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Wave shadowing and modulation of microwave backscatter from the ocean
Shadowing and modulation of microwave backscatter by ocean waves are studied using coherent X‐band radars. Two types of shadowing are investigated: geometric shadowing (complete blockage of incident rays) and partial shadowing (polarization‐dependent diffraction combined with weak scatterers). We po...
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Published in: | Journal of Geophysical Research: Oceans 2012-08, Vol.117 (C8), p.n/a |
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creator | Plant, William J. Farquharson, Gordon |
description | Shadowing and modulation of microwave backscatter by ocean waves are studied using coherent X‐band radars. Two types of shadowing are investigated: geometric shadowing (complete blockage of incident rays) and partial shadowing (polarization‐dependent diffraction combined with weak scatterers). We point out that the frequency of occurrence of zero signal‐to‐noise ratio samples cannot depend on the incident power level or the polarization if geometric shadowing occurs but can if partial shadowing exists. We then compare this behavior with observations, and show that the data do not support the hypothesis that geometric shadowing plays a significant role in low‐grazing‐angle microwave scattering from the ocean surface. Furthermore, our data indicate that partial shadowing only depends significantly on polarization for the steep waves found near shorelines. We also study the modulation of microwave backscatter by ocean waves using these data by looking at the phase differences between received power and scatterer velocity. These phase differences appear to be rather well explained by standard composite surface theory at VV polarization, having values that are positive looking up wave and negative looking down wave. For HH polarization, however, breaking effects come into play and overshadow composite surface effects of free waves. They cause the phase difference to be near zero for up wave looks and near 180° for down‐wave looks. A simple model that involves both breaking and freely propagating waves but does not include any shadowing effects is shown to account for observed phase differences at both polarizations to within about 10°.
Key Points
Shadowing does not occur in microwave backscatter from the ocean
Phase between wave‐modulated power and velocity depends on polarization |
doi_str_mv | 10.1029/2012JC007912 |
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Key Points
Shadowing does not occur in microwave backscatter from the ocean
Phase between wave‐modulated power and velocity depends on polarization</description><identifier>ISSN: 0148-0227</identifier><identifier>ISSN: 2169-9275</identifier><identifier>EISSN: 2156-2202</identifier><identifier>EISSN: 2169-9291</identifier><identifier>DOI: 10.1029/2012JC007912</identifier><language>eng</language><publisher>Washington, DC: Blackwell Publishing Ltd</publisher><subject>backscatter from ocean ; Earth sciences ; Earth, ocean, space ; Exact sciences and technology ; Geophysics ; Marine ; microwave shadowing ; Physical oceanography ; Radio ; Remote sensing ; wave modulation of backscatter</subject><ispartof>Journal of Geophysical Research: Oceans, 2012-08, Vol.117 (C8), p.n/a</ispartof><rights>2012. American Geophysical Union. All Rights Reserved.</rights><rights>2015 INIST-CNRS</rights><rights>Copyright American Geophysical Union 2012</rights><lds50>peer_reviewed</lds50><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c4461-6746d374118fe16ee228895d87e06addf5456b96f44952764e1b7245ee7e38453</citedby><cites>FETCH-LOGICAL-c4461-6746d374118fe16ee228895d87e06addf5456b96f44952764e1b7245ee7e38453</cites></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktopdf>$$Uhttps://onlinelibrary.wiley.com/doi/pdf/10.1029%2F2012JC007912$$EPDF$$P50$$Gwiley$$H</linktopdf><linktohtml>$$Uhttps://onlinelibrary.wiley.com/doi/full/10.1029%2F2012JC007912$$EHTML$$P50$$Gwiley$$H</linktohtml><link.rule.ids>315,786,790,11541,27957,27958,46503,46927,50923,51032</link.rule.ids><backlink>$$Uhttp://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=26370340$$DView record in Pascal Francis$$Hfree_for_read</backlink></links><search><creatorcontrib>Plant, William J.</creatorcontrib><creatorcontrib>Farquharson, Gordon</creatorcontrib><title>Wave shadowing and modulation of microwave backscatter from the ocean</title><title>Journal of Geophysical Research: Oceans</title><addtitle>J. Geophys. Res</addtitle><description>Shadowing and modulation of microwave backscatter by ocean waves are studied using coherent X‐band radars. Two types of shadowing are investigated: geometric shadowing (complete blockage of incident rays) and partial shadowing (polarization‐dependent diffraction combined with weak scatterers). We point out that the frequency of occurrence of zero signal‐to‐noise ratio samples cannot depend on the incident power level or the polarization if geometric shadowing occurs but can if partial shadowing exists. We then compare this behavior with observations, and show that the data do not support the hypothesis that geometric shadowing plays a significant role in low‐grazing‐angle microwave scattering from the ocean surface. Furthermore, our data indicate that partial shadowing only depends significantly on polarization for the steep waves found near shorelines. We also study the modulation of microwave backscatter by ocean waves using these data by looking at the phase differences between received power and scatterer velocity. These phase differences appear to be rather well explained by standard composite surface theory at VV polarization, having values that are positive looking up wave and negative looking down wave. For HH polarization, however, breaking effects come into play and overshadow composite surface effects of free waves. They cause the phase difference to be near zero for up wave looks and near 180° for down‐wave looks. A simple model that involves both breaking and freely propagating waves but does not include any shadowing effects is shown to account for observed phase differences at both polarizations to within about 10°.
Key Points
Shadowing does not occur in microwave backscatter from the ocean
Phase between wave‐modulated power and velocity depends on polarization</description><subject>backscatter from ocean</subject><subject>Earth sciences</subject><subject>Earth, ocean, space</subject><subject>Exact sciences and technology</subject><subject>Geophysics</subject><subject>Marine</subject><subject>microwave shadowing</subject><subject>Physical oceanography</subject><subject>Radio</subject><subject>Remote sensing</subject><subject>wave modulation of backscatter</subject><issn>0148-0227</issn><issn>2169-9275</issn><issn>2156-2202</issn><issn>2169-9291</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2012</creationdate><recordtype>article</recordtype><recordid>eNp9kE9Lw0AQxRdRsFRvfoCACB6M7uzf5ChVq6UoiOJx2SYTjU2ydTe1-u1dqRTx4Fzm8ntv3jxCDoCeAmX5GaPAJiNKdQ5siwwYSJUyRtk2GVAQWUoZ07tkP4RXGkdIJSgMyOWTfcckvNjSreruObFdmbSuXDa2r12XuCpp68K71Tc1s8U8FLbv0SeVd23Sv2DiCrTdHtmpbBNw_2cPyePV5cPoOp3ejW9G59O0EEJBqrRQJdcCIKsQFCJjWZbLMtNIlS3LSsZYs1xVQuSSaSUQZpoJiaiRZ0LyITle-y68e1ti6E1bhwKbxnbolsFADnkus3gnood_0Fe39F1MZ4ByDhoU55E6WVPxxxA8Vmbh69b6zwiZ71rN71ojfvRjamMRTeVtV9Rho2GKa8oFjRxfc6u6wc9_Pc1kfD8CJjREVbpW1aHHj43K-rlRmmtpnm7H5hYuxtdTuDcT_gXycJGi</recordid><startdate>201208</startdate><enddate>201208</enddate><creator>Plant, William J.</creator><creator>Farquharson, Gordon</creator><general>Blackwell Publishing Ltd</general><general>American Geophysical Union</general><scope>BSCLL</scope><scope>IQODW</scope><scope>AAYXX</scope><scope>CITATION</scope><scope>3V.</scope><scope>7TG</scope><scope>7TN</scope><scope>7XB</scope><scope>88I</scope><scope>8FK</scope><scope>ABUWG</scope><scope>AFKRA</scope><scope>ATCPS</scope><scope>AZQEC</scope><scope>BENPR</scope><scope>BHPHI</scope><scope>BKSAR</scope><scope>CCPQU</scope><scope>DWQXO</scope><scope>F1W</scope><scope>GNUQQ</scope><scope>H96</scope><scope>HCIFZ</scope><scope>KL.</scope><scope>L.G</scope><scope>M2P</scope><scope>PATMY</scope><scope>PCBAR</scope><scope>PQEST</scope><scope>PQQKQ</scope><scope>PQUKI</scope><scope>PRINS</scope><scope>PYCSY</scope><scope>Q9U</scope></search><sort><creationdate>201208</creationdate><title>Wave shadowing and modulation of microwave backscatter from the ocean</title><author>Plant, William J. ; Farquharson, Gordon</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c4461-6746d374118fe16ee228895d87e06addf5456b96f44952764e1b7245ee7e38453</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2012</creationdate><topic>backscatter from ocean</topic><topic>Earth sciences</topic><topic>Earth, ocean, space</topic><topic>Exact sciences and technology</topic><topic>Geophysics</topic><topic>Marine</topic><topic>microwave shadowing</topic><topic>Physical oceanography</topic><topic>Radio</topic><topic>Remote sensing</topic><topic>wave modulation of backscatter</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Plant, William J.</creatorcontrib><creatorcontrib>Farquharson, Gordon</creatorcontrib><collection>Istex</collection><collection>Pascal-Francis</collection><collection>CrossRef</collection><collection>ProQuest Central (Corporate)</collection><collection>Meteorological & Geoastrophysical Abstracts</collection><collection>Oceanic Abstracts</collection><collection>ProQuest Central (purchase pre-March 2016)</collection><collection>Science Database (Alumni Edition)</collection><collection>ProQuest Central (Alumni) (purchase pre-March 2016)</collection><collection>ProQuest Central (Alumni)</collection><collection>ProQuest Central</collection><collection>ProQuest Agriculture & Environmental Science Database</collection><collection>ProQuest Central Essentials</collection><collection>AUTh Library subscriptions: ProQuest Central</collection><collection>ProQuest Natural Science Collection</collection><collection>Earth, Atmospheric & Aquatic Science Collection</collection><collection>ProQuest One Community College</collection><collection>ProQuest Central</collection><collection>ASFA: Aquatic Sciences and Fisheries Abstracts</collection><collection>ProQuest Central Student</collection><collection>Aquatic Science & Fisheries Abstracts (ASFA) 2: Ocean Technology, Policy & Non-Living Resources</collection><collection>SciTech Premium Collection (Proquest) (PQ_SDU_P3)</collection><collection>Meteorological & Geoastrophysical Abstracts - Academic</collection><collection>Aquatic Science & Fisheries Abstracts (ASFA) Professional</collection><collection>ProQuest Science Journals</collection><collection>Environmental Science Database</collection><collection>ProQuest Earth, Atmospheric & Aquatic Science Database</collection><collection>ProQuest One Academic Eastern Edition (DO NOT USE)</collection><collection>ProQuest One Academic</collection><collection>ProQuest One Academic UKI Edition</collection><collection>ProQuest Central China</collection><collection>Environmental Science Collection</collection><collection>ProQuest Central Basic</collection><jtitle>Journal of Geophysical Research: Oceans</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Plant, William J.</au><au>Farquharson, Gordon</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Wave shadowing and modulation of microwave backscatter from the ocean</atitle><jtitle>Journal of Geophysical Research: Oceans</jtitle><addtitle>J. Geophys. Res</addtitle><date>2012-08</date><risdate>2012</risdate><volume>117</volume><issue>C8</issue><epage>n/a</epage><issn>0148-0227</issn><issn>2169-9275</issn><eissn>2156-2202</eissn><eissn>2169-9291</eissn><notes>ONR - No. NNX11AL27G; No. F012919; No. APS-11-12</notes><notes>BOEM - No. A100747</notes><notes>istex:B719510CD0A49DBC97745228A98A3CC3D08FC294</notes><notes>ark:/67375/WNG-N1DGHL1R-J</notes><notes>ArticleID:2012JC007912</notes><notes>Tab-delimited Table 1.Tab-delimited Table 2.</notes><notes>ObjectType-Article-1</notes><notes>SourceType-Scholarly Journals-1</notes><notes>ObjectType-Feature-2</notes><notes>content type line 23</notes><abstract>Shadowing and modulation of microwave backscatter by ocean waves are studied using coherent X‐band radars. Two types of shadowing are investigated: geometric shadowing (complete blockage of incident rays) and partial shadowing (polarization‐dependent diffraction combined with weak scatterers). We point out that the frequency of occurrence of zero signal‐to‐noise ratio samples cannot depend on the incident power level or the polarization if geometric shadowing occurs but can if partial shadowing exists. We then compare this behavior with observations, and show that the data do not support the hypothesis that geometric shadowing plays a significant role in low‐grazing‐angle microwave scattering from the ocean surface. Furthermore, our data indicate that partial shadowing only depends significantly on polarization for the steep waves found near shorelines. We also study the modulation of microwave backscatter by ocean waves using these data by looking at the phase differences between received power and scatterer velocity. These phase differences appear to be rather well explained by standard composite surface theory at VV polarization, having values that are positive looking up wave and negative looking down wave. For HH polarization, however, breaking effects come into play and overshadow composite surface effects of free waves. They cause the phase difference to be near zero for up wave looks and near 180° for down‐wave looks. A simple model that involves both breaking and freely propagating waves but does not include any shadowing effects is shown to account for observed phase differences at both polarizations to within about 10°.
Key Points
Shadowing does not occur in microwave backscatter from the ocean
Phase between wave‐modulated power and velocity depends on polarization</abstract><cop>Washington, DC</cop><pub>Blackwell Publishing Ltd</pub><doi>10.1029/2012JC007912</doi><tpages>14</tpages><oa>free_for_read</oa></addata></record> |
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source | Wiley; Wiley-Blackwell AGU Digital Archive |
subjects | backscatter from ocean Earth sciences Earth, ocean, space Exact sciences and technology Geophysics Marine microwave shadowing Physical oceanography Radio Remote sensing wave modulation of backscatter |
title | Wave shadowing and modulation of microwave backscatter from the ocean |
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