Long-term trends and year-to-year variability of mid-latitude mesosphere/lower thermosphere winds

Portnyagin, Yu. I.; Merzlyakov, E. G.; Solovjova, T.V.; Jacobi, Ch.; Kürschner, D.; Manson, A. H.; Meek, C. E.

doi:10.1016/j.jastp.2006.04.004

Cited by 61 publications

(80 citation statements)

References 19 publications

(39 reference statements)

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“…Analysis of wind datasets has shown that the winds in the MLT region change on the interdecadal time scale, thus indicating possible climatic changes in the MLT wind regime. Some recent results on long-term changes in MLT winds have been published by Jacobi et al (2001Jacobi et al ( , 2005, Bremer et al (1997), Merzlyakov and Portnyagin (1999) and Portnyagin et al (2006). They show that different MLT wind parameters have significantly changed since the beginning of the regular wind measurements in the early 1960s.…”

Section: Non-stationary Trends Discrepancies and Missing Informationmentioning

confidence: 92%

“…Results using radar measurements are still inconclusive, generally showing a decrease in tidal amplitudes since the 1960s (Bremer et al, 1997) at mid and high latitudes, which is in accordance with modelling (Ross and Walterscheid, 1991), but the studies have relied on partly inhomogeneous datasets. Additionally, closer inspection of the semidiurnal tide time series shows that the negative trend seems to cease after the mid 1980s (Jacobi et al, 1997;Portnyagin et al, 2006), or may even reverse. Observations at Scott Base, Antarctica reveal a positive trend since the late 1980s (Baumgaertner et al, 2005).…”

Section: Non-stationary Trends Discrepancies and Missing Informationmentioning

confidence: 99%

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Emerging pattern of global change in the upper atmosphere and ionosphere

et al. 2008

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Abstract. In the upper atmosphere, greenhouse gases produce a cooling effect, instead of a warming effect. Increases in greenhouse gas concentrations are expected to induce substantial changes in the mesosphere, thermosphere, and ionosphere, including a thermal contraction of these layers. In this article we construct for the first time a pattern of the observed long-term global change in the upper atmosphere, based on trend studies of various parameters. The picture we obtain is qualitative, and contains several gaps and a few discrepancies, but the overall pattern of observed long-term changes throughout the upper atmosphere is consistent with model predictions of the effect of greenhouse gas increases. Together with the large body of lower atmospheric trend research, our synthesis indicates that anthropogenic emissions of greenhouse gases are affecting the atmosphere at nearly all altitudes between ground and space.

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Section: Non-stationary Trends Discrepancies and Missing Informationmentioning

confidence: 92%

Section: Non-stationary Trends Discrepancies and Missing Informationmentioning

confidence: 99%

Emerging pattern of global change in the upper atmosphere and ionosphere

et al. 2008

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“…So, the increase in the northward wind or/and decrease in the southward one shows an increase in the mean annual daily value of the northward wind. The mid-latitude average MLT northward wind velocity increase for some Northern Hemisphere regions is known (Portnyagin et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

“…The phenomena showing on long-term changes in the upper atmosphere wind are known. Recently, the midlatitude mean mesosphere-lower thermosphere (MLT) northward wind velocity increase for some Northern Hemisphere regions has been revealed (Portnyagin et al, 2006). Earlier, a negative long-term trend of the ionosphere F2 layer peak height for two Southern Hemisphere sites was noted by Jarvis et al (1998) and explained by the decrease in F2 layer altitude as a result of thermospheric cooling and the consequent fall in the altitude of fixed pressure levels.…”

Section: Theoretical Simulationmentioning

confidence: 99%

Different long-term trends of the oxygen red 630.0 nm line nightglow intensity as the result of lowering the ionosphere F2 layer

et al. 2008

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have been analyzed. It is shown that a decrease in the long-term trend of the mean annual red 630.0 nm line intensity from the premidnight value (+0.770±1.045 R/year) to its minimum negative value (−1.080±0.670 R/year) at the midnight/after midnight is a possible result of the observed lowering of the peak height of the ionosphere F2 layer electron density hmF2 (−0.455±0.343 km/year). A theoretical simulation is carried out using a simple Chapman-type layer (damping in time) for the height distribution of the F2 layer electron density. The estimated values of the lowering in the hmF2, the increase in the red line intensity at pre-midnight and its decrease at midnight/after midnight are close to their observational ones, when a negative trend in the total neutral density of the upper atmosphere and an increase in the mean northward wind (or its possible consequence -a decrease in the southward one) are assumed.

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“…Changes in temperature affect the wind field. Recent results on long-term changes in MLT winds have been published by and Portnyagin et al (2006). They showed that MLT wind parameters have significantly changed since the beginning of the early 1960s.…”

Section: Introductionmentioning

confidence: 99%

Low-frequency lower E-region wind and reflection height measurements as sensor for climate variability

Jacobi

2008

Adv. Radio Sci.

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Abstract. Measurements of reflection heights of lowfrequency (LF) radio waves at oblique incidence and estimates of mesosphere/lower thermosphere (MLT) region horizontal winds applying the D1 spaced receiver method on LF field strength registrations are analyzed with respect to possible long-term trends and interdecadal variability in the time interval from ∼1980 to date. While no clear signal of mesospheric height trend is registered during the last two decades, significant trends of MLT horizontal winds are found. These trends are non-linear, in particular a change of trends around 1990 is found, which is probably connected with changes in tropospheric and stratospheric conditions at that time.

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Long-term trends and year-to-year variability of mid-latitude mesosphere/lower thermosphere winds

Cited by 61 publications

References 19 publications

Emerging pattern of global change in the upper atmosphere and ionosphere

Emerging pattern of global change in the upper atmosphere and ionosphere

Different long-term trends of the oxygen red 630.0 nm line nightglow intensity as the result of lowering the ionosphere F2 layer

Low-frequency lower E-region wind and reflection height measurements as sensor for climate variability

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