can now be realized through application of off-
0.6
the-shelf 10-GHz and 24-GHz microwave trans-
ceiver modules consisting of a horn antenna, cir-
culator, diode mixer, and Gunn oscillator. These
0.4
modules only require connections to dc power
and to a data acquisition computer to realize a
0.2
Doppler radar system, encouraging long-term or
Radar
permanent mounting of sensors at strategic points
Video
on a river to provide early warning and continu-
0
200
400
600
800
0
1000
ous monitoring of ice freeze-up or breakup. A lap-
Time (s)
top computer equipped with a PCMCIA data ac-
Figure 14. Comparison of ice velocity results for the
quisition card enhances system portability and re-
frazil run after the video results are multiplied by a con-
duces power requirements.
stant that equates the mean velocity of each record.
ity polynomials are compared in Figure 14 after
LITERATURE CITED
the video velocity polynomial is multiplied by
Arcone, S.A. (1991) Dielectric constant and layer
1.041 to correct for the difference in the means.
thickness interpretation of helicopter-borne short-
Discounting the tail of the radar polynomial that
pulse radar waveforms reflected from wet and dry
is an end-effect of the final oscillation, the RMS
river-ice sheets, IEEE TGARS, 29: 768777.
difference between these curves is 0.014 m/s, or
Arcone, S.A. and A.J. Delaney (1987) Helicopter-
0.026 when normalized by the mean velocity. Ex-
borne short-pulse radar profiles of river-ice sheets
cept for the oscillations induced by strong and
in Alaska. Journal of Glaciology, 97: 333341.
sparse reflectors, the Doppler radar and video
Barton, D.K. (1964) Radar System Analysis. New
data agreement is well within the measurement
York: Prentice-Hall.
errors of the methods. The Doppler radar system
Ferrick, M.G., P.B. Weyrick and S.T. Hunnewell
again provided an excellent velocity measure-
(1992) Analysis of river ice motion near a breaking
ment with minimal processing.
front. Canadian Journal of Civil Engineering, 19: 105
116.
Ferrick, M.G., P.B. Weyrick and D.F. Nelson (1993) A
CONCLUSIONS
kinematic model of river ice motion during dynam-
Doppler ice velocity measurements are made
ic breakup. Nordic Hydrology, 24: 111-134.
remotely, can be displayed in real time, and are
Lewis, E.O., B.W . Currie and S.Haykin (1987) Detec-
not affected by light, fog, or ice motion conditions.
tion and Classification of Ice. New York: John Wiley
and Sons.
Doppler radar can measure and resolve the veloc-
Prowse,T.D. and M.N. Demuth (1991) Measurement
ity of ice moving in a river with precision com-
of freeze-up and break-up ice velocities. In Proceed-
parable to or better than analysis-intensive video
ings of the 48th Eastern Snow Conference, Guelph,
techniques, over the complete range of ice and vel-
Ontario, 57 June, p. 325331.
ocity conditions. The maximum error in Doppler
radar measurement of river ice motion is about 5%
Prentice-Hall.
of the velocity. Agreement between the mean
Skolnik, M.I. (1980) Introduction to Radar Systems.
Doppler and video velocities was obtained within
New York: McGraw-Hill.
7% for the ice breakup case study and 4% for the
Yankielun, N.E. and M.G. Ferrick (1993) Automat-
frazil run. Video grid distortion during breakup
ic, continuous river stage measurement with a mil-
and sparse radar targets during the frazil run are
limeter-wave FM-CW radar. USA Cold Regions Re-
likely causes of these systematic differences in vel-
search and Engineering Laboratory, CRREL Report
ocity. The RMS differences between the mean-
93-24.
corrected velocity curves were about 3% for both
Yankielun, N.E., S.A. Arcone and R.K. Crane (1992)
cases. A high gain, narrow-beam antenna im-
Thickness profiling of freshwater ice using a milli-
proved signal-to-noise performance of our Dop-
meter-wave FM-CW radar. IEEE Transactions on
pler radar system and minimized data processing
Geoscience and Remote Sensing, 80: 10941100.
requirements. An increase in the source frequency
Yankielun, N.E., M.G. Ferrick and P.B. Weyrick
of the system provided a proportional increase in
(1993) Development of an airborne millimeter-
the velocity resolution.
wave FM-CW radar for mapping river ice. Canadian
Significant cost reduction and miniaturization
Journal of Civil Engineering, 20: 10571064.
11
Previous Page
