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Experiment 1
Experiment 1 is intended to provide initial conditions for future calving experiments using the circular 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 circular domain from no initial ice thickness to an ice sheet in steady state with a calving front located in a circular 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.
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.
In this particular experiment, the exact position of the grounding line is not as relavent as the calving front position. As long as their is a symmetrical domain with a circular ice shelf then no tuning of the exact grounding line position is required.
A snapshot of ice thickness, velocities and mask on the common results grid should be provided for the final, steady state ice sheet. 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 321 by 321, with X and Y values ranging from -800 km to 800 km. We also ask that participants provide a profile of results, sampled on the same order of resolution as the native model grid (albeit with some interpolation), on the eight experimental profiles originating from the domain center located at (0,0).
- Profile A (along the line x=0 in the positive y direction)
- Profile B (along the line y=x in the positive x and y direction)
- Profile C (along the line y=0 in the positive x direction)
- Profile D (along the line y=-x in the positive x and negative y direction)
- Profile E (along the line x=0 in the negative y direction)
- Profile F (along the line y=x in the negative x and y direction)
- Profile G (along the line y=0 in the negative x direction)
- Profile H (along the line y=-x in the negative x and positive y direction)
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 for experiment 1 (others are in progress). 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 |
lithkA | land_ice_thickness_along_profile_A | Profile A ice thickness | m |
sA | distance_along_profile_A | Distance from start of profile A | m |
xvelmeanA | land_ice_vertical_mean_x_velocity_along_profile_A | Profile A X velocity | m a-1 |
yvelmeanA | land_ice_vertical_mean_y_velocity_along_profile_A | Profile A Y velocity | m a-1 |
maskA | Ice mask along profile A | grounded=1, floating=2, open ocean=3 | |
xcfA | x_calving_front_on_profile_A | Profile A calving front X position | m |
ycfA | x_calving_front_on_profile_A | Profile A calving front Y position | m |
xvelmeancfA | land_ice_vertical_mean_x_velocity_at_calving_front_on_profile_A | Profile A Calving Front X velocity | m a-1 |
yvelmeancfA | land_ice_vertical_mean_y_velocity_at_calving_front_on_profile_A | Profile A Calving Front Y velocity | m a-1 |
lithkcfA | land_ice_thickness_at_calving_front_on_profile_A | Profile A Calving Front ice thickness | m |
lithkB | land_ice_thickness_along_profile_B | Profile B ice thickness | m |
sB | distance_along_profile_B | Distance from start of profile B | m |
xvelmeanB | land_ice_vertical_mean_x_velocity_along_profile_B | Profile B X velocity | m a-1 |
yvelmeanb | land_ice_vertical_mean_y_velocity_along_profile_B | Profile B Y velocity | m a-1 |
maskB | Ice mask along profile B | grounded=1, floating=2, open ocean=3 | |
xcfB | x_calving_front_on_profile_B | Profile B calving front X position | m |
ycfB | x_calving_front_on_profile_B | Profile B calving front Y position | m |
xvelmeancfB | land_ice_vertical_mean_x_velocity_at_calving_front_on_profile_B | Profile B Calving Front X velocity | m a-1 |
yvelmeancfB | land_ice_vertical_mean_y_velocity_at_calving_front_on_profile_B | Profile B Calving Front Y velocity | m a-1 |
lithkcfB | land_ice_thickness_at_calving_front_on_profile_B | Profile B Calving Front ice thickness | m |
lithkC | land_ice_thickness_along_profile_C | Profile C ice thickness | m |
sC | distance_along_profile_C | Distance from start of profile C | m |
xvelmeanC | land_ice_vertical_mean_x_velocity_along_profile_C | Profile C X velocity | m a-1 |
yvelmeanC | land_ice_vertical_mean_y_velocity_along_profile_C | Profile C Y velocity | m a-1 |
maskC | Ice mask along profile C | grounded=1, floating=2, open ocean=3 | |
xcfC | x_calving_front_on_profile_C | Profile C calving front X position | m |
ycfC | x_calving_front_on_profile_C | Profile C calving front Y position | m |
xvelmeancfC | land_ice_vertical_mean_x_velocity_at_calving_front_on_profile_C | Profile C Calving Front X velocity | m a-1 |
yvelmeancfC | land_ice_vertical_mean_y_velocity_at_calving_front_on_profile_C | Profile C Calving Front Y velocity | m a-1 |
lithkcfC | land_ice_thickness_at_calving_front_on_profile_C | Profile C Calving Front ice thickness | m |
lithkD | land_ice_thickness_along_profile_D | Profile D ice thickness | m |
sD | distance_along_profile_D | Distance from start of profile D | m |
xvelmeanD | land_ice_vertical_mean_x_velocity_along_profile_D | Profile D X velocity | m a-1 |
yvelmeanD | land_ice_vertical_mean_y_velocity_along_profile_D | Profile D Y velocity | m a-1 |
maskD | Ice mask along profile D | grounded=1, floating=2, open ocean=3 | |
xcfD | x_calving_front_on_profile_D | Profile D calving front X position | m |
ycfD | x_calving_front_on_profile_D | Profile D calving front Y position | m |
xvelmeancfD | land_ice_vertical_mean_x_velocity_at_calving_front_on_profile_D | Profile D Calving Front X velocity | m a-1 |
yvelmeancfD | land_ice_vertical_mean_y_velocity_at_calving_front_on_profile_D | Profile D Calving Front Y velocity | m a-1 |
lithkcfD | land_ice_thickness_at_calving_front_on_profile_D | Profile D Calving Front ice thickness | m |
lithkE | land_ice_thickness_along_profile_E | Profile E ice thickness | m |
sE | distance_along_profile_E | Distance from start of profile E | m |
xvelmeanE | land_ice_vertical_mean_x_velocity_along_profile_E | Profile E X velocity | m a-1 |
yvelmeanE | land_ice_vertical_mean_y_velocity_along_profile_E | Profile E Y velocity | m a-1 |
maskE | Ice mask along profile E | grounded=1, floating=2, open ocean=3 | |
xcfE | x_calving_front_on_profile_E | Profile E calving front X position | m |
ycfE | x_calving_front_on_profile_E | Profile E calving front Y position | m |
xvelmeancfE | land_ice_vertical_mean_x_velocity_at_calving_front_on_profile_E | Profile E Calving Front X velocity | m a-1 |
yvelmeancfE | land_ice_vertical_mean_y_velocity_at_calving_front_on_profile_E | Profile E Calving Front Y velocity | m a-1 |
lithkcfE | land_ice_thickness_at_calving_front_on_profile_E | Profile E Calving Front ice thickness | m |
lithkF | land_ice_thickness_along_profile_F | Profile F ice thickness | m |
sF | distance_along_profile_F | Distance from start of profile F | m |
xvelmeanF | land_ice_vertical_mean_x_velocity_along_profile_F | Profile F X velocity | m a-1 |
yvelmeanF | land_ice_vertical_mean_y_velocity_along_profile_F | Profile F Y velocity | m a-1 |
maskF | Ice mask along profile F | grounded=1, floating=2, open ocean=3 | |
xcfF | x_calving_front_on_profile_F | Profile F calving front X position | m |
ycfF | x_calving_front_on_profile_F | Profile F calving front Y position | m |
xvelmeancfF | land_ice_vertical_mean_x_velocity_at_calving_front_on_profile_F | Profile F Calving Front X velocity | m a-1 |
yvelmeancfF | land_ice_vertical_mean_y_velocity_at_calving_front_on_profile_F | Profile F Calving Front Y velocity | m a-1 |
lithkcfF | land_ice_thickness_at_calving_front_on_profile_F | Profile F Calving Front ice thickness | m |
lithkG | land_ice_thickness_along_profile_G | Profile G ice thickness | m |
sG | distance_along_profile_G | Distance from start of profile G | m |
xvelmeanG | land_ice_vertical_mean_x_velocity_along_profile_G | Profile G X velocity | m a-1 |
yvelmeanG | land_ice_vertical_mean_y_velocity_along_profile_G | Profile G Y velocity | m a-1 |
maskG | Ice mask along profile G | grounded=1, floating=2, open ocean=3 | |
xcfG | x_calving_front_on_profile_G | Profile G calving front X position | m |
ycfG | x_calving_front_on_profile_G | Profile G calving front Y position | m |
xvelmeancfG | land_ice_vertical_mean_x_velocity_at_calving_front_on_profile_G | Profile G Calving Front X velocity | m a-1 |
yvelmeancfG | land_ice_vertical_mean_y_velocity_at_calving_front_on_profile_G | Profile G Calving Front Y velocity | m a-1 |
lithkcfG | land_ice_thickness_at_calving_front_on_profile_G | Profile G Calving Front ice thickness | m |
lithkH | land_ice_thickness_along_profile_H | Profile H ice thickness | m |
sH | distance_along_profile_H | Distance from start of profile H | m |
xvelmeanH | land_ice_vertical_mean_x_velocity_along_profile_H | Profile H X velocity | m a-1 |
yvelmeanH | land_ice_vertical_mean_y_velocity_along_profile_H | Profile H Y velocity | m a-1 |
maskH | Ice mask along profile H | grounded=1, floating=2, open ocean=3 | |
xcfH | x_calving_front_on_profile_H | Profile H calving front X position | m |
ycfH | x_calving_front_on_profile_H | Profile H calving front Y position | m |
xvelmeancfH | land_ice_vertical_mean_x_velocity_at_calving_front_on_profile_H | Profile H Calving Front X velocity | m a-1 |
yvelmeancfH | land_ice_vertical_mean_y_velocity_at_calving_front_on_profile_H | Profile H Calving Front Y velocity | m a-1 |
lithkcfH | land_ice_thickness_at_calving_front_on_profile_H | Profile H Calving Front ice thickness | m |
Example results for this experiment using the Kori model are shown below.
Fig.1 - Steady state solution to Experiment 1. Imposed calving front position is shown in red, grounding line in white and velocity vectors in black Fig.2 - Ice thickness along the four profiles from the steady state solution to Experiment 1 Fig.3 - Ice thickness along half of thefour profiles from the steady state solution to Experiment 1