scholarly journals A Doppler radar for continuous remote measurement of river ice velocity

1996 ◽  
Vol 23 (2) ◽  
pp. 408-417
Author(s):  
M. G. Ferrick ◽  
N. E. Yankielun ◽  
D. F. Nelson
Keyword(s):  
Velocity Measurement ◽  
Measurement Errors ◽  
Doppler Radar ◽  
Full Range ◽  
Radar System ◽  
River Ice ◽  
Remote Measurement ◽  
Connecticut River ◽  
Ice Dynamics ◽  
Ice Velocity

River ice velocity measurements are fundamental to analyses of river ice dynamics. Ice velocity measurement with a continuous-wave Doppler radar system having real-time data acquisition and digital signal processing capability was evaluated during a river breakup and a frazil run on the Connecticut River. This system can be rapidly deployed, requires minimal operator interaction, will continuously acquire, process, store, and display ice velocity data, and does not depend on visibility conditions. In parallel, video records of ice motion were obtained at the same location for later manual processing and comparison with the radar results. We describe the Doppler radar system and obtain bounding estimates of possible measurement errors. The principal error in Doppler ice velocity measurement is due to the beam width of the radar antenna, and an analytical method is developed to minimize this error. Measured ice velocities ranged from 1 to 2.5 m/s during the river breakup, and from 0.5 to 0.65 m/s in the frazil run. Quantitative comparisons between the radar and video results show fundamental agreement between these measurement methods, and demonstrate that Doppler radar is an effective, efficient, and precise tool for obtaining river ice velocities over the full range of possible ice and velocity conditions. Key words: Doppler radar, river ice velocity, velocity measurement, error analysis, river breakup, frazil run.

Data-Based Quadrature Imbalance Compensation for a CW Doppler Radar System

2013 ◽  
Vol 61 (4) ◽  
pp. 1718-1724 ◽  
Author(s):  
Aditya Singh ◽  
Xiaomeng Gao ◽  
Ehsan Yavari ◽  
Mari Zakrzewski ◽  
Xi Hang Cao ◽  
...  
Keyword(s):  
Doppler Radar ◽  
Radar System

scholarly journals Geospatial simulations of airborne ice-penetrating radar surveying reveal elevation under-measurement bias for ice-sheet bed topography

2020 ◽  
Vol 61 (81) ◽  
pp. 46-57 ◽  
Author(s):  
Oliver T. Bartlett ◽  
Steven J. Palmer ◽  
Dustin M. Schroeder ◽  
Emma J. MacKie ◽  
Timothy T. Barrows ◽  
...  
Keyword(s):  
Measurement Errors ◽  
Survey Design ◽  
Ice Sheet ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Ice Dynamics ◽  
Outlet Glacier ◽  
Bed Topography ◽  
Novel Approach

AbstractAirborne radio-echo sounding (RES) surveys are widely used to measure ice-sheet bed topography. Measuring bed topography as accurately and widely as possible is of critical importance to modelling ice dynamics and hence to constraining better future ice response to climate change. Measurement accuracy of RES surveys is influenced both by the geometry of bed topography and the survey design. Here we develop a novel approach for simulating RES surveys over glaciated terrain, to quantify the sensitivity of derived bed elevation to topographic geometry. Furthermore, we investigate how measurement errors influence the quantification of glacial valley geometry. We find a negative bias across RES measurements, where off-nadir return measurement error is typically −1.8 ± 11.6 m. Topographic highlands are under-measured an order of magnitude more than lowlands. Consequently, valley depth and cross-sectional area are largely under-estimated. While overall estimates of ice thickness are likely too high, we find large glacier valley cross-sectional area to be under-estimated by −2.8 ± 18.1%. Therefore, estimates of ice flux through large outlet glaciers are likely too low when this effect is not taken into account. Additionally, bed mismeasurements potentially impact our appreciation of outlet-glacier stability.

scholarly journals Assessing ice margin fluctuations on differing timescales: Chronological constraints from Sermeq Kujatdleq and Nordenskiöld Gletscher, central West Greenland

The Holocene ◽  
2018 ◽  
Vol 28 (7) ◽  
pp. 1160-1172 ◽  
Author(s):  
Samuel E Kelley ◽  
Jason P Briner ◽  
Sandy L O’Hara
Keyword(s):  
Late Holocene ◽  
Sediment Cores ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Dynamics ◽  
West Greenland ◽  
Southern Site ◽  
Ice Velocity ◽  
Observational Record ◽  
Local Variability

The observational record of ice margin position reveals asynchrony in both the timing and magnitude of Greenland Ice Sheet (GrIS) margin fluctuations and illustrates the complex reactions of ice sheets to climatic perturbations. In this study, we reconstruct the timing and pattern of middle- and late-Holocene GrIS margin fluctuations at two locations, ~190 km apart, in central West Greenland using radiocarbon-dated sediment cores from proglacial-threshold lakes. Our results demonstrate that deglaciation occurs at both sites during the early Holocene, with the ice sheet remaining in a smaller-than-present ice margin configuration until ~500 years ago when it readvanced into lake catchments at both sites. At our northern site, Sermeq Kujatdleq, the late-Holocene advance of the GrIS approached maximum position during the past 280 years, with the culmination of the advance occurring at AD 1992–1994, and modern retreat was underway by AD 1998–2001. In contrast, field and observational evidence suggest that the GrIS at our southern site, Nordenskiöld Gletscher, has been advancing or stable throughout the 20th century. These results, in conjunction with previous work in the region, highlight the asynchronous nature of late-Holocene advances and subsequent modern retreat, implying that local variability, such as ice velocity or ice dynamics, is responsible for modulating ice margin response to changes in climate on these decadal to centennial timescales. Additional high-resolution records of past ice sheet fluctuations are needed to inform and more accurately constrain our predictions of future cryosphere response to changes in climate.

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