SeaWinds on ADEOS-II and QuikScat
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 is scheduled
for Launch in early 2000 aboard ADEOS-II.
SeaWinds on QuikScat is 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
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 will be 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 are very encouraging
and 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.) Initial results for ice motion tracking are also encouraging.
These results can be viewed from Mark Drinkwater's web
site (follow the Research then Antarctic Sea Ice links).
QuikScat Data Products
Under the direction of Dr. Long, the MERS lab will produce a series
of standard image products from SeaWinds data. These products are
described in the MERS QuikScat Products
home page which has links to sample data products and data reading
QuikScat Calibration Ground Station
A specialized calibration ground station (CGS) has been developed
to aid in the calibration of SeaWinds. BYU has been involved in
the development and analysis of the QuikScat CGS. Further information
is available here.
Selected MERS 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. 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, Jan. 1997.
- 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, Jan. 1997.
- 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, "Sea Ice Mapping Algorithm for QuikSCAT
and Seawinds," Proceedings of the International Geoscience
and Remote Sensing Symposium, pp. 1686-1688, Seattle, Washington,
6-10 July, 1998.