Scattering cross section of mesospheric echoes and turbulence parameters from Gadanki radar observations

Selvaraj, Daisy Flora; Patra, Amit; Chandra, H.; Sinha, H. S. S.; Das, Uma

doi:10.1016/j.jastp.2014.08.004

Cited by 8 publications

(12 citation statements)

References 32 publications

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“…We have followed the Gaussian curve fitting method used earlier by Selvaraj et al . [] for analyzing the mesospheric observations from Gadanki. The curve fitting method has been adopted mainly for estimating variances (second moment, σ 2 ) of the observed Doppler spectra, which have been used for computing the turbulence parameters.…”

Section: Observations and Data Analysiscontrasting

confidence: 62%

“…Individual values of ε , K , l o , and L B (figure not shown) are found to be in the range of 0.4–183 mW kg −1 , 0.7–309 m 2 s −1 , 2–44 m, and 77–1645 m, respectively, which are very similar to those reported earlier by Selvaraj et al . []. We have also noted that the height profiles of inner scale and outer scale of turbulence estimated in the present analysis are similar to those reported earlier by Selvaraj et al .…”

Section: Observational Resultsmentioning

confidence: 99%

“…We have also noted that the height profiles of inner scale and outer scale of turbulence estimated in the present analysis are similar to those reported earlier by Selvaraj et al . [] and followed the height variations modeled by Hocking [].…”

Section: Observational Resultsmentioning

confidence: 99%

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On the seasonal variations of reflectivity and turbulence characteristics of low‐latitude mesospheric echoes over Gadanki

2016

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Gadanki radar observations of the low‐latitude mesospheric echoes studied earlier have shown that while both occurrence rate and signal‐to‐noise ratio of the mesospheric echoes peak in the equinoxes turbulent kinetic energy (TKE) dissipation rate and eddy diffusivity, estimated using spectral width of these echoes, peak in the summer. This seasonal difference is apparently inconsistent with the understanding that the mesospheric echoes are generated by turbulence. In this paper, we analyze Gadanki radar observations of mesospheric echoes made during 2011 and 2012 and study seasonal variations in reflectivity and TKE dissipation rate in an attempt to address the aforementioned puzzle. We show that both reflectivity and TKE dissipation rate in the mesosphere show semiannual variations peaking in the equinoxes, which are vastly different from those reported earlier. We also show that seasonal variations in reflectivity and TKE dissipation rate have a close correspondence with gravity wave activity. These results are found to be consistent with the gravity wave breaking hypothesis generating turbulence and radar echoes in the low‐latitude mesosphere.

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Section: Observations and Data Analysiscontrasting

confidence: 62%

Section: Observational Resultsmentioning

confidence: 99%

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On the seasonal variations of reflectivity and turbulence characteristics of low‐latitude mesospheric echoes over Gadanki

2016

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“…The layered properties of mesospheric echoing phenomenon while remains to be fully understood, they would provide important information in studying mesospheric dynamics in terms of winds, gravity waves, and turbulence. Preliminary examination of these observations and comparison with those reported earlier (Kumar et al, ; Selvaraj et al, ) suggest that the fine structures, which could not be discernible before, are discernible due to enhanced sensitivity of the AIR (~20 dB).…”

Section: Sample Observationssupporting

confidence: 55%

The Advanced Indian MST Radar (AIR): System Description and Sample Observations

et al. 2020

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An upgraded version of the Indian MST radar, called Advanced Indian Mesosphere-Stratosphere-Troposphere (MST) radar (AIR), has recently been commissioned. The prime objective of constructing the AIR is to make it a more useful instrument for conducting new experiments, which enable us to broaden our knowledge on the dynamical and electrodynamical processes including coupling from the boundary layer to the ionosphere. The AIR works at 53 MHz, and the system has been rebuilt, keeping the original square antenna array consisting of 1,024 Yagi antennae. The AIR is a high-power, fully active phased array system with dedicated 1-kW solid-state transmit-receive units, providing a total peak power of 1,024 kW, and control systems that allow steering the beam with 360°azimuth and 24°zenith agility. Also, the antenna system has been configured with modularity and scalability, which facilitates selection of antenna subarray and aperture for carrying out multireceiver experiments. The antenna radiation pattern tests reveal that the beam width and first side lobe level are close to the designed values of 2.2°and −13.2 dB, respectively. Currently, the system is equipped with 18 receivers to carry out spaced receiver experiments. The transmitters have been designed to transmit very short and long pulses for studying boundary layer to ionosphere. This paper presents the system description of the AIR and sample observations made using the system in Doppler beam swinging mode demonstrating its capabilities for studying neutral atmosphere and ionosphere.

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“…The improved sensitivity of MAARSY of about 17 dB compared to ALWIN leads to a minimum detection limit for PMWE volume reflectivity of about The detection of much weaker PMWE using MAARSY compared to previous results obtained at this location is comparable with observations of lower mesospheric echoes obtained at Jicamarca, Peru, and Gadanki, India. Lehmacher et al [2009] reported the detection of radar cross sections of mesospheric layers in the range from 10 −18 m −1 to 10 −16 m −1 using the Jicamarca incoherent scatter radar, obviously as a result of the detectability advantage of the large Jicamarca radar, that is, by the order of 10 Selvaraj et al [2014] found the radar scattering cross sections obtained at Gadanki to be as low as 3.1 ⋅ 10 −18 m −1 and as high as 10…”

Section: Observations Of Polar Mesosphere Winter Echoes At Andøya Fromentioning

confidence: 99%

Extended observations of polar mesosphere winter echoes over Andøya (69°N) using MAARSY

Latteck

Strelnikova

2015

JGR Atmospheres

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The results obtained by MAARSY show that the PMWE season starts clearly at the beginning of September with a mean seasonal occurrence rate of about 16%, but a strong seasonal variability with maxima up to 70% in the seasonal variation of the individual years. The end of the winter season is hard to determine since mesospheric echoes have also been observed below altitudes of 80km during nonwinter months, particularly around the end of May, i.e., the beginning of the polar mesospheric summer echo season, indicating that the physical mechanism for creating the lower mesospheric echoes is present during the early summer months as well.

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Scattering cross section of mesospheric echoes and turbulence parameters from Gadanki radar observations

Cited by 8 publications

References 32 publications

On the seasonal variations of reflectivity and turbulence characteristics of low‐latitude mesospheric echoes over Gadanki

On the seasonal variations of reflectivity and turbulence characteristics of low‐latitude mesospheric echoes over Gadanki

The Advanced Indian MST Radar (AIR): System Description and Sample Observations

Extended observations of polar mesosphere winter echoes over Andøya (69°N) using MAARSY

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