Observational evidence of the semiannual oscillation in the tropical middle atmosphere—A review

1980 ◽  
Vol 118 (1) ◽  
pp. 217-238 ◽  
Author(s):  
Isamu Hirota
Keyword(s):  
Middle Atmosphere ◽  
Observational Evidence ◽  
Semiannual Oscillation

scholarly journals Possible effect of extreme solar energetic particle event of 20 January 2005 on polar stratospheric aerosols: direct observational evidence

2012 ◽  
Vol 12 (2) ◽  
pp. 769-778 ◽  
Author(s):  
I. A. Mironova ◽  
I. G. Usoskin ◽  
G. A. Kovaltsov ◽  
S. V. Petelina
Keyword(s):  
Cosmic Rays ◽  
Energetic Particle ◽  
Middle Atmosphere ◽  
Solar Energetic Particle ◽  
Cosmic Ray ◽  
Observational Evidence ◽  
Temporal Association ◽  
Polar Regions ◽  
Solar Energetic Particle Event ◽  
Stratospheric Aerosols

Abstract. Energetic cosmic rays are the main source of ionization of the low-middle atmosphere, leading to associated changes in atmospheric properties. Via the hypothetical influence of ionization on aerosol growth and facilitated formation of clouds, this may be an important indirect link relating solar variability to climate. This effect is highly debated, however, since the proposed theoretical mechanisms still remain illusive and qualitative, and observational evidence is inconclusive and controversial. Therefore, important questions regarding the existence and magnitude of the effect, and particularly the fraction of aerosol particles that can form and grow, are still open. Here we present empirical evidence of the possible effect caused by cosmic rays upon polar stratospheric aerosols, based on a case study of an extreme solar energetic particle (SEP) event of 20 January 2005. Using aerosol data obtained over polar regions from different satellites with optical instruments that were operating during January 2005, such as the Stratospheric Aerosol and Gas Experiment III (SAGE III), and Optical Spectrograph and Infrared Imaging System (OSIRIS), we found a significant simultaneous change in aerosol properties in both the Southern and Northern Polar regions in temporal association with the SEP event. We speculate that ionization of the atmosphere, which was abnormally high in the lower stratosphere during the extreme SEP event, might have led to formation of new particles and/or growth of preexisting ultrafine particles in the polar stratospheric region. However, a detailed interpretation of the effect is left for subsequent studies. This is the first time high vertical resolution measurements have been used to discuss possible production of stratospheric aerosols under the influence of cosmic ray induced ionization. The observed effect is marginally detectable for the analyzed severe SEP event and can be undetectable for the majority of weak-moderate events. The present interpretation serves as a conservative upper limit of solar energetic particle effect upon polar stratospheric aerosols.

Middle atmosphere dynamical sources of the semiannual oscillation in the thermosphere and ionosphere

2017 ◽  
Vol 44 (1) ◽  
pp. 12-21 ◽  
Author(s):  
M. Jones ◽  
J. T. Emmert ◽  
D. P. Drob ◽  
D. E. Siskind
Keyword(s):  
Middle Atmosphere ◽  
Semiannual Oscillation

Observational evidence of polar mesospheric ozone loss following substorm events

2021 ◽  
Author(s):  
Keeta Chapman-Smith ◽  
Annika Seppälä ◽  
Craig Rodger ◽  
Aaron Hendry
Keyword(s):  
Middle Atmosphere ◽  
Energetic Particles ◽  
Observational Evidence ◽  
Electron Precipitation ◽  
Data Sets ◽  
Ozone Loss ◽  
Mesospheric Ozone ◽  
Ozone Monitoring ◽  
The Impact

<p>Ozone in the polar middle atmosphere is known to be affected by charged energetic particles precipitating into the atmosphere from the magnetosphere. In recent years there has been increased interest in the sources and consequences of electron precipitation into the atmosphere. Substorms are an important source of electron precipitation. They occur hundreds of times a year and drive processes which cause electrons to be lost into our atmosphere. The electrons ionise neutrals in the atmosphere resulting in the production of HO<sub>x</sub> and NO<sub>x</sub>, which catalytically destroy ozone. Simulations have examined substorm driven ozone loss and shown it is likely to be significant. However, this has not previously been verified from observations. Here we use polar mesospheric ozone observations from the Global Ozone Monitoring by Occultation of Stars (GOMOS) and Microwave Limb Sounder (MLS) instruments to investigate the impact of substorms. Using the superposed epoch technique we find consistent 10-20% reduction in mesospheric ozone in both data sets. This provides the first observational evidence that substorms are important to the ozone balance within the atmosphere.<span> </span></p>

Influence of the stratospheric shrinkage on the detected CCMI simulation trends

2020 ◽  
Author(s):  
Petr Pisoft ◽  
Petr Šácha
Keyword(s):  
Geopotential Height ◽  
Middle Atmosphere ◽  
Observational Evidence ◽  
Positive Trend ◽  
Local Function ◽  
Gradual Reduction ◽  
Changing Climate ◽  
Shrinkage Effect ◽  
Non Local ◽  
Stratospheric Cooling

<p>There is a well-established observational evidence that the tropopause is shifting upward. More generally, warming of the troposphere is directly connected with a positive trend of geopotential of pressure levels in the troposphere, which reaches its maximum around the tropopause. In the stratosphere, the geopotential height trends are affected by the stratospheric cooling resulting in a gradual reduction of the upward shift and even its reversal in the upper stratosphere. That leads to a decreasing trend of the stratospheric thickness - a so-called stratospheric shrinkage. In GCMs, shrinkage is one of the strongest and most robust fingerprints of the changing climate. In this study, we investigate the question whether the shrinkage presents additional dynamical feedback influencing other detected trends in the middle atmosphere (besides the influence of vertical shift). Analyzing set of CCMI models, we compute inter-model correlations of shrinkage with trends of various variables to separate the possible shrinkage effect, which is otherwise a non-local function of the temperature.</p>

scholarly journals Climatology of the semiannual oscillation of the tropical middle atmosphere

1997 ◽  
Vol 102 (D22) ◽  
pp. 26019-26032 ◽  
Author(s):  
Rolando R. Garcia ◽  
Timothy J. Dunkerton ◽  
Ruth S. Lieberman ◽  
Robert A. Vincent
Keyword(s):  
Middle Atmosphere ◽  
Semiannual Oscillation

scholarly journals Observational evidence of the influence of Antarctic stratospheric ozone variability on middle atmosphere dynamics

2015 ◽  
Vol 42 (19) ◽  
pp. 7853-7859 ◽  
Author(s):  
N. Venkateswara Rao ◽  
P. J. Espy ◽  
R. E. Hibbins ◽  
D. C. Fritts ◽  
A. J. Kavanagh
Keyword(s):  
Middle Atmosphere ◽  
Stratospheric Ozone ◽  
Observational Evidence ◽  
Middle Atmosphere Dynamics

scholarly journals The Semiannual Oscillation of the Tropical Zonal Wind in the Middle Atmosphere Derived from Satellite Geopotential Height Retrievals

2017 ◽  
Vol 74 (8) ◽  
pp. 2413-2425 ◽  
Author(s):  
Anne K. Smith ◽  
Rolando R. Garcia ◽  
Andrew C. Moss ◽  
Nicholas J. Mitchell
Keyword(s):  
Zonal Wind ◽  
Geopotential Height ◽  
Middle Atmosphere ◽  
Dominant Mode ◽  
Quasi Biennial Oscillation ◽  
Zonal Winds ◽  
Broadband Emission ◽  
The Tropics ◽  
Biennial Oscillation ◽  
Semiannual Oscillation

Abstract The dominant mode of seasonal variability in the global tropical upper-stratosphere and mesosphere zonal wind is the semiannual oscillation (SAO). However, it is notoriously difficult to measure winds at these heights from satellite or ground-based remote sensing. Here, the balance wind relationship is used to derive monthly and zonally averaged zonal winds in the tropics from satellite retrievals of geopotential height. Data from the Aura Microwave Limb Sounder (MLS) cover about 12.5 yr, and those from the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER) cover almost 15 yr. The derived winds agree with direct wind observations below 10 hPa and above 80 km; there are no direct wind observations for validation in the intervening layers of the middle atmosphere. The derived winds show the following prominent peaks associated with the SAO: easterly maxima near the solstices at 1.0 hPa, westerly maxima near the equinoxes at 0.1 hPa, and easterly maxima near the equinoxes at 0.01 hPa. The magnitudes of these three wind maxima are stronger during the first cycle (January at 1.0 hPa and March at 0.1 and 0.01 hPa). The month and pressure level of the wind maxima shift depending on the phase of the quasi-biennial oscillation (QBO) at 10 hPa. During easterly QBO, the westerly maxima are shifted upward, are about 10 m s−1 stronger, and occur approximately 1 month later than those during the westerly QBO phase.

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