scholarly journals Nocturnal thermal structure of the mesosphere and lower thermosphere region at Maui, Hawaii (20.7°N), and Starfire Optical Range, New Mexico (35°N)

2005 ◽  
Vol 110 (D9) ◽  
Author(s):  
Xinzhao Chu
Keyword(s):  
New Mexico ◽  
Thermal Structure ◽  
Lower Thermosphere ◽  
Optical Range ◽  
Mesosphere And Lower Thermosphere

scholarly journals Cooling of the mesosphere and lower thermosphere due to doubling of CO2

1998 ◽  
Vol 16 (11) ◽  
pp. 1501-1512 ◽  
Author(s):  
R. A. Akmaev ◽  
V. I. Fomichev
Keyword(s):  
Middle Atmosphere ◽  
Thermal Structure ◽  
Lower Thermosphere ◽  
Thermal Response ◽  
Co2 Concentration ◽  
Lower Atmosphere ◽  
Heating Rates ◽  
Density Reduction ◽  
Mesosphere And Lower Thermosphere ◽  
Thermospheric Dynamics

Abstract. A new parameterization of infrared radiative transfer in the 15-μm CO2 band has been incorporated into the Spectral mesosphere/lower thermosphere model (SMLTM). The parameterization is applicable to calculations of heating rates above approximately 15 km for arbitrary vertical profiles of the CO2 concentration corresponding to the surface mixing ratio in the range 150–720 ppm. The sensitivity of the mesosphere and lower thermosphere (MLT) to doubling of CO2 has been studied. The thermal response in the MLT is mostly negative (cooling) and much stronger than in the lower atmosphere. An average cooling at the stratopause is about 14 K. It gradually decreases to approximately 8 K in the upper mesosphere and again increases to about 40–50 K in the thermosphere. The cooling and associated thermal shrinking result in a substantial density reduction in the MLT that reaches 40–45% in the thermosphere. Various radiative, chemical, and dynamical feedbacks potentially important for the thermal response in the MLT are discussed. It is noted that the results of simulations are strikingly similar to observations of long-term trends in the MLT. This suggests that during the last 3–4 decades the thermal structure in the real upper atmosphere has undergone substantial changes driven by forcing comparable with that due to doubling of CO2.Key words. Meteorology and atmospheric dynamics (Climatology · Middle atmosphere dynamics · Thermospheric dynamics)

scholarly journals Overturning instability in the mesosphere and lower thermosphere: analysis of instability conditions in lidar data

2009 ◽  
Vol 27 (7) ◽  
pp. 2937-2945 ◽  
Author(s):  
L. Hurd ◽  
M. F. Larsen ◽  
A. Z. Liu
Keyword(s):  
New Mexico ◽  
Inflection Point ◽  
Lower Thermosphere ◽  
Static Stability ◽  
Lidar Data ◽  
University Of Illinois ◽  
Lidar Measurements ◽  
Mesosphere And Lower Thermosphere ◽  
The University ◽  
Vertical Scales

Abstract. Resonant sodium lidar measurements from the transition region between the mesosphere and lower thermosphere have revealed frequently-occurring overturning events characterized by vertical scales of ~3–6 km and timescales of several hours. Larsen et al. (2004) proposed that a convective roll instability, similar to that found in the planetary boundary layer, is the likely mechanism responsible for the events. This type of instability requires an inflection point in the background winds near the center of the vortex roll with a low static stability region capped by an inversion. The earlier paper argued that the conditions required to support the instability are common in the altitude range where the features are found. In this paper, we use data from the University of Illinois sodium lidar that was located at the Starfire Optical Range near Albuquerque, New Mexico, and from the Maui/MALT Lidar Facility in Hawaii and present several cases that are used to examine the behavior of the inflection point in detail as a function of time during the evolution of the overturning event. In addition, we examine the background static stability conditions using the temperature data from the lidar.

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.

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

The wind regime of the mesosphere and lower thermosphere during the DYANA campaign—II. Semi-diurnal tide

1994 ◽  
Vol 56 (13-14) ◽  
pp. 1731-1752 ◽  
Author(s):  
Yu.I. Portnyagin ◽  
N.A. Makarov ◽  
R.P. Chebotarev ◽  
A.M. Nikonov ◽  
E.S. Kazimirovsky ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Diurnal Tide ◽  
Wind Regime ◽  
Mesosphere And Lower Thermosphere

The coupling of planetary waves, tides and gravity waves in the mesosphere and lower thermosphere

1999 ◽  
Vol 24 (11) ◽  
pp. 1571-1576 ◽  
Author(s):  
P.J.S. Williams ◽  
N.J. Mitchell ◽  
A.G. Beard ◽  
V.St.C. Howells ◽  
H.G. Muller
Keyword(s):  
Gravity Waves ◽  
Lower Thermosphere ◽  
Planetary Waves ◽  
Mesosphere And Lower Thermosphere
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