Team
Wissenschaftliche Mitarbeitende

M.Sc. Timm Schultz

Kontakt

work +49 6151 16-22747

Work L5|01 545
Franziska-Braun-Straße 7
64287 Darmstadt

On Stress in Marshmallows and Firn – Beitrag zum „International Firn Workshop“

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TFM4all

Timm's Firn Model (TFM) provides a leightweight and fast simulation framework for firn densification compuations. To proove that my simulation framework is the fastest around I set up TFM4all.

You can request a firn profile at any location on earth (make sure your coordinates are located on ice, otherwise you'll receive an error message) using the form below. Simply type in a pair of coordinates, the firn densification model you prefer and a mail address so I can send you the results. You will receive an email containing the results in the form of a file containing comma separated values and a first simple plot.

Forcing

To force the model we currently use ERA5-Land monthly averaged data beginning in 1950 and ending End of June 2022. This means that the firn profile you'll receive represents the state of June 30th 2022. The oldest firn within the profile was deposited on January 1st 1950.

In my opinion one should be careful in interpreting simulated firn profiles in excess of the available forcing. Nevertheless a spin up is needed to build up the firn profile properly. We perfom a five hundred year spinup using constant mean forcing data. Afterwards the period from 1950 to 2022 is simulated.

One of the surface forcing properties is the inital firn density. Unfortunately there are no good data one could use for the simulations. Therefore at the moment a fixed inital surface density of 360 kg/m**-3 is used. I will think of a better solution for the future.

Feedback

If something is not working, you have an idea, you want to simulate something else, or you simply like this idea don't hesitate to contact me.

References

References for the firn densification models and some further things I use to run TFM4all can be found at the end of this page. For more information on the model and its concepts see:

Schultz, T., Müller, R., Gross, D., and Humbert, A. On the contribution of grain boundary sliding type creep to firn densification – an assessment using an optimization approach. The Cryosphere, 16, 143-158, https://doi.org/10.5194/tc-16-143-2022, 2022.

Forcing

Munoz Sabater, J. ERA5-Land monthly averaged data from 1981 to present. Copernicus Climate Change Serveice (C3S) Climate Data Store (CDS). https://doi.org/10.24381/cds.68d2bb30.

Firn Densification Models

Medley, B., Neumann, T. A., Zwally, H. J., Smith, B. E., and Stevens, C. M. Simulations of firn processes over the Greenland and Antarctic ice sheets: 1980-2021.The Cryosphere, 16, 3971-4011, https://doi.org/10.5194/tc-16-3971-2022, 2022.

Herron, M. M. and Langway Jr., C. C. Firn Densification: An Empirical Model. Journal of Glaciology, 25 (93), 373-385, https://doi.org/10.3189/S0022143000015239, 1980.

Arthern, R. J., Vaughan, D. G., Rankin, A. M., Mulvaney, R., and Thomas, E. R. In situ measurements of Antarctic snow compaction compared with predicitions of models.Journal of Geophysical Research, Earth Surface, 115 (F3), https://doi.org/10.1029/2009JF001306, 2010.

Ligtenberg, S. R. M., Helsen, M. M., and van den Broeke, M. R. An improved semi-empirical model for the densification of Antarctic firn. The Cryosphere, 5, 809-819, https://doi.org/10.5194/tc-5-809-2011, 2011.

Simonsen, S. B., Stenseng, L., Adalgeisdottir, G., Fausto, R. S., Hvidberg, C. S., and Lucas-Picher, P. Assessing a multilayered dynamic firn-compaction model for Greenland with ASIRAS radar measurements. Journal of Glaciology, 59 (215), 545-558, https://doi.org/10.3189/2013JoG12J158, 2013.

Arthern, R. J. and Wingham, D. J. The Natural Fluctuations of Firn Densification and Their Effect on the Geodetic Determination of Ice Sheet Mass Balance. Climatic Change, 40, 605-624, https://doi.org/10.1023/A:1005320713306, 1998.

Li, J. and Zwally, H. J. Modeling the density variation in the shallow firn layer. Annals of Glaciology, 38, 309-313, https://doi.org/10.3189/172756404781814988, 2004.

Helsen, M. M., van den Broeke, M. R., van de Wal R. S., van de Berg, W. J., van Meijgaard, E., Davis, C. H., Li, Y., and Goodwin, I. Elevation Changes in Antarctica Mainly Determined by Accumulation Variability. Science, 320 (5883), 1626-1629, https://doi.org/10.1126/science.1153894, 2008.

Bréant, C., Martinerie, P., Orsi, A., Arnaud, L., and Landais, A. Modelling firn thickness evolution during the last deglaciation: constraints on sensitivity to temperature and impurities. Clim. Past, 13, 833-853, https://doi.org/10.5194/cp-13-833-2017, 2017.

Zwinger, T., Greve, R., Gagliardini, O., Shiraiwa, T., and Lyly, M. A full Stokes-flow thermo-mechanical model for firn and ice applied to the Gorshkov crater glacier, Kamchatka. 45, 29-37, https://doi.org/10.3189/172756407782282543, 2007.

Greve, R. and Blatter, H. Dynamics of Ice Sheets and Glaciers.Springer, 2009.

Gagliardini, O. and Meyssonnier, J. Flow simulation of a firn-covered cold glacier. Annals of Glaciology, 24, 242-248, https://doi.org/10.3189/S0260305500012246, 1997.

Ice Masks

Morlighem, M. MEaSUREs BedMachine Antarctica, Version 2. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/E1QL9HFQ7A8M.

Morlighem, M., Rignot, E., Binder, T., Blankenship, D. D., Drews, R., Eagles, G. O., et al. Deep glacial troughs and stabilizing ridges unveiled beneath the margings of the Antarctic ice sheet. Nature Geoscience, 13, 132-137, https://doi.org/10.1038/s41561-019-0510-8, 2020.

Howat, I. M., Negrete, A., and Smith, B. E. The Greenland Ice Mapping Project (GIMP) land classification and surface elevation datasets. The Cryosphere, 8, 1509-1518, https://doi.org/10.5194/tc-8-1509-2014, 2014.