ICESat-2 Ground Tracks

A note for end users:
The KMLs provided below are estimates of locations and times of the ICESat-2 reference ground track and beams.  Prior to April 1 2019, we were not pointing at our RGT and as such, data collected during that time was not along planned RGTs and these KMLs should not be used in an attempt to sync with data collected between October 2018 and April 1, 2019.  The geolocation information provided in ICESat-2 data available for download at NSIDC reflects where data was actually collected.

Below are links to the kmz files for all of the laser tracks over each 91-day repeat period. Kmz Files for other areas upcoming or on request. Note that the locations and times are estimates, but should be correct to within a few minutes in time and better than 100m in the predicted locations. 

Overall Mission Orbits

These files contain the nominal mission orbits and beam locations, the files have seven tracks per orbit: one for each of the six beams of ICESat-2, and the seventh for the Reference Ground Track (RGT). The RGT is an imaginary line through the six-beam pattern that is handy for getting a sense of where the orbits fall on Earth, and which the mission uses to point the observatory. However, the six tracks for the six beams are our best estimate of where the beams will actually fall on Earth’s surface.
Antarctic Orbit
Arctic Orbit
Western Hemisphere Ground Tracks
Eastern Hemisphere Ground Tracks

Time Specific Orbits

These files contain the reference ground track time and locations for specific date ranges. Updated KML files have been posted to this website containing individual files for each RGT with a date and time stamp posted every 420 kilometers along-track (roughly 1 minute of flight time in between each point).  Our first RGT is #234; this is where the time series begins.  The date of each RGT is in the file name, so the user can easily ascertain where and when ICESat-2 will be on a particular day.

RGTs with Dates and Times (UTC) for October 13 - December 28, 2018
RGTs with Dates and Times (UTC) for December 28 (2018) - March 29, 2019
RGTs with Dates and Times (UTC) for March 29 - June 28, 2019

RGTs with Dates and Times (UTC) for July 9 - September 26, 2019 -- ICESat-2 was in safe-hold from June 26 through July 9, 2019.  ATLAS was off during this time, so we were not collecting data or pointing at our reference ground track.  We resumed RGT pointing shortly after the laser was turned back on, and on July 31, we began vegetation off-pointing at RGT 518.
RGTs with Dates and Times (UTC) for September 26 - December 26, 2019
 

  • These files are posted at a fairly low resolution in order to make the file size manageable, with one point approximately every 7 kilometers.
     
  • Over the polar areas and oceans, ICESat-2 will repeat its ground tracks every 91 days as it orbits; over land the satellite will point slightly off the RGT to measure more of Earth’s forests. The transitions between repeat-track pointing and off-pointing are included in these ground tracks. Near the poles, the difference between the two is subtle, but it becomes more pronounced near the equator.
     
  • Remember that while these represent the nominal location of the sub-satellite point with associated date/time of the ICESat-2 overpass, the mission requirements are for 45 meter pointing control which currently appears to be met.

 

Key ICESat-2/ATLAS Performance Specifications
For detailed information about ICESat-2 and ATLAS specifications, please see Neumann et al., 2019.

 Nominal duration of mission 3 Years
 Number of beams 6 organized in 3 pairs
 Beam pattern
 Footprint size 17 m 
 Field of view 45 m
 Pulse repetition frequency 10kHz (~0.7m on the ground)
 Laser wavelength 532 nm
 Pointing control 45 m
 Pointing knowledge 6.5 m
 Single-photon time-of-flight precision 800 ps

ATLAS expected performance in range using the current best estimates for winter and
summer conditions.

Target type Lambertian surface reflectance
(532nm)
N signal photons per shot
(weak beam)
N signal photons per shot
(strong beam)
100-shot std dev (weak beam) 100-shot std dev (strong beam)
 Ice sheet (interior) 0.9 -0.98 0.4 - 3.0 1.6 - 12.0 4 - 9 2 - 4
 Ice sheet (glaciers) 0.6 - 0.9 0.6 - 1.0 0.6 - 3.9  12 - 29 6 - 14
 Sea Ice 0.8 - 0.9 0.6 - 2.1 2.3 - 8.5 5 - 8 3 - 4
 Leads  * - 0.2
(much higher when specular)
0.05 - 0.2 0.2 - 1.0 2 - 5 2 - 5

Orbit and coverage

 Inclination 92 degrees
(coverage up to 88 degrees north and south)
 Altitude ~500 km
 Semi-major axis 6855 km
Coverage

91-day exact repeat orbit
with monthly sub-cycle for the polar regions and oceans.
Operational off-nadir pointing over land areas
to generate a dense grid of data over 2 years

 

 

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