Fresnel scatter revisited-comparison of 50 MHz radar and radiosondes in the Arctic, the Tropics and Antarctica
High-resolution radiosondes and calibrated radars operating close to 50 MHz, are used to examine the relationship between the strength of radar scatter and refractive index gradient. Three radars are used, in Kiruna in Arctic Sweden, at Gadanki in southern India and at the Swedish/Finnish base Wasa/...
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ftindianacasci:oai:repository.ias.ac.in:69414 2023-05-15T13:46:14+02:00 Fresnel scatter revisited-comparison of 50 MHz radar and radiosondes in the Arctic, the Tropics and Antarctica Kirkwood, S. Belova, E. Satheesan, K. Narayana Rao, T. Rajendra Prasad, T. Satheesh Kumar, S. 2010 application/pdf http://repository.ias.ac.in/69414/ http://repository.ias.ac.in/69414/1/69414.pdf http://www.ann-geophys.net/28/1993/2010/angeo-28-1993-2010.html unknown Copernicus Group http://repository.ias.ac.in/69414/1/69414.pdf Kirkwood, S. Belova, E. Satheesan, K. Narayana Rao, T. Rajendra Prasad, T. Satheesh Kumar, S. (2010) Fresnel scatter revisited-comparison of 50 MHz radar and radiosondes in the Arctic, the Tropics and Antarctica Annales Geophysicae, 28 (10). pp. 1993-2005. ISSN 0992-7689 QE Geology Article PeerReviewed 2010 ftindianacasci 2013-01-20T12:39:54Z High-resolution radiosondes and calibrated radars operating close to 50 MHz, are used to examine the relationship between the strength of radar scatter and refractive index gradient. Three radars are used, in Kiruna in Arctic Sweden, at Gadanki in southern India and at the Swedish/Finnish base Wasa/Aboa in Queen Maud Land, Antarctica. Calibration is accomplished using the daily variation of galactic noise measured at each site. Proportionality between radar scatter strength and the square of the mean gradient of potential refractive index, M 2 , is found in the upper troposphere and lower stratosphere at all three sites, confirming previously reported results from many VHF radars. If the radar scatter is interpreted as Fresnel scatter, the constant of proportionality between radar scatter and M 2 is found to be the same, within the calibration uncertainties, for all three radars. The radiosondes show evidence of distinct layering with sharp gradients, extending over 10s of kilometers horizontally, but the scatter is found to be two orders of magnitude weaker than would be expected from true Fresnel scatter from such layers. Using radar reflectivities resolved to a few 100 ms, we show that this is due to strong temporal variability in the scattering conditions, possibly due to undulations of the scattering layers. The constancy of the radar scatter – M 2 relationship between the different sites suggests an unexpected uniformity in these perturbations between very different regions of the globe. Article in Journal/Newspaper Antarc* Antarctica Arctic Arctic Kiruna Queen Maud Land Indian Academy of Sciences: Publication of Fellows Aboa ENVELOPE(-13.417,-13.417,-73.050,-73.050) Arctic Kiruna Queen Maud Land ENVELOPE(12.000,12.000,-72.500,-72.500) Wasa ENVELOPE(-13.408,-13.408,-73.043,-73.043) |
institution |
Open Polar |
collection |
Indian Academy of Sciences: Publication of Fellows |
op_collection_id |
ftindianacasci |
language |
unknown |
topic |
QE Geology |
spellingShingle |
QE Geology Kirkwood, S. Belova, E. Satheesan, K. Narayana Rao, T. Rajendra Prasad, T. Satheesh Kumar, S. Fresnel scatter revisited-comparison of 50 MHz radar and radiosondes in the Arctic, the Tropics and Antarctica |
topic_facet |
QE Geology |
description |
High-resolution radiosondes and calibrated radars operating close to 50 MHz, are used to examine the relationship between the strength of radar scatter and refractive index gradient. Three radars are used, in Kiruna in Arctic Sweden, at Gadanki in southern India and at the Swedish/Finnish base Wasa/Aboa in Queen Maud Land, Antarctica. Calibration is accomplished using the daily variation of galactic noise measured at each site. Proportionality between radar scatter strength and the square of the mean gradient of potential refractive index, M 2 , is found in the upper troposphere and lower stratosphere at all three sites, confirming previously reported results from many VHF radars. If the radar scatter is interpreted as Fresnel scatter, the constant of proportionality between radar scatter and M 2 is found to be the same, within the calibration uncertainties, for all three radars. The radiosondes show evidence of distinct layering with sharp gradients, extending over 10s of kilometers horizontally, but the scatter is found to be two orders of magnitude weaker than would be expected from true Fresnel scatter from such layers. Using radar reflectivities resolved to a few 100 ms, we show that this is due to strong temporal variability in the scattering conditions, possibly due to undulations of the scattering layers. The constancy of the radar scatter – M 2 relationship between the different sites suggests an unexpected uniformity in these perturbations between very different regions of the globe. |
format |
Article in Journal/Newspaper |
author |
Kirkwood, S. Belova, E. Satheesan, K. Narayana Rao, T. Rajendra Prasad, T. Satheesh Kumar, S. |
author_facet |
Kirkwood, S. Belova, E. Satheesan, K. Narayana Rao, T. Rajendra Prasad, T. Satheesh Kumar, S. |
author_sort |
Kirkwood, S. |
title |
Fresnel scatter revisited-comparison of 50 MHz radar and radiosondes in the Arctic, the Tropics and Antarctica |
title_short |
Fresnel scatter revisited-comparison of 50 MHz radar and radiosondes in the Arctic, the Tropics and Antarctica |
title_full |
Fresnel scatter revisited-comparison of 50 MHz radar and radiosondes in the Arctic, the Tropics and Antarctica |
title_fullStr |
Fresnel scatter revisited-comparison of 50 MHz radar and radiosondes in the Arctic, the Tropics and Antarctica |
title_full_unstemmed |
Fresnel scatter revisited-comparison of 50 MHz radar and radiosondes in the Arctic, the Tropics and Antarctica |
title_sort |
fresnel scatter revisited-comparison of 50 mhz radar and radiosondes in the arctic, the tropics and antarctica |
publisher |
Copernicus Group |
publishDate |
2010 |
url |
http://repository.ias.ac.in/69414/ http://repository.ias.ac.in/69414/1/69414.pdf http://www.ann-geophys.net/28/1993/2010/angeo-28-1993-2010.html |
long_lat |
ENVELOPE(-13.417,-13.417,-73.050,-73.050) ENVELOPE(12.000,12.000,-72.500,-72.500) ENVELOPE(-13.408,-13.408,-73.043,-73.043) |
geographic |
Aboa Arctic Kiruna Queen Maud Land Wasa |
geographic_facet |
Aboa Arctic Kiruna Queen Maud Land Wasa |
genre |
Antarc* Antarctica Arctic Arctic Kiruna Queen Maud Land |
genre_facet |
Antarc* Antarctica Arctic Arctic Kiruna Queen Maud Land |
op_relation |
http://repository.ias.ac.in/69414/1/69414.pdf Kirkwood, S. Belova, E. Satheesan, K. Narayana Rao, T. Rajendra Prasad, T. Satheesh Kumar, S. (2010) Fresnel scatter revisited-comparison of 50 MHz radar and radiosondes in the Arctic, the Tropics and Antarctica Annales Geophysicae, 28 (10). pp. 1993-2005. ISSN 0992-7689 |
_version_ |
1766238742862888960 |