Low‐latitude mesospheric mean winds observed by Gadanki mesosphere‐stratosphere‐troposphere (MST) radar and comparison with rocket, High Resolution Doppler Imager (HRDI), and MF radar measurements and HWM93

Kumar, G. Kishore; Ratnam, M. Venkat; Patra, Amit; Rao, V. Ramgopal; Rao, Sandhya; Kumar, Karanam Kishore; Gurubaran, S.; Ramkumar, Geetha; Rao, D. Narayana

doi:10.1029/2008jd009862

Cited by 21 publications

(29 citation statements)

References 43 publications

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“…6). That is in line with the study by Kishore Kumar et al (2008), where they reported the mean meridional wind in the low latitude mesosphere to be up to 40 m s −1 . Unfortunately, we have no information about zonal wind (which is in general larger than the meridional one and can reach 70 m s −1 according to Fig.…”

Section: Spectral Width Correction For Beam Broadeningsupporting

confidence: 78%

Spectral characteristics and scatter cross-section of low latitude mesospheric echoes measured by the Indian MST radar at Gadanki

et al. 2012

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Abstract. In November 2008 and in March and April 2009the Indian MST radar (53 MHz) at Gadanki was operated during the daytime in a special experiment, with 600 m altitude resolution, for understanding the characteristics of lowlatitude mesospheric echoes (LLME). The data of three days when the echoes were strongest have been analysed in terms of spectral widths and radar volume reflectivities. Spectral widths of LLME show some decrease with altitude, with median values of 4-6 m s −1 at 69-72 km and of 2-4 m s −1 at 73-78 km. This corresponds to 20-200 mW kg −1 turbulent energy dissipation rates. It has been shown that stronger echoes have broader spectra consistent with a turbulent scattering mechanism. For the first time, the volume reflectivities for the strong LLME for Gadanki have also been calculated. They are in the range of 10 −17 -10 −15 m −1 , so LLME at Gadanki are somewhat stronger than those reported so far from Jicamarca, Peru (Lehmacher et al., 2009).

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Section: Spectral Width Correction For Beam Broadeningsupporting

confidence: 78%

Spectral characteristics and scatter cross-section of low latitude mesospheric echoes measured by the Indian MST radar at Gadanki

et al. 2012

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“…The horizontal wind velocity is calculated from the time derivative of horizontal displacement of the chaff tracked by radar (Kishore Kumar et al, 2008). Launches were made every Wednesday, that is, on International Geophysical Day using rocketsondes with chaff payloads.…”

Section: M-100 Rocketsondementioning

confidence: 99%

“…Temperature retrieved from the atmospheric 2.80-μm CO 2 emission is used in the present study. HRDI is another instrument onboard UARS which measures horizontal wind field in the stratosphere (10-40 km) and the mesosphere and lower thermosphere (50-115 km) by making use of Doppler shift of molecular oxygen rotational lines with an accuracy of approximately 5 m/s (Kishore Kumar et al, 2008). For obtaining reasonable number of observations, we considered a grid size of 10°× 20°(lat × lon) with Thumba (8.…”

Section: Haloe and Hrdi Onboard Uarsmentioning

confidence: 99%

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

2019

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In recent years, the middle atmosphere has evoked great scientific interest as long‐term changes can be clearly captured owing to the large perturbation amplitudes at these altitudes. In the present study, more than 25 years of the data are used to investigate the long‐term trends in the middle atmosphere by suitably combining the observations from different techniques (Rocketsonde, High‐Resolution Doppler Imager (HRDI)/Upper Atmosphere Research Satellite (UARS), Halogen Occultation Experiment (HALOE)/UARS, Sounding of the Atmosphere using Broadband Emission Radiometry (SABER)/Thermosphere Ionosphere Mesosphere Energetic Dynamics (TIMED), and Mesosphere‐stratosphere‐troposphere (MST) radar) from Indian region. As different instruments/techniques are used and the time periods are not the same, extreme care has been taken while merging various data sets to obtain meaningful long‐term trends. To understand the observed long‐term trends, Whole Atmosphere Community Climate Model–eXtended model simulations for the Indian low‐latitude regions are also used. A significant cooling trend of ~−1.7 ± 0.5 K/decade between 30 and 80 km is noticed. Large decreasing trend (~5 m/s/decade) in the eastward winds is noticed which is significant between 70 and 80 km only changing from strong eastward wind in 1970s to weak westward wind in recent decade. No significant trends are observed in the meridional wind. These observations are well captured by the Whole Atmosphere Community Climate Model–eXtended model simulations while considering changes in concentrations of greenhouse gases including carbon dioxide (CO2), methane (CH4), water vapor (H2O), and chlorofluorocarbon species that cause depletion of stratospheric ozone (O3). Thus, it is prudent to conclude that long‐term decreasing trends in the zonal winds and cooling trends in the temperature in the middle atmosphere are caused to a large extent by greenhouse gases suggesting the role of anthropogenic changes in the dynamics of the middle atmosphere.

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“…Winds are also very important in understanding circulation patterns, oscillations in the middle atmosphere and in redistributing chemical constituents. 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).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2011

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Abstract. The All-Sky interferometric meteor (SKYiMET) radar (MR) derived winds in the vicinity of the equatorial electrojet (EEJ) are discussed. As Thumba (8.5 • N, 77 • E; dip lat. 0.5 • N) is under the EEJ belt, there has been some debate on the reliability of the meteor radar derived winds near the EEJ height region. In this regard, the composite diurnal variations of zonal wind profiles in the mesosphere-lower thermosphere (MLT) region derived from TIMED Doppler Interferometer (TIDI) and ground based meteor radar at Thumba are compared. In this study, emphasis is given to verify the meteor radar observations at 98 km height region, especially during the EEJ peaking time (11:00 to 14:00 LT). The composite diurnal cycles of zonal winds over Thumba are constructed during four seasons of the year 2006 using TIDI and meteor radar observations, which showed good agreement especially during the peak EEJ hours, thus assuring the reliability of meteor radar measurements of neutral winds close to the EEJ height region. It is evident from the present study that on seasonal scales, the radar measurements are not biased by the EEJ. The day-time variations of HF radar measured E-region drifts at the EEJ region are also compared with MR measurements to show there are large differences between ionospheric drifts and MR measurements. The significance of the present study lies in validating the meteor radar technique over Thumba located at magnetic equator by comparing with other than the radio technique for the first time.

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Low‐latitude mesospheric mean winds observed by Gadanki mesosphere‐stratosphere‐troposphere (MST) radar and comparison with rocket, High Resolution Doppler Imager (HRDI), and MF radar measurements and HWM93

Cited by 21 publications

References 43 publications

Spectral characteristics and scatter cross-section of low latitude mesospheric echoes measured by the Indian MST radar at Gadanki

Spectral characteristics and scatter cross-section of low latitude mesospheric echoes measured by the Indian MST radar at Gadanki

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

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

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