Experiment 3
Experiment 3 is intended to provide initial conditions for future calving experiments using the Thule domain as well as test participating models capability to maintain a steady unchanging calving front. To this end. we spin up an ice sheet in the Thule domain from no initial ice thickness to an ice sheet in steady state with a calving front located in a circul with radius 750 km from the centre of the domain. The calving front position should be maintained by imposing a calving rate that is equal and opposite to the ice velocity at the calving front, resulting in a calving front position that does not move. The Thule domain has at least two possible steady states depending on whether the simulation spins up from zero initial ice thickness or has a large initial ice thickness. In this case, the intended steady state is that which is achieved from zero initial ice thickness, with the ice ungrounded from the Benett underwater ridges located under the North and South Tsalal ice shelves. It may be necessary for participants to tune the suggested experimental parameters (bed slipperiness, etc.) to achieve this.
Note that, in this particular experiment, we are not interested in the exact means by which this steady state condition is achieved but instead are concerned with the final steady state. For example, when using the Kori ice model to perform this experiment we first ran the model to a steady state with no imposed calving front position, allowing the model to evolve across the entire model domain. We then directly imposed a calving front in the required position, allowing the model to achieve a new steady state in line with the calving front position. Finaly, we switched to maintaining the calving front position via means of an applied calving rate rather than "hard coding" it to be in a specific location.
A snapshot of ice thickness, velocities and mask on the common results grid should be provided every 100 years of simulation time (with t-0 being the steady state conditions obtained from Experiment 3). The common results grid is a regular, uniform grid of 800 km by 800 km with a resolution of 5 km centered on the middle of the domain (0,0). This gives dimensions of 161 by 161, with X and Y values ranging from -800 km to 800 km. We also ask that participants provide a profile of results every year of simulation time (with t-0 being the steady state conditions obtained from Experiment 3) sampled of the same order as the native model resolution (albeit with some interpolation) along the eight experimental profiles of the Thule domain, namely;
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"Caprona A profile" for the Caprona A ice shelf between (-390 km, 0 km) and (-590 km, 450 km)
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"Caprona B profile" for the Caprona B ice shelf between ( 390 km, 0 km) and ( 590 km, 450 km)
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"Caprona C profile" for the Caprona C ice shelf between (-390 km, 0 km) and (-590 km, -450 km)
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"Caprona D profile" for the Caprona D ice shelf between ( 390 km, 0 km) and ( 590 km, -450 km)
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"Halbrane A profile" for the Halbrane A ice stream and North Tsalal ice shelf between (-150 km, 0 km) and (-150 km, 740 km)
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"Halbrane B profile" for the Halbrane B ice stream and North Tsalal ice shelf between ( 150 km, 0 km) and ( 150 km, 740 km)
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"Halbrane C profile" for the Halbrane C ice stream and South Tsalal ice shelf between (-150 km, 0 km) and (-150 km, -740 km)
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"Halbrane D profile" for the Halbrane D ice stream and South Tsalal ice shelf between ( 150 km, 0 km) and ( 150 km, -740 km)
For example, the results from Kori uses the following points Circle_Profiles.csv
Ice thickness should be given in units of meters, whilst velocity should be seperated into an X and Y component alligend with the results grid in units of m/a. All results should be interpolated onto the results grid in a linear fashion. Ice mask should be equal to 1 for grounded ice, 2 for floating ice, and 3 for open ocean with no ice. Results should be interpolated onto the results grid using a nearest neighbour method, such that its values are whole integers. Values of ice velocity and thickness that are in the open ocean should be set to NaN values, regardless of whether individual models utilising some manner of minimum ice thickness to represent open ocean or similar.
Results should be submitted as a NETcdf file, with naming convention of "CalvingMIP_EXPNUMBER_MODELNAME_INSTITUTION NAME.nc". For example, the results for Experiment 1 made using the Kori model by the group from Université libre de Bruxelles would be named "CalvingMIP_EXP1_Kori_ULB.nc". A list of the required data fields is below. To aid analysis of results, please make sure that variable names are an exact match A matlab script that correctly formats results into this format is available in the code section. An example of correctly formatted results are available from the PROTECT data servers, access available upon request.
Naming conventions have been chosen to, as far as possible, be compatible with the ISMIP6 naming conventions to allow for later comparison between projects.
Of particular note for CalvingMIP is the variable 'tendlicalvf', tendency of land ice mass due to calving. To avoid confusion, we define this variable to be the total, domain wide mass flux of ice at the calving front (Calving front ice velocity times calving front ice thickness times ice density) irrespective of whether the calving front is advancing, retreating or stationary.
| NetCDF Variable name | NetCDF Standard name | Description | Units |
|---|---|---|---|
| Time | Simulation time | a | |
| X | X coordinates of results grid | m | |
| Y | X coordinates of results grid | m | |
| xvelmean | land_ice_vertical_mean_x_velocity | X velocity | m a-1 |
| yvelmean | land_ice_vertical_mean_y_velocity | Y velocity | m a-1 |
| lithk | land_ice_thickness | Ice thickness | m |
| mask | Ice mask | grounded=1, floating=2, open ocean=3 | |
| topg | bedrock_altimetry | Bedrock height | m |
| iareafl | grounded_ice_sheet_area | Total area of grounded ice | m2 |
| iareagr | bedrock_altimetry | Total area of floating ice | m2 |
| lim | land_ice_mass | Total mass of ice in the domain | kg |
| limnsw | land_ice_mass_not_displacing_sea_water | Total mass of ice in the domain that does not disoalce seawater (grounded) | kg |
| tendlicalvf | tendency_of_land_ice_mass_due_to_calving | Total mass flux across the calving front | kg a-1 |
| tendligroundf | tendency_of_grounded_ice_mass | Total mass flux across the grounding line | kg a-1 |
| iareatotalNW | total_ice_area_NorthWest | Total area of grounded and floating ice in positive Y, negative X quadrant | m2 |
| iareatotalNE | total_ice_area_NorthEast | Total area of grounded and floating ice in positive Y, positive X quadrant | m2 |
| iareatotalSW | total_ice_area_SouthWest | Total area of grounded and floating ice in negative Y, negative X quadrant | m2 |
| iareatotalSE | total_ice_area_SouthEast | Total area of grounded and floating ice in negative Y, positive X quadrant | m2 |
| lithkCapA | land_ice_thickness_along_Caprona_A | Caprona A ice thickness | m |
| sCapA | distance_along_profile_A | Distance from start of Caprona A | m |
| xvelmeanCapA | land_ice_vertical_mean_x_velocity_along_Caprona_A | Caprona A X velocity | m a-1 |
| yvelmeanCapA | land_ice_vertical_mean_y_velocity_along_Caprona_A | Caprona A Y velocity | m a-1 |
| maskCapA | Ice mask along Caprona A | grounded=1, floating=2, open ocean=3 | |
| xcfCapA | x_calving_front_on_Caprona_A | Caprona A calving front X position | m |
| ycfCapA | x_calving_front_on_Caprona_A | Caprona A calving front Y position | m |
| xvelmeancfCapA | land_ice_vertical_mean_x_velocity_at_calving_front_on_Caprona_A | Caprona A Calving Front X velocity | m a-1 |
| yvelmeancfCapA | land_ice_vertical_mean_y_velocity_at_calving_front_on_Caprona_A | Caprona A Calving Front Y velocity | m a-1 |
| lithkcfCapA | land_ice_thickness_at_calving_front_on_profile_A | Caprona A Calving Front ice thickness | m |
| lithkCapB | land_ice_thickness_along_Caprona_B | Caprona B ice thickness | m |
| sCapB | distance_along_Caprona_B | Distance from start of Caprona B | m |
| xvelmeanCapB | land_ice_vertical_mean_x_velocity_along_Caprona_B | Caprona B X velocity | m a-1 |
| yvelmeanCapB | land_ice_vertical_mean_y_velocity_along_Caprona_B | Caprona B Y velocity | m a-1 |
| maskCapB | Ice mask along Caprona B | grounded=1, floating=2, open ocean=3 | |
| xcfCapB | x_calving_front_on_Caprona_B | Caprona B calving front X position | m |
| ycfCapB | x_calving_front_on_Caprona_B | Caprona B calving front Y position | m |
| xvelmeancfCapB | land_ice_vertical_mean_x_velocity_at_calving_front_on_Caprona_B | Caprona B Calving Front X velocity | m a-1 |
| yvelmeancfCapB | land_ice_vertical_mean_y_velocity_at_calving_front_on_Caprona_B | Caprona B Calving Front Y velocity | m a-1 |
| lithkcfCapB | land_ice_thickness_at_calving_front_on_Caprona_B | Caprona B Calving Front ice thickness | m |
| lithkCapC | land_ice_thickness_along_Caprona_C | Caprona C ice thickness | m |
| sCapC | distance_along_Caprona_C | Distance from start of Caprona C | m |
| xvelmeanCapC | land_ice_vertical_mean_x_velocity_along_Caprona_C | Caprona C X velocity | m a-1 |
| yvelmeanCapC | land_ice_vertical_mean_y_velocity_along_Caprona_C | Caprona C Y velocity | m a-1 |
| maskCapC | Ice mask along Caprona C | grounded=1, floating=2, open ocean=3 | |
| xcfCapC | x_calving_front_on_Caprona_C | Caprona C calving front X position | m |
| ycfCapC | x_calving_front_on_Caprona_C | Caprona C calving front Y position | m |
| xvelmeancfCapC | land_ice_vertical_mean_x_velocity_at_calving_front_on_Caprona_C | Caprona C Calving Front X velocity | m a-1 |
| yvelmeancfCapC | land_ice_vertical_mean_y_velocity_at_calving_front_on_Caprona_C | Caprona C Calving Front Y velocity | m a-1 |
| lithkcfCapC | land_ice_thickness_at_calving_front_on_Caprona_C | Caprona C Calving Front ice thickness | m |
| lithkCapD | land_ice_thickness_along_Caprona_D | Caprona D ice thickness | m |
| sCapD | distance_along_Caprona_D | Distance from start of Caprona D | m |
| xvelmeanCapD | land_ice_vertical_mean_x_velocity_along_Caprona_D | Caprona D X velocity | m a-1 |
| yvelmeanCapD | land_ice_vertical_mean_y_velocity_along_Caprona_D | Caprona D Y velocity | m a-1 |
| maskCapD | Ice mask along Caprona D | grounded=1, floating=2, open ocean=3 | |
| xcfCapD | x_calving_front_on_Caprona_D | Caprona D calving front X position | m |
| ycfCapD | x_calving_front_on_Caprona_D | Caprona D calving front Y position | m |
| xvelmeancfCapD | land_ice_vertical_mean_x_velocity_at_calving_front_on_Caprona_D | Caprona D Calving Front X velocity | m a-1 |
| yvelmeancfCapD | land_ice_vertical_mean_y_velocity_at_calving_front_on_Caprona_D | Caprona D Calving Front Y velocity | m a-1 |
| lithkcfCapD | land_ice_thickness_at_calving_front_on_Caprona_D | Caprona D Calving Front ice thickness | m |
| lithkHalA | land_ice_thickness_along_Halbrane_A | Halbrane A ice thickness | m |
| sHalA | distance_along_profile_A | Distance from start of Halbrane A | m |
| xvelmeanHalA | land_ice_vertical_mean_x_velocity_along_Halbrane_A | Halbrane A X velocity | m a-1 |
| yvelmeanHalA | land_ice_vertical_mean_y_velocity_along_Halbrane_A | Halbrane A Y velocity | m a-1 |
| maskHalA | Ice mask along Halbrane A | grounded=1, floating=2, open ocean=3 | |
| xcfHalA | x_calving_front_on_Halbrane_A | Halbrane A calving front X position | m |
| ycfHalA | x_calving_front_on_Halbrane_A | Halbrane A calving front Y position | m |
| xvelmeancfHalA | land_ice_vertical_mean_x_velocity_at_calving_front_on_Halbrane_A | Halbrane A Calving Front X velocity | m a-1 |
| yvelmeancfHalA | land_ice_vertical_mean_y_velocity_at_calving_front_on_Halbrane_A | Halbrane A Calving Front Y velocity | m a-1 |
| lithkcfHalA | land_ice_thickness_at_calving_front_on_Halbrane_A | Halbrane A Calving Front ice thickness | m |
| lithkHalB | land_ice_thickness_along_Halbrane_B | Halbrane B ice thickness | m |
| sHalB | distance_along_Halbrane_B | Distance from start of Halbrane B | m |
| xvelmeanHalB | land_ice_vertical_mean_x_velocity_along_Halbrane_B | Halbrane B X velocity | m a-1 |
| yvelmeanHalB | land_ice_vertical_mean_y_velocity_along_Halbrane_B | Halbrane B Y velocity | m a-1 |
| maskHalB | Ice mask along Halbrane B | grounded=1, floating=2, open ocean=3 | |
| xcfHalB | x_calving_front_on_Halbrane_B | Halbrane B calving front X position | m |
| ycfHalB | x_calving_front_on_Halbrane_B | Halbrane B calving front Y position | m |
| xvelmeancfHalB | land_ice_vertical_mean_x_velocity_at_calving_front_on_Halbrane_B | Halbrane B Calving Front X velocity | m a-1 |
| yvelmeancfHalB | land_ice_vertical_mean_y_velocity_at_calving_front_on_Halbrane_B | Halbrane B Calving Front Y velocity | m a-1 |
| lithkcfHalB | land_ice_thickness_at_calving_front_on_Halbrane_B | Halbrane B Calving Front ice thickness | m |
| lithkHalC | land_ice_thickness_along_Halbrane_C | Halbrane C ice thickness | m |
| sHalC | distance_along_Halbrane_C | Distance from start of Halbrane C | m |
| xvelmeanHalC | land_ice_vertical_mean_x_velocity_along_Halbrane_C | Halbrane C X velocity | m a-1 |
| yvelmeanHalC | land_ice_vertical_mean_y_velocity_along_Halbrane_C | Halbrane C Y velocity | m a-1 |
| maskHalC | Ice mask along Halbrane C | grounded=1, floating=2, open ocean=3 | |
| xcfHalC | x_calving_front_on_Halbrane_C | Halbrane C calving front X position | m |
| ycfHalC | x_calving_front_on_Halbrane_C | Halbrane C calving front Y position | m |
| xvelmeancfHalC | land_ice_vertical_mean_x_velocity_at_calving_front_on_Halbrane_C | Halbrane C Calving Front X velocity | m a-1 |
| yvelmeancfHalC | land_ice_vertical_mean_y_velocity_at_calving_front_on_Halbrane_C | Halbrane C Calving Front Y velocity | m a-1 |
| lithkcfHalC | land_ice_thickness_at_calving_front_on_Halbrane_C | Halbrane C Calving Front ice thickness | m |
| lithkHalD | land_ice_thickness_along_Halbrane_D | Halbrane D ice thickness | m |
| sHalD | distance_along_Halbrane_D | Distance from start of Halbrane D | m |
| xvelmeanHalD | land_ice_vertical_mean_x_velocity_along_Halbrane_D | Halbrane D X velocity | m a-1 |
| yvelmeanHalD | land_ice_vertical_mean_y_velocity_along_Halbrane_D | Halbrane D Y velocity | m a-1 |
| maskHalD | Ice mask along Halbrane D | grounded=1, floating=2, open ocean=3 | |
| xcfHalD | x_calving_front_on_Halbrane_D | Halbrane D calving front X position | m |
| ycfHalD | x_calving_front_on_Halbrane_D | Halbrane D calving front Y position | m |
| xvelmeancfHalD | land_ice_vertical_mean_x_velocity_at_calving_front_on_Halbrane_D | Halbrane C Calving Front X velocity | m a-1 |
| yvelmeancfHalD | land_ice_vertical_mean_y_velocity_at_calving_front_on_Halbrane_D | Halbrane C Calving Front Y velocity | m a-1 |
| lithkcfHalD | land_ice_thickness_at_calving_front_on_Halbrane_D | Halbrane D Calving Front ice thickness | m |
Example results for this experiment using the Kori model are shown below.
