Long‐Term Trends in the Low‐Latitude Middle Atmosphere Temperature and Winds: Observations and WACCM‐X Model Simulations

2019 ◽  
Vol 124 (8) ◽  
pp. 7320-7331 ◽  
Author(s):  
M. Venkat Ratnam ◽  
S.T. Akhil Raj ◽  
Liying Qian
Keyword(s):  
Middle Atmosphere ◽  
Low Latitude ◽  
Model Simulations ◽  
Atmosphere Temperature ◽  
Long Term Trends

scholarly journals Summertime stratospheric processes at northern mid-latitudes: comparisons between MANTRA balloon measurements and the Canadian Middle Atmosphere Model

2008 ◽  
Vol 8 (7) ◽  
pp. 2057-2071 ◽  
Author(s):  
S. M. L. Melo ◽  
R. Blatherwick ◽  
J. Davies ◽  
P. Fogal ◽  
J. de Grandpré ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Chemical Species ◽  
Late Summer ◽  
Vertical Diffusion ◽  
Long Term Trends ◽  
Trend Assessment ◽  
Atmosphere Model ◽  
Vertical Diffusion Coefficient ◽  
Balloon Measurements

Abstract. In this paper we report on a study conducted using the Middle Atmospheric Nitrogen TRend Assessment (MANTRA) balloon measurements of stratospheric constituents and temperature and the Canadian Middle Atmosphere Model (CMAM). Three different kinds of data are used to assess the inter-consistency of the combined dataset: single profiles of long-lived species from MANTRA 1998, sparse climatologies from the ozonesonde measurements during the four MANTRA campaigns and from HALOE satellite measurements, and the CMAM climatology. In doing so, we evaluate the ability of the model to reproduce the measured fields and to thereby test our ability to describe mid-latitude summertime stratospheric processes. The MANTRA campaigns were conducted at Vanscoy, Saskatchewan, Canada (52° N, 107° W) in late August and early September of 1998, 2000, 2002 and 2004. During late summer at mid-latitudes, the stratosphere is close to photochemical control, providing an ideal scenario for the study reported here. From this analysis we find that: (1) reducing the value for the vertical diffusion coefficient in CMAM to a more physically reasonable value results in the model better reproducing the measured profiles of long-lived species; (2) the existence of compact correlations among the constituents, as expected from independent measurements in the literature and from models, confirms the self-consistency of the MANTRA measurements; and (3) the 1998 measurements show structures in the chemical species profiles that can be associated with transport, adding to the growing evidence that the summertime stratosphere can be much more disturbed than anticipated. The mechanisms responsible for such disturbances need to be understood in order to assess the representativeness of the measurements and to isolate long-term trends.

scholarly journals Long‐Term Variability and Tendencies in Middle Atmosphere Temperature and Zonal Wind From WACCM6 Simulations During 1850–2014

2020 ◽  
Vol 125 (24) ◽  
Author(s):  
K. Ramesh ◽  
Anne K. Smith ◽  
Rolando R. Garcia ◽  
Daniel R. Marsh ◽  
S. Sridharan ◽  
...  
Keyword(s):  
Zonal Wind ◽  
Middle Atmosphere ◽  
Atmosphere Temperature

scholarly journals Meteor heights during the recent solar minimum

2014 ◽  
Vol 12 ◽  
pp. 161-165 ◽  
Author(s):  
Ch. Jacobi
Keyword(s):  
Solar Cycle ◽  
Solar Minimum ◽  
Middle Atmosphere ◽  
Low Frequency ◽  
Late Summer ◽  
Vhf Radar ◽  
Linear Temperature ◽  
Reflection Height ◽  
Atmosphere Temperature

Abstract. Average meteor heights have been continuously observed using a SKiYMET VHF radar at Collm (51.3° N, 13.0° E) since late summer of 2004. Initially, the daily mean meteor height was about 89.4 km. Since that time, average meteor heights have decreased. This is consistent with earlier results on middle atmosphere temperature change from the literature and from earlier results of low-frequency reflection height changes measured at Kühlungsborn and Collm. During the recent solar minimum 2008/2009 the meteor heights further decreased. Linear fitting of a trend and a solar cycle to the heights reveals a linear decrease of about −56 m year−1 and a solar cycle effect of +450 m per 100 sfu. Assuming that meteor heights, on a long-term average, approximately refer to a level of constant pressure, this decrease can be converted to a mean middle atmosphere linear temperature decrease of −0.23 K year−1 and a solar cycle effect of +1.8 K per 100 sfu during the last decade, which is in the range of observed trends reported in the literature.

scholarly journals Long-term Measurements of Nighttime LF Radio Wave Reflection Heights over Central Europe

2005 ◽  
Vol 3 ◽  
pp. 427-430
Author(s):  
C. Jacobi ◽  
D. Kürschner
Keyword(s):  
Middle Atmosphere ◽  
Low Frequency ◽  
Radio Waves ◽  
Quasi Biennial Oscillation ◽  
Reflection Height ◽  
Stratospheric Wind ◽  
E Region ◽  
Long Term Trends ◽  
Cooling Trend

Abstract. The nighttime ionospheric absolute reflection height of low-frequency (LF) radio waves at oblique incidence has been measured continuously since late 1982 using 1.8kHz sideband phase comparisons between the sky wave and the ground wave of a commercial 177kHz LF transmitter. The dataset allows the analysis of long-term trends and other regular variations of the reflection height. Beside the clear signal of the 11-year solar cycle a quasi-biennial oscillation is visible in LF reflection heights, which is correlated to the equatorial stratospheric wind field. A long-term decreasing reflection height trend is found, confirming results from other measurements and theoretical estimations. The results can be interpreted as a long-term decrease of the height levels of fixed electron density in the lower E region, reflecting a long-term cooling trend of the middle atmosphere.

scholarly journals Response of the Middle Atmosphere to Solar Variability — Model Simulations

1994 ◽  
Vol 143 ◽  
pp. 315-329
Author(s):  
Theresa Y. W. Huang ◽  
Guy P. Brasseur
Keyword(s):  
Solar Cycle ◽  
Middle Atmosphere ◽  
Temperature Response ◽  
Solar Variability ◽  
Solar Cycles ◽  
Heating Rates ◽  
Model Simulations ◽  
Recent Developments ◽  
Indirect Feedback

Solar flux variations could affect the middle atmosphere through modulating the photolysis of chemical series and solar heating rates. Indirect feedback effects from chemical, radiative, and dynamical interactions could provide additional sources for perturbations in the middle atmosphere. In this paper, recent developments in modeling the effect of solar variability on the middle atmosphere is described. For the 27-day solar rotational cycle, the temperature and ozone response in the stratosphere predicted by one- and two-dimensional models compares well with data analyses. For the 11-year solar cycle, model simulations suggest a non-negligible ozone/temperature response compared to changes produced by anthropogenic perturbations in the stratosphere. There is no sufficient long-term atmospheric dataset to establish a statistically significant correlation with the 11-year solar cycle. But in general, agreement between the observational analysis (for periods of one to two solar cycles) and model simulations of the long-term solar variability effect is unsatisfactory.

scholarly journals Climatology and Long-Term Trends in the Stratospheric Temperature and Wind Using ERA5

2021 ◽  
Vol 13 (23) ◽  
pp. 4923
Author(s):  
Michal Kozubek ◽  
Jan Laštovička ◽  
Radek Zajicek
Keyword(s):  
North Atlantic ◽  
Middle Atmosphere ◽  
Southern Oscillation ◽  
Quasi Biennial Oscillation ◽  
Stratospheric Temperature ◽  
Wind Climatology ◽  
Long Term Trends ◽  
The Impact ◽  
Biennial Oscillation

This study analyses long-term trends in temperature and wind climatology based on ERA5 data. We study climatology and trends separately for every decade from 1980 to 2020 and their changes during this period. This study is focused on the pressure levels between 100–1 hPa, which essentially covers the whole stratosphere. We also analyze the impact of the sudden stratospheric warmings (SSW), North Atlantic Oscillation (NAO), El Nino Southern Oscillation (ENSO) and Quasi-biennial oscillation (QBO). This helps us to find details of climatology and trend behavior in the stratosphere in connection to these phenomena. ERA5 is one of the newest reanalysis, which is widely used for the middle atmosphere. We identify the largest differences which occur between 1990–2000 and 2000–2010 in both temperature climatology and trends. We suggest that these differences could relate to the different occurrence frequency of SSWs in 1990–2000 versus 2000–2010.

Diurnal tide in the low-latitude troposphere and stratosphere: Long-term trends and role of the extended solar minimum

2014 ◽  
Vol 121 ◽  
pp. 168-176 ◽  
Author(s):  
M. Venkat Ratnam ◽  
N. Venkateswara Rao ◽  
C. Vedavathi ◽  
B.V. Krishna Murthy ◽  
S. Vijaya Bhaskara Rao
Keyword(s):  
Solar Minimum ◽  
Diurnal Tide ◽  
Low Latitude ◽  
Long Term Trends
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