texamples.rst - pism - [fork] customized build of PISM, the parallel ice sheet model (tillflux branch)
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texamples.rst (5525B)
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1 .. include:: shortcuts.txt
2
3 .. _sec-forcing-examples:
4
5 Examples and corresponding options
6 ----------------------------------
7
8 This section gives a very brief overview of some coupling options. Please see sections
9 referenced below for more information.
10
11 One way coupling to a climate model
12 +++++++++++++++++++++++++++++++++++
13
14 One-way coupling of PISM to a climate model can be achieved by reading a NetCDF file with
15 time- and space-dependent climate data produced by a climate model.
16
17 There are two cases:
18
19 - coupling to a climate model that includes surface (firn, snow) processes
20 - coupling to a climate model providing near-surface air temperature and precipitation
21
22 .. _sec-example-surface-given:
23
24 Reading ice surface temperature and mass balance
25 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
26
27 This is the simplest case. It is often the preferred case, for example when the climate
28 model in use has high quality surface mass and energy sub-models which are then preferred
29 to the highly simplified (e.g. temperature index) surface models in PISM.
30
31 :|variables|: :var:`climatic_mass_balance`, :var:`ice_surface_temp`
32 :|options|: :opt:`-surface given -surface_given_file forcing.nc`
33 :|seealso|: :ref:`sec-surface-given`
34
35 .. _sec-example-atmosphere-given:
36
37 Reading air temperature and precipitation
38 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
39
40 As mentioned above, if a climate model provides near-surface air temperature and
41 precipitation, these data need to be converted into top-of-the-ice temperature and
42 climatic mass balance.
43
44 One way to do that is by using a temperature index (PDD) model component included in PISM.
45 This component has adjustable parameters; default values come from :cite:`RitzEISMINT`.
46
47 :|variables|: :var:`precipitation`, :var:`air_temp`
48 :|options|: :opt:`-atmosphere given -atmosphere_given_file forcing.nc -surface pdd`
49 :|seealso|: :ref:`sec-atmosphere-given`, :ref:`sec-surface-pdd`
50
51 If melt is negligible :opt:`-surface pdd` should be replaced with :opt:`-surface simple`
52 (see section :ref:`sec-surface-simple`).
53
54 .. _sec-example-atmosphere-anomalies:
55
56 Using climate anomalies
57 +++++++++++++++++++++++
58
59 Prognostic modeling experiments frequently use time- and space-dependent air temperature
60 and precipitation anomalies.
61
62 :|variables|: :var:`precipitation`,
63 :var:`air_temp`,
64 :var:`precipitation_anomaly`,
65 :var:`air_temp_anomaly`
66 :|options|: :opt:`-atmosphere given,anomaly`,
67 :opt:`-atmosphere_given_file forcing.nc`,
68 :opt:`-atmosphere_anomaly_file anomalies.nc`,
69 :opt:`-surface simple`
70 :|seealso|: :ref:`sec-atmosphere-given`,
71 :ref:`sec-atmosphere-anomaly`,
72 :ref:`sec-surface-simple`
73
74 The ``simple`` surface model component re-interprets precipitation as climatic mass
75 balance, which is useful in cases when there is no melt (Antarctic simulations is an
76 example).
77
78 Simulations of the Greenland ice sheet typically use :opt:`-surface pdd` instead of
79 :opt:`-surface simple`.
80
81 .. _sec-example-searise-greenland:
82
83 SeaRISE-Greenland
84 +++++++++++++++++
85
86 The SeaRISE-Greenland setup uses a parameterized near-surface air temperature
87 :cite:`Faustoetal2009` and a constant-in-time precipitation field read from an input
88 (:opt:`-i`) file. A temperature-index (PDD) scheme is used to compute the climatic mass
89 balance.
90
91
92 :|variables|: :var:`precipitation`,
93 :var:`lat`,
94 :var:`lon`
95 :|options|: :opt:`-atmosphere searise_greenland -surface pdd`
96 :|seealso|: :ref:`sec-atmosphere-searise-greenland`,
97 :ref:`sec-surface-pdd`
98
99 The air temperature parameterization is a function of latitude (:var:`lat`), longitude
100 (:var:`lon`) and surface elevation (dynamically updated by PISM).
101
102 .. _sec-example-searise-greenland-paleo:
103
104 SeaRISE-Greenland paleo-climate run
105 +++++++++++++++++++++++++++++++++++
106
107 The air temperature parameterization in the previous section is appropriate for present
108 day modeling. PISM includes some mechanisms allowing for corrections taking into account
109 differences between present and past climates. In particular, one can use ice-core derived
110 scalar air temperature offsets :cite:`JohnsenetalGRIP`, precipitation adjustments
111 :cite:`Huybrechts02`, and sea level offsets from SPECMAP :cite:`Imbrieetal1984`.
112
113 :|variables|: :var:`precipitation`,
114 :var:`delta_T`,
115 :var:`delta_SL`,
116 :var:`lat`,
117 :var:`lon`
118 :|options|: :opt:`-atmosphere searise_greenland,delta_T -atmosphere_delta_T_file
119 delta_T.nc -surface pdd -sea_level constant,delta_sl -ocean_delta_sl_file
120 delta_SL.nc`
121 :|seealso|: :ref:`sec-atmosphere-searise-greenland`,
122 :ref:`sec-atmosphere-delta-t`,
123 :ref:`sec-surface-pdd`,
124 :ref:`sec-ocean-constant`,
125 :ref:`sec-ocean-delta-sl`
126
127 Note that the temperature offsets are applied to *air* temperatures at the *atmosphere
128 level*. This ensures that `\Delta T` influences the PDD computation.
129
130 .. _sec-example-antarctica-paleo:
131
132 Antarctic paleo-climate runs
133 ++++++++++++++++++++++++++++
134
135 :|variables|: :var:`climatic_mass_balance`,
136 :var:`air_temp`,
137 :var:`delta_T`,
138 :var:`delta_SL`
139 :|options|: :opt:`-surface given,delta_T -surface_delta_T_file delta_T.nc -sea_level
140 constant,delta_sl -ocean_delta_sl_file delta_SL.nc`
141 :|seealso|: :ref:`sec-surface-given`,
142 :ref:`sec-surface-delta-t`,
143 :ref:`sec-ocean-constant`,
144 :ref:`sec-ocean-delta-sl`