6 year mean prevailing winds and tides measured by VHF meteor radar over Collm (51.3°N, 13.0°E)

Jacobi, Christoph

doi:10.1016/j.jastp.2011.04.010

Cited by 61 publications

(81 citation statements)

References 36 publications

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“…The seasonal cycles are similar to those reported earlier e.g. by Jacobi (2012). The left panel of Fig.…”

Section: Meteor Radar Wind Measurements At Collmsupporting

confidence: 89%

“…At Collm Observatory (51.3 • N, 13 • E), a SKiYMET meteor radar is operated on 36.2 MHz since summer 2004 (Jacobi, 2012). Original pulse repetition frequency (prf) was 2144 Hz (effectively 536 Hz, due to 4-point coherent integration), power was 6 kW and the transmitting antenna was a 3-element Yagi.…”

Section: Meteor Radar Wind Measurements At Collmmentioning

confidence: 99%

“…Note that the nominal heights not necessarily correspond to the mean heights within the gates, because the meteors show a vertical distribution with increasing/decreasing count rates with height below/above about 90 km (Stober et al, 2008;Jacobi, 2012). Therefore, below/above 90 km mean heights tend to be higher/lower than nominal heights, and due to the small number of meteors at high altitudes, a substantial difference is visible for 98 km nominal altitude, so that the real mean height is closer to 97 km than 98 km (Jacobi, 2012). For the other height gates, the difference between real and nominal height may be neglected.…”

Section: Meteor Radar Wind Measurements At Collmmentioning

confidence: 99%

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El Niño influence on the mesosphere/lower thermosphere circulation at midlatitudes as seen by a VHF meteor radar at Collm (51.3 ° N, 13 ° E)

et al. 2017

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Abstract. Mesosphere/lower thermosphere (MLT) zonal winds continuously measured by a VHF meteor radar at Collm, Germany (51.3 • N, 13.0 • E) in the height range 82 -97 km from 2004 to date are analyzed with respect to the signature of El Niño. The comparison of Niño3 equatorial SST index and MLT wind time series shows that in January and especially in February zonal winds are positively correlated with the Niño3 index. We note a delay of about one month of the MLT zonal wind effect with respect to equatorial sea surface temperature variability. The signal is strong for the upper altitudes (above 90 km) accessible to the radar observations, but weakens with decreasing height. This reflects the fact that during El Niño years the westerly winter middle atmosphere wind jet is weaker, and this is also the case with the easterly lower thermospheric jet. Owing to the reversal of the absolute El Niño signal from negative to positive with altitude, at the height of the maximum meteor flux, which is around 90 km, the El Niño signal is weak. The experimental results can be qualitatively reproduced by numerical experiments using a mechanistic global circulation model with prescribed tropospheric temperatures and latent heat release for El Niño and La Niña conditions.

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“…The seasonal cycles are similar to those reported earlier e.g. by Jacobi (2012). The left panel of Fig.…”

Section: Meteor Radar Wind Measurements At Collmsupporting

confidence: 89%

Section: Meteor Radar Wind Measurements At Collmmentioning

confidence: 99%

Section: Meteor Radar Wind Measurements At Collmmentioning

confidence: 99%

See 1 more Smart Citation

El Niño influence on the mesosphere/lower thermosphere circulation at midlatitudes as seen by a VHF meteor radar at Collm (51.3 ° N, 13 ° E)

et al. 2017

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“…The investigated height interval is divided into six non-overlapping height gates, binned at 82, 85, 88, 91, 94 and 98 km. Note that the real mean meteor height in the uppermost gate is only 97 km due to the decreasing rates with altitude (Jacobi, 2012). The radial wind velocity is obtained from the Doppler phase progression with time at each receiver.…”

Section: Measurements and Data Analysismentioning

confidence: 99%

“…The procedure is described in detail in Jacobi (2012). Threemonthly running means are calculated using vector averaging for the phases and arithmetic averaging for the amplitudes.…”

Section: Measurements and Data Analysismentioning

confidence: 99%

Terdiurnal signatures in sporadic <i>E</i> layers at midlatitudes

2013

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Abstract. Global Positioning System radio occultation measurements by the FORMOsa SATellite mission-3/Constellation Observing System for Meteorology, Ionosphere and Climate satellites were used to analyse the behaviour of the signature of the terdiurnal tide in sporadic E (E S ) layers at midlatitudes (43-63 • N). According to theory, the occurrence of E S is expected when the vertical zonal wind shear, which is mainly owing to solar tides, is negative. 4 yr means, based on 3-monthly running mean zonal means from December 2006-November 2010, were constructed for the terdiurnal oscillation in the occurrence frequency of E S . Comparison of the results with VHF meteor radar observations of the terdiurnal tide and the 8 h oscillation in the vertical zonal wind shear at Collm, Germany (51.3 • N, 13 • E) shows a clear correspondence between the 8 h in E S and in wind shear signature.

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Autonomous identification and classification of ionospheric sporadicEin digital ionograms

Ghosh

Berkey

2015

Earth and Space Science

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This paper introduces a methodology to autonomously identify and classify ionospheric sporadic E layers (E s ) from digital ionograms acquired using a NOAA dynasonde operated at the Bear Lake Observatory (BLO) in northern Utah. This approach uses a windowed-fuzzy clustering technique to group ionospheric echoes present in digital ionograms, employing the transitive property of equivalence. The algorithm introduces a variance constraint to automatically determine the number and size of the clusters present in the data set. Principal component analysis (PCA) of the cluster shapes is employed for curvature estimation and to enable classification of the data into the four principal types of temperate latitude sporadic E. A visual evaluation of the autonomously classified ionograms suggests that the algorithm accurately identifies ∼95% of the sporadic E echoes present in the BLO data set. The paper also includes a "proof-of-concept" analysis of the methodology, deriving E s parameters for summer and winter intervals, that explicitly characterizes the diurnal and seasonal variations present in the E region at 42 ∘ N. This analysis was derived from approximately 34,000 digital ionograms acquired over 4 months. While the experimental data show lower peak E region heights than predicted by modeling studies, they are generally consistent with GPS satellite occultation measurements. Our analysis of the temporal variation of f o E during summer and winter intervals is inconsistent with previous results that suggest a seasonal E region density anomaly. The results confirm, however, the ionospheric effect of increased NO densities in both the summer and winter E region, as predicted by modeling studies. The identification of sporadic E using the approach outlined in this work markedly facilitates the analysis of E s parameters, as well as eliminating any human biases from the ionogram analysis process.

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6 year mean prevailing winds and tides measured by VHF meteor radar over Collm (51.3°N, 13.0°E)

Cited by 61 publications

References 36 publications

El Niño influence on the mesosphere/lower thermosphere circulation at midlatitudes as seen by a VHF meteor radar at Collm (51.3 ° N, 13 ° E)

El Niño influence on the mesosphere/lower thermosphere circulation at midlatitudes as seen by a VHF meteor radar at Collm (51.3 ° N, 13 ° E)

Terdiurnal signatures in sporadic <i>E</i> layers at midlatitudes

Autonomous identification and classification of ionospheric sporadicEin digital ionograms

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6 year mean prevailing winds and tides measured by VHF meteor radar over Collm (51.3°N, 13.0°E)

Cited by 61 publications

References 36 publications

El Niño influence on the mesosphere/lower thermosphere circulation at midlatitudes as seen by a VHF meteor radar at Collm (51.3 ° N, 13 ° E)

El Niño influence on the mesosphere/lower thermosphere circulation at midlatitudes as seen by a VHF meteor radar at Collm (51.3 ° N, 13 ° E)

Terdiurnal signatures in sporadic &lt;i&gt;E&lt;/i&gt; layers at midlatitudes

Autonomous identification and classification of ionospheric sporadicEin digital ionograms

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Resources

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El Niño influence on the mesosphere/lower thermosphere circulation at midlatitudes as seen by a VHF meteor radar at Collm (51.3 ° N, 13 ° E)

El Niño influence on the mesosphere/lower thermosphere circulation at midlatitudes as seen by a VHF meteor radar at Collm (51.3 ° N, 13 ° E)

Terdiurnal signatures in sporadic <i>E</i> layers at midlatitudes