Example 4. Unusual Data Object (Ozonesondes)

Consider a data object consisting of balloon-borne observations of ozone concentrations at varying pressure levels over a set of 2000 stations on 365 days. We consider two different methods of specifying these data:

In the first case, we will define a complex data object (an ``ozonesonde data vector'') consisting of a single Level 0 dimension with two components: ozone concentration and pressure. The station identifier we will treat as a Level 1 dimension, and the Level 2 dimension is time. The data will be written out in the order (station ID, ozonesonde data component, time). In this case, the data object dimensional record fields will be as follows (indices start at 1):

OBJDESC.

NDIM0 = 1

NDIM1 = 1

NDIM2 = 1

NDIM3 = 0

DIMSPEC0.

INDEX = 2

GPTNUM = 2

DIMSPEC1.

INDEX = 1

DESNUM = 1

DIMSPEC2.

INDEX = 3

GPTNUM = 365

DESCRIP0.

DATFMT = (single precision floating-point, single precision floating-point)

VARTYPE = (ozone concentration, pressure)

UNITS = (ppmv, mb)

DESCRIP1.

DEXSORT = 1

NDEX = 1

RECSORT = 0

START = 1

END = -1

GPTNUM = 2000

DUPNUM = 0

DESSUP = 0

DESFMT = long integer

DESTYPE = station identifier

UNITS = no units

STORG = 0

DESCVAL.

DLEVEL = 1

LEVEL = 1

DINDEX = 0

DEXSORT = 1

NDEX = 1

RECSORT = 0

AVALS = (list of 2000 station identifiers)

DESCRIP2.

NDEX = 1

DUPNUM = 0

DESSUP = 0

DESFMT = long integer

DESTYPE = time

UNITS = day of year

STORG = 1

DESCVAL.

DLEVEL = 2

LEVEL = 2

DINDEX = 0

DEXSORT = 1

NDEX = 1

RECSORT = 0

AVALS = (1, 1)

Alternatively, we can treat pressure as a Level 1 dimension. The first 6 months of data contain ozonesondes at the same 18 pressure levels, while the last 6 months contain the data at 15 levels, different from the set in the early period. The data array is written in the order (station identifier, pressure, time). Note that the ozone data are now simple scalars. The data dimensional record fields will be as follows (indices start at 1):

OBJDESC.

NDIM0 = 1

NDIM1 = 2

NDIM2 = 1

NDIM3 = 0

DIMSPEC0.

INDEX = -1

GPTNUM = 1

DIMSPEC1.

INDEX = (1, 2)

DESNUM = (1, 2)

DIMSPEC2.

INDEX = 3

GPTNUM = 365

DESCRIP0.

DATFMT = single precision floating-point

VARTYPE = ozone concentration

UNITS = ppmv

DESCRIP1.

DEXSORT = 1

NDEX = 1

RECSORT = 0

START = 1

END = -1

GPTNUM = 2000

DUPNUM = 0

DESSUP = 0

DESFMT = long integer

DESTYPE = station identifier

UNITS = no units

STORG = 0

DESCVAL.

DLEVEL = 1

LEVEL = 1

DINDEX = 0

DEXSORT = 1

NDEX = 1

RECSORT = 0

AVALS = (list of 2000 station identifiers)

DESCRIP1.

DEXSORT = 65538

NDEX = 2

RECSORT = 1

START = 1

END = 181

GPTNUM = 18

DUPNUM = 0

DESSUP = 0

DESFMT = single precision floating-point

DESTYPE = pressure

UNITS = mb

STORG = 0

DESCVAL.

DLEVEL = 1

LEVEL = 1

DINDEX = 0

DEXSORT = 65538

NDEX = 2

RECSORT = 1

AVALS = (list of 18 pressure levels)

DESCRIP1.

DEXSORT = 655362

NDEX = 2

RECSORT = 10

START = 182

END = -1

GPTNUM = 15

DUPNUM = 0

DESSUP = 0

DESFMT = single precision floating-point

DESTYPE = pressure

UNITS = mb

STORG = 0

DESCVAL.

DLEVEL = 1

LEVEL = 1

DINDEX = 0

DEXSORT = 655362

NDEX = 2

RECSORT = 10

AVALS = (list of 15 pressure levels)

DESCRIP2.

NDEX = 1

DUPNUM = 0

DESSUP = 0

DESFMT = long integer

DESTYPE = time

UNITS = day of year

STORG = 1

DESCVAL.

DLEVEL = 2

LEVEL = 2

DINDEX = 0

DEXSORT = 1

NDEX = 1

RECSORT = 0

AVALS = (1, 1)