tindex.rst - pism - [fork] customized build of PISM, the parallel ice sheet model (tillflux branch)
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tindex.rst (2984B)
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1 .. include:: shortcuts.txt
2
3 .. _sec-climate-forcing:
4
5 Climate forcing
6 ===============
7
8 PISM has a well-defined separation of climate forcing from ice dynamics. This manual is
9 about the climate forcing interface.
10
11 By contrast, most options documented in the :ref:`sec-users-manual` control the ice
12 dynamics part. The User's Manual does, however, give an :ref:`overview of PISM's surface
13 (atmosphere) and ocean (sub-shelf) interfaces <sec-climate-inputs>`. At these interfaces
14 the surface mass and energy balances are determined and/or passed to the ice dynamics
15 code.
16
17 To get started with climate forcing usage we need to introduce some language to describe
18 parts of PISM. In this manual a *component* is a piece of PISM code, usually a C++ class.
19 A combination of components (or, in some cases, one component) makes up a "model" --- an
20 implementation of a physical/mathematical description of a system.
21
22 PISM's climate forcing code has two kinds of components.
23
24 - Ones that can be used as "stand-alone" models, such as the implementation of the PDD
25 scheme (section :ref:`sec-surface-pdd`). These are *model components*.
26 - Ones implementing "corrections" of various kinds, such as lapse rate corrections
27 (sections :ref:`sec-surface-elevation-change` and :ref:`sec-atmosphere-elevation-change`) or
28 ice-core derived offsets (sections :ref:`sec-surface-delta-t` and
29 :ref:`sec-ocean-delta-sl`, for example). These are called *modifier components* or
30 *modifiers*.
31
32 Model components and modifiers can be chained as shown in
33 :numref:`fig-climate-input-data-flow`. For example,
34
35 .. code-block:: none
36
37 -ocean constant,delta_T -ocean_delta_T_file delta_T.nc
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39 combines the component providing constant (both in space and time) ocean boundary
40 conditions with a modifier that applies scalar temperature offsets. This combination
41 one of the many ocean models that can be chosen using components as building blocks.
42
43 Section :ref:`sec-forcing-examples` gives examples of combining components to choose
44 models. Before that we address how PISM handles model time (Section
45 :ref:`sec-model-time`).
46
47 .. admonition:: Summary of the main idea in using this manual
48
49 Setting up PISM's climate interface *requires* selecting one surface and one ocean
50 component. The surface component may use an atmosphere component also; see
51 :numref:`fig-climate-input-data-flow`. Command-line options :opt:`-atmosphere`,
52 :opt:`-surface` and :opt:`-ocean` each take a comma-separated list of keywords as an
53 argument; the first keyword *has* to correspond to a model component, the rest can be
54 "modifier" components. Any of these options can be omitted to use the default
55 atmosphere, surface or ocean model components, but one has to explicitly choose a model
56 component to use a modifier. Model components and modifiers are chained as in
57 :numref:`fig-climate-input-data-flow`.
58
59 .. toctree::
60
61 time.rst
62
63 examples.rst
64
65 testing.rst
66
67 surface.rst
68
69 atmosphere.rst
70
71 ocean.rst