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Experiment 1

JRowanJordan edited this page Apr 25, 2024 · 33 revisions

Overview

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.

Required Results

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

Example results for this experiment using the Kori model are shown below.

Exp1-IceThickness

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

Exp1-Profiles

Fig.2 - Ice thickness along the four profiles from the steady state solution to Experiment 1

Exp1-Profiles_Zoom

Fig.3 - Ice thickness along half of thefour profiles from the steady state solution to Experiment 1