scholarly journals Diurnal nonmigrating tides in the tropical lower thermosphere

2003 ◽  
Vol 55 (7) ◽  
pp. 419-426 ◽  
Author(s):  
Jeffrey M. Forbes ◽  
Maura E. Hagan ◽  
Saburo Miyahara ◽  
Yasunobu Miyoshi ◽  
Xiaoli Zhang
Keyword(s):  
Lower Thermosphere ◽  
Nonmigrating Tides

scholarly journals First results from the CAWSES-India Tidal Campaign

2008 ◽  
Vol 26 (8) ◽  
pp. 2323-2331 ◽  
Author(s):  
S. Gurubaran ◽  
D. Narayana Rao ◽  
G. Ramkumar ◽  
T. K. Ramkumar ◽  
G. Dutta ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Weather Data ◽  
Atmospheric Tides ◽  
Data Sets ◽  
Low Latitude ◽  
First Results ◽  
Mesosphere And Lower Thermosphere ◽  
Nonmigrating Tides ◽  
The Western Pacific ◽  
Mlt Region

Abstract. The first CAWSES-India Tidal Campaign was conducted by the Indian scientific community during March–April 2006. The objectives of this campaign were: (1) To determine the characteristics of tides in the troposphere and lower stratosphere (0–20 km) and mesosphere and lower thermosphere (MLT) region (80–100 km), (2) to explore and identify what lower atmospheric processes drive middle atmospheric tides in the Indian continental region and (3) to provide information on those short-term variabilities of MLT tides that are likely to have an impact on the ionospheric variabilities and contribute to the upper atmospheric weather. Data sets from experiments conducted at the three low latitude radar sites, namely, Trivandrum (8.5° N, 76.9° E), Tirunelveli (8.7° N, 77.8° E) and Gadanki (13.5° N, 79.2° E) and fortnightly rocket launches from Thumba were made use of in this study. An important observational finding reported in this work is that the radar observations at Tirunelveli/Trivandrum indicate the presence of 15–20 day modulation of diurnal tide activity at MLT heights during the February–March period. A similar variation in the OLR fields in the western Pacific (120–160° longitude region) suggests a possible link between the observed tidal variabilities and the variations in the deep tropical convection through the nonmigrating tides it generates.

scholarly journals Identification of the mechanisms responsible for anomalies in the tropical lower thermosphere/ionosphere caused by the January 2009 sudden stratospheric warming

2019 ◽  
Vol 9 ◽  
pp. A39 ◽  
Author(s):  
Maxim V. Klimenko ◽  
Vladimir V. Klimenko ◽  
Fedor S. Bessarab ◽  
Timofei V. Sukhodolov ◽  
Pavel A. Vasilev ◽  
...  
Keyword(s):  
Electric Field ◽  
Phase Change ◽  
Lower Thermosphere ◽  
Upper Atmosphere ◽  
Electron Content ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Low Latitude ◽  
Plasma Drift ◽  
Solar Tide

We apply the Entire Atmosphere GLobal (EAGLE) model to investigate the upper atmosphere response to the January 2009 sudden stratospheric warming (SSW) event. The model successfully reproduces neutral temperature and total electron content (TEC) observations. Using both model and observational data, we identify a cooling in the tropical lower thermosphere caused by the SSW. This cooling affects the zonal electric field close to the equator, leading to an enhanced vertical plasma drift. We demonstrate that along with a SSW-related wind disturbance, which is the main source to form a dynamo electric field in the ionosphere, perturbations of the ionospheric conductivity also make a significant contribution to the formation of the electric field response to SSW. The post-sunset TEC enhancement and pre-sunrise electron content reduction are revealed as a response to the 2009 SSW. We show that at post-sunset hours the SSW affects low-latitude TEC via a disturbance of the meridional electric field. We also show that the phase change of the semidiurnal migrating solar tide (SW2) in the neutral wind caused by the 2009 SSW at the altitude of the dynamo electric field generation has a crucial importance for the SW2 phase change in the zonal electric field. Such changes lead to the appearance of anomalous diurnal variability of the equatorial electromagnetic plasma drift and subsequent low-latitudinal TEC disturbances in agreement with available observations. Plain Language Summary – Entire Atmosphere GLobal model (EAGLE) interactively calculates the troposphere, stratosphere, mesosphere, thermosphere, and plasmasphere–ionosphere system states and their response to various natural and anthropogenic forcing. In this paper, we study the upper atmosphere response to the major sudden stratospheric warming that occurred in January 2009. Our results agree well with the observed evolution of the neutral temperature in the upper atmosphere and with low-latitude ionospheric disturbances over America. For the first time, we identify an SSW-related cooling in the tropical lower thermosphere that, in turn, could provide additional information for understanding the mechanisms for the generation of electric field disturbances observed at low latitudes. We show that the SSW-related vertical electromagnetic drift due to electric field disturbances is a key mechanism for interpretation of an observed anomalous diurnal development of the equatorial ionization anomaly during the 2009 SSW event. We demonstrate that the link between thermospheric winds and the ionospheric dynamo electric field during the SSW is attained through the modulation of the semidiurnal migrating solar tide.

scholarly journals Large-Scale Waves in the Mesosphere and Lower Thermosphere Observed by SABER

2005 ◽  
Vol 62 (12) ◽  
pp. 4384-4399 ◽  
Author(s):  
Rolando R. Garcia ◽  
Ruth Lieberman ◽  
James M. Russell ◽  
Martin G. Mlynczak
Keyword(s):  
Large Scale ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Normal Modes ◽  
Zonal Winds ◽  
Broadband Emission ◽  
Summer Hemisphere ◽  
Mean Structure ◽  
Mesosphere And Lower Thermosphere ◽  
The Tropics

Abstract Observations made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board NASA’s Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics (TIMED) satellite have been processed using Salby’s fast Fourier synoptic mapping (FFSM) algorithm. The mapped data provide a first synoptic look at the mean structure and traveling waves of the mesosphere and lower thermosphere (MLT) since the launch of the TIMED satellite in December 2001. The results show the presence of various wave modes in the MLT, which reach largest amplitude above the mesopause and include Kelvin and Rossby–gravity waves, eastward-propagating diurnal oscillations (“non-sun-synchronous tides”), and a set of quasi-normal modes associated with the so-called 2-day wave. The latter exhibits marked seasonal variability, attaining large amplitudes during the solstices and all but disappearing at the equinoxes. SABER data also show a strong quasi-stationary Rossby wave signal throughout the middle atmosphere of the winter hemisphere; the signal extends into the Tropics and even into the summer hemisphere in the MLT, suggesting ducting by westerly background zonal winds. At certain times of the year, the 5-day Rossby normal mode and the 4-day wave associated with instability of the polar night jet are also prominent in SABER data.

Horizontal extension of acoustic resonance between the ground and the lower thermosphere

2012 ◽  
Vol 75-76 ◽  
pp. 127-132 ◽  
Author(s):  
Mitsuru Matsumura ◽  
Hiroyuki Shinagawa ◽  
Toshihiko Iyemori
Keyword(s):  
Lower Thermosphere ◽  
Acoustic Resonance

Modeling of nonmigrating tides in the middle atmosphere

2011 ◽  
Vol 51 (1) ◽  
pp. 105-115 ◽  
Author(s):  
E. V. Suvorova ◽  
A. I. Pogoreltsev
Keyword(s):  
Middle Atmosphere ◽  
Nonmigrating Tides

scholarly journals Some results of comparison between the lower thermosphere zonal winds as seen by the ground-based radars and WINDII on UARS

1999 ◽  
Vol 51 (7-8) ◽  
pp. 701-709 ◽  
Author(s):  
Yu. I. Portnyagin ◽  
T. V. Solovjova ◽  
D. Y. Wang
Keyword(s):  
Lower Thermosphere ◽  
Zonal Winds

Climatological modeling of horizontal winds in the mesosphere and lower thermosphere over a mid-latitude station in China

2015 ◽  
Vol 56 (7) ◽  
pp. 1354-1365 ◽  
Author(s):  
Xin Yao ◽  
Tao Yu ◽  
Biqiang Zhao ◽  
You Yu ◽  
Libo Liu ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Latitude Station ◽  
Mesosphere And Lower Thermosphere
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