Mean winds and tides in the Arctic mesosphere and lower thermosphere

Mitchell, N. J.; Pancheva, D.; Middleton, H. R.; Hagan, M. E.

doi:10.1029/2001ja900127

Cited by 105 publications

(129 citation statements)

References 22 publications

(59 reference statements)

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“…First of all, the amplitudes of oscillations observed at Esrange are greater than the values obtained at Dixon and even of the same order as amplitudes of oscillations observed at middle-latitudes. Mitchell et al (2002) noted similar differences, except for the tides. Fortunately, the phases and frequencies of oscillations usually are very consistent for data obtained by different techniques.…”

Section: Measurements and Data Analysissupporting

confidence: 49%

High- and mid-latitude quasi-2-day waves observed simultaneouslyby four meteor radars during summer 2000

Merzlyakov

Pancheva²,

Mitchell³

et al. 2004

Ann. Geophys.

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Abstract.Results from the analysis of MLT wind measurements at Dixon (73.5 • N, 80 • E), Esrange (68 • N, 21 • E), Castle Eaton (UK) (53 • N, 2 • W), and Obninsk (55 • N, 37 • E) during summer 2000 are presented in this paper. Using S-transform or wavelet analysis, quasi-two-day waves (QTDWs) are shown to appear simultaneously at high-and mid-latitudes and reveal themselves as several bursts of wave activity. At first this activity is preceded by a 51-53 h wave with S=3 observed mainly at mid-latitudes. After a short recess (or quiet time interval for about 10 days near day 205), we observe a regular sequence of three bursts, the strongest of them corresponding to a QTDW with a period of 47-48 h and S=4 at mid-altitudes.We hypothesize that these three bursts may be the result of constructive and destructive interference between several spectral components: a 47-48 h component with S=4; a 60-h component with S=3; and a 80-h component with S=2. The magnitudes of the lower (higher) zonal wave-number components increase (decrease) with increasing latitude. The S-transform or wavelet analysis indicates when these spectral components create the wave activity bursts and gives a range of zonal wave numbers for observed bursts from about 4 to about 2 for mid-and high-latitudes. The main spectral component at Dixon and Esrange latitudes is the 60-h oscillation with S=3. The zonal wave numbers and frequencies of the observed spectral components hint at the possible occurrence of the nonlinear interaction between the primary QTDWs and other planetary waves. Using a simple 3-D nonlinear numerical model, we attempt to simulate some of the observed features and to explain them as a consequence of the nonlinear interaction between the primary 47-48 h and the 9-10 day waves, and the resulting linear superposition of primary and secondary waves. In addition to the QTDW bursts, we also infer forcing of the 4-day wave with S=2 and the 6-7 day wave with S=1, possibly arising from nonlinear decoupling of the 60-h wave with S=3. The starting mechanism for this decoupling is the Rossby wave instability (e.g.Correspondence to: E. Merzlyakov (eugmer@typhoon.obninsk.org) Baines, 1976). This result is consistent with the day-to-day wind variability during the observed QTDW events. An interesting feature of the final stage of the observed QTDW activity in summer 2000 is the occurrence of strong 4-5 day waves with S=3.

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Section: Measurements and Data Analysissupporting

confidence: 49%

High- and mid-latitude quasi-2-day waves observed simultaneouslyby four meteor radars during summer 2000

Merzlyakov

Pancheva²,

Mitchell³

et al. 2004

Ann. Geophys.

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“…Manson et al, 1988Manson et al, , 1989Manson et al, , 2009Vincent et al, 1988;Avery et al, 1989;Portnyagin et al, 1993;Fraser et al, 1995;Mitchell et al, 2002). At these latitudes the diurnal tidal modes are predominantly trapped, and so in the MLT region the semidiurnal tide has larger amplitudes.…”

Section: R N Davis Et Al: Mesospheric Tides Over Ascension Islandmentioning

confidence: 99%

“…Burrage et al, 1995;Fraser et al, 1995;Chang and Avery, 1997;Mitchell et al, 2002;Andrioli et al, 2009;Manson et al, 1999).…”

Section: R N Davis Et Al: Mesospheric Tides Over Ascension Islandmentioning

confidence: 99%

“…The fits were applied to windows of four-day length, stepped in one-day increments through the time series of zonal and meridional winds (e.g. Mitchell et al, 2002;Kumar et al, 2008). Each height gate was treated separately and a requirement made that results were only recorded if data were present for more than 70 % of the hours within each 4-day window.…”

Section: Data and Analysismentioning

confidence: 99%

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The diurnal and semidiurnal tides over Ascension Island (° S, 14° W) and their interaction with the stratospheric quasi-biennial oscillation: studies with meteor radar, eCMAM and WACCM

et al. 2013

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The diurnal zonal vertical wavelengths are similar to the meridional, except for the winter months when the zonal vertical wavelengths are much longer, occasionally exceeding 100 km. Semidiurnal amplitudes are observed to be significantly smaller than diurnal amplitudes. Semidiurnal vertical wavelengths range from 20 to more than 100 km. Our observations of tidal amplitudes and phases are compared with the predictions of the extended Canadian Middle Atmosphere Model (eCMAM) and the Whole Atmosphere Community Climate Model (WACCM). Both eCMAM and WACCM reproduce the trend for greater diurnal amplitudes in the meridional component than the zonal. However, eCMAM tends to overestimate meridional amplitudes, while WACCM underestimates both zonal and meridional amplitudes. Vertical wavelength predictions are generally good for both models; however, eCMAM predicts shorter diurnal zonal vertical wavelengths than are observed in winter, while WACCM predicts longer zonal vertical wavelengths than observed for the semidiurnal tide for most months. Semidiurnal amplitude predictions are generally good for both models. It is found that larger-than-average diurnal and semidiurnal tidal amplitudes occur when the stratospheric quasi-biennial oscillation (QBO) at 10 hPa is eastwards, and smaller-than-average amplitudes occur when it is westwards. Correlations between the amplitude perturbations and the El Niño Southern Oscillation are also found. The precise mechanism for these correlations remains unclear.

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“…Nevertheless, in the Arctic MF and Meteor radars have been used to establish a limited number of simple climatologies of the zonal and meridional mean winds. These include the MF radar studies of Portnyagin et al (1992Portnyagin et al ( , 1993Portnyagin et al ( , 2004; Dowdy et al (2001Dowdy et al ( , 2007a; Hall et al (2003); Kishore et al (2003) and the meteor radar studies of Hocking (2001); Mitchell et al (2002); Hall et al (2003).…”

Section: Introductionmentioning

confidence: 99%

Dynamics of the Antarctic and Arctic mesosphere and lower thermosphere – Part 1: Mean winds

et al. 2010

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Abstract. Zonal and meridional winds have been measured in the upper mesosphere and lower thermosphere at polar latitudes using two ground-based meteor radars. One radar is located at Rothera (68 • S, 68 • W) in the Antarctic and has been operational since February 2005. The second radar is located at Esrange (68 • N, 21 • E) in the Arctic and has been operational since October 1999. Both radars have produced relatively continuous measurements. Here we consider measurements made up to the end of 2009. Both radars are of similar design and at conjugate geographical latitudes, making the results directly comparable and thus allowing investigation of the differences in the mean winds of the Antarctic and Arctic regions. The data from each radar have been used to construct climatologies of monthly-mean zonal and meridional winds at heights between 80 and 100 km. Both Antarctic and Arctic data sets reveal seasonally varying zonal and meridional winds in which the broad pattern repeats from year to year. In particular, the zonal winds display a strong shear in summer associated with the upper part of the westward summertime zonal jet. The winds generally reverse to eastward flow at heights of ∼90 km. The zonal winds are eastward throughout the rest of the year. The meridional winds are generally equatorward over both sites, although brief episodes of poleward flow are often evident near the equinoxes and during winter. The strongest equatorward flows occur at heights of ∼90 km during summer.There are significant differences between the mean winds observed in the Antarctic and Arctic. In particular, the westward winds in summer are stronger and occur earlier in the season in the Antarctic compared with the Arctic. The eastward winds evident above the summertime zonal wind reversal are significantly stronger in the Arctic. The summertime equatorward flow in the Antarctic is slightly weaker, but occurs over a greater depth than is the case in the Arctic.Correspondence to: D. J. Sandford (d.j.sandford@bath.ac.uk) Comparisons of these observations with those of the URAP and HWM-07 empirical models reveal a number of significant differences. In particular, the zonal winds observed in the Antarctic during wintertime are significantly weaker than those of URAP. However, the URAP zonal winds are a good match to the observations of the Arctic. Significant differences are evident between the observations and HWM-07. In particular, the strong wintertime zonal winds of the Arctic in HWM-07 are not evident in the observations and the summertime zonal winds in HWM-07 are systematically stronger than observed. The agreement with meridional winds is generally poor.There is a significant amount of inter-annual variability in the observed zonal and meridional winds. Particularly high variability is observed in the Arctic zonal winds in spring and is probably associated with stratospheric warmings.

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Mean winds and tides in the Arctic mesosphere and lower thermosphere

Cited by 105 publications

References 22 publications

High- and mid-latitude quasi-2-day waves observed simultaneouslyby four meteor radars during summer 2000

High- and mid-latitude quasi-2-day waves observed simultaneouslyby four meteor radars during summer 2000

The diurnal and semidiurnal tides over Ascension Island (° S, 14° W) and their interaction with the stratospheric quasi-biennial oscillation: studies with meteor radar, eCMAM and WACCM

Dynamics of the Antarctic and Arctic mesosphere and lower thermosphere – Part 1: Mean winds

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