The SeaWinds Scatterometer
The SeaWinds scatterometer flew on QuikSCAT (1999-) and ADEOS-II (2002).
The slightly modified engineering model flew on the
ISS (2014-2016). By JPL convention SeaWinds on the QuikSCAT
mission is known
as QuikSCAT, while SeaWinds on ADEOS-II is known as SeaWinds.
The modified SeaWinds on the ISS is known as RapidSCAT.
SeaWinds on ADEOS
II (127K gif)and SeaWinds
on QuikSCAT (101K gif) are follow-on missions to the successful
NASA Scatterometer (NSCAT)
mission. SeaWinds is a scanning dual pencil-beam Ku-band scatterometer.
SeaWinds on ADEOS II operated for nine
months aboard ADEOS-II until the satellite power system failed. SeaWinds on QuikSCAT was a fast-track
SeaWinds instrument flying on a dedicated spacecraft. SeaWinds was
successfully launched in June 1999 aboard the QuikBird spacecraft
atop a Titan launch vehicle
(144K gif). QuikSCAT Logo
(101K gif). Additional animated images are available from the
RapidSCAT is a slightly modified SeaWinds flying on the International Space Station (ISS) that was launched in Aug. 2014. The instrument ceased working when its ISS power adapter failed after nearly two years of operation. The RapidSCAT modifications included a different antenna to provide a larger beamwidth and larger incidence angles. The transmit/receive timing was also altered to account for lower altitude operation from the ISS compared to QuikSCAT and ADEOS-II for which SeaWinds was designed.
Selected SeaWinds Projects
Students in the MERS lab wrote the software to compute the so-called "X"-factor used
in computing sigma-0 from the power measurements. The resulting code and tables were
used by JPL for processing QuikSCAT and SeaWinds data. This work was extended to
compute the measurement spatial response function, which is used for reconstruction
and resolution enhancement. Code to compute the response function is availble from
MERS software page.
Iceberg Tracking with SeaWinds on QuikSCAT data
SeaWinds is designed to measure
ocean winds (299k Quiktime movie), but is useful in many other
applications. One of the more innovative new applications is in
iceberg tracking. Shortly after instrument turn on in early July,
1999, QuikSCAT located a massive iceberg, later identified as B10A,
floating in the Drake Passage between South America and Antarctica.
Its location was relayed to the National
Ice Center who issued a shipping advisory on the story. JPL
issued a Press Release
on the story. The 38 km by 77 km iceberg was first spotted in an
enhanced resolution image
(157K gif) produced by Dr. Long from QuikSCAT data using the SIRF
algorithm. He also generated an animated movie [JD
194-276 (455K mpeg)] [JD
200-298 (300K AVI)] [JD
200-298 (372K QuikTime)] [JD
200-298 (4MB QuikTime)] of the iceberg movement. Each image
in this movie was produced with one day of QuikSCAT data.
Other images of this iceberg have been collected from satellite
sensors, for example, a Radarsat
SAR image (125K jpg), DMSP
OLS (686K jpg) and LandSat
image (196K jpg) (closeup
115K jpg) (from the National
Ice Center web site). The National
Ice Center is a branch of the National
Oceanic and Atmospheric Administration (NOAA)). The UMET office
out of the Falklands recently flew an aircraft to make observations
(156K gif) of the iceberg.
In early October, 1999, B10A was joined by another superberg,
A22B (12 NM x 35 NM), in the Drake Passage. A22B originally calved
from the Ronne Iceshelf in 1986 and has been floating in the Weddell
Sea until just recently. It can be seen moving northward in the
QuikSCAT movies [JD
200,1999 - 098,2000 (3MB mpeg)] [JD
200,1999 - 098,2000 (3.8MB QuickTime)] [JD
274,1999 - 098,2000 (8.9MB AVI)] . Each image in this movie
was produced with one day of QuikSCAT data. An AVHRR
visible image (2.1MB) from Oct. 13, 1999 shows both icebergs.
On January 11, 2000 B10A broke up in at least two smaller pieces
while it was just west of South Georgia Island. A22B, an equally
large iceberg is nearby. An image
(4MB gif) image shows a time sequence of enhanced resolution
scatterometer observations of B10A's break up on JD11, 2000 near
South Georgia Island in the South Atlantic. A22B is nearby. The
image consists of 6 rows of images with time running to the right.
For each day there are two images, one morning and one evening.
The top row images were created from SeaWinds 13.5 GHz V-pol 'eggs'
using the SIR resolution enhancement algorithm. The pixel resolution
is ~2.225 km. The second row was created from SeaWinds 13.5 GHz
H-pol 'eggs'. The last rows were created from 'slices' measurements
using the SIRF resolution enhancement algorithm while the center
rows were done with the AVE algorithm. Note that the intrinsic resolution
of the SeaWinds sensor is approximately 7x25 km but is improved
with the algorithms. Since the algorithms tend to have artifacts
over the ocean, seeing all the versions can be helpful for interpretting
the images. The ocean appears dark when the wind speed is low and
lightens for higher wind speeds which accounts for the lightening
and darkening of the images. Generally, glacial ice shows up brightly
against the ocean, but can be hid when the wind speed is high. The
images show that on JD9 B10A is in one piece but that by JD12 it
is clearly in multiple pieces. The demise of B10A and A22B just
NW of South Georgia Island can be seen in the the following animations:
2000 (1.6MB mpeg)] [JD
1-128, 2000 (3.5MB QuickTime)] [JD
1-128, 2000 (12.4MB avi)]. A longer time series of these movies
can be seen in [JD
1-221, 2000 (34.5MB avi)] [JD
1-221, 2000 (37.7MB animated gif)] [JD
1-221, 2000 (4.8MB mpeg)] [JD
1-221, 2000 (5.5MB QuickTime)]. An ascii
file (11k) containing the positions of the icebergs from JD200,
1999 through their demise is available.
The calving and motion of major icebergs in the Weddell and Ross
Seas of Antarctica can be seen in these animations: (these have
been reduced in resolution for easier download and viewing) [Weddell
Sea JD 137-225, 2000 (14.4MB avi)] [Weddell
Sea JD 137-225, 2000 (15.2MB animated gif)] [Weddell
Sea JD 137-225, 2000 (1.5MB mpeg)] [Weddell
Sea JD 137-225, 2000 (3.0MB QuickTime)] and [Ross
Sea JD 90-226, 2000 (16.8MB avi)] [Ross
Sea JD 90-226, 2000 (50.9MB animated gif)] [Ross
Sea JD 90-226, 2000 (4.0MB QuikTime)]. The dynamics of both
the sea ice motion and major icebergs are clearly evident.
Sea Ice Extent from SeaWinds on QuikSCAT data
Besides tracking icebergs QuikSCAT data has been very useful in
other polar ice studies. A key application is sea ice extent mapping.
results (1.1MB gif) from applying Remund and Long's ice edge
detection algorithm for Antarctica to QuikSCAT data
illustrate the resolution of the processed data. A [JD
200-266 mpeg movie (366K)] [JD
200-350 AVI movie (1MB)] [JD
200-350 QuikTime movie (1.25MB)] of ice-masked images is available.
(In the movie, white areas in the sea-ice are due to missing scatterometer
data.) The full QuikSCAT data set has been processed this way, resulting in a decade-long data set (Remund and Long, 2015). This has been augmented with OSCAT data (Lindell and Long, 2016). The
resulting product is available from the
Scatterometer Climate Record Pathfinder (SCP) web page.
QuikSCAT Data Products
Under the direction of Dr. Long, the MERS lab have produced a series
of standard image products from SeaWinds data. Some of these products are
described in the MERS QuikSCAT Products
home page, with the complete data set available through the
Scatterometer Climate Record Pathfinder (SCP) web page.
QuikSCAT Calibration Ground Station
A specialized calibration ground station (CGS) was developed
to aid in the calibration of SeaWinds. BYU was involved in
the development and analysis of the QuikSCAT CGS and operated
this ground station for many years. Further information
is available here.
- P.K. Yoho and D.G. Long, "Model-based ground station calibration
for SeaWinds on QuikSCAT," in Earth Observing Systems IV,
William L. Barnes, Editor, Proceedings of SPIE Vol. 4483,
29 July -- 3 Aug. 2001.
- P.K. Yoho and D.G. Long, "Improved Timing Calibration of
QuikSCAT," Proceedings of the International Geoscience
and Remote Sensing Symposium, pp. 1591-1593, Sydney, Australia,
9-13 July 2001.
The RapidSCAT scatterometer consists of the slightly modified
SeaWinds engineering unit flown on the International Space Station (ISS).
Unlike all other scatterometers which operated in a sun-synchronous
orbit, the ISS orbit was non-sun-synchronous which enabled RapidSCAT
to study the variations in surface backscatter versus local time of day,
see A.P. Paget, D.G. Long, and N.M. Madsen, "RapidScat Diurnal Cycles Over Land," IEEE Transactions on Geoscience and Remote Sensing, Vol. 54, No. 6, pp. 3336-3344, doi:10.1109/TGRS.2016.2515022, 2016 and N.M. Madsen and D.G. Long, "Calibration and Validation of the RapidScat Scatterometer Using Tropical Rainforests," IEEE Transactions on Geoscience and Remote Sensing, Vol. 54, No. 5, pp. 2846-2854, doi:10.1109/TGRS.2015.2506463, 2016.
Following up on their earlier work on the SeaWinds X-factor, BYU MERS students modified SeaWinds X-factor code to find ways to compute the RapidSCAT X-factor, create X-factor tables that could be used with the SeaWinds code. MERS students also participated in system calibration (Madsen and Long, 2016).
Selected MERS SeaWinds and QuikSCAT Publications
The MERS laboratory has been involved in the design analysis of
the SeaWinds system in support of JPL. Several papers and reports
have been generated. Some sample papers include: (More
- D.B. Lindell and D.G. Long, "Multiyear Arctic Sea Ice Classification Using OSCAT and QuikSCAT", IEEE Transactions on Geoscience and Remote Sensing, Vol. 54, No. 1, pp. 167-175, doi:10.1109/TGRS.2015.2452215, 2016.
- Q.D. Remund and D.G. Long, "A Decade of QuikSCAT Scatterometer Sea Ice Extent Data", IEEE Transactions on Geoscience and Remote Sensing, doi:10.1109/TGRS.2013.2281056, Vol. 52. No. 7, pp. 4281-4290, 2014.
- W.J. Hullinger and D.G. Long, "Mitigation of Sea Ice Contamination in QuikSCAT Wind Retrieval", IEEE Transactions on Geoscience and Remote Sensing, doi:10.1109/TGRS.2013.2258400, Vol. 52. No. 4, pp. 1, 2014.
- A.M. Swan and D.G. Long, "Multi-Year Arctic Sea Ice Classification Using QuikSCAT", IEEE Transactions on Geoscience and Remote Sensing, doi:10.1109/TGRS.2012.2184123, Vol. 50, No. 9, pp. 3317-3326, 2012.
- F. Said and D.G. Long, "Determining Selected Tropical Cyclone Characteristics using QuikSCAT's Ultra-High Resolution Images", IEEE Journal of Selected Topics in Earth Observations and Remote Sensing, doi:10.1109/JSTARS.2011.2138119, Vol. 4, No. 4, pp. 857-869, 2011.
- M.P. Owen and D.G. Long, "Simultaneous Wind and Rain Estimation for QuikSCAT at Ultra-High Resolution", IEEE Transactions on Geoscience and Remote Sensing, doi:10.1109/TGRS.2010.2102361, Vol. 49, No. 6, pp. 1865-1878, Jun. 2011.
- K.M. Stuart and D.G. Long, "Tracking large tabular icebergs using the SeaWinds Ku-band microwave scatterometer", Deep-Sea Research Part II, doi:10.1016/j.dsr2.2010.11.004, Vol. 58, pp. 1285-1300, 2011.
- A.M. Plagge, D.C. Vandemark, and D.G. Long, "Coastal Validation of Ultra-High Resolution Wind Vector Retrieval from QuikSCAT in the Gulf of Maine", IEEE Geoscience and Remote Sensing Letters, Vol. 6, No 3, pp. 413-417, doi:10.1109/TGRS.2009.2014852, 2009.
- P.S. Chang, Z. Jelenak, J.M. Sienkiewicz, R. Knabb, M.J. Brennan, D.G. Long, and M. Freeberg, "Operational Use and Impact of Satellite Remotely Sensed Ocean Surface Vector Winds in the Marine Warning and Forecasting Environment," Oceanography, Vol. 22, No. 2, pp. 194-207, 2009.
- M.P. Owen and D.G. Long, "Land Contamination Compensation for QuikSCAT Near-Coastal Wind Retrieval," IEEE Transactions on Geoscience and Remote Sensing, doi:10.1109/TGRS.2008.2005633, Vol. 47, No 3, pp. 839-850, 2009.
- B.A. Williams and D.G. Long, "Estimation of Hurricane Winds from SeaWinds at Ultra High Resolution", IEEE Transactions on Geoscience and Remote Sensing, Vol. 46, No. 10, pp. 2924-2935, doi:10.1109/TGRS.2008.924096, 2008.
- J.R. Allen and D.G. Long, "Microwave Observations of Daily Antarctic Sea-Ice Edge Expansion and Contraction Rates," Geoscience and Remote Sensing Letters, Vol. 3, No. 1, pp. 54-58, doi:10.1109/TGRS.2005.856710, 2006.
- L.B. Kunz and D.G. Long, "Calibrating SeaWinds and QuikSCAT
Scatterometers Using Natural Land Targets," Geoscience
and Remote Sensing Letters, Vol. 2, No. 2, pp. 182-186,
- H.S. Anderson and D.G. Long, "Sea Ice Mapping Method for
SeaWinds," IEEE Transactions on Geoscience and Remote
Sensing, Vol. 43, No. 3, pp. 647-657,
- I.S. Ashcraft and D.G. Long, "Observation and Characterization
of Radar Backscatter over Greenland," IEEE Transactions
on Geoscience and Remote Sensing, Vol. 43, No. 2, pp 237-246,
- H. Stephen and D.G. Long, "Microwave Backscatter Modeling
of Erg Surfaces in the Sahara Desert," IEEE Transactions
on Geoscience and Remote Sensing, Vol. 43, No. 2, pp. 238-247,
- J. Haarpainter, R.T. Tonboe, D.G. Long and M. L. VanWoert, "Automatic
Detection and Validity of the Sea Ice Edge: An Application of
Enhanced Resolution QuikScat/SeaWinds Data," IEEE Transactions
on Geoscience and Remote Sensing, Vol. 42, No. 7, pp. 1433-1443,
- P.K. Yoho and D.G. Long, "Correlation and Covariance of
Satellite Scatterometer Measurements," IEEE Transactions
on Geoscience and Remote Sensing, Vol. 42, No. 6, pp. 1176-1187,
- D.W. Draper and D.G. Long, "Simultaneous Wind and Rain
Retrieval Using SeaWinds Data," IEEE Transactions on
Geoscience and Remote Sensing, Vol. 42, No. 7, pp. 1411-1423,
- D.W. Draper and D.G. Long, "Assessing the Quality of SeaWinds
Rain Measurements,” IEEE Transactions on Geoscience and
Remote Sensing, Vol. 42, No. 7, pp. 1424-1432,
- P.K. Yoho and D.G. Long, "An Improved Simulation Model
for Spaceborne Scatterometer Measurements," IEEE Transactions
on Geoscience and Remote Sensing, Vol. 41, No. 11, pp. 2692-2695,
- M.W. Spencer, W-Y Tsai, and D.G. Long, "High Resolution
Measurements with a Spaceborne Pencil-Beam Scatterometer Using
Combined Range/Doppler Discrimination Techniques," IEEE
Transactions on Geoscience and Remote Sensing, Vol. 41, No.
3, pp. 567-581,
- I.S. Ashcraft and D.G. Long, "The Spatial Response Function
of SeaWinds Backscatter Measurements," in Proceedings of SPIE
Vol. 5151 Earth Observing Systems VIII, William L. Barnes,
Editor, (SPIE, Bellingham, WA) pp. 609-618,
doi:10.1117/12.506291, Aug. 2003.
- M.W. Spencer, C. Wu, and D.G. Long, "Improved Resolution Backscatter
Measurements with the SeaWinds Pencil-Beam Scatterometer," IEEE
Transactions on Geoscience and Remote Sensing, Vol. 38, No.
- D.G. Long and M.W. Spencer, "Radar Backscatter Measurement
Accuracy for a Spaceborne Pencil-Beam Wind Scatterometer with
Transmit Modulation," IEEE Transactions on Geoscience
and Remote Sensing, Vol. 35, No. 1, pp. 102-114,
- M.W. Spencer, C. Wu, and D.G. Long, "Tradeoffs in the Design
of a Spaceborne Scanning Pencil-beam Scatterometer," IEEE
Transactions on Geoscience and Remote Sensing, Vol. 35, No.
1, pp. 115-126,
- I.S. Ashcraft, D.G. Long, A. Anderson, S. Richards, M. Spencer,
and B. Jones, "Sigma-0 Retrieval from SeaWinds on QuikScat,"
in Earth Observing Systems IV, William L. Barnes, Editor, Proceedings
of SPIE Vol. 3750, pp. 171-178, Denver, Colorado,
19-20 July 1999.
- D.G. Long and M.W. Spencer, "Performance Analysis for
the SeaWinds Scatterometer," Proceedings of the International
Geoscience and Remote Sensing Symposium, Lincoln, Nebraska,
27-31 May, pp. 1463-1465, 1996.
- Q.P. Remund and D.G. Long, "Iterative Estimation of Antarctic
Sea Ice Extent Using Seawinds Data," Proceedings of the International
Geoscience and Remote Sensing Symposium, pp. 491-493, Hilton
Hawaiian Village, Honolulu, Hawaii,
doi:10.1109/IGARSS.2000.861606, 24-28 July 2000.