scholarly journals Cooperative wind observation in the upper mesosphere and lower thermosphere with foil chaff technique, the MU radar, and Yamagawa MF radar

1999 ◽  
Vol 51 (7-8) ◽  
pp. 719-729 ◽  
Author(s):  
Y. Murayama ◽  
K. Igarashi ◽  
I. Nishimuta ◽  
R. Yamazaki ◽  
K. -I. Oyama ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Wind Observation ◽  
Mu Radar ◽  
Mesosphere And Lower Thermosphere ◽  
Mf Radar

scholarly journals A comparison of 11-year mesospheric and lower thermospheric winds determined by meteor and MF radar at 69 ° N

2017 ◽  
Vol 35 (4) ◽  
pp. 893-906 ◽  
Author(s):  
Sven Wilhelm ◽  
Gunter Stober ◽  
Jorge L. Chau
Keyword(s):  
Lower Thermosphere ◽  
Meridional Wind ◽  
Correction Factors ◽  
Data Set ◽  
Wind Measurements ◽  
Mesosphere And Lower Thermosphere ◽  
Thermospheric Winds ◽  
Good Agreement ◽  
Mlt Region ◽  
Mf Radar

Abstract. The Andenes Meteor Radar (MR) and the Saura Medium Frequency (MF) Radar are located in northern Norway (69° N, 16° E) and operate continuously to provide wind measurements of the mesosphere and lower thermosphere (MLT) region. We compare the two systems to find potential biases between the radars and combine the data from both systems to enhance altitudinal coverage between 60 and 110 km. The systems have altitudinal overlap between 78 and 100 km at which we compare winds and tides on the basis of hourly winds with 2 km altitude bins. Our results indicate reasonable agreement for the zonal and meridional wind components between 78 and 92 km. An exception to this is the altitude range below 84 km during the summer, at which the correlation decreases. We also compare semidiurnal and diurnal tides according to their amplitudes and phases with good agreement below 90 km for the diurnal and below 96 km for the semidiurnal tides. Based on these findings we have taken the MR data as a reference. By comparing the MF and MR winds within the overlapping region, we have empirically estimated correction factors to be applied to the MF winds. Existing gaps in that data set will be filled with weighted MF data. This weighting is done due to underestimated wind values of the MF compared to the MR, and the resulting correction factors fit to a polynomial function of second degree within the overlapping area. We are therefore able to construct a consistent and homogenous wind from approximately 60 to 110 km.

scholarly journals MF radar observations of the diurnal tide over Syowa, Antarctica (69° S, 40° E)

2009 ◽  
Vol 27 (7) ◽  
pp. 2653-2659 ◽  
Author(s):  
Y. Tomikawa ◽  
M. Tsutsumi
Keyword(s):  
Lower Thermosphere ◽  
Radar Data ◽  
Diurnal Tide ◽  
Syowa Station ◽  
Meridional Winds ◽  
Realistic Representation ◽  
Height Dependence ◽  
Mesosphere And Lower Thermosphere ◽  
The Antarctic ◽  
Mf Radar

Abstract. Characteristics of the diurnal tide in the Antarctic mesosphere and lower thermosphere (MLT) are investigated using 10 years of medium frequency (MF) radar data from Syowa Station (69° S, 39.6° E). Seasonal variations and height dependence of the diurnal amplitude and phase of zonal and meridional winds are mostly consistent with previous studies using the other Antarctic station data. The meridional momentum flux due to the diurnal tide shows a seasonal variation clearly different between above and below 90 km, which has never been reported in the literature. Finally, a cause of some discrepancy in the characteristics of the diurnal tide between the observation and simulation (i.e., GSWM-02) is discussed. It implies that the realistic representation of gravity waves in the simulation is crucial for realistic modeling of the diurnal tide.

scholarly journals Diurnal variation of short-period (20–120 min) gravity waves in the equatorial Mesosphere and Lower Thermosphere and its relation to deep tropical convection

2011 ◽  
Vol 29 (4) ◽  
pp. 623-629 ◽  
Author(s):  
N. Venkateswara Rao ◽  
Y. Shibagaki ◽  
T. Tsuda
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Theoretical Calculations ◽  
Lower Thermosphere ◽  
Tropical Convection ◽  
Peak Activity ◽  
Medium Frequency ◽  
Short Period ◽  
Mesosphere And Lower Thermosphere ◽  
Mf Radar

Abstract. We study short period gravity waves (20–120 min) in the equatorial Mesosphere and Lower Thermosphere (MLT) using a Medium Frequency (MF) radar at Pameungpeuk (7.4° S, 107.4° E), Indonesia. In particular, we study local time and seasonal variation of the gravity wave variance and its relation to tropical convection. The gravity wave variance at 88 km enhances between 20:00 LT and 07:00 LT, with a peak at 02:00–03:00 LT. The enhancement is mainly observed during February–April and September–October and shows inter-annual variability. Convective activity over the same location persists from 16:00–21:00 LT with a peak activity ~18:00 LT and enhances between November–April. Time delay between the peak of convection and that of gravity wave activity ranges 1–15 h, which is consistent with theoretical calculations and previous reports based on reverse ray tracing analysis.

MF radar observations of 6.5-day wave in the equatorial mesosphere and lower thermosphere

2004 ◽  
Vol 66 (6-9) ◽  
pp. 507-515 ◽  
Author(s):  
P. Kishore ◽  
S.P. Namboothiri ◽  
K. Igarashi ◽  
S. Gurubaran ◽  
S. Sridharan ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Radar Observations ◽  
Mesosphere And Lower Thermosphere ◽  
Mf Radar

scholarly journals Climatological studies of the quasi 16-day oscillations in the mesosphere and lower thermosphere at Yamagawa (31.2° N, 130.6° E), Japan

2002 ◽  
Vol 20 (8) ◽  
pp. 1239-1246 ◽  
Author(s):  
S. P. Namboothiri ◽  
P. Kishore ◽  
K. Igarashi
Keyword(s):  
Lower Thermosphere ◽  
Maximum Amplitude ◽  
Wave Activity ◽  
Vertical Wavelength ◽  
Meteorology And Atmospheric Dynamics ◽  
Highly Sensitive ◽  
Height Dependence ◽  
Mesosphere And Lower Thermosphere ◽  
Thermospheric Dynamics ◽  
Mf Radar

Abstract. The 16-day wave climatology at Yamagawa (31.2° N, 130.6° E) is investigated by analyzing the mesosphere and lower thermosphere (MLT) wind data collected with the recently installed MF radar. We have utilized the continuous data gathered during the five-year period 1996–2000. The wave climatology clearly shows some seasonal variations. The period of late autumn-spring is marked with larger wave activity, with the strongest waves being observed in the winter months. The maximum amplitude observed at Yamagawa is about 20 m/s, which is comparatively larger than the amplitudes observed at mid-latitude stations. The height dependence of the 16-day wave suggests that the maximum amplitude is observed at altitudes below 80 km. The summer months are characterized with much weaker wave activity. The vertical wavelength appears to be larger in the winter months and shorter in the summer months. The present analysis again confirms that the 16-day wave is highly sensitive to the background mean winds. Eastward motion of the background winds is a more favourable condition for the 16-day wave penetration to the MLT heights. The wave features show some signs of interannual variability. Overall, the observed features of the 16-day wave at Yamagawa, which is located at the edge of the subtropical latitudes, show some correspondence with the results reported for mid-latitude stations.Key words. Meteorology and atmospheric dynamics (climatology; thermospheric dynamics)

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
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