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Time series of (a) the tendency of zonal mean zonal wind of each identified SSW event, and (b) the zonal mean polar temperature (black) and zonal wind (red, positive eastward) averaged by all the identified SSW events, at 10 hPa averaged between 60 and 90 @BULLET N. The vertical dashed line indicates the central date (day 0) when the decreasing rate of zonal winds for each SSW event is the largest. The horizontal dashed lines in (a) correspond to 0 and −2 m s −1 day −1 .
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Spatial and temporal variabilities of Kelvin waves during stratospheric sudden warming (SSW) events are investigated by the ERA-Interim reanalysis data, and the results are validated by the COSMIC temperature data. A case study on an exceptionally large SSW event in 2009, and a composite analysis comprising 18 events from 1980-2013 are presented. D...
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Context 1
... that we excluded several events (e.g. the four events in 2008) since they are too close to be distinguished as individ- ual events. Figure 1a shows the time tendencies of these 19 identi- fied events. It is clearly seen that the maximum deceleration values of zonal mean polar zonal wind of these events can exceed −2 m s −1 day −1 (positive eastward). ...
Context 2
... identi- fied events. It is clearly seen that the maximum deceleration values of zonal mean polar zonal wind of these events can exceed −2 m s −1 day −1 (positive eastward). The variations of zonal mean polar temperature and zonal wind at 10 hPa, which are averaged by all the identified events mentioned above from day −15 to day 15, are shown in Fig. 1b. The common features of the SSWs are well represented in the averaged event: the polar temperature during the compos- ite event starts to increase from 203 K on day −8 and peaks (about 222 K) on day 3, while the polar eastward zonal wind starts to decrease from 50 m s −1 on day −3 and minimizes (about −5 m s −1 ) on day ...
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Citations
... The wind reversal in the lower mesosphere is associated with the major SSW with the central date of 23 January 2010 (Jia et al., 2016). Figure 2 shows the zonal wind velocity for both the noMEE (upper panel) and the MEE (lower panel) case. ...
Medium energy electron (MEE) (30–1,000 keV) precipitation enhances the production of nitric (NOx) and hydrogen oxides (HOx) throughout the mesosphere, which can destroy ozone (O3) in catalytic reactions. The dynamical effect of the direct mesospheric O3 reduction has long been an outstanding question, partly due to the concurrent feedback from the stratospheric O3 reduction. To overcome this challenge, the Whole Atmosphere Community Climate Model version 6 is applied in the specified dynamics mode for the year 2010, with and without MEE ionization rates. The results demonstrate that MEE ionization rates can modulate temperature, zonal wind and the residual circulation affecting NOx transport. The required fluxes of MEE to impose dynamical changes depend on the dynamical preconditions. During the Northern Hemispheric winter, even weak ionization rates can modulate the mesospheric signal of a sudden stratospheric warming event. The result provides a first step in a paradigm shift for the understanding of the MEE direct effect.
... They reported that the observed quasi-16 day waves are amplified in MLT winds and modulate the semidiurnal tides in F 2 layer critical frequency. Aside from the planetary wave, atmospheric Kelvin waves during SSW events were investigated by Jia et al. [84] using ERA-Interim reanalysis data and verified with COSMIC temperature data. They concluded that the Kelvin wave activity shows obvious coupling with the convection localized in the India Ocean and western Pacific region. ...
In this paper we summarize the research results by Chinese scientists in 2016-2018. The focuses are placed on the researches of the middle and upper atmosphere, specifically the researches associated with ground-based observation capability development, dynamical processes, and properties of circulation and chemistry-climate coupling of the middle atmospheric layers.
... They have demonstrated that the characteristic variations of winds and temperature are associated with the SSW events from observations and simulations. In recent years, many studies are interested in the significant atmosphere changes over tropical latitudes [21][22][23][24] and midlatitudes [25][26][27][28] during SSW. Chandran and Collins [29] studied the middle and low latitude effects of SSW events on temperature and zonal-mean winds in the middle atmosphere using a composite of SSW events between 1988 and 2010 by WACCM simulations. ...
Based on the data at ~40°N at different longitudes during different stratospheric sudden warming (SSW) events, the responses of zonal winds in the stratosphere, mesosphere and lower thermosphere to SSWs are studied in this paper. The variations of zonal wind over Langfang, China (39.4°N, 116.7°E) by MF radar and the modern era retrospective-analysis for research and applications (MERRA) wind data during 2010 and 2013 SSW and over Fort Collins, USA (41°N, 105°W) by lidar and MERRA wind data during 2009 SSW are compared. Results show that the zonal wind at ~40°N indeed respond to the SSWs while different specifics are found in different SSW events or at different locations. The zonal wind has significant anomalies during the SSWs. Over Langfang, before the onset of 2010 and 2013 SSW, the zonal wind reverses from eastward to westward below about 60–70 km and accelerates above this region, while westward wind prevails from 30 to 100 km after the onset of 2010 SSW, and westward wind prevails in 30–60 and 85–100 km and eastward wind prevails in 60–85 km after the onset of 2013 SSW. Over Fort Collins during 2009 SSW, eastward wind reverses to westward in 20–30 km before the onset while westward wind prevails in 20–30 and 60–97 km and eastward wind prevails in 30–60 and in 97–100 km after the onset. Moreover, simulations by the specified dynamics version of the whole atmosphere community climate model (SD-WACCM) are taken to explain different responding specifics of zonal wind to SSW events. It is found that the modulation of planetary wave (PW) plays the main role. Different phases of PWs would lead to the different zonal wind along with longitudes and the different amplitudes and phases in different SSW events can lead to the different zonal wind responses.
