The vertically integrated emission rate,centroid altitude,peak emission rate,and peak height of the hydroxyl(OH)airglow were calculated from Thermosphere Ionosphere Mesosphere Energetics and Dynamics(TIMED)/Sounding o...The vertically integrated emission rate,centroid altitude,peak emission rate,and peak height of the hydroxyl(OH)airglow were calculated from Thermosphere Ionosphere Mesosphere Energetics and Dynamics(TIMED)/Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)observations to study the seasonal and interannual variations in the intensity and location of the OH emission.The emission rate is inversely proportional to the height of the emission,with the semiannual oscillation dominating at low latitudes and the annual oscillation dominating at higher latitudes.The OH emission is modulated by the quasibiennial oscillation at the equator,and the quasibiennial oscillation signal is weak at other latitudes.We represented the vertical transport of atomic oxygen by using atomic oxygen concentrations obtained from a global atmospheric model,the Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension simulations.Compared with the amplitudes of the migrating diurnal tide(DW1)calculated from temperature data observed by TIMED/SABER,we found that both the vertical transport of atomic oxygen and DW1 amplitudes in the equatorial region exhibit semiannual oscillation and quasibiennial oscillation,which have a strong correlation with the variations in the amplitude and phase of semiannual oscillation and quasibiennial oscillation in OH emission.It is likely that the DW1 affects the vertical transport of atomic oxygen that is involved in the reaction to produce O3,thus affecting the OH emission.We analyzed the relationship between OH emission and solar activity by using the solar radio flux at 10.7 cm as a proxy for solar activity.The results showed that the OH emission is well correlated with solar activity,and the modulation of OH emission by solar activity has a significant latitudinal variation.The small correlation between emission height and solar activity indicates that solar activity modulates OH emission mainly through chemical rather than dynamic processes.展开更多
We investigated the interannual variations of the winter stratospheric polar vortex in this paper. EOF analysis shows that two modes of variability dominate the stratospheric polar vortex on interannual timescales The...We investigated the interannual variations of the winter stratospheric polar vortex in this paper. EOF analysis shows that two modes of variability dominate the stratospheric polar vortex on interannual timescales The leading mode （EOF1） reflects the intensity variation of the polar vortex and is characterized by a geopotential height seesaw between the polar region and the mid-latitudes. The second one （EOF2） exhibits variation in the zonal asymmetric part of the polar vortex, which mainly describes the stationary planetary wave activity. As the strongest interannual variation signal in the atmosphere, the QBO has been shown to influence mainly the strength of the polar vortex. On the other hand, the ENSO cycle, as the strongest interannual variation signal in the ocean, has been shown to be mainly associated with the variation of stationary planetary wave activity in the stratosphere. Possible influences of the stratospheric polar vortex on the tropospheric circulation are also discussed in this paper.展开更多
The QBO (quasi-biennial oscillation) in the climate system, with a mean cycle-length slightly above or below 2 years, is studied in a simple forced dynamical system. The fundamental cause of the quasi-biennial periodi...The QBO (quasi-biennial oscillation) in the climate system, with a mean cycle-length slightly above or below 2 years, is studied in a simple forced dynamical system. The fundamental cause of the quasi-biennial periodicity of the QBO is nonlinear resonance of the system to the seasonal forcing that is modulated by the 11-yr solar cycle. For a given nonlinearity, the cycle-length and the amplitude of the QBO depend on the intensity of both the unmodulated seasonal cycle and the 11-yr solar cycle, which may be one of the reasons why the QBO properties in climate vary with time and space.展开更多
Anomalous changes of zonal wind quasi-biennial oscillation(QBO)in winter 2015−2016 have received close attention.Combining radiosonde and satellite observations and reanalysis data,we investigate anomalous changes in ...Anomalous changes of zonal wind quasi-biennial oscillation(QBO)in winter 2015−2016 have received close attention.Combining radiosonde and satellite observations and reanalysis data,we investigate anomalous changes in temperature and ozone QBOs from the lower to middle stratosphere.As wind shear direction is reversed due to unexpected changes of zonal wind QBO at about 24−30 km,the shortest cold phase at 21−27 km appears in temperature QBO.This is different from the completely interrupted westward phase in zonal wind QBO,while the longest cold phase above almost 27 km lasts for 2−3 years from 2015 to 2017,owing to the absence of corresponding warm phase.Meridional scale reduction of temperature QBO causes a small temperature anomaly,thus the thermal wind relationship looks seemingly different from that in the other regular QBO cycles.QBO in the ozone mixing ratio anomaly shows a double-peak with inverse phase,and its phase below(above)30 km is in agreement with(opposite to)the phase of temperature QBO because of different control mechanisms of ozone.Following temperature QBO variation,QBO in the ozone mixing ratio anomaly exhibits a less positive phase at 20−30 km in 2016−2017,and a very long positive phase above 30 km from 2015 to 2017.QBO in total column ozone shows a small peak in winter 2016−2017 since ozone is mainly concentrated at 20 to 30 km.Anomalous changes of temperature and ozone QBOs due to unexpected QBO zonal wind variation can be well-explained according to thermal wind balance and thermodynamic balance.展开更多
Analysis has been implemented of 1970-1992 tropical Pacific wind stress anomaly and sea surface temperature anomaly (SSTA) datasets, indicating that quasi-biennial oscillation (QBO) of the tropical Pacific WS and SSTA...Analysis has been implemented of 1970-1992 tropical Pacific wind stress anomaly and sea surface temperature anomaly (SSTA) datasets, indicating that quasi-biennial oscillation (QBO) of the tropical Pacific WS and SSTA is featured both by a standing and a progressive form, the former emerging in the most intense centers of action and the latter travelling east- or west-ward out of the SSTA sources. Results show that the SSTA is in the warm (cold) phase as zonal component of euqatorial wind stress anomaly gets weakened (reinforced) and the QBO of wind stress anomaly is well related to the El Nino cycle.展开更多
基金the National Natural Science Foundation of China(Grant Numbers 42374195 and 42188101)a fellowship from the China National Postdoctoral Program for Innovative Talents(Grant Number BX20230273).
文摘The vertically integrated emission rate,centroid altitude,peak emission rate,and peak height of the hydroxyl(OH)airglow were calculated from Thermosphere Ionosphere Mesosphere Energetics and Dynamics(TIMED)/Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)observations to study the seasonal and interannual variations in the intensity and location of the OH emission.The emission rate is inversely proportional to the height of the emission,with the semiannual oscillation dominating at low latitudes and the annual oscillation dominating at higher latitudes.The OH emission is modulated by the quasibiennial oscillation at the equator,and the quasibiennial oscillation signal is weak at other latitudes.We represented the vertical transport of atomic oxygen by using atomic oxygen concentrations obtained from a global atmospheric model,the Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension simulations.Compared with the amplitudes of the migrating diurnal tide(DW1)calculated from temperature data observed by TIMED/SABER,we found that both the vertical transport of atomic oxygen and DW1 amplitudes in the equatorial region exhibit semiannual oscillation and quasibiennial oscillation,which have a strong correlation with the variations in the amplitude and phase of semiannual oscillation and quasibiennial oscillation in OH emission.It is likely that the DW1 affects the vertical transport of atomic oxygen that is involved in the reaction to produce O3,thus affecting the OH emission.We analyzed the relationship between OH emission and solar activity by using the solar radio flux at 10.7 cm as a proxy for solar activity.The results showed that the OH emission is well correlated with solar activity,and the modulation of OH emission by solar activity has a significant latitudinal variation.The small correlation between emission height and solar activity indicates that solar activity modulates OH emission mainly through chemical rather than dynamic processes.
基金supported by the National Basic Research Program of China (Grant No.2009CB421405)the National Natural Science Foundation of China (Grant Nos. 40775035 and 40730952)
文摘We investigated the interannual variations of the winter stratospheric polar vortex in this paper. EOF analysis shows that two modes of variability dominate the stratospheric polar vortex on interannual timescales The leading mode （EOF1） reflects the intensity variation of the polar vortex and is characterized by a geopotential height seesaw between the polar region and the mid-latitudes. The second one （EOF2） exhibits variation in the zonal asymmetric part of the polar vortex, which mainly describes the stationary planetary wave activity. As the strongest interannual variation signal in the atmosphere, the QBO has been shown to influence mainly the strength of the polar vortex. On the other hand, the ENSO cycle, as the strongest interannual variation signal in the ocean, has been shown to be mainly associated with the variation of stationary planetary wave activity in the stratosphere. Possible influences of the stratospheric polar vortex on the tropospheric circulation are also discussed in this paper.
基金This work was supported by the Director's Funds of LASG and the Innovative Funds of the Institute of Atmospheric Physics, Chinese Academy of Sciences.
文摘The QBO (quasi-biennial oscillation) in the climate system, with a mean cycle-length slightly above or below 2 years, is studied in a simple forced dynamical system. The fundamental cause of the quasi-biennial periodicity of the QBO is nonlinear resonance of the system to the seasonal forcing that is modulated by the 11-yr solar cycle. For a given nonlinearity, the cycle-length and the amplitude of the QBO depend on the intensity of both the unmodulated seasonal cycle and the 11-yr solar cycle, which may be one of the reasons why the QBO properties in climate vary with time and space.
基金supported by the National Natural Science Foundation of China(through grants 41974176 and 41674151).
文摘Anomalous changes of zonal wind quasi-biennial oscillation(QBO)in winter 2015−2016 have received close attention.Combining radiosonde and satellite observations and reanalysis data,we investigate anomalous changes in temperature and ozone QBOs from the lower to middle stratosphere.As wind shear direction is reversed due to unexpected changes of zonal wind QBO at about 24−30 km,the shortest cold phase at 21−27 km appears in temperature QBO.This is different from the completely interrupted westward phase in zonal wind QBO,while the longest cold phase above almost 27 km lasts for 2−3 years from 2015 to 2017,owing to the absence of corresponding warm phase.Meridional scale reduction of temperature QBO causes a small temperature anomaly,thus the thermal wind relationship looks seemingly different from that in the other regular QBO cycles.QBO in the ozone mixing ratio anomaly shows a double-peak with inverse phase,and its phase below(above)30 km is in agreement with(opposite to)the phase of temperature QBO because of different control mechanisms of ozone.Following temperature QBO variation,QBO in the ozone mixing ratio anomaly exhibits a less positive phase at 20−30 km in 2016−2017,and a very long positive phase above 30 km from 2015 to 2017.QBO in total column ozone shows a small peak in winter 2016−2017 since ozone is mainly concentrated at 20 to 30 km.Anomalous changes of temperature and ozone QBOs due to unexpected QBO zonal wind variation can be well-explained according to thermal wind balance and thermodynamic balance.
基金This work is supported by the National Natural Science Project Founndation of China.
文摘Analysis has been implemented of 1970-1992 tropical Pacific wind stress anomaly and sea surface temperature anomaly (SSTA) datasets, indicating that quasi-biennial oscillation (QBO) of the tropical Pacific WS and SSTA is featured both by a standing and a progressive form, the former emerging in the most intense centers of action and the latter travelling east- or west-ward out of the SSTA sources. Results show that the SSTA is in the warm (cold) phase as zonal component of euqatorial wind stress anomaly gets weakened (reinforced) and the QBO of wind stress anomaly is well related to the El Nino cycle.
