived observed positive North Atlantic Oscillation(NAO)events(referred to as NAO+_LE and NAO+_SE)and long-and short-lived observed negative NAO events(referred to as NAO−_LE and NAO−_SE).Composite results indicate that the NAO-like circulation anomalies associated with the long-lived NAO events can reach the stratosphere,while they are primarily confined to the troposphere in the short-lived NAO events.Thus,the coupling/connection of stratospheric and tropospheric circulation anomalies is much better(worse)in the long-lived(short-lived)NAO events.A series of modified stratospheric initial-value experiments conducted with a simplified model indicate that a better(worse)connection between stratospheric and tropospheric circulation anomalies in the initial-value fields tend to gradually induce the NAO-like tropospheric circulation anomalies in the troposphere on the subsequent days,and thus naturally elongate(reduce)the lifetimes of the original NAO events by altering the tropospheric synoptic eddy vorticity flux over the North Atlantic region.展开更多
The unique geographical location and high altitude of the Tibetan Plateau can greatly influence regional weather and climate.In particular, the Asian summer monsoon(ASM) anticyclone circulation system over the Tibetan...The unique geographical location and high altitude of the Tibetan Plateau can greatly influence regional weather and climate.In particular, the Asian summer monsoon(ASM) anticyclone circulation system over the Tibetan Plateau is recognized to be a significant transport pathway for water vapor and pollutants to enter the stratosphere. To improve understanding of these physical processes, a multi-location joint atmospheric experiment was performed over the Tibetan Plateau from late July to August in 2018, funded by the fiveyear(2018–2022) STEAM(stratosphere and troposphere exchange experiment during ASM) project, during which multiple platforms/instruments—including long-duration stratospheric balloons, dropsondes, unmanned aerial vehicles, special sounding systems, and ground-based and satellite-borne instruments—will be deployed. These complementary methods of data acquisition are expected to provide comprehensive atmospheric parameters(aerosol, ozone, water vapor, CO_2, CH_4, CO, temperature, pressure,turbulence, radiation, lightning and wind); the richness of this approach is expected to advance our comprehension of key mechanisms associated with thermal, dynamical, radiative, and chemical transports over the Tibetan Plateau during ASM activity.展开更多
The Indian summer monsoon is one of the most dominant tropical circulation systems in the general circulation of the atmosphere. The country receives more than 80% of the annual rainfall during a short span of four mo...The Indian summer monsoon is one of the most dominant tropical circulation systems in the general circulation of the atmosphere. The country receives more than 80% of the annual rainfall during a short span of four months (June to September) of the southwest monsoon season. Variability in the quantum of rainfall during the monsoon season has profound impacts on water resources, power generation, agriculture, economics and ecosystems in the country. The inter annual variability of Indian Summer Monsoon Rainfall (ISMR) depends on atmospheric and oceanic conditions prevailed during the season. In this study we have made an attempt to understand the variation of the of zonal winds in the tropical Upper Troposphere and Lower Stratosphere (UT/LS) region during deficient and Excess rainfall years of Indian summer monsoon and its relation to Indian Summer Monsoon Rainfall (ISMR). It is found that in the equatorial Upper Troposphere zonal winds have westerly anomalies during deficient rainfall year’s and easterly anomaly during excess rainfall years of Indian summer monsoon and opposite zonal wind anomaly is noted in the equatorial Lower Stratosphere during the deficient and excess rainfall years of Indian summer monsoon. It is also found that the June to September upper troposphere zonal winds averaged between 15°N and 15°S latitudes have a long-term trend during 1960 to 1998. Over this period the tropical easterlies and the tropical jet stream have weakened with time.展开更多
We present characterizations of the dynamic turbulence in the lower stratosphere measured by a new balloon-based system designed for detecting finer scale dynamic turbulence. The balloon-based system included a consta...We present characterizations of the dynamic turbulence in the lower stratosphere measured by a new balloon-based system designed for detecting finer scale dynamic turbulence. The balloon-based system included a constant temperature anemometer(CTA) operating at a sampling rate of 2 k Hz at an ascent speed of 5 m s^(-1)(corresponding to a vertical resolution of 2.5 mm), an industrial personal computer, batteries, sensors for ambient temperature and humidity, an A/D converter, and others. The system was successfully launched to 24 km altitude over Bayannur City, Inner Mongolia Province. Results show the spatial intermittence of the turbulence layers, with clear boundaries between turbulent and nonturbulent regions. This is the first time that the dynamic turbulence spectrum down to the viscous sub-range has been obtained throughout the lower stratosphere over China. With that, the energy dissipation rates of dynamic turbulence could be calculated with high precision. The profile of the dissipation rates varied from 7.37 × 10^(-7) to 4.23 W kg^(-1) and increased with altitude in the stratosphere.展开更多
An investigation of the influence of the relief of a planet on the global circulation of the Earth’s atmosphere is an important problem. Beyond doubt, mountains affect the global circulation of the troposphere, howev...An investigation of the influence of the relief of a planet on the global circulation of the Earth’s atmosphere is an important problem. Beyond doubt, mountains affect the global circulation of the troposphere, however, their influence on the global circulation of the stratosphere and mesosphere is not evident. In the present study, to investigate the influence of the relief of a planet on the global circulation of the Earth’s stratosphere and mesosphere, the non-hydrostatic mathematical model, developed earlier in the Polar Geophysical Institute, is utilized. Calculations were made for two distinct cases. The relief of the planet was taken into account for the first case. Unlike, the Earth’s surface was assumed to be smooth for the second case. Simulations were performed for the winter period in the northern hemisphere (January). Simulation results, obtained for both considered cases, are qualitatively similar at the levels of stratosphere and mesosphere, however, some noticeable distinctions exist. The horizontal domains exist, where the simulated horizontal and vertical components of the neutral wind velocity, obtained for two considered cases, differ noticeably at the levels of the stratosphere and mesosphere. Some of these horizontal domains are not connected with positions of mountains at the Earth’s surface. On the contrary, some of these horizontal domains are situated above mountains.展开更多
The impact of La Ni?a on the winter Arctic stratosphere has thus far been an ambiguous topic of research. Contradictory results have been reported depending on the La Ni?a events considered. This study shows that this...The impact of La Ni?a on the winter Arctic stratosphere has thus far been an ambiguous topic of research. Contradictory results have been reported depending on the La Ni?a events considered. This study shows that this is mainly due to the decadal variation of La Ni?a's impact on the winter Arctic stratosphere since the late 1970 s. Specifically,during the period1951–78,the tropospheric La Ni?a teleconnection exhibits a typical negative Pacific–North America pattern,which strongly inhibits the propagation of the planetary waves from the extratropical troposphere to the stratosphere,and leads to a significantly strengthened stratospheric polar vortex. In contrast,during 1979–2015,the La Ni?a teleconnection shifts eastwards,with an anomalous high concentrated in the northeastern Pacific. The destructive interference of the La Ni?a teleconnection with climatological stationary waves seen in the earlier period reduces greatly,which prevents the drastic reduction of planetary wave activities in the extratropical stratosphere. Correspondingly,the stratospheric response shows a less disturbed stratospheric polar vortex in winter.展开更多
The behaviour of relative diffusion theory and Gifford’s random-force theory for long-range atmospheric diffusion is examined. When a puff scale is smaller than the Lagrangian length scale, 2KTL, an accelerative rela...The behaviour of relative diffusion theory and Gifford’s random-force theory for long-range atmospheric diffusion is examined. When a puff scale is smaller than the Lagrangian length scale, 2KTL, an accelerative relative diffusion region exists, i.e., σy xt 3 / 2. While the puff diffusion enters a two-dimensional turbulence region. in which the diffusion scale is larger than 500 km, or time scale is larger than 1 day, divergence and convergence are main cause of horizontal diffusion. Between the two above-mentioned regimes, diffusion deviation is given by σy=2KT. The large-scale horizontal relative diffusion parameters were obtained by analyzing the data of radioactive cloud width collected in air nuclear tests.展开更多
The representation of the Arctic stratospheric circulation and the quasi-biennial oscillation(QBO)during the period 1981–2019 in a 40-yr Chinese global reanalysis dataset(CRA-40)is evaluated by comparing two widely u...The representation of the Arctic stratospheric circulation and the quasi-biennial oscillation(QBO)during the period 1981–2019 in a 40-yr Chinese global reanalysis dataset(CRA-40)is evaluated by comparing two widely used reanalysis datasets,ERA-5 and MERRA-2.CRA-40 demonstrates a comparable performance with ERA-5 and MERRA-2 in characterizing the winter and spring circulation in the lower and middle Arctic stratosphere.Specifically,differences in the climatological polar-mean temperature and polar night jet among the three reanalyses are within±0.5 K and±0.5 m s^(–1),respectively.The onset dates of the stratospheric sudden warming and stratospheric final warming events at 10 hPa in CRA-40,together with the dynamics and circulation anomalies during the onset process of warming events,are nearly identical to the other two reanalyses with slight differences.By contrast,the CRA-40 dataset demonstrates a deteriorated performance in describing the QBO below 10 hPa compared to the other two reanalysis products,manifested by the larger easterly biases of the QBO index,the remarkably weaker amplitude of the QBO,and the weaker wavelet power of the QBO period.Such pronounced biases are mainly concentrated in the period 1981–98 and largely reduced by at least 39%in 1999–2019.Thus,particular caution is needed in studying the QBO based on CRA-40.All three reanalyses exhibit greater disagreement in the upper stratosphere compared to the lower and middle stratosphere for both the polar region and the tropics.展开更多
The seasonal variation of inertia gravity-wave activity in the lower stratosphere (17―24 km) over Beijing is studied based on the high vertical resolution radionsonde observa- tions (from December 2001 to February 20...The seasonal variation of inertia gravity-wave activity in the lower stratosphere (17―24 km) over Beijing is studied based on the high vertical resolution radionsonde observa- tions (from December 2001 to February 2003) of Beijing Observatory (116°28′E, 39°48′N). Some of the important gravity-wave parameters, such as intrinsic frequency, and propagation direction, are estimated according to the polarized relation among gravity-wave wind components and temperature. Time series of wave energy show that the largest wave amplitudes occur during the winter and the least during the summer, and the average of the KE:PE ratios is about 2.6. Zonal and meridional wind perturbations have almost the same roots of mean variances, which shows that the wave energy in the lower stratosphere is isotropic horizontally. The motion and tem- perature fields are dominated by waves with vertical wavelengths of 1.5―3 km, which occupy above 80% samples, with a mean value of about 2.3 km. The horizontal wavelengths are mainly distributed between 100―800 km, averaging 445 km. The ratio of the mean horizontal to vertical wavelength is about 200:1, which indicates that the wave propagates nearly horizontally, with a very small vertical angle. The intrinsic frequency is estimated by fitting a polarized ellipse to the wind perturbations after band-filtering waves with a wavelength of 1.5―3 km, and the results show that the intrinsic frequency is dominated by 1f―3.5f, with an averaging value of 2f, corre- sponding to an intrinsic time period of 9 hours. Wave energy is found to propagate mainly upward, and in the horizontal direction, there is clear azimuthal anisotropy, with predominate northwest propagation against the prevailing wind.展开更多
This paper proposes a hybrid architecture based on Multi-disciplinary Design Optimization(MDO) with the Variable Complexity Modeling(VCM) method, to solve the problem of general design optimization for a stratosphere ...This paper proposes a hybrid architecture based on Multi-disciplinary Design Optimization(MDO) with the Variable Complexity Modeling(VCM) method, to solve the problem of general design optimization for a stratosphere airship. Firstly, MDO based on the Concurrent SubSpace Optimization(CSSO) strategy is improved for handling the subsystem coupling problem in stratosphere airship design which contains aerodynamics, structure, and energy. Secondly, the VCM method based on the surrogate model is presented for reducing the computational complexity in high-fidelity modeling without loss of accuracy. Moreover, the global-to-local optimization strategy is added to the architecture to enhance the process. Finally, the result gives a prominent stratosphere airship general solution that validates the feasibility and efficiency of the optimization architecture. Besides, a sensitivity analysis is conducted to outline the critical impact upon stratosphere airship design.展开更多
Due to the significant changes they bring to high latitude stratospheric temperature and wind,stratospheric sudden warmings(SSWs)can have an impact on the propagation and energy distribution of gravity waves(GWs).The ...Due to the significant changes they bring to high latitude stratospheric temperature and wind,stratospheric sudden warmings(SSWs)can have an impact on the propagation and energy distribution of gravity waves(GWs).The variation characteristics of GWs during SSWs have always been an important issue.Using temperature data from January to March in 2014−2016,provided by the Constellation Observing System for Meteorology,Ionosphere and Climate(COSMIC)mission,we have analyzed global GW activity at 15−40 km in the Northern Hemisphere during SSW events.During the SSWs that we studied,the stratospheric temperature rose in one or two longitudinal regions in the Northern Hemisphere;the areas affected extended to the east of 90°W.During these SSWs,the potential energy density(E_(p)of GWs expanded and covered a larger range of longitude and altitude,exhibiting an eastward and downward extension.The E_(p)usually increased,while partially filtered by the eastward zonal winds.When zonal winds weakened or turned westward,E_(p)began to strengthen.After SSWs,the E_(p)usually decreased.These observations can serve as a reference for analyzing the interaction mechanism between SSWs and GWs in future work.展开更多
An autonomous altitude adjustment system for a stratospheric satellite(StratoSat)platform is proposed.This platform consists of a helium balloon,a ballonet,and a two-way blower.The helium balloon generates lift to bal...An autonomous altitude adjustment system for a stratospheric satellite(StratoSat)platform is proposed.This platform consists of a helium balloon,a ballonet,and a two-way blower.The helium balloon generates lift to balance the platform gravity.The two-way blower inflates and deflates the ballonet to regulate the buoyancy.Altitude adjustment is achieved by tracking the differential pressure difference(DPD),and a threshold switching strategy is used to achieve blower flow control.The vertical acceleration regulation ability is decided not only by the blower flow rate,but also by the designed margin of pressure difference(MPD).Pressure difference is a slow-varying variable compared with altitude,and it is adopted as the control variable.The response speed of the actuator to disturbance can be delayed,and the overshoot caused by the large inertia of the platform is inhibited.This method can maintain a high tracking accuracy and reduce the complexity of model calculation,thus improving the robustness of controller design.展开更多
Two one-dimensional radiative-convective models with the same scheme and the different ranges that one is fromsurface to stratopause and the other is from surface to tropopause,have been developed to study the role pl...Two one-dimensional radiative-convective models with the same scheme and the different ranges that one is fromsurface to stratopause and the other is from surface to tropopause,have been developed to study the role played by thestratosphere in greenhouse effect.It is shown that the addition of stratospheric response may lead to an increase of 7—50percent in radiative forcing at the tropopause,and an increase of 20—60 percent in surface temperature when the con-centration of the same gas in the two models increases at the same time;and when the same change in radiative forcing atthe tropopause due to the same agent in the two models occurs,the addition of stratospheric response may lead to an in-crease of 5—20 percent in surface temperature;and allowing for the stratospheric adjustment means that the tempera-ture responses to the same flux change due to different causes are in far disagreement.展开更多
El Nio usually happens with the anomaly of general circulation of atmosphere and climate in the world. El Nio has close statistical relationships with the rainfall decrease in Africa, the monsoon weakening in India, a...El Nio usually happens with the anomaly of general circulation of atmosphere and climate in the world. El Nio has close statistical relationships with the rainfall decrease in Africa, the monsoon weakening in India, and the Australian aridity. In recent years, it is also pointed out that there is a certain correlation between El Nio and Chinese climate and weather. In El Nio year, the summer temperature is lower than normal in the northeast of China. The happening and development of El Nio can also cause the anomalies of rainfalls in Changjiang River valley and the typhoon in China. Therefore, the fore-展开更多
Purpose–The purpose of this paper is to improve the control precision of the station-keeping control for a stratosphere airship through the feedforward-feedback PID controller which is designed by the wind speed pred...Purpose–The purpose of this paper is to improve the control precision of the station-keeping control for a stratosphere airship through the feedforward-feedback PID controller which is designed by the wind speed prediction based on the incremental extreme learning machine(I-ELM).Design/methodology/approach–First of all,the online prediction of wind speed is implemented by the I-ELM with rolling time.Second,the feedforward-feedback PID controller is designed through the position information of the airship and the predicted wind speed.In the end,the one-dimensional dynamic model of the stratosphere airship is built,and the controller is applied in the numerical simulation.Findings–Based on the conducted numerical simulations,some valuable conclusions are obtained.First,through the comparison between the predicted value and true value of the wind speed,the wind speed prediction based on I-ELM is very accurate.Second,the feedforward-feedback PID controller designed in this paper is very effective.Originality/value–This paper is very valuable to the research of a high-accuracy station-keeping control of stratosphere airship.展开更多
An engineering system approach of 2-D cylindrical model of transient mass balance calculations of ozone and other concerned chemicals along with fourteen photolysis, ozone-generating and ozone-depleting chemical react...An engineering system approach of 2-D cylindrical model of transient mass balance calculations of ozone and other concerned chemicals along with fourteen photolysis, ozone-generating and ozone-depleting chemical reaction equations was developed, validated, and used for studying the ozone concentrations, distribution and peak of the layer, ozone depletion and total ozone abundance in the stratosphere. The calculated ozone concentrations and profile at both the Equator and a 60˚N location were found to follow closely with the measured data. The calculated average ozone concentration was within 1% of the measured average, and the deviation of ozone profiles was within 14%. The monthly evolution of stratospheric ozone concentrations and distribution above the Equator was studied with results discussed in details. The influences of slow air movement in both altitudinal and radial directions on ozone concentrations and profile in the stratosphere were explored and discussed. Parametric studies of the influences of gas diffusivities of ozone D<sub>O3</sub> and active atomic oxygen D<sub>O</sub> on ozone concentrations and distributions were also studied and delineated. Having both influences through physical diffusion and chemical reactions, the diffusivity (and diffusion) of atomic oxygen D<sub>O</sub> was found to be more sensitive and important than that of ozone D<sub>O3</sub> on ozone concentrations and distribution. The 2-D ozone model present in this paper for stratospheric ozone and its layer and depletion is shown to be robust, convenient, efficient, and executable for analyzing the complex ozone phenomena in the stratosphere. .展开更多
基金supported by Grant Nos.41875047 and 91837206 from the National Natural Science Foundation of China(NSFC)Grant No.JIH2308007 from Fudan University。
文摘Temperature trends in the upper stratosphere are investigated using satellite measurements from Stratospheric Sounding Unit(SSU)outputs and simulations from chemistry-climate models(CCMs)and the Coupled Model Intercomparison Project Phase 6(CMIP6).Observational evidence shows a lack of cooling in the Antarctic,in contrast to strong cooling at other latitudes,during austral winter over 1979-97.Analysis of CCM simulations for a longer period of1961-97 also shows a significant contrast in the upper stratospheric temperature trends between the Antarctic and lower latitudes.Results from two sets of model integrations with fixed ozone-depleting substances(ODSs)and fixed greenhouse gases(GHGs)at their 1960 levels suggest that the ODSs have made a major contribution to the lack of cooling in the Antarctic upper stratosphere.Results from CMIP6 simulations with prescribed GHGs and ozone confirm that changes in the dynamical processes associated with observed ozone depletion are largely responsible for the lack of cooling in the Antarctic upper stratosphere.The lack of cooling is found to be dynamically induced through increased upward wave activity into the upper stratosphere,which is attributed mainly to ODSs forcing.Specifically,the radiative cooling caused by the ozone depletion results in a stronger meridional temperature gradient between middle and high latitudes in the upper stratosphere,allowing more planetary waves propagating upward to warm the Antarctic upper stratosphere.These findings improve our understanding of the chemistry-climate coupling in the southern upper stratosphere.
基金supprted by the National Natural Sice Fondationes of Chinme under crrne Nos 40475033 and 40305009.
文摘On the basis of the EOF analysis of global geopotential height anomaly (GHA) field at 10 hPa level, the arctic oscillation (AO) and the means antarctic oscillation (AAO) can be detected more obviously at the upper level of atmosphere than the AO or the AAO in surface layer. Unlike the hemisphere pattern of the AO and the AAO in the surface lager given by previous authors, the AO or the AAO in the stratosphere has its global features. The zonal oscillations-the Southern Oscillation (SO) and the north oscillation (NO) in atmospheric surface layer become less clear in the upper air. The first mode (AO mode, abbreviated to AOM hereafter) and the second mode (AAO mode, abbreviated to AAOM hereafter) respectively have 41.47% and 27.04% of the total variance contribution. The cumulative variance contribution of the first two modes reaches 68.51%. These two modes are the main components for the interdecadal or decadal oscillation in the stratosphere. In addition, there still exist two kinds of oscillation patterns with less probability, namely, the symmetric pattern at mid-high latitudes in the Southern Hemisphere and the asymmetric pattern. Spectral analysis shows that the AOM and the AAOM all have a spectral peak for 22 a period, being consistent with the periodic variations of the solar magnetic field, and a peak for 11 a period, being consistent with the period of the numbers of sunspots. Step filter analysis shows that the influencing factor for the upper atmospheric oscillation is the solar activity. The fluctuation of the solar magnetic field is the more influencing factor than the variation of the sunspot number.
文摘To enhance the controllability of stratosphere airship,a vectored electric propulsion system is used.By using the Lagrangian method,a kinetic model of the vectored electric propulsion system is established and validated through ground tests.The fake gyroscopic torque is first proposed,which the vector mechanism should overcome besides the inertial torque and the gravitational torque.The fake gyroscopic torque is caused by the difference between inertial moments about two principal inertial axes of the propeller in the rotating plane,appears only when the propeller is rotating and is proportional with the rotation speed.It is a sinusoidal pulse,with a frequency that is twice of the rotation speed.Considering the fake gyroscope torque pulse and aerodynamic efficiency,three blade propeller is recommended for the vectored propulsion system used for stratosphere airship.
基金This work was supported by National Natural Science Foundation of China(Grant No.41790473).
文摘Utilizing three different sets of reanalysis data,this study examines the long-and short-lived observed positive North Atlantic Oscillation(NAO)events(referred to as NAO+_LE and NAO+_SE)and long-and short-lived observed negative NAO events(referred to as NAO−_LE and NAO−_SE).Composite results indicate that the NAO-like circulation anomalies associated with the long-lived NAO events can reach the stratosphere,while they are primarily confined to the troposphere in the short-lived NAO events.Thus,the coupling/connection of stratospheric and tropospheric circulation anomalies is much better(worse)in the long-lived(short-lived)NAO events.A series of modified stratospheric initial-value experiments conducted with a simplified model indicate that a better(worse)connection between stratospheric and tropospheric circulation anomalies in the initial-value fields tend to gradually induce the NAO-like tropospheric circulation anomalies in the troposphere on the subsequent days,and thus naturally elongate(reduce)the lifetimes of the original NAO events by altering the tropospheric synoptic eddy vorticity flux over the North Atlantic region.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant Nos. XDA17010101, XDA17010102, XDA17010103, XDA17010104 and XDA17010105)
文摘The unique geographical location and high altitude of the Tibetan Plateau can greatly influence regional weather and climate.In particular, the Asian summer monsoon(ASM) anticyclone circulation system over the Tibetan Plateau is recognized to be a significant transport pathway for water vapor and pollutants to enter the stratosphere. To improve understanding of these physical processes, a multi-location joint atmospheric experiment was performed over the Tibetan Plateau from late July to August in 2018, funded by the fiveyear(2018–2022) STEAM(stratosphere and troposphere exchange experiment during ASM) project, during which multiple platforms/instruments—including long-duration stratospheric balloons, dropsondes, unmanned aerial vehicles, special sounding systems, and ground-based and satellite-borne instruments—will be deployed. These complementary methods of data acquisition are expected to provide comprehensive atmospheric parameters(aerosol, ozone, water vapor, CO_2, CH_4, CO, temperature, pressure,turbulence, radiation, lightning and wind); the richness of this approach is expected to advance our comprehension of key mechanisms associated with thermal, dynamical, radiative, and chemical transports over the Tibetan Plateau during ASM activity.
文摘The Indian summer monsoon is one of the most dominant tropical circulation systems in the general circulation of the atmosphere. The country receives more than 80% of the annual rainfall during a short span of four months (June to September) of the southwest monsoon season. Variability in the quantum of rainfall during the monsoon season has profound impacts on water resources, power generation, agriculture, economics and ecosystems in the country. The inter annual variability of Indian Summer Monsoon Rainfall (ISMR) depends on atmospheric and oceanic conditions prevailed during the season. In this study we have made an attempt to understand the variation of the of zonal winds in the tropical Upper Troposphere and Lower Stratosphere (UT/LS) region during deficient and Excess rainfall years of Indian summer monsoon and its relation to Indian Summer Monsoon Rainfall (ISMR). It is found that in the equatorial Upper Troposphere zonal winds have westerly anomalies during deficient rainfall year’s and easterly anomaly during excess rainfall years of Indian summer monsoon and opposite zonal wind anomaly is noted in the equatorial Lower Stratosphere during the deficient and excess rainfall years of Indian summer monsoon. It is also found that the June to September upper troposphere zonal winds averaged between 15°N and 15°S latitudes have a long-term trend during 1960 to 1998. Over this period the tropical easterlies and the tropical jet stream have weakened with time.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA17010102)。
文摘We present characterizations of the dynamic turbulence in the lower stratosphere measured by a new balloon-based system designed for detecting finer scale dynamic turbulence. The balloon-based system included a constant temperature anemometer(CTA) operating at a sampling rate of 2 k Hz at an ascent speed of 5 m s^(-1)(corresponding to a vertical resolution of 2.5 mm), an industrial personal computer, batteries, sensors for ambient temperature and humidity, an A/D converter, and others. The system was successfully launched to 24 km altitude over Bayannur City, Inner Mongolia Province. Results show the spatial intermittence of the turbulence layers, with clear boundaries between turbulent and nonturbulent regions. This is the first time that the dynamic turbulence spectrum down to the viscous sub-range has been obtained throughout the lower stratosphere over China. With that, the energy dissipation rates of dynamic turbulence could be calculated with high precision. The profile of the dissipation rates varied from 7.37 × 10^(-7) to 4.23 W kg^(-1) and increased with altitude in the stratosphere.
文摘An investigation of the influence of the relief of a planet on the global circulation of the Earth’s atmosphere is an important problem. Beyond doubt, mountains affect the global circulation of the troposphere, however, their influence on the global circulation of the stratosphere and mesosphere is not evident. In the present study, to investigate the influence of the relief of a planet on the global circulation of the Earth’s stratosphere and mesosphere, the non-hydrostatic mathematical model, developed earlier in the Polar Geophysical Institute, is utilized. Calculations were made for two distinct cases. The relief of the planet was taken into account for the first case. Unlike, the Earth’s surface was assumed to be smooth for the second case. Simulations were performed for the winter period in the northern hemisphere (January). Simulation results, obtained for both considered cases, are qualitatively similar at the levels of stratosphere and mesosphere, however, some noticeable distinctions exist. The horizontal domains exist, where the simulated horizontal and vertical components of the neutral wind velocity, obtained for two considered cases, differ noticeably at the levels of the stratosphere and mesosphere. Some of these horizontal domains are not connected with positions of mountains at the Earth’s surface. On the contrary, some of these horizontal domains are situated above mountains.
基金jointly supported by an NSFC project (Grant Nos.41505034,41630423)the China National 973 project (Grant No.2015CB453200)+8 种基金NSF (AGS1565653)NSFC project (Grant No.41475084)NRL (Grant No.N00173-161G906)Jiangsu NSF key project (Grant No.BK20150062)the Startup Foundation for Introducing Talent of NUIST (Grant No.2014R010)a project funded by the Jiangsu Shuang-Chuang Team (Grant No.R2014SCT001)the Startup Foundation for Introducing Talent of NUIST (Grant No.2014R010)the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe China Scholarship Council for funding and travel support
文摘The impact of La Ni?a on the winter Arctic stratosphere has thus far been an ambiguous topic of research. Contradictory results have been reported depending on the La Ni?a events considered. This study shows that this is mainly due to the decadal variation of La Ni?a's impact on the winter Arctic stratosphere since the late 1970 s. Specifically,during the period1951–78,the tropospheric La Ni?a teleconnection exhibits a typical negative Pacific–North America pattern,which strongly inhibits the propagation of the planetary waves from the extratropical troposphere to the stratosphere,and leads to a significantly strengthened stratospheric polar vortex. In contrast,during 1979–2015,the La Ni?a teleconnection shifts eastwards,with an anomalous high concentrated in the northeastern Pacific. The destructive interference of the La Ni?a teleconnection with climatological stationary waves seen in the earlier period reduces greatly,which prevents the drastic reduction of planetary wave activities in the extratropical stratosphere. Correspondingly,the stratospheric response shows a less disturbed stratospheric polar vortex in winter.
文摘The behaviour of relative diffusion theory and Gifford’s random-force theory for long-range atmospheric diffusion is examined. When a puff scale is smaller than the Lagrangian length scale, 2KTL, an accelerative relative diffusion region exists, i.e., σy xt 3 / 2. While the puff diffusion enters a two-dimensional turbulence region. in which the diffusion scale is larger than 500 km, or time scale is larger than 1 day, divergence and convergence are main cause of horizontal diffusion. Between the two above-mentioned regimes, diffusion deviation is given by σy=2KT. The large-scale horizontal relative diffusion parameters were obtained by analyzing the data of radioactive cloud width collected in air nuclear tests.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41975048, 42030605, and 42175069)the Natural Science Foundation of Jiangsu Province (Grant No.BK20191404)
文摘The representation of the Arctic stratospheric circulation and the quasi-biennial oscillation(QBO)during the period 1981–2019 in a 40-yr Chinese global reanalysis dataset(CRA-40)is evaluated by comparing two widely used reanalysis datasets,ERA-5 and MERRA-2.CRA-40 demonstrates a comparable performance with ERA-5 and MERRA-2 in characterizing the winter and spring circulation in the lower and middle Arctic stratosphere.Specifically,differences in the climatological polar-mean temperature and polar night jet among the three reanalyses are within±0.5 K and±0.5 m s^(–1),respectively.The onset dates of the stratospheric sudden warming and stratospheric final warming events at 10 hPa in CRA-40,together with the dynamics and circulation anomalies during the onset process of warming events,are nearly identical to the other two reanalyses with slight differences.By contrast,the CRA-40 dataset demonstrates a deteriorated performance in describing the QBO below 10 hPa compared to the other two reanalysis products,manifested by the larger easterly biases of the QBO index,the remarkably weaker amplitude of the QBO,and the weaker wavelet power of the QBO period.Such pronounced biases are mainly concentrated in the period 1981–98 and largely reduced by at least 39%in 1999–2019.Thus,particular caution is needed in studying the QBO based on CRA-40.All three reanalyses exhibit greater disagreement in the upper stratosphere compared to the lower and middle stratosphere for both the polar region and the tropics.
基金supported by the Knowledge Innovation Project of the CAS(Grant No.KZCX3-SW-217)the National Natural Science Foundation of China(Grant Nos.40375013 and 40333034).
文摘The seasonal variation of inertia gravity-wave activity in the lower stratosphere (17―24 km) over Beijing is studied based on the high vertical resolution radionsonde observa- tions (from December 2001 to February 2003) of Beijing Observatory (116°28′E, 39°48′N). Some of the important gravity-wave parameters, such as intrinsic frequency, and propagation direction, are estimated according to the polarized relation among gravity-wave wind components and temperature. Time series of wave energy show that the largest wave amplitudes occur during the winter and the least during the summer, and the average of the KE:PE ratios is about 2.6. Zonal and meridional wind perturbations have almost the same roots of mean variances, which shows that the wave energy in the lower stratosphere is isotropic horizontally. The motion and tem- perature fields are dominated by waves with vertical wavelengths of 1.5―3 km, which occupy above 80% samples, with a mean value of about 2.3 km. The horizontal wavelengths are mainly distributed between 100―800 km, averaging 445 km. The ratio of the mean horizontal to vertical wavelength is about 200:1, which indicates that the wave propagates nearly horizontally, with a very small vertical angle. The intrinsic frequency is estimated by fitting a polarized ellipse to the wind perturbations after band-filtering waves with a wavelength of 1.5―3 km, and the results show that the intrinsic frequency is dominated by 1f―3.5f, with an averaging value of 2f, corre- sponding to an intrinsic time period of 9 hours. Wave energy is found to propagate mainly upward, and in the horizontal direction, there is clear azimuthal anisotropy, with predominate northwest propagation against the prevailing wind.
基金supported in part by the National Key R&D Program of China(No.2016YFB1200100)
文摘This paper proposes a hybrid architecture based on Multi-disciplinary Design Optimization(MDO) with the Variable Complexity Modeling(VCM) method, to solve the problem of general design optimization for a stratosphere airship. Firstly, MDO based on the Concurrent SubSpace Optimization(CSSO) strategy is improved for handling the subsystem coupling problem in stratosphere airship design which contains aerodynamics, structure, and energy. Secondly, the VCM method based on the surrogate model is presented for reducing the computational complexity in high-fidelity modeling without loss of accuracy. Moreover, the global-to-local optimization strategy is added to the architecture to enhance the process. Finally, the result gives a prominent stratosphere airship general solution that validates the feasibility and efficiency of the optimization architecture. Besides, a sensitivity analysis is conducted to outline the critical impact upon stratosphere airship design.
基金the National Science Foundation of Hunan Province,China(Grant No.2022JJ40471)the Research Foundation of the Education Bureau of Hunan Province,China(Grant No.22B0345)the Key Laboratory of Geospace Envi-ronment,Chinese Academy of Sciences,University of Science&Technology of China(Grant No.GE2023-01).
文摘Due to the significant changes they bring to high latitude stratospheric temperature and wind,stratospheric sudden warmings(SSWs)can have an impact on the propagation and energy distribution of gravity waves(GWs).The variation characteristics of GWs during SSWs have always been an important issue.Using temperature data from January to March in 2014−2016,provided by the Constellation Observing System for Meteorology,Ionosphere and Climate(COSMIC)mission,we have analyzed global GW activity at 15−40 km in the Northern Hemisphere during SSW events.During the SSWs that we studied,the stratospheric temperature rose in one or two longitudinal regions in the Northern Hemisphere;the areas affected extended to the east of 90°W.During these SSWs,the potential energy density(E_(p)of GWs expanded and covered a larger range of longitude and altitude,exhibiting an eastward and downward extension.The E_(p)usually increased,while partially filtered by the eastward zonal winds.When zonal winds weakened or turned westward,E_(p)began to strengthen.After SSWs,the E_(p)usually decreased.These observations can serve as a reference for analyzing the interaction mechanism between SSWs and GWs in future work.
基金the National Natural Science Foundation of China(No.52175103)。
文摘An autonomous altitude adjustment system for a stratospheric satellite(StratoSat)platform is proposed.This platform consists of a helium balloon,a ballonet,and a two-way blower.The helium balloon generates lift to balance the platform gravity.The two-way blower inflates and deflates the ballonet to regulate the buoyancy.Altitude adjustment is achieved by tracking the differential pressure difference(DPD),and a threshold switching strategy is used to achieve blower flow control.The vertical acceleration regulation ability is decided not only by the blower flow rate,but also by the designed margin of pressure difference(MPD).Pressure difference is a slow-varying variable compared with altitude,and it is adopted as the control variable.The response speed of the actuator to disturbance can be delayed,and the overshoot caused by the large inertia of the platform is inhibited.This method can maintain a high tracking accuracy and reduce the complexity of model calculation,thus improving the robustness of controller design.
文摘Two one-dimensional radiative-convective models with the same scheme and the different ranges that one is fromsurface to stratopause and the other is from surface to tropopause,have been developed to study the role played by thestratosphere in greenhouse effect.It is shown that the addition of stratospheric response may lead to an increase of 7—50percent in radiative forcing at the tropopause,and an increase of 20—60 percent in surface temperature when the con-centration of the same gas in the two models increases at the same time;and when the same change in radiative forcing atthe tropopause due to the same agent in the two models occurs,the addition of stratospheric response may lead to an in-crease of 5—20 percent in surface temperature;and allowing for the stratospheric adjustment means that the tempera-ture responses to the same flux change due to different causes are in far disagreement.
文摘El Nio usually happens with the anomaly of general circulation of atmosphere and climate in the world. El Nio has close statistical relationships with the rainfall decrease in Africa, the monsoon weakening in India, and the Australian aridity. In recent years, it is also pointed out that there is a certain correlation between El Nio and Chinese climate and weather. In El Nio year, the summer temperature is lower than normal in the northeast of China. The happening and development of El Nio can also cause the anomalies of rainfalls in Changjiang River valley and the typhoon in China. Therefore, the fore-
基金This work is supported by National Natural Science Foundation(NNSF)of China under Grant Nos 61603320,61273199 and 61673327.
文摘Purpose–The purpose of this paper is to improve the control precision of the station-keeping control for a stratosphere airship through the feedforward-feedback PID controller which is designed by the wind speed prediction based on the incremental extreme learning machine(I-ELM).Design/methodology/approach–First of all,the online prediction of wind speed is implemented by the I-ELM with rolling time.Second,the feedforward-feedback PID controller is designed through the position information of the airship and the predicted wind speed.In the end,the one-dimensional dynamic model of the stratosphere airship is built,and the controller is applied in the numerical simulation.Findings–Based on the conducted numerical simulations,some valuable conclusions are obtained.First,through the comparison between the predicted value and true value of the wind speed,the wind speed prediction based on I-ELM is very accurate.Second,the feedforward-feedback PID controller designed in this paper is very effective.Originality/value–This paper is very valuable to the research of a high-accuracy station-keeping control of stratosphere airship.
文摘An engineering system approach of 2-D cylindrical model of transient mass balance calculations of ozone and other concerned chemicals along with fourteen photolysis, ozone-generating and ozone-depleting chemical reaction equations was developed, validated, and used for studying the ozone concentrations, distribution and peak of the layer, ozone depletion and total ozone abundance in the stratosphere. The calculated ozone concentrations and profile at both the Equator and a 60˚N location were found to follow closely with the measured data. The calculated average ozone concentration was within 1% of the measured average, and the deviation of ozone profiles was within 14%. The monthly evolution of stratospheric ozone concentrations and distribution above the Equator was studied with results discussed in details. The influences of slow air movement in both altitudinal and radial directions on ozone concentrations and profile in the stratosphere were explored and discussed. Parametric studies of the influences of gas diffusivities of ozone D<sub>O3</sub> and active atomic oxygen D<sub>O</sub> on ozone concentrations and distributions were also studied and delineated. Having both influences through physical diffusion and chemical reactions, the diffusivity (and diffusion) of atomic oxygen D<sub>O</sub> was found to be more sensitive and important than that of ozone D<sub>O3</sub> on ozone concentrations and distribution. The 2-D ozone model present in this paper for stratospheric ozone and its layer and depletion is shown to be robust, convenient, efficient, and executable for analyzing the complex ozone phenomena in the stratosphere. .
