Inter-campaign Bias Corrections Citations and References

Past ICB assessments, citations below from earlier work, provided for background:

Urban et al. 2012 (
Abstract: This paper summarizes inter-campaign bias estimation methods and results developed in support of Ice, Cloud and land Elevation Satellite (ICESat-1) mission validation. ICESat-1 made more than 2 billion laser altimeter measurements from 2003-2009. Due to laser lifetime issues, while continuing to address the mission's primary goal of detecting long-term ice sheet changes, data were collected in 18 distinct campaigns - approximately 33-day periods two or three times per year. The overall mission has met the requirement for delivering elevations with an accuracy of 15 cm or better; however, verification studies at several calibration/validation sites have detected significant inter-campaign elevation biases. Additionally, inter-campaign biases vary in different regions, over different surface types, different analysis methods, and data-release versions.The biases are summarized and evaluated for consistency of potential trends in residual bias in the final data Release 633 that would affect estimates of long-term elevation change rates.

Ewert et al. 2012 (doi: 10.1111/j.1365-246X.2012.05649.x)
Relative ICESat biases were determined by a regional crossover adjustment over the ice surface within the area of subglacial Lake Vostok, East Antarctica. Repeated GNSS observations at 56 sites distributed all over the lake area (2001-2013) as well as repeated kinematic GNSS profiling around Vostok station (2001-2013) have shown independently and consistently that the ice surface elevation above the lake has not changed significantly throughout the ICESat mission (Richter et al. 2008; Richter et al. 2014). Moreover, the ice above the lake has been shown to be in hydrostatic equilibrium (Ewert et al. 2012) which allows to extrapolate reliably the stability of the ice surface from the GNSS observation sites over the entire lake area. All data are GLA12, from Release 531. Note that the biases in the original publication are given with reverse sign with respect to the “conventional sign definition” in the Evaluation Criteria table.

Pritchard et al. 2012 (doi: 10.1038/nature10968)
ICESat biases were calculated from comparison between ICESat elevation data and mean sea surface elevations using Release 428 data. The values were provided through a personal communication with Tim Urban (2009) and can be found in the supplementary Table 2.

Shepherd et al. 2012 (doi: 10.1126/science.1228102)
ICESat biases were calculated from comparison between ICESat elevation data and mean sea surface elevations using both Release 633 and 428 data. The values were provided through a personal communication with Tim Urban and can be found in the supplementary Table 5.

Schutz et al. 2011 (
ICESat Science Team members have detected inter-campaign elevation biases from different areas and various surface types across the globe. The Release 33 data reprocessing (elevation level 633) includes the parameter i_ElevBiasCorr on GLA06/12/13/14/15 products. However, this bias has not been classified: different groups estimate different biases. Therefore, this parameter should not be used.

Siegfried et al. 2011 (doi: 10.1109/TGRS.2011.2127483)
This work estimates ICESat biases for mission phases L3I, L3J, L2D and L2E using GPS measurements and GLA12 data from Release ?31. The values can be found in Table 3, along with a comparison to biases from previous studies (Fricker et al. 2005, Wesche et al. 2009, and Urban (2010, personal communication).

Sorensen et al. 2011 (doi: 10.5194/tc-5-173-2011)
ICESat bias trend is estimated by O.B. Andersen and T. Bondo (Personal Communication, 2010), through comparison between Release ?31 GLA15 ocean altimetry data and the DNSC08 mean sea surface topography model. The trend is reported as 1.59 ± 0.4 cm/year (1.29 ± 0.4 cm/year after correction for sea level rise determined as 0.3 cm/year by Leuliette et al. (2004)). No individual mission campaign bias values are reported in this work. However, in the 2010 dissertation by Sorensen, individual campaign elevation bias values are shown in Figure 8.7 but not tabulated.

Zwally et al. 2011 (doi: 10.3189/002214311795306682)
ICESat biases are determined for 12 mission phases between L2A and L3I (fall 2003 to fall 2007), using data from Release 428 except for phase L2C where data from release 128 were used. Elevation measurements are compared to elevations of open water between sea ice in the Arctic Ocean.  The bias values are adjusted for a sea level rise rate of 0.3 cm/year.

Gunter et al. 2010 (doi: 10.1007/978-3-642-10634-7_75)
This approach determines ICESat elevation biases by assuming that height changes in parts of East Antarctica are flat. Determination of a flat region uses ECMWF (European Centre for Medium-Range Weather Forecasts) mean solid precipitation data over Antarctica from January 2003 to December 2007.  The region is shown in Fig. 75.3 and roughly corresponds to the same area outlined by Hofton et al. (2013). The bias rate calculated from this region, between 2003 and 2007, is 2.1 cm/year for crossover data (4.7 cm/year for repeat track data). No individual mission phase data are presented in this source. Release?

Urban 2010 (doi: 10.1109/TGRS.2011.2127483)
These ICESat bias values are found in Siegfried et al. (2011), Table 3, and are reported for mission phases L2a to L2f. The values were calculated following a sea surface model method outlined in Gunter et al. 2009, and reported by Tim Urban through personal communication to the author (Siegfried).  All values are from Release 431 data.

Gunter et al. 2009 (doi: 10.1007/s00190-009-0323-4)
ICESat intercampaign biases were derived over global oceans using a mean sea surface topography model based on TOPEX/Poseidon data, following the procedure of Urban and Schutz (2005). The trend determined for the time period 2003-2007, is 2.3 ± 0.9 cm/year. After adjusting this trend for sea level rise (0.3 cm/yr, following Leuliette et al. (2004)), the final bias correction was reported as 2.0 ± 0.9 cm/year. Individual mission phase values for L1a, L2a, L2b, L3a, L3b, L3c, L3d, L3e, L3f, L3g, and L3h, with associated errors, are shown in Figure 1 but are not tabulated. The companion table to this writeup reports values estimated from reading Figure 1. All data are from Release 428.

Riva et al. 2009 (doi:10.1016/j.epsl.2009.10.013)
ICESat biases were determined following a similar method to Gunter et al. (2008), by choosing an arid region of East Antarctica where ECMWF data indicate less than 2 cm water equivalent height per year of average solid precipitation between 2003 and 2006. The result was a bias rate of 2.6 cm/year, with a reported uncertainty of 0.3 cm/year. Release?

Wesche et al. 2009 (doi:10.1016/j.isprsjprs.2009.01.005)
ICESat biases were determined in a region of East Antarctica, in Dronning Maud Land. These biases are for mission phases L3G and L3H only, using Release 428 data, and were calculated by differencing crossover elevations in GLA12 data from a DEM constructed from GPS data collected in 1998/99 and 2000/01 campaigns. The bias correction is 11 cm for GPS minus GLA12 data, with a mean error of 23 cm.

Urban et al. 2008 (3645, IEEE Int. Geosci. and Rem. Sens. Symp., Boston, MA, July 7–11.)
ICESat elevation bias rate reported in Gunter et al. 2008 as roughly 2 cm/year. This is determined by Urban et al. (co-author on Gunter et al. 2008) by comparing a global mean sea surface model with ICESat data. It is also reported that this bias rate is only applicable for latitudes below 60 degrees, the coverage boundary for the sea surface models used. Release?

Urban and Schutz 2005 (doi:10.1029/2005GL024306)
Examined the accuracy of ICESat L2a data from GLA15 ocean elevations (Release 421) compared to TOPEX and mean sea surface elevations. This resulted in a mean difference of -11.7 ± 1.8 cm for the L2a period.  Data are found in Table 4.

Fricker et al. 2005 (doi:10.1029/2005GL023423)
Obtained differences between GPS reference elevations and ICESat-derived elevations for a region within the Salar de Uyuni, Bolivia for 6 mission phases (L2A, L2B, L2C, L3A,L3B, and L3C). Data come from two different ground tracks (Track 85, descending, and Track 360, ascending). Results are found in Table 1, and also found in Siegfried et al. 2011, Table 3. The results for the standard geolocated product, as well as the same product with the saturation correction applied, are reported as standard mean differences, in cm, and their associated standard deviation values.


Borsa AA, Moholdt G, Fricker HA, and Brunt KM (2014). A range correction for ICESat and its potential impact on ice-sheet mass balance studies. Cryosphere, 8

Borsa AA, Fricker HA, and Brunt KM (2017, submitted). ICESat post-mission elevation assessment from an independently surveyed terrestrial reference surface.  The Cryosphere

Ewert, H., Popov, S. V., Richter, A., Schwabe, J., Scheinert, M., and Dietrich, R. (2012). Precise analysis of ICESat altimetry data and assessment of the hydrostatic equilibrium for subglacial Lake Vostok, East Antarctica. Geophysical Journal International.

Fricker, H. A., Borsa, A., Minster, B., Carabajal, C., Quinn, K., and Bills, B. (2005). Assessment of ICESat performance at the salar de Uyuni, Bolivia. Geophysical Research Letters.

Gunter, B., Urban, T., Riva, R., Helsen, M., Harpold, R., Poole, S., … Tapley, B. (2009). A comparison of coincident GRACE and ICESat data over Antarctica. Journal of Geodesy.

Gunter, B. C., Riva, R. E. M., Urban, T., Harpold, R., Schutz, B., Nagel, P., and Helsen, M. (2010). Evaluation of GRACE and ICESat Mass Change Estimates Over Antarctica. In International Association of Geodesy Symposia.

Gunter, B. C., Didova, O., Riva, R. E. M., Ligtenberg, S. R. M., Lenaerts, J. T. M., King, M. A., … Urban, T. (2014). Empirical estimation of present-day Antarctic glacial isostatic adjustment and ice mass change. Cryosphere.

Helm, V., Humbert, A., and Miller, H. (2014). Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2. The Cryosphere, 8, 1539–1559.

Hofton, M. A., Luthcke, S. B., and Blair, J. B. (2013). Estimation of ICESat intercampaign elevation biases from comparison of lidar data in East Antarctica. Geophysical Research Letters.

Kwok R, Cunningham GF, Zwally HJ and Yi D (2007) Ice, Cloud, and land Elevation Satellite (ICESat) over Arctic sea ice: retrieval of freeboard. J. Geophys. Res., 112(C12), C12013 doi: 10.1029/2006JC003978.

Lenaerts, J. T. M., van den Broeke, M. R., van de Berg, W. J., van Meijgaard, E., and  Munneke, P. K.: A new, high-resolution surface mass balance map of Antarctica (1979-2010) based on regional atmospheric climate modeling, Geophys. Res. Lett., 39, L04501, 4501–4501, doi:10.1029/2011GL050713, 2012.

Leuliette, E. W., Nerem, R. S., and Mitchum, G. T. (n.d.). Calibration of TOPEX/Poseidon and Jason Altimeter Data to Construct a Continuous Record of Mean Sea Level Change. Retrieved from

Pritchard, H. D., Ligtenberg, S. R. M., Fricker, H. A., Vaughan, D. G., Van Den Broeke, M. R., and Padman, L. (2012). Antarctic ice-sheet loss driven by basal melting of ice shelves. Nature, 484.

Richter, A., Popov, S. V., Fritsche, M., Lukin, V. V., Matveev, A. Y., Ekaykin, A. A., … Dietrich, R. (2014). Height changes over subglacial Lake Vostok, East Antarctica: Insights from GNSS observations. Journal of Geophysical Research F: Earth Surface, 119, 2460–2480, doi:10.1002/2014JF003228.

Richter, A., Horwath, M. and Dietrich, R., 2016. Comment on Zwally and others (2015)-Mass gains of the Antarctic ice sheet exceed losses. Journal of Glaciology, 62(233), pp.604-606, doi: 10.1017/jog.2016.60.

Rio, M.H. and Hernandez, F. (2004). A mean dynamic topography computed over the world ocean from altimetry, in situ measurements, and a geoid model. Journal of Geophysical Research: Oceans, 109(C12), doi: 10.1029/2003JC002226.

Riva, R. E. M., Gunter, B. C., Urban, T. J., Vermeersen, B. L. A., Lindenbergh, R. C., Helsen, M. M., … Schutz, B. E. (2009). Glacial Isostatic Adjustment over Antarctica from combined ICESat and GRACE satellite data. Earth and Planetary Science Letters.

Sandberg, L., and Christian, C. (2010). Changes of the Greenland ice sheet -derived from ICESat and GRACE data. More?

Scambos, T., and Shuman, C. (2016). Comment on “mass gains of the Antarctic ice sheet exceed losses” by H. J. Zwally and others. Journal of Glaciology.

Shepherd, A., Ivins, E. R., Barletta, V. R., Bentley, M. J., Bettadpur, S., Briggs, K. H., … Jay Zwally, H. (2012). Supplementary Materials for A Reconciled Estimate of Ice-Sheet Mass Balance. Science, 338.

Schroeder, L., Horwath, M., Dietrich, R., Scheinert, M., Lichtenberg, S., van den Broeke, M., (2016). Long term elevation change of the Antarctic ice sheet from multi-mission satellite altimetry. American Geophysical Union Fall Meeting, abstract C14A-03.

Shuman, C., Harding, D., Cornejo, H., and Suchdeo, V. (2011). Assessment of Range Bias in the ICESat) Elevation Time Series and Elevation Changes at Large Subglacial Lake Sites, Antarctica. Geophysical Research Abstracts EGU General Assembly, 13, 2011–9259.

Siegfried, M. R., Hawley, R. L., and Burkhart, J. F. (2011). High-resolution ground-based GPS measurements show intercampaign bias in ICESat elevation data near summit, Greenland. In IEEE Transactions on Geoscience and Remote Sensing.

Sørensen, L. S., Simonsen, S. B., Nielsen, K., Lucas-Picher, P., Spada, G., Adalgeirsdottir, G., … Hvidberg, C. S. (2011). Mass balance of the Greenland ice sheet (2003-2008) from ICESat data - The impact of interpolation, sampling and firn density. Cryosphere.

Urban, T. J., and Schutz, B. E. (2005). ICESat sea level comparisons. Geophysical Research Letters.

Urban, T., Gutierrez, R., and Schutz, B. (2008). Analysis of ICESat laser altimetry elevations over surfaces: sea state and cloud effects, 3645, IEEE Int. Geosci. And Rem. Sens. Symp., Boston, MA, July 7-11.

Urban, T and 12 others (2012). Summary of ICESat-1 inter-campaign elevation biases and detection methods. EOS Trans. AGU, Fall Meet. Suppl., Abstract C13H-03

Urban, T., Pie, N., Felikson, D., and Schutz, B.E. (2013). Impacts on Greenland and Antarctica ice sheet mass balance from estimation of ICESat-1/GLAS inter-campaign biases over the oceans. EOS Trans. AGU, Fall Meet. Suppl., Abstract C21D-0660.

Urban et al. 2015 (doi: 10.1017/jog.2016.59)

Wesche, C., Riedel, S., and Steinhage, D. (2009). Precise surface topography of the grounded ice ridges at the Ekstr??misen, Antarctica, based on several geophysical data sets. ISPRS Journal of Photogrammetry and Remote Sensing.

Zwally HJ (2013). Correction to the ICESat data product surface elevations due to an error in the range determination from transmit-pulse reference-point selection (Centroid vs Gaussian) (Tech. rep.) National Snow and Ice Data Center, Boulder, CO, /data/icesat/correction-to-product-surface-elevations.html.

Zwally, H. J., Li, J., Robbins, J. W., Saba, J. L., Yi, D., and Brenner, A. C. (2015) Mass gains of the Antarctic ice sheet exceed losses. J. Glaciol.,61(230), 1019–1035 (doi: 10.3189/ 2015JoG15J071).

Zwally HJ and 5 others (2016a) Response to Comment by T. SCAMBOS and C. SHUMAN (2016) on ‘Mass gains of the Antarctic ice sheet exceed losses’ by H. J. Zwally and others (2015). J. Glaciol. doi: 10.1017/jog.2016.91.

Zwally HJ and 5 others (2016a) Response to Comment by A. Richter, M. Horwath, R. Dietrich (2016) on ‘Mass gains of the Antarctic ice sheet exceed losses’ by H. J. Zwally and others (2015). J. Glaciol. doi: 10.1017/jog.2016.92.