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Example 3. Tensor (Wind Stress)
Next, consider a data object consisting of a horizontal
wind stress tensor measured over an
-
coordinate grid at the surface of the earth.
The wind stress tensor has four components, two
along each of the dimensions of the grid. We
take the
and
to be the coordinates of a
grid on which the tensors are
defined. Suppose further that we attach no time to these data. (They may be
time-independent estimates to be used in some sort of simple model.)
Thus, there are two Level 0 dimensions, each having 2 grid
points:
,
,
,
, where
is the wind stress in the
direction on the surface normal to the
direction. The data have two Level 1 dimensions:
and
. The data object has data records, so it must have a
Level 2 dimension; we will use a generic index
counter as the Level 2 dimension.
To complicate matters just a little more, we will assume that the data
are written out as the array: S(wind stress in
direction,
, wind stress
in
direction,
). The data object fields
will be as follows (indices start at 1):
- OBJDESC.
- NDIM0 = 2
-
- NDIM1 = 2
-
- NDIM2 = 1
-
- NDIM3 = 0
- DIMSPEC0.
- INDEX = (1, 3)
-
- GPTNUM = (2, 2)
- DIMSPEC1.
- INDEX = (2, 4)
-
- DESNUM = (1, 1)
- DIMSPEC2.
- INDEX = -1
- DESCRIP0.
- DATFMT =
(single precision floating-point, single precision floating-point,
single precision floating-point,
single precision floating-point)
-
- VARTYPE = (
,
,
,
)
-
- UNITS = (Pa, Pa, Pa, Pa)
- DESCRIP1.
- DEXSORT = 1
-
-
- NDEX = 1
-
- RECSORT = 0
-
- START = 1
-
- END = -1
-
- GPTNUM = 100
-
- DUPNUM = 0
-
- DESSUP = 0
-
- DESFMT = long integer
-
- DESTYPE =
-
- UNITS = no units
-
- STORG = 1
- DESCVAL.
- DLEVEL = 1
-
-
- LEVEL = 1
-
- DINDEX = 0
-
- DEXSORT = 1
-
-
- NDEX = 1
-
- RECSORT = 0
-
- AVALS = (1, 1)
- DESCRIP1.
- DEXSORT = 2
-
-
- NDEX = 2
-
- RECSORT = 0
-
- START = 1
-
- END = -1
-
- GPTNUM = 75
-
- DUPNUM = 0
-
- DESSUP = 0
-
- DESFMT = long integer
-
- DESTYPE =
-
- UNITS = no units
-
- STORG = 1
- DESCVAL.
- DLEVEL = 1
-
-
- LEVEL = 1
-
- DINDEX = 0
-
- DEXSORT = 2
-
-
- NDEX = 2
-
- RECSORT = 0
-
- AVALS = (1, 1)
- DESCRIP2.
- NDEX = 0
-
- DUPNUM = 0
-
- DESSUP = 0
-
- DESFMT =
long integer
-
- DESTYPE = index
-
- UNITS = no units
-
- STORG = 1
- DESCVAL.
- DLEVEL = 2
-
-
- LEVEL = 2
-
- DINDEX = 0
-
- DEXSORT = 1
-
-
- NDEX = 1
-
- RECSORT = 0
-
- AVALS = (1, 1)
Next: Example 4. Unusual Data
Up: Dimensional Levels
Previous: Example 2. Vector (Wind)
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admin for code 916 group
2001-01-31