def config(self, step):
'''Generates a config file containing flags and parameters
for a particular experiment and step.
This takes care of flags and parameters that *cannot* be set using
command-line options. (We try to use command-line options whenever we can.)
'''
filename = "MISMIP_conf_%s_A%s.nc" % (self.experiment, step)
nc = NC(filename, 'w', format="NETCDF3_CLASSIC")
var = nc.createVariable("pism_overrides", 'i')
attrs = {
"is_dry_simulation": "no",
"include_bmr_in_continuity": "no",
"compute_surf_grad_inward_ssa": "no",
"ice_softness": MISMIP.A(self.experiment, step),
"ice_density": MISMIP.rho_i(),
"sea_water_density": MISMIP.rho_w(),
"bootstrapping_geothermal_flux_value_no_var": 0.0,
"Glen_exponent": MISMIP.n(),
"standard_gravity": MISMIP.g(),
"ocean_sub_shelf_heat_flux_into_ice": 0.0,
"bed_smoother_range": 0.0,
}
for name, value in attrs.iteritems():
var.setncattr(name, value)
nc.close()
return filename
def plot_flux(in_file, out_file):
print(
"Reading %s to plot ice flux for model %s, experiment %s, grid mode %s, step %s"
% (in_file, model, experiment, mode, step))
if out_file is None:
out_file = os.path.splitext(in_file)[0] + "-flux.pdf"
x = read(in_file, 'x')
flux_mag = read(in_file, 'flux_mag')
# plot positive xs only
flux_mag = flux_mag[x >= 0]
x = x[x >= 0]
figure(2)
hold(True)
plot(x / 1e3, flux_mag, 'k.-', markersize=10, linewidth=2)
plot(x / 1e3, x * MISMIP.a() * MISMIP.secpera(), 'r:', linewidth=1.5)
title("MISMIP experiment %s, step %d" % (experiment, step))
xlabel("x ($\mathrm{km}$)", size=14)
ylabel(r"flux ($\mathrm{m}^2\,\mathrm{a}^{-1}$)", size=14)
print("Saving '%s'...\n" % out_file)
savefig(out_file, dpi=300, facecolor='w', edgecolor='w')
def physics_options(self, input_file, step):
"Options corresponding to modeling choices."
config_filename = self.config(step)
options = ["-energy none", # isothermal setup; allows selecting cold-mode flow laws
"-ssa_flow_law isothermal_glen", # isothermal setup
"-yield_stress constant",
"-tauc %e" % MISMIP.C(self.experiment),
"-pseudo_plastic",
"-gradient eta",
"-pseudo_plastic_q %e" % MISMIP.m(self.experiment),
"-pseudo_plastic_uthreshold %e" % MISMIP.secpera(),
"-calving ocean_kill", # calving at the present front
"-ocean_kill_file %s" % input_file,
"-config_override %s" % config_filename,
"-ssa_method fd",
"-cfbc", # calving front boundary conditions
"-part_grid", # sub-grid front motion parameterization
"-ssafd_ksp_rtol 1e-7",
"-ys 0",
"-ye %d" % MISMIP.run_length(self.experiment, step),
"-options_left",
]
if self.model == 1:
options.extend(["-stress_balance ssa"])
else:
options.extend(["-stress_balance ssa+sia",
"-sia_flow_law isothermal_glen", # isothermal setup
])
return options
def plot_flux(in_file, out_file):
print("Reading %s to plot ice flux for model %s, experiment %s, grid mode %s, step %s" % (
in_file, model, experiment, mode, step))
if out_file is None:
out_file = os.path.splitext(in_file)[0] + "-flux.pdf"
x = read(in_file, 'x')
flux_mag = read(in_file, 'flux_mag')
# plot positive xs only
flux_mag = flux_mag[x >= 0]
x = x[x >= 0]
figure(2)
hold(True)
plot(x / 1e3, flux_mag, 'k.-', markersize=10, linewidth=2)
plot(x / 1e3, x * MISMIP.a() * MISMIP.secpera(), 'r:', linewidth=1.5)
title("MISMIP experiment %s, step %d" % (experiment, step))
xlabel("x ($\mathrm{km}$)", size=14)
ylabel(r"flux ($\mathrm{m}^2\,\mathrm{a}^{-1}$)", size=14)
print("Saving '%s'...\n" % out_file)
savefig(out_file, dpi=300, facecolor='w', edgecolor='w')
def physics_options(self, input_file, step):
"Options corresponding to modeling choices."
config_filename = self.config(step)
options = [
"-energy none", # isothermal setup; allows selecting cold-mode flow laws
"-ssa_flow_law isothermal_glen", # isothermal setup
"-yield_stress constant",
"-tauc %e" % MISMIP.C(self.experiment),
"-pseudo_plastic",
"-gradient eta",
"-pseudo_plastic_q %e" % MISMIP.m(self.experiment),
"-pseudo_plastic_uthreshold %e" % MISMIP.secpera(),
"-calving ocean_kill", # calving at the present front
"-ocean_kill_file %s" % input_file,
"-config_override %s" % config_filename,
"-ssa_method fd",
"-cfbc", # calving front boundary conditions
"-part_grid", # sub-grid front motion parameterization
"-ssafd_ksp_rtol 1e-7",
"-ys 0",
"-ye %d" % MISMIP.run_length(self.experiment, step),
"-options_left",
]
if self.model == 1:
options.extend(["-stress_balance ssa"])
else:
options.extend([
"-stress_balance ssa+sia",
"-sia_flow_law isothermal_glen", # isothermal setup
])
return options
def config(self, step):
'''Generates a config file containing flags and parameters
for a particular experiment and step.
This takes care of flags and parameters that *cannot* be set using
command-line options. (We try to use command-line options whenever we can.)
'''
filename = "MISMIP_conf_%s_A%s.nc" % (self.experiment, step)
nc = NC(filename, 'w', format="NETCDF3_CLASSIC")
var = nc.createVariable("pism_overrides", 'i')
attrs = {"is_dry_simulation": "no",
"include_bmr_in_continuity": "no",
"compute_surf_grad_inward_ssa": "no",
"ice_softness": MISMIP.A(self.experiment, step),
"ice_density": MISMIP.rho_i(),
"sea_water_density": MISMIP.rho_w(),
"bootstrapping_geothermal_flux_value_no_var": 0.0,
"Glen_exponent": MISMIP.n(),
"standard_gravity": MISMIP.g(),
"ocean_sub_shelf_heat_flux_into_ice": 0.0,
}
if self.model != 1:
attrs["bed_smoother_range"] = 0.0
for name, value in attrs.iteritems():
var.setncattr(name, value)
nc.close()
return filename
def plot_profile(in_file, out_file):
print(
"Reading %s to plot geometry profile for model %s, experiment %s, grid mode %s, step %s"
% (in_file, model, experiment, mode, step))
if out_file is None:
out_file = os.path.splitext(in_file)[0] + "-profile.pdf"
mask = read(in_file, 'mask')
usurf = read(in_file, 'usurf')
topg = read(in_file, 'topg')
thk = read(in_file, 'thk')
x = read(in_file, 'x')
# theoretical grounding line position
xg = MISMIP.x_g(experiment, step)
# modeled grounding line position
xg_PISM = find_grounding_line(x, topg, thk, mask)
# mask out ice-free areas
usurf = np.ma.array(usurf, mask=mask == 4)
# compute the lower surface elevation
lsrf = topg.copy()
lsrf[mask == 3] = -MISMIP.rho_i() / MISMIP.rho_w() * thk[mask == 3]
lsrf = np.ma.array(lsrf, mask=mask == 4)
# convert x to kilometers
x /= 1e3
figure(1)
ax = subplot(111)
hold(True)
plot(x, np.zeros_like(x), ls='dotted', color='red')
plot(x, topg, color='black')
plot(x, usurf, 'o', color='blue', markersize=4)
plot(x, lsrf, 'o', color='blue', markersize=4)
xlabel('distance from the divide, km')
ylabel('elevation, m')
title("MISMIP experiment %s, step %d" % (experiment, step))
text(0.6,
0.9,
"$x_g$ (model) = %4.0f km" % (xg_PISM / 1e3),
color='r',
transform=ax.transAxes)
text(0.6,
0.85,
"$x_g$ (theory) = %4.0f km" % (xg / 1e3),
color='black',
transform=ax.transAxes)
_, _, ymin, ymax = axis(xmin=0, xmax=x.max())
vlines(xg / 1e3, ymin, ymax, linestyles='dashed', color='black')
vlines(xg_PISM / 1e3, ymin, ymax, linestyles='dashed', color='red')
print("Saving '%s'...\n" % out_file)
savefig(out_file)
def plot_profile(in_file, out_file):
print("Reading %s to plot geometry profile for model %s, experiment %s, grid mode %s, step %s" % (
in_file, model, experiment, mode, step))
if out_file is None:
out_file = os.path.splitext(in_file)[0] + "-profile.pdf"
mask = read(in_file, 'mask')
usurf = read(in_file, 'usurf')
topg = read(in_file, 'topg')
thk = read(in_file, 'thk')
x = read(in_file, 'x')
# theoretical grounding line position
xg = MISMIP.x_g(experiment, step)
# modeled grounding line position
xg_PISM = find_grounding_line(x, topg, thk, mask)
# mask out ice-free areas
usurf = np.ma.array(usurf, mask=mask == 4)
# compute the lower surface elevation
lsrf = topg.copy()
lsrf[mask == 3] = -MISMIP.rho_i() / MISMIP.rho_w() * thk[mask == 3]
lsrf = np.ma.array(lsrf, mask=mask == 4)
# convert x to kilometers
x /= 1e3
figure(1)
ax = subplot(111)
hold(True)
plot(x, np.zeros_like(x), ls='dotted', color='red')
plot(x, topg, color='black')
plot(x, usurf, 'o', color='blue', markersize=4)
plot(x, lsrf, 'o', color='blue', markersize=4)
xlabel('distance from the divide, km')
ylabel('elevation, m')
title("MISMIP experiment %s, step %d" % (experiment, step))
text(0.6, 0.9, "$x_g$ (model) = %4.0f km" % (xg_PISM / 1e3), color='r',
transform=ax.transAxes)
text(0.6, 0.85, "$x_g$ (theory) = %4.0f km" % (xg / 1e3), color='black',
transform=ax.transAxes)
_, _, ymin, ymax = axis(xmin=0, xmax=x.max())
vlines(xg / 1e3, ymin, ymax, linestyles='dashed', color='black')
vlines(xg_PISM / 1e3, ymin, ymax, linestyles='dashed', color='red')
print("Saving '%s'...\n" % out_file)
savefig(out_file)
def thickness(experiment,
step,
x,
calving_front=1750e3,
semianalytical_profile=True):
# we expect x to have an odd number of grid points so that one of them is
# at 0
if x.size % 2 != 1:
raise ValueError("x has to have an odd number of points, got %d",
x.size)
x_nonnegative = x[x >= 0]
if not semianalytical_profile:
thk_nonnegative = np.zeros_like(x_nonnegative) + 10
else:
thk_nonnegative = MISMIP.thickness(experiment, step, x_nonnegative)
thk_nonnegative[x_nonnegative > calving_front] = 0
thk = np.zeros_like(x)
thk[x >= 0] = thk_nonnegative
thk[x < 0] = thk_nonnegative[:0:-1]
return np.tile(thk, (3, 1))
def __init__(self,
experiment,
model=1,
mode=1,
Mx=None,
Mz=15,
semianalytic=True,
initials="ABC",
executable=None):
self.model = model
self.mode = mode
self.experiment = experiment
self.initials = initials
self.semianalytic = semianalytic
if executable:
self.executable = executable
if mode == 3:
self.Mx = Mx
else:
self.Mx = 2 * MISMIP.N(self.mode) + 1
self.My = 3
if self.experiment == "2b":
self.Lz = 7000
else:
self.Lz = 6000
def config(self, step):
'''Generates a config file containing flags and parameters
for a particular experiment and step.
This takes care of flags and parameters that *cannot* be set using
command-line options. (We try to use command-line options whenever we can.)
'''
filename = "MISMIP_conf_%s_A%s.nc" % (self.experiment, step)
nc = NC(filename, 'w', format="NETCDF3_CLASSIC")
var = nc.createVariable("pism_overrides", 'i')
attrs = {
"ocean.always_grounded":
"no",
"geometry.update.use_basal_melt_rate":
"no",
"stress_balance.ssa.compute_surface_gradient_inward":
"no",
"flow_law.isothermal_Glen.ice_softness":
MISMIP.A(self.experiment, step),
"constants.ice.density":
MISMIP.rho_i(),
"constants.sea_water.density":
MISMIP.rho_w(),
"bootstrapping.defaults.geothermal_flux":
0.0,
"stress_balance.ssa.Glen_exponent":
MISMIP.n(),
"constants.standard_gravity":
MISMIP.g(),
"ocean.sub_shelf_heat_flux_into_ice":
0.0,
}
if self.model != 1:
attrs["stress_balance.sia.bed_smoother.range"] = 0.0
for name, value in attrs.items():
var.setncattr(name, value)
nc.close()
return filename
def physics_options(self, step):
"Options corresponding to modeling choices."
config_filename = self.config(step)
options = [
"-cold", # allow selecting cold-mode flow laws
"-sia_flow_law isothermal_glen", # isothermal setup
"-ssa_flow_law isothermal_glen", # isothermal setup
"-no_energy", # isothermal setup
"-ssa_sliding", # use SSA
"-hold_tauc",
"-tauc %e" % MISMIP.C(self.experiment),
"-pseudo_plastic",
"-gradient eta",
"-pseudo_plastic_q %e" % MISMIP.m(self.experiment),
"-pseudo_plastic_uthreshold %e" % MISMIP.secpera(),
"-ocean_kill", # calving at the present front
"-config_override %s" % config_filename,
"-ssa_method fd", # use the FD solver that includes PIK improvements
"-cfbc", # calving front boundary conditions
"-part_grid", # sub-grid front motion parameterization
"-ksp_rtol 1e-7",
"-ys 0",
"-ye %f" % MISMIP.run_length(self.experiment, step),
"-options_left",
]
if self.model == 1:
options.extend(["-no_sia"])
else:
options.extend(["-sia"])
if self.mode in (2, 3):
options.extend(["-skip", "-skip_max 10"])
return options
def thickness(experiment, step, x, calving_front=1750e3, semianalytical_profile=True):
# we expect x to have an odd number of grid points so that one of them is
# at 0
if x.size % 2 != 1:
raise ValueError("x has to have an odd number of points, got %d", x.size)
x_nonnegative = x[x >= 0]
if not semianalytical_profile:
thk_nonnegative = np.zeros_like(x_nonnegative) + 10
else:
thk_nonnegative = MISMIP.thickness(experiment, step, x_nonnegative)
thk_nonnegative[x_nonnegative > calving_front] = 0
thk = np.zeros_like(x)
thk[x >= 0] = thk_nonnegative
thk[x < 0] = thk_nonnegative[:0:-1]
return np.tile(thk, (3, 1))
def thickness(x, step, Q0, H0, calving_front=1750e3, perturbation='default'):
# we expect x to have an odd number of grid points so that one of them is
# at 0
if x.size % 2 != 1:
raise ValueError("x has to have an odd number of points, got %d",
x.size)
dx = x[1] - x[0]
A0 = MISMIP.A('1a', step)
print(A0, A0**(-1.0 / 3.0))
B0 = A0**(-1.0 / MISMIP.n())
#C = (900.0*9.8/(4.0*B0)*(1.0-900.0/1000.0))**3.0
C = (MISMIP.rho_i() * MISMIP.g() / (4.0 * B0) *
(1.0 - MISMIP.rho_i() / MISMIP.rho_w()))**MISMIP.n()
thk = (4.0 * C * np.maximum(x - 100e3, eps) / Q0 + H0**(-4.0))**(-0.25)
#thk = (x-100e3)*(-1e-4) + 800.0
thk[x < 100e3] = 800.0
thk[0] = 0.0
if perturbation == 'p1':
#perturbation i
thk[x > calving_front - 1 * dx] -= 50.0
elif perturbation == 'p2':
#perutbation i-1
thk[x > calving_front - 2 * dx] -= 50.0
thk[x > calving_front - 1 * dx] += 50.0
elif perturbation == 'p3':
#perutbation i-2
thk[x > calving_front - 3 * dx] -= 50.0
thk[x > calving_front - 2 * dx] += 50.0
#perutbation gli+1
#thk[ x > 100e3 + 0.5*dx ] -= 200.0
#thk[ x > 100e3+1.5*dx ] += 200.0
#perutbation gli+2
#thk[ x > 100e3 + 1.5*dx ] -= 200.0
#thk[ x > 100e3+2.5*dx ] += 200.0
thk[x > calving_front] = 0.0
return np.tile(thk, (3, 1))
def pism_bootstrap_file(filename,
step,
v0,
H0,
calving_front=1750e3,
N=None,
p="default"):
import PISMNC
xx = x(N)
yy = y(xx)
print("dx", xx[1] - xx[0])
v0 = v0 / MISMIP.secpera()
#H0 = 800.0
Q0 = H0 * v0
topg = bed_topography(xx)
thk = thickness(xx, step, Q0, H0, calving_front, p)
smb = surface_mass_balance(xx)
temp = ice_surface_temp(xx)
vel = Q0 / np.maximum(thk, eps) * MISMIP.secpera()
vel[thk == 0.0] = 0.0
#vel = np.nan_to_num(Q0/thk)*MISMIP.secpera()
bcm = bcmask(xx)
vel0 = np.zeros_like(vel)
okill = ocean_kill(thk)
nc = PISMNC.PISMDataset(filename, 'w', format="NETCDF3_CLASSIC")
nc.create_dimensions(xx, yy)
nc.define_2d_field('topg',
attrs={
'units': 'm',
'long_name': 'bedrock surface elevation',
'standard_name': 'bedrock_altitude'
})
nc.write('topg', topg)
nc.define_2d_field('thk',
attrs={
'units': 'm',
'long_name': 'ice thickness',
'standard_name': 'land_ice_thickness'
})
nc.write('thk', thk)
nc.define_2d_field(
'climatic_mass_balance',
attrs={
'units': 'kg m-2 / s',
'long_name':
'ice-equivalent surface mass balance (accumulation/ablation) rate',
'standard_name': 'land_ice_surface_specific_mass_balance_flux'
})
nc.write('climatic_mass_balance', smb)
nc.define_2d_field(
'ice_surface_temp',
attrs={
'units':
'Kelvin',
'long_name':
'annual average ice surface temperature, below firn processes'
})
nc.write('ice_surface_temp', temp)
nc.define_2d_field('land_ice_area_fraction_retreat',
attrs={
'units': '',
'long_name': 'mask where -ocean_kill cuts off ice'
})
nc.write('land_ice_area_fraction_retreat', okill)
nc.define_2d_field('u_ssa_bc', attrs={'units': 'm/yr'})
nc.write('u_ssa_bc', vel)
nc.define_2d_field('v_ssa_bc', attrs={'units': 'm/yr'})
nc.write('v_ssa_bc', vel0)
nc.define_2d_field('bc_mask', attrs={})
nc.write('bc_mask', bcm)
nc.close()
def surface_mass_balance(x):
"""Computes the surface mass balance."""
return np.tile(np.zeros_like(x) + MISMIP.a(), (3, 1)) * MISMIP.rho_i()
def bed_topography(experiment, x):
"""Computes bed elevation as a function of x.
experiment can be '1a', '1b', '2a', '2b', '3a', '3b'.
"""
return np.tile(-MISMIP.b(experiment, np.abs(x)), (3, 1))
def f(j):
"See equation (7) in Pattyn et al, 'Role of transition zones in marine ice sheet dynamics', 2005."
z_sl = 0
return (z_sl - topg[j]) * MISMIP.rho_w() / (MISMIP.rho_i() * thk[j])
def bed_topography(experiment, x):
"""Computes bed elevation as a function of x.
experiment can be '1a', '1b', '2a', '2b', '3a', '3b'.
"""
return np.tile(-MISMIP.b(experiment, np.abs(x)), (3, 1))
def surface_mass_balance(x):
"""Computes the surface mass balance."""
return np.tile(np.zeros_like(x) + MISMIP.a(), (3, 1))
def x(mismip_mode, N=None):
if mismip_mode in (1, 2):
return np.linspace(-MISMIP.L(), MISMIP.L(),
2 * MISMIP.N(mismip_mode) + 1)
return np.linspace(-MISMIP.L(), MISMIP.L(), N)
def f(j):
"See equation (7) in Pattyn et al, 'Role of transition zones in marine ice sheet dynamics', 2005."
z_sl = 0
return (z_sl - topg[j]) * MISMIP.rho_w() / (MISMIP.rho_i() * thk[j])
def x(N=None):
return np.linspace(0, MISMIP.L(), N)