International Archives of Photogrammetry and Remote Sensing, Vol. 32, Part 3W14, La Jolla, CA, 9-11 Nov. 1999 
AIRBORNE LASER PROFILING OF ANTARCTIC ICE STREAM FOR CHANGE DETECTION 
Blue Spikes, Bea Csatho, Ian Whillans 
Byrd Polar Research Center, The Ohio State University, 1090 Carmack Rd. Columbus, OH 43210 
[spikes.2, csatho.1, whillans+]@osu.edu 
KEY WORDS: Antarctica, Laser Altimetry, Accuracy, Repeatability, Ice Stream, and Mass Balance 
ABSTRACT 
The mass balance of ice in Antarctica is a prime need in science. The ice sheets are major variables in the global budget that controls 
sea level. It could be that thinning of the ice sheets accounts for the current rate of rise of sea level. There is a limited suite of 
techniques available for measuring mass-balance in Antarctica. A report is presented on the first of intended repeat surface mapping 
from an aircraft with GPS position determination and a downward-looking laser ranger. This method has the great merit of being 
precise and of covering large regions. Moreover, laser flights are used to make topographic maps and describe the shape of unusual 
portions of the ice sheet. The detection of special surface features raises the possibility of some mechanical understanding of ice 
sheet change. 
ice ridges that may be frozen to underlying bedrock. The 
1. INTRODUCTION details of how ice Seas operate are not well Bndarsiond; 
However, some of these ice streams are known to be changing 
very quickly with time (Hamilton et al., 1998; Bindschadler and 
Vornberger, 1998; Joughin et al, 1999; Hamilton, pers. 
comm.). The cause for the changes is a topic of some debate 
within the science community. 
Laser altimetry is expected to solve many central problems in 
Antarctica. A major concern is how ice thickness may be 
changing and affecting global sea level. A deeper issue is 
locating the source of ice thickness change and determining its 
propagation style so that the cause and effect of changes may be 
deduced. Studies have shown laser altimetry to be a valuable 
tool in mapping and monitoring glacier thickness in Alaska 
(Echelmeyer et al, 1996; Adalgeirsdóttir et al., 1998) and 
Greenland (Csatho et al., 1996; Krabill et al, 1995; Garvin and 
Williams, 1993; Krabill et al., 1999). The use of laser altimetry 
to monitor changes occurring in Antarctica is the subject of the 
present contribution. 
  
This report addresses first results of precision airborne laser 
altimetry in Antarctica. First flights were conducted during the 
1997-98 austral summer. Repeat flights are scheduled for 
January 2000. Data from the first flights have been used to 
make surface maps of four fast-flowing regions of West 
Antarctica, although only the results from Ice Stream C are 
presented here. There are numerous flight-to-flight crosses 
with one another to assess repeatability. Other flights cross 
areas surveyed using snowmobile mounted GPS to assess 
system accuracy. Long baseline accuracy is determined using 
  
flights that go near mass-balance measurement sites known as 
  
  
  
   
   
   
    
  
  
  
  
  
  
  
  
  
   
     
      
   
  
  
  
  
  
  
  
  
     
   
   
    
  
  
  
coffee-cans that are part of another study (Hamilton et al., 1998 
and Hamilton, pers. comm.). Future surveys of the same 
regions will be used to determine elevation changes over time. 
Fig. 1. Inset is a map of Antarctica with the location of the ice stream 
region enclosed in a black box. The large map is an enlargement of the 
ice stream region with laser survey lines (black grids) superimposed 
over a mosaic of advanced very high resolution radiometer imagery 
2. WORK AREA (Mullins, 1999). 
Unique features of West Antarctica, known as ice streams, are 
the focus of this study (Fig. 1). The ice streams are the major 
conduits that drain West Antarctica. They are located to the 
east of the Ross Sea meeting the Ross Ice Shelf along the Siple 
Coast. The ice streams are broad, typically around 50 km, and 
long, usually greater than 500 km, zones of rapid water- 
lubricated flow. Unlike mountain glaciers, the ice streams do 
not follow bedrock troughs. The ice streams are separated by 
3. DESCRIPTION OF LASER ALTIMETRY 
SYSTEM 
Equipment is mounted on a ski-equipped Twin Otter aircraft 
that is operated by the NSF-SOAR (National Science 
Foundation-Support Office for Aerogeophysical Research) 
facility. The geophysical systems on board include a