The role of equatorial waves in the semiannual oscillation of the middle Atmosphere

2000 ◽  
pp. 161-176 ◽  
Author(s):  
Rolando R. Garcia
Keyword(s):  
Middle Atmosphere ◽  
Equatorial Waves ◽  
Semiannual Oscillation

scholarly journals On the role of dust storms in triggering atmospheric gravity waves observed in the middle atmosphere

2011 ◽  
Vol 29 (9) ◽  
pp. 1647-1654 ◽  
Author(s):  
S. K. Das ◽  
A. Taori ◽  
A. Jayaraman
Keyword(s):  
Gravity Waves ◽  
Dust Storm ◽  
Hot Spots ◽  
Middle Atmosphere ◽  
Thermal Structure ◽  
Dust Storms ◽  
Storm Events ◽  
Atmospheric Perturbations ◽  
Atmospheric Gravity

Abstract. Lower atmospheric perturbations often produce measurable effects in the middle and upper atmosphere. The present study demonstrates the response of the middle atmospheric thermal structure to the significant enhancement of the lower atmospheric heating effect caused by dust storms observed over the Thar Desert, India. Our study from multi-satellite observations of two dust storm events that occurred on 3 and 8 May 2007 suggests that dust storm events produce substantial changes in the lower atmospheric temperatures as hot spots which can become sources for gravity waves observed in the middle atmosphere.

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

scholarly journals Ionospheric measurements during the CRISTA/MAHRSI campaign: their implications and comparison with previous campaigns

1999 ◽  
Vol 17 (8) ◽  
pp. 1040-1052
Author(s):  
J. Laštovicka ◽  
D. Pancheva ◽  
D. Altadill ◽  
E. A. Benediktov ◽  
J. Boška ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Space Shuttle ◽  
Lower Ionosphere ◽  
Data Series ◽  
Short Term ◽  
Climatological Data ◽  
Middle Latitudes ◽  
Solar Influence ◽  
The Given

Abstract. The CRISTA/MAHRSI experiment on board a space shuttle was accompanied by a broad campaign of rocket, balloon and ground-based measurements. Supporting lower ionospheric ground-based measurements were run in Europe and Eastern Asia between 1 October-30 November, 1994. Results of comparisons with long ionospheric data series together with short-term comparisons inside the interval October-November, 1994, showed that the upper middle atmosphere  (h = 80-100 km) at middle latitudes of the Northern Hemisphere in the interval of the CRISTA/MAHRSI experiment (4-12 November, 1994) was very close to its expected climatological state. In other words, the average results of the experiment can be used as climatological data, at least for the given area/altitudes. The role of solar/geomagnetic and "meteorological" control of the lower ionosphere is investigated and compared with the results of MAP/WINE, MAC/SINE and DYANA campaigns. The effects of both solar/geomagnetic and global meteorological factors on the lower ionosphere are found to be weak during autumn 1994 compared to those in MAP/WINE and DYANA winters, and they are even slightly weaker than those in MAP/SINE summer. The comparison of the four campaigns suggests the following overall pattern: in winter the lower ionosphere at northern middle latitudes appears to be fairly well "meteorologically" controlled with a very weak solar influence. In summer, solar influence is somewhat stronger and dominates the weak "meteorological" influence, but the overall solar/meteorological control is weaker than in winter. In autumn we find the weakest overall solar/meteorological control, local effects evidently dominate.Key words. Ionosphere (ionosphere · atmosphere interactions; mid-latitude ionosphere)

scholarly journals First multi-year occultation observations of CO<sub>2</sub> in the MLT by ACE satellite: observations and analysis using the extended CMAM

2010 ◽  
Vol 10 (3) ◽  
pp. 1133-1153 ◽  
Author(s):  
S. R. Beagley ◽  
C. D. Boone ◽  
V. I. Fomichev ◽  
J. J. Jin ◽  
K. Semeniuk ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Formation Rate ◽  
Lower Thermosphere ◽  
Eddy Diffusion ◽  
Photolysis Rates ◽  
Candidate Species ◽  
Rocket Measurements ◽  
The Impact ◽  
Co Observations

Abstract. This paper presents the first global set of observations of CO2 in the mesosphere and lower thermosphere (MLT) obtained by the ACE-FTS instrument on SCISAT-I, a small Canadian satellite launched in 2003. The observations use the solar occultation technique and document the fall-off in the mixing ratio of CO2 in the MLT region. The beginning of the fall-off of the CO2, or "knee" occurs at about 78 km and lies higher than in the CRISTA-1 measurements (~70 km) but lower than in the SABER 1.06 (~80 km) and much lower than in rocket measurements. We also present the measurements of CO obtained concurrently which provide important constraints for analysis. We have compared the ACE measurements with simulations of the CO2 and CO distributions in the vertically extended version of the Canadian Middle Atmosphere Model (CMAM). Applying standard chemistry we find that we cannot get agreement between the model and ACE CO2 observations although the CO observations are adequately reproduced. There appears to be about a 10 km offset compared to the observed ACE CO2, with the model "knee" occurring too high. In analyzing the disagreement, we have investigated the variation of several parameters of interest (photolysis rates, formation rate for CO2, and the impact of uncertainty in turbulent eddy diffusion) in order to explore parameter space for this problem. Our conclusions are that there must be a loss process for CO2, about 2–4~times faster than photolysis that will sequester the carbon in some form other than CO and we have speculated on the role of meteoritic dust as a possible candidate. In addition, from this study we have highlighted a possible important role for unresolved vertical eddy diffusion in 3-D models in determining the distribution of candidate species in the mesosphere which requires further study.

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