Ka-Band Doppler Scatterometry over a Loop Current Eddy
Doppler scatterometry is a promising new technique for the simultaneous measurement of ocean surface currents and winds. These measurements have been recommended by the recent US NRC Decadal Review for NASA as being priority variables for the coming decade of Earth observations. In addition, current...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2020-07-01
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| Series: | Remote Sensing |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2072-4292/12/15/2388 |
| _version_ | 1827712367612395520 |
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| author | Ernesto Rodríguez Alexander Wineteer Dragana Perkovic-Martin Tamás Gál Steven Anderson Seth Zuckerman James Stear Xiufeng Yang |
| author_facet | Ernesto Rodríguez Alexander Wineteer Dragana Perkovic-Martin Tamás Gál Steven Anderson Seth Zuckerman James Stear Xiufeng Yang |
| author_sort | Ernesto Rodríguez |
| collection | DOAJ |
| description | Doppler scatterometry is a promising new technique for the simultaneous measurement of ocean surface currents and winds. These measurements have been recommended by the recent US NRC Decadal Review for NASA as being priority variables for the coming decade of Earth observations. In addition, currents and winds are useful for many applications, including assessing the operating conditions for oil platforms or tracking the dispersal of plastic or oil by surface currents and winds. While promising, Doppler scatterometry is relatively new and understanding the measurement characteristics is an important area of research. To this end, Chevron sponsored the deployment of DopplerScatt, a NASA/JPL Ka-band Doppler scatterometer, over instrumented sites located at the edge of a Gulf of Mexico Loop Current Eddy (LCE). In addition to in situ measurements, coincident synoptic maps of surface currents were collected by the Areté ROCIS instrument, an optical current measurement system. Here we report on the results of this experiment for both surface currents and winds. Surface current comparisons show that the Ka-band Current Geophysical Model Function (CGMF) needs to include wind drift currents, which could not be estimated with prior data sets. Once the CGMF is updated, ROCIS and DopplerScatt show good agreement for surface current speeds, but, at times, direction differences on the order of 10° can occur. Remote sensing optical and radar data agree better among themselves than with ADCP currents measured at 5 m depth, showing that remote sensing is sensitive to the the currents in top 1 m of the ocean. The LCE data provided a unique opportunity to study the effects of surface currents and stability conditions on scatterometer winds. We show that, like Ku-band, Ka-band estimates of winds are related to neutral winds (and wind stress) and are referenced relative to the moving frame provided by the current. This is useful for the study of air-sea interactions, but must be accounted for when using scatterometer winds for weather prediction. |
| first_indexed | 2024-03-10T18:13:59Z |
| format | Article |
| id | doaj.art-65468dedf77d4b37ab9285acf7549fe5 |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-10T18:13:59Z |
| publishDate | 2020-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-65468dedf77d4b37ab9285acf7549fe52023-11-20T07:52:33ZengMDPI AGRemote Sensing2072-42922020-07-011215238810.3390/rs12152388Ka-Band Doppler Scatterometry over a Loop Current EddyErnesto Rodríguez0Alexander Wineteer1Dragana Perkovic-Martin2Tamás Gál3Steven Anderson4Seth Zuckerman5James Stear6Xiufeng Yang7Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USAJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USAJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USAJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USAAreté, Northridge, CA 91324, USAAreté, Northridge, CA 91324, USAChevron Energy Technology Company, Houston, TX 77002, USAChevron Energy Technology Company, Houston, TX 77002, USADoppler scatterometry is a promising new technique for the simultaneous measurement of ocean surface currents and winds. These measurements have been recommended by the recent US NRC Decadal Review for NASA as being priority variables for the coming decade of Earth observations. In addition, currents and winds are useful for many applications, including assessing the operating conditions for oil platforms or tracking the dispersal of plastic or oil by surface currents and winds. While promising, Doppler scatterometry is relatively new and understanding the measurement characteristics is an important area of research. To this end, Chevron sponsored the deployment of DopplerScatt, a NASA/JPL Ka-band Doppler scatterometer, over instrumented sites located at the edge of a Gulf of Mexico Loop Current Eddy (LCE). In addition to in situ measurements, coincident synoptic maps of surface currents were collected by the Areté ROCIS instrument, an optical current measurement system. Here we report on the results of this experiment for both surface currents and winds. Surface current comparisons show that the Ka-band Current Geophysical Model Function (CGMF) needs to include wind drift currents, which could not be estimated with prior data sets. Once the CGMF is updated, ROCIS and DopplerScatt show good agreement for surface current speeds, but, at times, direction differences on the order of 10° can occur. Remote sensing optical and radar data agree better among themselves than with ADCP currents measured at 5 m depth, showing that remote sensing is sensitive to the the currents in top 1 m of the ocean. The LCE data provided a unique opportunity to study the effects of surface currents and stability conditions on scatterometer winds. We show that, like Ku-band, Ka-band estimates of winds are related to neutral winds (and wind stress) and are referenced relative to the moving frame provided by the current. This is useful for the study of air-sea interactions, but must be accounted for when using scatterometer winds for weather prediction.https://www.mdpi.com/2072-4292/12/15/2388surface currentsocean vector windsscatterometryDoppler |
| spellingShingle | Ernesto Rodríguez Alexander Wineteer Dragana Perkovic-Martin Tamás Gál Steven Anderson Seth Zuckerman James Stear Xiufeng Yang Ka-Band Doppler Scatterometry over a Loop Current Eddy Remote Sensing surface currents ocean vector winds scatterometry Doppler |
| title | Ka-Band Doppler Scatterometry over a Loop Current Eddy |
| title_full | Ka-Band Doppler Scatterometry over a Loop Current Eddy |
| title_fullStr | Ka-Band Doppler Scatterometry over a Loop Current Eddy |
| title_full_unstemmed | Ka-Band Doppler Scatterometry over a Loop Current Eddy |
| title_short | Ka-Band Doppler Scatterometry over a Loop Current Eddy |
| title_sort | ka band doppler scatterometry over a loop current eddy |
| topic | surface currents ocean vector winds scatterometry Doppler |
| url | https://www.mdpi.com/2072-4292/12/15/2388 |
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