The footprint/altitude ratio for helicopter electromagnetic sounding of sea‐ice thickness: Comparison of theoretical and field estimates

Geophysics ◽  
1995 ◽  
Vol 60 (2) ◽  
pp. 374-380 ◽  
Author(s):  
Austin Kovacs ◽  
J. Scott Holladay ◽  
Clyde J. Bergeron
Keyword(s):  
Sea Ice ◽  
Ice Thickness ◽  
Remote Measurement ◽  
Sea Ice Thickness ◽  
Airborne Measurements ◽  
Sensing Technology ◽  
Induction Sounding ◽  
Coil Antenna ◽  
Ice Water ◽  
Lateral Variations

Helicopter‐towed electromagnetic (HEM) induction sounding systems are typically used for geologic surveys. More recently, HEM systems have been used for the remote measurement of sea‐ice thickness and shallow sea bathymetry. An important aspect of this remote sensing technology is the area, or footprint, in which the secondary field is predominantly generated by induced currents. A knowledge of the size of the footprint is important to understanding the accuracy of HEM sounding results over lateral variations in relief or conductivity. Conventional wisdom among workers in the field held that the footprint diameter is a few times the HEM antenna altitude. We confirm this view using airborne measurements over sea ice to calculate the footprint size/antenna altitude ratio. These findings are compared to various theoretical estimates and are found to be in reasonable agreement. For a vertical coaxial coil antenna arrangement, the apparent footprint diameter was found to be about 1.3 times the antenna height above the sea‐ice/water interface, and for a horizontal coplanar coil figuration the ratio is about 3.8 times the antenna height.

scholarly journals A sea-ice thickness retrieval model for 1.4 GHz radiometry and application to airborne measurements over low salinity sea-ice

2010 ◽  
Vol 4 (4) ◽  
pp. 583-592 ◽  
Author(s):  
L. Kaleschke ◽  
N. Maaß ◽  
C. Haas ◽  
S. Hendricks ◽  
G. Heygster ◽  
...  
Keyword(s):  
Sea Ice ◽  
Brightness Temperature ◽  
Ice Thickness ◽  
First Year ◽  
Sea Ice Thickness ◽  
Model Calculations ◽  
Airborne Measurements ◽  
Low Salinity ◽  
Research Aircraft ◽  
L Band

Abstract. In preparation for the European Space Agency's (ESA) Soil Moisture and Ocean Salinity (SMOS) mission, we investigated the potential of L-band (1.4 GHz) radiometry to measure sea-ice thickness. Sea-ice brightness temperature was measured at 1.4 GHz and ice thickness was measured along nearly coincident flight tracks during the SMOS Sea-Ice campaign in the Bay of Bothnia in March 2007. A research aircraft was equipped with the L-band Radiometer EMIRAD and coordinated with helicopter based electromagnetic induction (EM) ice thickness measurements. We developed a three layer (ocean-ice-atmosphere) dielectric slab model for the calculation of ice thickness from brightness temperature. The dielectric properties depend on the relative brine volume which is a function of the bulk ice salinity and temperature. The model calculations suggest a thickness sensitivity of up to 1.5 m for low-salinity (multi-year or brackish) sea-ice. For Arctic first year ice the modelled thickness sensitivity is less than half a meter. It reduces to a few centimeters for temperatures approaching the melting point. The campaign was conducted under unfavorable melting conditions and the spatial overlap between the L-band and EM-measurements was relatively small. Despite these disadvantageous conditions we demonstrate the possibility to measure the sea-ice thickness with the certain limitation up to 1.5 m. The ice thickness derived from SMOS measurements would be complementary to ESA's CryoSat-2 mission in terms of the error characteristics and the spatiotemporal coverage. The relative error for the SMOS ice thickness retrieval is expected to be not less than about 20%.

The Estimate of Sea Ice Thickness Based on the Relative Albedo of NOAA/AVHRR

2011 ◽  
Vol 356-360 ◽  
pp. 2816-2819
Author(s):  
Shuai Yuan ◽  
Wei Gu ◽  
Wei Bin Chen
Keyword(s):  
Sea Ice ◽  
Coastal Area ◽  
Preliminary Analysis ◽  
Bohai Sea ◽  
Average Error ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Noaa Avhrr ◽  
Avhrr Data ◽  
Ice Water

The estimate of sea ice thickness is the academic base of sea ice research in Bohai Sea. According to the ice-water spectrum differences and the correlation between ice thickness and albedo, this paper comes up with a sea ice thickness inversion model based on the relative albedo of NOAA/AVHRR data. The results are better in the coastal area and the average error of this method is about 21%. Then a preliminary analysis has been made on the errors of the estimate of sea ice thickness.

Sounding sea ice thickness using a portable electromagnetic induction instrument

Geophysics ◽  
1991 ◽  
Vol 56 (12) ◽  
pp. 1992-1998 ◽  
Author(s):  
Austin Kovacs ◽  
Rexford M. Morey
Keyword(s):  
Sea Ice ◽  
Electromagnetic Induction ◽  
Direct Determination ◽  
Conductivity Measurement ◽  
Field Trials ◽  
The Arctic ◽  
Ice Thickness ◽  
Remote Measurement ◽  
Sea Ice Thickness ◽  
Processing Module

Field trials using a man‐portable, commercially available, electromagnetic induction (EMI) sounding instrument, with a plug‐in data processing module for the remote measurement of sea ice thickness, are discussed. The processing module was made to allow for the direct determination of sea ice thickness and to show the result in a numerical display. The processing module system was capable of estimating ice thickness within 10 percent of the the true ice value for ice from about 0.7 to 3.5 m thick, the thickest of undeformed ice in our study area. However, since seawater under the Arctic pack ice has relatively uniform conductivity (2.55 ± 0.05 S/m), a simplified method can be used for estimating sea ice thickness using just an EMI instrument. This technique uses only the EMI conductivity measurement, is easy to put into use, and does not rely on theoretically derived look‐up tables or phasor diagrams, which may not be accurate for the conditions of the area.

scholarly journals A sea ice thickness retrieval model for 1.4 GHz radiometry and application to airborne measurements over low salinity sea ice

2009 ◽  
Vol 3 (3) ◽  
pp. 995-1022 ◽  
Author(s):  
L. Kaleschke ◽  
N. Maaß ◽  
C. Haas ◽  
S. Hendricks ◽  
G. Heygster ◽  
...  
Keyword(s):  
Sea Ice ◽  
Brightness Temperature ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Model Calculations ◽  
Airborne Measurements ◽  
Low Salinity ◽  
Research Aircraft ◽  
L Band ◽  
Spatio Temporal

Abstract. In preparation for the European Space Agency's (ESA) Soil Moisture and Ocean Salinity (SMOS) mission we investigated the potential of L-band (1.4 GHz) radiometery to measure sea ice thickness. Sea ice brightness temperature was measured at 1.4 GHz and ice thickness were measured along nearly coincident flight tracks during the SMOS Sea-Ice campaign in the Bay of Bothnia in March 2007. A research aircraft was equipped with the L-band Radiometer EMIRAD and coordinated with helicopter based electromagnetic induction (EM) ice thickness measurements. We developed a three layer (ocean-ice-atmosphere) dielectric slab model for the calculation of ice thickness from brightness temperature. The dielectric properties depend on the relative brine volume which is a function of the bulk ice salinity and temperature. The model calculations suggest a thickness sensitivity of up to 1.5 m for low-salinity (multi-year or brackish) sea ice. For Arctic first year ice the modeled thickness sensitivity is roughly half a meter. It reduces to a few centimeters for temperatures approaching the melting point. Although the campaign was conducted under such unfavorable melting conditions and despite limited spatial overlap between the L-band and EM-measurements was small we demonstrate a large potential for retrieving the ice thickness in the range of 0.2 to 1.5 m. Furthermore, we show that the ice thickness derived from SMOS measurements would be complementary to ESA's CryoSat-2 mission in terms of the error characteristics and the spatio-temporal coverage.

scholarly journals Ship-borne electromagnetic induction Sounding of Sea-ice thickness in the Southern Sea of Okhotsk

2006 ◽  
Vol 44 ◽  
pp. 253-260 ◽  
Author(s):  
Shotaro Uto ◽  
Takenobu Toyota ◽  
Haruhito Shimoda ◽  
Kazutaka Tateyama ◽  
Kunio Shirasawa
Keyword(s):  
Sea Ice ◽  
Sea Of Okhotsk ◽  
Theoretical Calculations ◽  
Multilayered Structure ◽  
Ice Thickness ◽  
Total Thickness ◽  
Sea Ice Thickness ◽  
Inductive Instrument ◽  
The Difference ◽  
Induction Sounding

AbstractRecent observations have revealed that dynamical thickening is dominant in the growth process of Sea ice in the Southern Sea of Okhotsk. That indicates the importance of understanding the nature of thick deformed ice in this area. The objective of the present paper is to establish a Ship-based method for observing the thickness of deformed ice with reasonable accuracy. Since February 2003, one of the authors has engaged in the core Sampling using a Small basket from the icebreaker Soya. Based on these results, we developed a new model which expressed the internal Structure of pack ice in the Southern Sea of Okhotsk, as a one-dimensional multilayered Structure. Since 2004, the electromagnetic (EM) inductive Sounding of Sea-ice thickness has been conducted on board Soya. By combining the model and theoretical calculations, a new algorithm was developed for transforming the output of the EM inductive instrument to ice + Snow thickness (total thickness). Comparison with total thickness by drillhole observations Showed fair agreement. The probability density functions of total thickness in 2004 and 2005 Showed Some difference, which reflected the difference of fractions of thick deformed ice.

scholarly journals Empirical sea ice thickness retrieval during the freeze up period from SMOS high incident angle observations

2013 ◽  
Vol 7 (4) ◽  
pp. 4379-4405 ◽  
Author(s):  
M. Huntemann ◽  
G. Heygster ◽  
L. Kaleschke ◽  
T. Krumpen ◽  
M. Mäkynen ◽  
...  
Keyword(s):  
Sea Ice ◽  
Climate Modeling ◽  
Incidence Angle ◽  
Incident Angle ◽  
The Arctic ◽  
Ice Thickness ◽  
Growth Data ◽  
Sea Ice Thickness ◽  
Airborne Measurements ◽  
Brightness Temperatures

Abstract. Sea ice thickness information is needed for climate modeling and ship operations. Here a method to detect the thickness of sea ice up to 50 cm during the freezeup season based on high incidence angle observations of the Soil Moisture and Ocean Salinity (SMOS) satellite working at 1.4 GHz is suggested. By comparison of thermodynamic ice growth data with SMOS brightness temperatures, a high correlation to intensity and an anti correlation to the difference between vertically and horizontally polarised brightness temperatures at incidence angles between 40 and 50 ° are found and used to develop an empirical retrieval sensitive to thin sea ice up to 50 cm thickness. It shows high correlations with ice thickness data from airborne measurements and reasonable ice thickness patterns for the Arctic freeze up period.

scholarly journals Electromagnetic Induction Sounding of Sea Ice Thickness

1996 ◽  
Author(s):  
Austin Kovacs ◽  
Deborah Diemand ◽  
John J. Bayer ◽  
Jr
Keyword(s):  
Sea Ice ◽  
Electromagnetic Induction ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Induction Sounding

scholarly journals Signatures of supercooling: McMurdo Sound platelet ice

2012 ◽  
Vol 58 (207) ◽  
pp. 38-50 ◽  
Author(s):  
Alexander J. Gough ◽  
Andrew R. Mahoney ◽  
Pat J. Langhorne ◽  
Michael J.M. Williams ◽  
Natalie J. Robinson ◽  
...  
Keyword(s):  
Sea Ice ◽  
Volume Fraction ◽  
Ice Crystals ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Ice Shelves ◽  
Antarctic Sea Ice ◽  
Oceanic Heat Flux ◽  
Small Crystals ◽  
Ice Water

AbstractNear ice shelves around Antarctica the ocean becomes supercooled and has been observed to carry small suspended ice crystals. Our measurements demonstrate that these small crystals are persistently present in the water column beneath the winter fast ice, and when incorporated in sea ice they reduce the mean grain size of the sea-ice cover. By midwinter, larger ice crystals below the ice/water interface are observed to form a porous sub-ice platelet layer with an ice volume fraction of 0.25 ± 0.06. The magnitude and direction of the oceanic heat flux varied between (5 ± 6) Wm-2 (upwards) and (-15 ± 10) Wm-2 (downwards) in May, but by September it settled between (-6 ± 2) and (-11 ± 2) W m-2. The negative values imply that the ocean acts as a heat sink which is responsible for the growth of 12% of the ice thickness between June and September. This oceanic contribution should not be ignored in models of Antarctic sea-ice thickness close to an ice shelf.

Sign in / Sign up

Export Citation Format

Share Document