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| Titel |
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 |
| VerfasserIn |
A. H. Manson, C. E. Meek, X. Xu, T. Aso, J. R. Drummond, C. M. Hall, W. K. Hocking, M. Tsutsumi, W. E. Ward |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 29, no. 10 ; Nr. 29, no. 10 (2011-10-31), S.1939-1954 |
| Datensatznummer |
250017117
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| Publikation (Nr.) |
 copernicus.org/angeo-29-1939-2011.pdf |
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| Zusammenfassung |
Operation of a Meteor Radar (MWR) at Eureka, Ellesmere Island (80° N,
86° W) began in February 2006: this is the location of the Polar
Environmental and Atmospheric Research Laboratory (PEARL), operated by the
"Canadian Network for the Detection of Atmospheric Change" (CANDAC). The
first 36 months of tidal wind data (82–97 km) are here combined with
contemporaneous tides from the Meteor Radar (MWR) at Adventdalen, Svalbard
(78° N, 16° E), to provide the first significant evidence for
interannual variability (IAV) of the High Arctic's diurnal and semidiurnal
migrating (MT) and non-migrating tides (NMT).
The 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 non-migrating tides (MT, NMT)
determines dominant tides for each month and height. Existence of NMT is
consistent 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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