Climatology of the mesopause relative density using a global distribution of meteor radars
<p>The existing distribution of meteor radars located from high- to low-latitude regions provides a favorable temporal and spatial coverage for investigating the climatology of the global mesopause density. In this study, we report the climatology of the mesopause relative density estimated us...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-06-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/19/7567/2019/acp-19-7567-2019.pdf |
| Summary: | <p>The existing distribution of meteor radars located from high- to
low-latitude regions provides a favorable temporal and spatial coverage for
investigating the climatology of the global mesopause density. In this
study, we report the climatology of the mesopause relative density estimated
using multiyear observations from nine meteor radars, namely, the Davis
Station (68.6<span class="inline-formula"><sup>∘</sup></span> S, 77.9<span class="inline-formula"><sup>∘</sup></span> E), Svalbard (78.3<span class="inline-formula"><sup>∘</sup></span> N,
16<span class="inline-formula"><sup>∘</sup></span> E) and Tromsø (69.6<span class="inline-formula"><sup>∘</sup></span> N, 19.2<span class="inline-formula"><sup>∘</sup></span> E) meteor
radars located at high latitudes; the Mohe (53.5<span class="inline-formula"><sup>∘</sup></span> N,
122.3<span class="inline-formula"><sup>∘</sup></span> E), Beijing (40.3<span class="inline-formula"><sup>∘</sup></span> N, 116.2<span class="inline-formula"><sup>∘</sup></span> E),
Mengcheng (33.4<span class="inline-formula"><sup>∘</sup></span> N, 116.6<span class="inline-formula"><sup>∘</sup></span> E) and Wuhan (30.5<span class="inline-formula"><sup>∘</sup></span> N, 114.6<span class="inline-formula"><sup>∘</sup></span> E) meteor radars located in the midlatitudes; and the
Kunming (25.6<span class="inline-formula"><sup>∘</sup></span> N, 103.8<span class="inline-formula"><sup>∘</sup></span> E) and Darwin (12.3<span class="inline-formula"><sup>∘</sup></span> S, 130.8<span class="inline-formula"><sup>∘</sup></span> E) meteor radars located at low latitudes. The daily
mean relative density was estimated using ambipolar diffusion coefficients
derived from the meteor radars and temperatures from the Microwave Limb
Sounder (MLS) on board the Aura satellite. The seasonal variations in the
Davis Station meteor radar relative densities in the southern polar
mesopause are mainly dominated by an annual oscillation (AO). The mesopause
relative densities observed by the Svalbard and Tromsø meteor radars at
high latitudes and the Mohe and Beijing meteor radars at high midlatitudes
in the Northern Hemisphere show mainly an AO and a relatively weak
semiannual oscillation (SAO). The mesopause relative densities observed by
the Mengcheng and Wuhan meteor radars at lower midlatitudes and the Kunming
and Darwin meteor radars at low latitudes show mainly an AO. The SAO is
evident in the Northern Hemisphere, especially at high latitudes, and its
largest amplitude, which is detected at the Tromsø meteor radar, is
comparable to the AO amplitudes. These observations indicate that the
mesopause relative densities over the southern and northern high latitudes
exhibit a clear seasonal asymmetry. The maxima of the yearly variations in
the mesopause relative densities display a clear latitudinal variation
across the spring equinox as the latitude decreases; these latitudinal
variation characteristics may be<span id="page7568"/> related to latitudinal changes influenced
by gravity wave forcing. In addition to an AO, the mesopause relative
densities over low latitudes also clearly show an intraseasonal variation
with a periodicity of 30–60 <span class="inline-formula">d</span>.</p> |
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| ISSN: | 1680-7316 1680-7324 |