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/...
Published in: | Annales Geophysicae |
---|---|
Main Authors: | , , , , , |
Format: | Text |
Language: | English |
Published: |
2018
|
Subjects: | |
Online Access: | https://doi.org/10.5194/angeo-28-1993-2010 https://angeo.copernicus.org/articles/28/1993/2010/ |
id |
ftcopernicus:oai:publications.copernicus.org:angeo7205 |
---|---|
record_format |
openpolar |
spelling |
ftcopernicus:oai:publications.copernicus.org:angeo7205 2023-05-15T13:36:36+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. 2018-09-27 application/pdf https://doi.org/10.5194/angeo-28-1993-2010 https://angeo.copernicus.org/articles/28/1993/2010/ eng eng doi:10.5194/angeo-28-1993-2010 https://angeo.copernicus.org/articles/28/1993/2010/ eISSN: 1432-0576 Text 2018 ftcopernicus https://doi.org/10.5194/angeo-28-1993-2010 2020-07-20T16:26:17Z 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. Text Antarc* Antarctica Arctic Kiruna Queen Maud Land Copernicus Publications: E-Journals 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) Annales Geophysicae 28 10 1993 2005 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
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 |
Text |
author |
Kirkwood, S. Belova, E. Satheesan, K. Narayana Rao, T. Rajendra Prasad, T. Satheesh Kumar, S. |
spellingShingle |
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 |
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 |
publishDate |
2018 |
url |
https://doi.org/10.5194/angeo-28-1993-2010 https://angeo.copernicus.org/articles/28/1993/2010/ |
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 Kiruna Queen Maud Land |
genre_facet |
Antarc* Antarctica Arctic Kiruna Queen Maud Land |
op_source |
eISSN: 1432-0576 |
op_relation |
doi:10.5194/angeo-28-1993-2010 https://angeo.copernicus.org/articles/28/1993/2010/ |
op_doi |
https://doi.org/10.5194/angeo-28-1993-2010 |
container_title |
Annales Geophysicae |
container_volume |
28 |
container_issue |
10 |
container_start_page |
1993 |
op_container_end_page |
2005 |
_version_ |
1766081363599949824 |