Complementary criteria for identifying regions of intense atmospheric turbulence using lower VHF radar

Hooper, David A; Thomas, L.

doi:10.1016/s1364-6826(97)00054-0

Cited by 28 publications

(25 citation statements)

References 46 publications

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“…These observations have shown that there could be significant contribution from the enhancement in N 2 (Hooper and Thomas, 1998). Luce et al (2001) have discussed contribution of temperature sheets to the aspect sensitive radar echoes.…”

Section: Introductionmentioning

confidence: 90%

“…There are only a few studies related to aspect sensitivity from tropical latitudes (Röttger et al, 1981;Worthington et al, 1999;Damle et al, 1994;Jain et al, 1997). Recently, there have been considerable efforts to understand radar backscatter and the aspect sensitivity of the radar echoes in terms of background atmospheric parameters (Tsuda et al, 1997a,b;Jain et al, 1997;Hooper and Thomas, 1998;Palmer et al, 1998;Worthington et al, 1999;Hobbs and Reid, 2000;Jain et al, , 2003.…”

Section: Introductionmentioning

confidence: 99%

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Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sonde

et al. 2004

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Abstract. Simultaneous observations made on four days using the MST radar and GPS-sonde at Gadanki (13.5 • N, 79.2 • E), a tropical station in India, are presented to address the aspect sensitivity of radar backscatters observed at different heights. The observations show that wherever stability parameter N 2 is high, vertical shear of horizontal wind is low and Richardson number (R i ) is high, the aspect sensitivity is high indicating that the aspect sensitive radar backscatters are due to thermal structures in the atmosphere. Such a case can be seen very clearly in the upper troposphere and lower stratosphere. At some heights, where N 2 is high, R i is high, but shears are relatively weak, the aspect sensitivity is found to almost disappear, indicating that some amount of shear provides favorable conditions for causing aspect sensitivity. Aspect sensitivity does not occur at all where N 2 is low or negative and R i is low in spite of wind shear being either high or low, indicating that the regions are well mixed and hence turbulent. The study also shows a power difference in the symmetric beams. A case study on this aspect suggests that this asymmetry is due to the tilting of layers by the action of atmospheric waves. There is indication that these waves are generated through Kelvin-Helmholtz-instability (KHI).

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sonde

et al. 2004

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“…This has led to an alternative form of the expression of the radar return signal power (for example . This assumption quoted by Hooper and Thomas (1998) where L 0 may depend on N 2 resulting in η proportional to N 4 has given correct results concerning humidity retrieval (Tsuda et al, 2001;Klaus et al, 2006). 3810 V. Klaus: Temperature retrieval with VHF radar Fig.…”

Section: Practical Implementationmentioning

confidence: 79%

“…However, a number of radiosonde comparisons made at different times and locations has confirmed the proportionality of M 2 with the radar reflectivity η (Röttger, 1979;Tsuda et al, 1988;Hocking and Mu, 1997;Hooper and Thomas, 1998;Low et al, 1998). Local tests at CNRM/Toulouse have confirmed these results showing that the best temperature results were obtained with L 0 considered as constant, but taking a different value from the troposphere to the stratosphere.…”

Section: Practical Implementationmentioning

confidence: 95%

Temperature retrieval with VHF radar using combined techniques

Klaus¹

2008

Ann. Geophys.

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Abstract. The purpose of this study is to evaluate the practical contribution of a VHF radar to high time resolution automatic temperature profiling both for research and operational applications in the frame of an integrated system of ground-based remote-sensing instruments. Based on the most prominent results already mentioned about this instrumentation, different techniques, related to the temperature data retrieval, are experimentally tested and documented using the INSU/Meteo 45 MHz wind profiler operating at CNRM/Toulouse or during cooperative campaigns. In parallel to the self-sufficient Radio Acoustic Sounding System (RASS), other approaches, using the Brunt-Vaisala frequency measurements, allow an extension of height coverage up to the higher troposphere and the tropopause. As only temperature gradients can be measured by this way, complementary data from other instruments are desirable. This makes it particularly fitted to an integrated remote-sensing system operating from the ground combining wind profilers with GPS, radiometers, lidar ceilometers and sodars.

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“…At oblique angles, with beam zenith angle (χ) greater than or equal to 10 • (i.e. χ ≥ 10 • ), it is generally presumed that echos arise mainly due to radio refractivity structures associated with turbulence (Hooper and Thomas, 1998). The received radar echo intensity is therefore aspect sensitive and this particular feature is utilised to determine the horizontal correlation length and the characteristics of the radar backscatterers giving rise to observed echo (Hooper and Thomas, 1995;Jain et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

VHF radar observation of atmospheric winds, associated shears and C2n at a tropical location: interdependence and seasonal pattern

Ghosh

Kumar

et al. 2001

Ann. Geophys.

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Abstract. The turbulence refractivity structure constant (C 2 n ) is an important parameter of the atmosphere. VHF radars have been used extensively for the measurements of C 2 n . Presently, most of such observations are from mid and high latitudes and only very limited observations are available for equatorial and tropical latitudes. Indian MST radar is an excellent tool for making high-resolution measurements of atmospheric winds, associated shears and turbulence refractivity structure constant (C 2 n ). This radar is located at Gadanki (13.45 • N, 79.18 • E), a tropical station in India. The objective of this paper is to bring out the height structure of C 2 n for different seasons using the long series of data (September 1995 -August 1999) from Indian MST radar. An attempt is also made to understand such changes in the height structure of C 2 n in relation to background atmospheric parameters such as horizontal winds and associated shears. The height structure of C 2 n , during the summer monsoon and post-monsoon season, shows specific height features that are found to be related to Tropical Easterly Jet (TEJ) winds.It is important to examine the nature of the radar back scatterers and also to understand the causative mechanism of such scatterers. Aspect sensitivity of the received radar echo is examined for this purpose. It is observed that radar back-scatterers at the upper tropospheric and lower stratospheric heights are more anisotropic, with horizontal correlation length of 10-20 m, as compared to those observed at lower and middle tropospheric heights.

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Complementary criteria for identifying regions of intense atmospheric turbulence using lower VHF radar

Cited by 28 publications

References 46 publications

Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sonde

Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sonde

Temperature retrieval with VHF radar using combined techniques

VHF radar observation of atmospheric winds, associated shears and <b>C<sup>2</sup></b><b><sub>n</sub></b> at a tropical location: interdependence and seasonal pattern

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Complementary criteria for identifying regions of intense atmospheric turbulence using lower VHF radar

Cited by 28 publications

References 46 publications

Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sonde

Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sonde

Temperature retrieval with VHF radar using combined techniques

VHF radar observation of atmospheric winds, associated shears and &lt;b&gt;C&lt;sup&gt;2&lt;/sup&gt;&lt;/b&gt;&lt;b&gt;&lt;sub&gt;n&lt;/sub&gt;&lt;/b&gt; at a tropical location: interdependence and seasonal pattern

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VHF radar observation of atmospheric winds, associated shears and <b>C<sup>2</sup></b><b><sub>n</sub></b> at a tropical location: interdependence and seasonal pattern