Initial results from SKiYMET meteor radar at Thumba (8.5°N, 77°E): 1. Comparison of wind measurements with MF spaced antenna radar system

Abstract

[1] In the present communication, initial results from the allSKy interferometric METeor (SKiYMET) radar installed at Thumba (8.5°N, 77°E) are presented. The meteor radar system provides hourly zonal and meridional winds in the mesosphere lower thermosphere (MLT) region. The meteor radar measured zonal and meridional winds are compared with nearby MF radar at Tirunalveli (8.7°N, 77.8°E). The present study provided an opportunity to compare the winds measured by the two different techniques, namely, interferometry and spaced antenna drift methods. Simultaneous wind measurements for a total number of 273 days during September 2004 to May 2005 are compared. The comparison showed a very good agreement between these two techniques in the height region 82-90 km and poor agreement above this height region. In general, the zonal winds compare very well as compared to the meridional winds. The observed discrepancies in the wind comparison above 90 km are discussed in the light of existing limitations of both the radars. The detailed analysis revealed the consistency of the measured winds by both the techniques. However, the discrepancies are observed at higher altitudes and are attributed to the contamination of MF radar neutral wind measurements with Equatorial Electro Jet (EEJ) induced inospheric drifts rather than the limitations of the spaced antenna technique. The comparison of diurnal variation of zonal winds above 90 km measured by both the radars is in reasonably good agreement in the absence of EEJ (during local nighttime). It is also been noted that the difference in the zonal wind measurements by both the radars is directly related to the strength of EEJ, which is a noteworthy result from the present study.Citation: Kumar, K. K., G. Rankumar, and S. T. Shelbi (2007), Initial results from SKiYMET meteor radar at Thumba (8.5°N, 77°E): 1. Comparison of wind measurements with MF spaced antenna radar system, Radio Sci., 42, RS6008,

First observational study during a solar eclipse event on variations in the horizontal winds simultaneously in the troposphere-stratosphere-mesosphere-lower-thermosphere region over the equatorial station Thumba (8.5°N, 77°E)

“…The winds derived from the Thumba meteor radar are well comparable with MF radar (Kumar et al, 2007) and TIDI observations , and the meteor-radar-derived mesopause temperature is well comparable with SABER and dayglow photometer (Das et al, 2012). For the present study, we have used the wind measurements on the control and eclipse day.…”

“…For the present study, we have used the wind measurements on the control and eclipse day. A general description of the meteor wind radar can be found in Hocking et al (2001), and the Thumba meteor radar description and initial results can be found in Deepa et al (2006) and Kumar et al (2007). In the case of meteor radar, the radial velocity can be measured with an accuracy of 5% or better.…”

Meteor radar measurements of MLT winds near the equatorial electro jet region over Thumba (8.5° N, 77° E): comparison with TIDI observations

“…However, there is always a quantum of doubt about the meteor radar wind estimations over the magnetic equator and till now there were no comparison of these measurements other than with radio techniques. Kumar et al (2007b) compared the present meteor and MF radar wind measurements, which employ interferometry and spaced antenna drift techniques respectively. The MF radar is located at Tirunelveli (8.7 • N, 77.8 • E) which is also in the vicinity of the magnetic dip equator.…”

“…However, in recent years, there has been some debate on the reliability of the winds measured by the meteor radar at the 98 km height region (the maximum height where we obtain continuous data from the meteor radar at Thumba) as Thumba is located in the vicinity of the magnetic dip equator where there is a presence of the equatorial electrojet (EEJ), a strong zonally flowing current system which peaks around 105 km over the magnetic equator (Kumar et al, 2007b(Kumar et al, , 2009Dhanya and Gurubaran, 2009). The debate was started by Dhanya and Gurubaran (2009) and the important aspect of their query is the scattering of radio waves by the irregularities that grow on the meteor trail as a result of plasma instabilities induced by EEJ.…”

“…Therefore, long term wind observations have been made across the globe and studies have been carried out in this regard using various instruments (Manson et al, 1992;Middleton et al, 2002, Kishore Kumar et al, 2008. Wind measurements in the MLT region are primarily obtained from rocket soundings, radars like MF, MST and meteor wind radars (Vincent, 1984;Manson et al, 1991;Kumar et al, 2007b), and satellites (Huang et al, 2006).…”