Characteristics of Arctic winds at CANDAC-PEARL (80° N, 86° W) and Svalbard (78° N, 16° E) for 2006–2009: radar observations and comparisons with the model CMAM-DAS

Manson, A. H.; Meek, C. E.; Xinwen, Xu; Asô, T.; Drummond, J. R.; Hall, C. M.; Hocking, W. K.; Tsutsumi, Masaki; Ward, W. E.

doi:10.5194/angeo-29-1927-2011

Cited by 8 publications

(14 citation statements)

References 41 publications

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“…Xu et al, 2009a, b), as was the case for 2006/2007 (Paper 1). This is consistent with the prevalence of anticyclones to form in the Pacific-Western Canada longitudinal sector, and the cyclone to be resident over Scandinavia (Manson et al, 2008(Manson et al, , 2011Xu et al, 2009b).…”

Section: Semidiurnal Tides: Means Variations and Nmt Featuressupporting

confidence: 62%

“…4): this year represents the frequent and special physical situation when the meridional wintercentred monthly mean winds at Svalbard are dominantly southward (Manson et al, 2011). In the plots we include radar-values up to 88 km, which is the highest height used from CMAM; on the other hand, and since the Svalbardwinds extend down to 73 km, CMAM values down to there are included for Svalbard-comparisons.…”

Section: Comparisons Of the 2007 Arctic Diurnal Tides In Cmam-das Witmentioning

confidence: 99%

“…We use two MWR (Meteor Wind) radars of similar design (Hall et al, 2003;Hocking and Hocking, 2002 Manson et al ( , 2011. The unique spectral Canadian Middle Atmosphere Model (CMAM, e.g.…”

Section: Meteor Radar Winds and The Atmospheric Model Cmam-dasmentioning

confidence: 99%

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Characteristics of Arctic tides at CANDAC-PEARL (80° N, 86° W) and Svalbard (78° N, 16° E) for 2006–2009: radar observations and comparisons with the model CMAM-DAS

et al. 2011

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Abstract. Operation of a Meteor Radar (MWR) at EuThe three-year monthly means for both diurnal (DT) and semi-diurnal (SDT) winds demonstrate significantly different amplitudes and phases at Eureka and Svalbard. Typically the summer-maximizing DT is much larger (∼24 m s −1 at 97 km) at Eureka, while the Svalbard tide (5-24 m s −1 at 97 km)) is almost linear (north-south) rather than circular. Interannual variations are smallest in the summer and autumn months. The High Arctic SDT has maxima centred on August/September, followed in size by the winter features; and is much larger at Svalbard (24 m s −1 at 97 km, versus 14-18 m s −1 in central Canada). Depending on the location, the IAV are largest in spring/winter (Eureka) and summer/autumn (Svalbard).Fitting of wave-numbers for the migrating and nonmigrating tides (MT, NMT) determines dominant tides for each month and height. Existence of NMT is consisCorrespondence to: A. H. Manson (alan.manson@usask.ca) tent with nonlinear interactions between migrating tides and (quasi) stationary planetary wave (SPW) S = 1 (SPW1). For the diurnal oscillation, NMT s = 0 for the east-west (EW) wind component dominates (largest tide) in the late autumn and winter (November-February); and s = +2 is frequently seen in the north-south (NS) wind component for the same months. The semi-diurnal oscillation's NMT s = +1 dominates from March to June/July. There are patches of s = +3 and +1, in the late fall-winter. These wave numbers are also consistent with SPW1-MT interactions.Comparisons for 2007 of the observed DT and SDT at 78-80 • N, with those within the Canadian Middle Atmosphere Model Data Assimilation System CMAM-DAS, are a major feature of this paper. The diurnal tides for the two locations have important similarities as observed and modeled, with seasonal maxima in the mesosphere from April to October, and similar phases with long/evanescent wavelengths. However, differences are also significant: observed Eureka amplitudes are generally larger than the model; and at Svalbard the modeled tide is classically circular, rather than anomalous. For the semi-diurnal tide, the amplitudes and phases differ markedly between Eureka and Svalbard for both MWR-radar data and CMAM-DAS data. The seasonal variations from observed and modeled archives also differ at each location. Tidal NMT-amplitudes and wave-numbers for the model differ substantially from observations.

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Section: Semidiurnal Tides: Means Variations and Nmt Featuressupporting

confidence: 62%

Section: Comparisons Of the 2007 Arctic Diurnal Tides In Cmam-das Witmentioning

confidence: 99%

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Characteristics of Arctic tides at CANDAC-PEARL (80° N, 86° W) and Svalbard (78° N, 16° E) for 2006–2009: radar observations and comparisons with the model CMAM-DAS

et al. 2011

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“…Further references to long-term change in the middle and upper atmosphere in general can be found in Cnossen et al (2015). Background winds and superimposed tides thus affecting gravity wave propagation and filtering in the atmosphere underlying the UMLT also vary from location to location at high latitude, and the two studies by Manson et al (2011) study this zonal difference and compare with a current model. However, for approximately 10 • further north than the Tromsø radar site, these studies give valuable background information, not only on the wind field but also on tidal amplitude perturbation due to deposition of gravity waves' horizontal momentum.…”

Section: Discussionmentioning

confidence: 99%

Change in turbopause altitude at 52 and 70° N

Hall¹,

Holmen

Meek

et al. 2016

Atmos. Chem. Phys.

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Abstract. The turbopause is the demarcation between atmospheric mixing by turbulence (below) and molecular diffusion (above). When studying concentrations of trace species in the atmosphere, and particularly long-term change, it may be important to understand processes present, together with their temporal evolution that may be responsible for redistribution of atmospheric constituents. The general region of transition between turbulent and molecular mixing coincides with the base of the ionosphere, the lower region in which molecular oxygen is dissociated, and, at high latitude in summer, the coldest part of the whole atmosphere.This study updates previous reports of turbopause altitude, extending the time series by half a decade, and thus shedding new light on the nature of change over solar-cycle timescales. Assuming there is no trend in temperature, at 70 • N there is evidence for a summer trend of ∼ 1.6 km decade −1 , but for winter and at 52 • N there is no significant evidence for change at all. If the temperature at 90 km is estimated using meteor trail data, it is possible to estimate a cooling rate, which, if applied to the turbopause altitude estimation, fails to alter the trend significantly irrespective of season.The observed increase in turbopause height supports a hypothesis of corresponding negative trends in atomic oxygen density, [O]. This supports independent studies of atomic oxygen density, [O], using mid-latitude time series dating from 1975, which show negative trends since 2002.

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“…Some wind data have already been published in collaboration with the Svalbard MR (Manson et al, 2009(Manson et al, , 2011. The present paper is our first look at Eureka meteor radar temperatures.…”

Section: Introductionmentioning

confidence: 99%

Eureka, 80° N, SKiYMET meteor radar temperatures compared with Aura MLS values

et al. 2013

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The meteor trail echo decay rates are analysed on-site to provide daily temperatures near 90 km. In order to get temperatures from trail decay times, either knowledge of the pressure or the background temperature height gradient near 90 km is required (Hocking, 1999). Hocking et al. (2004) have developed an empirical 90 km temperature gradient model depending only on latitude and time of year, which is used in the SKiYMET on-site meteor temperature analysis.

Here we look at the sensitivity of the resulting temperature to the assumed gradient and compare it and the temperatures with daily AuraMLS averages near Eureka. Generally there is good agreement between radar and satellite for winter temperatures and their short-term variations. However there is a major difference in mid-summer both in the temperatures and the gradients. Increased turbulence in summer, which may overwhelm the ambipolar diffusion even at 90 km, is likely a major factor.

These differences are investigated by generating ambipolar-controlled decay times from satellite pressure and temperature data at a range of heights and comparing with radar measurements. Our study suggests it may be possible to use these data to estimate eddy diffusion coefficients at heights below 90 km. Finally the simple temperature analysis (using satellite pressures), and a standard meteor wind analysis are used to compare mean diurnal variations of temperature (T) with those of zonal wind (U) and meridional wind (V) in composite multi-year monthly intervals

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Characteristics of Arctic winds at CANDAC-PEARL (80° N, 86° W) and Svalbard (78° N, 16° E) for 2006–2009: radar observations and comparisons with the model CMAM-DAS

Cited by 8 publications

References 41 publications

Characteristics of Arctic tides at CANDAC-PEARL (80° N, 86° W) and Svalbard (78° N, 16° E) for 2006–2009: radar observations and comparisons with the model CMAM-DAS

Characteristics of Arctic tides at CANDAC-PEARL (80° N, 86° W) and Svalbard (78° N, 16° E) for 2006–2009: radar observations and comparisons with the model CMAM-DAS

Change in turbopause altitude at 52 and 70° N

Eureka, 80° N, SKiYMET meteor radar temperatures compared with Aura MLS values

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