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Description
| All-Greenland Surface and Total Mass Balance annual time series after
Data file and notes
Greenland_mass_balance_totals_1840-2012_ver_20141130_with_uncert_via_Kjeldsen_et_al_2015.csv
Column headers:
year accumulation accumulation 1sigma melt melt 1sigma retention retention 1sigma runoff runoff 1sigma discharge from 6 year lagged average runoff discharge 1sigma TMB TMB 1sigma
1840 645.43 65.82 277.70 64.34 143.07 48.72 173.56 46.15 406.08 36.65 65.79
Units: Gt per year, temperature in deg. C
Column description: “1sigma” refers to uncertainty; “accumulation” is snow accumulation equivalent with tp minus vapor lsos; “melt” is snow or ice converted to liquid; “retention” is nternal accumulation; “runoff” is liquid melt water exiting ice sheet; “SMB” is surface mass balance; “TMB” is total mass balance
From these data SMB can be computed as: accumulation - runoff - discharge
Time series visualization code and data: https://github.com/jasonebox/TMB_Greenland_1840-2012
Issues: https://github.com/jasonebox/TMB_Greenland_1840-2012/issues
Description
The Box (2013) 171 year (1840-2010) surface mass balance reconstruction is developed from linear regression parameters that describe the correlation between a.) spatially discontinuous in-situ monthly air temperature records (Cappelen, 2011; Cappelen et al., 2001, 2006; Vinther et al., 2006) or firn/ice cores (Box et al., 2013) and b.) spatially continuous outputs from regional climate model RACMO version 2.1 (Ettema et al., 2010). A 43-year overlap period 1960–2012 with RACMO2.1 is used to determine regression parameters on a 5 km grid cell basis. Then the predictor (air temperature and firn/ice core) data span 1840 to 2012. A fundamental assumption is that the calibration factors, regression slope and offset for the calibration period 1960–2012 are stationary over time. See “part I” of Box et al. (2013) for a description of the method, which includes a formal approach to estimate uncertainty.
The Box (2013) 171 year (1840-2010) SMB reconstruction is refined in (Kjeldsen et al., 2015) to incorporate: including peripheral ice masses in addition to the ice sheet; a more sophisticated meltwater retention scheme (Pfeffer et al., 1991); multiple in-situ records are weighted in their contribution to the estimated value; the annual accumulation rates from ice cores are dispersed into a monthly temporal resolution by weighting the monthly (based on the 1960–2012 RACMO2.1 data) fraction of the annual total for each grid cell in the domain and the revised surface mass balance data end with year 2012.
The 173 year (1840-2012) reconstruction of annual total mass balance (TMB) is after (Box and Colgan, 2013) improved in (Kjeldsen et al., 2015). Annual solid ice discharge (D) was estimated via a fit of unsmoothed solid ice discharge data (Rignot et al., 2008, 2011) with Box (2013) runoff data having a 6-year trailing average in Kjeldsen et al. (2015). The physical basis for the SID parameterization using runoff is described in (Box and Colgan, 2013).
Works Cited
· Box, J. E.: Greenland Ice Sheet Mass Balance Reconstruction. Part II: Surface Mass Balance (1840–2010), J. Clim., 26(18), 6974–6989, 2013.
· Box, J. E. and Colgan, W.: Greenland Ice Sheet Mass Balance Reconstruction. Part III: Marine Ice Loss and Total Mass Balance (1840–2010), J. Clim., 26(18), 6990–7002, 2013.
· Box, J. E., Cressie, N., Bromwich, D. H., Jung, J.-H., van den Broeke, M., van Angelen, J. H., Forster, R. R., Miège, C., Mosley-Thompson, E., Vinther, B. and McConnell, J. R.: Greenland Ice Sheet Mass Balance Reconstruction. Part I: Net Snow Accumulation (1600–2009), J. Clim., 26(11), 3919–3934, 2013.
· Cappelen, J.: DMI monthly climate data collection 1768– 2010, Denmark, the Faroe Islands and Greenland, Danish Meteorological Institute., 2011.
· Cappelen, J., Jørgensen, B. V., Laursen, E. V., Stannius, L. S. and Thomsen, R. S.: The observed climate of Greenland, 1958–99 with climatological standard normals, Danish Meteorological Institute., Technical Report 00-18, 151 pp., 2001.
· Cappelen, J., Laursen, E. V., Jørgensen, P. V. and Kern-Hansen, C.: DMI monthly climate data collection 1768–2005, Denmark, the Faroe Islands and Greenland, Danish Meteorological Institute., 2006.
· Ettema, J., van den Broeke, M. R., van Meijgaard, E., van de Berg, W. J., Box, J. E. and Steffen, K.: Climate of the Greenland ice sheet using a high-resolution climate model – Part 1: Evaluation, The Cryosphere, 4(4), 511–527, 2010.
· Kjeldsen, K. K., Korsgaard, N. J., Bjørk, A. A., Khan, S. A., Box, J. E., Funder, S., Larsen, N. K., Bamber, J. L., Colgan, W., van den Broeke, M., Siggaard-Andersen, M.-L., Nuth, C., Schomacker, A., Andresen, C. S., Willerslev, E. and Kjær, K. H.: Spatial and temporal distribution of mass loss from the Greenland Ice Sheet since AD 1900, Nature, 528(7582), 396–400, 2015.
· Pfeffer, W. T., Meier, M. F. and Illangasekare, T. H.: Retention of Greenland runoff by refreezing: Implications for projected future sea level change, J. Geophys. Res., 96, 22,117, 1991.
· Rignot, E., Box, J. E., Burgess, E. and Hanna, E.: Mass balance of the Greenland ice sheet from 1958 to 2007, Geophysical Research Letters, 35(20), doi:10.1029/2008gl035417, 2008.
· Rignot, E., Velicogna, I., van den Broeke, M. R., Monaghan, A. and Lenaerts, J. T. M.: Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise, Geophys. Res. Lett., 38(5), doi:10.1029/2011gl046583, 2011.
· Vinther, B. M., Andersen, K. K., Jones, P. D., Briffa, K. R. and Cappelen, J.: Extending Greenland temperature records into the late eighteenth century, J. Geophys. Res., 111(D11), doi:10.1029/2005jd006810, 2006. |
