In:
Annales Geophysicae, Copernicus GmbH, Vol. 36, No. 2 ( 2018-03-05), p. 301-310
Abstract:
Abstract. Nowadays, the study of the upper atmosphere is increasing, mostly because of
the need to understand the patterns of Earth's atmosphere. Since studies on
global warming have become very important for the development of new
technologies, understanding all regions of the atmosphere becomes an
unavoidable task. In this paper, we aim to analyze the temperature
variability and its trend in the mesosphere and lower thermosphere (MLT)
region during a period of 12 years (from 2003 to 2014). For this purpose,
three different heights, i.e., 85, 90 and 95 km, were focused on in order to
investigate the upper atmosphere, and a geographic region different to other
studies was chosen, in the southern region of Brazil, centered in the city of
Santa Maria, RS (29∘41′02′′ S; 53∘48′25′′ W). In
order to reach the objectives of this work, temperature data from the SABER
instrument (Sounding of the Atmosphere using Broadband Emission Radiometry),
aboard NASA's Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED)
satellite, were used. Finally, two cases were studied related to distinct
grids of latitude/longitude used to obtain the mean temperature profiles. The
first case considered a grid of 20∘ × 20∘ lat/long,
centered in Santa Maria, RS, Brazil. In the second case, the region was
reduced to a size of 15∘ × 15∘ in order to compare
the results and discuss the two cases in terms of differences or similarities
in temperature trends. Observations show that the size of the geographical
area used for the average temperature profiles can influence the results of
variability and trend of the temperature. In addition, reducing the time
duration of analyses from 24 to 12 h a day also influences the trend
significantly. For the smaller geographical region
(15∘ × 15∘) and the 12 h daily time window
(09:00–21:00 UT) it was found that the main contributions for the
temperature variability at the three heights were the annual and semi-annual
cycles and the solar flux influence. A smaller trend
(−0.02 ± 0.16 % decade−1) was found at 90 km height and
small positive trends (0.58 ± 0.26 % and
0.41 ± 0.19 % decade−1) were found at altitudes of 85 and
95 km, respectively.. Keywords. Atmospheric composition and structure (middle atmosphere – composition and chemistry; pressure, density, and temperature) – meteorology and atmospheric dynamics (climatology)
Type of Medium:
Online Resource
ISSN:
1432-0576
DOI:
10.5194/angeo-36-301-2018
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
1458425-6
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