Section 7: Multi-source Data Sets

7.1 NMC History Tapes

During the field phase of ERICA Geoff DiMego created 59 magnetic tapes
containing the data and analyses from the NMC operational model runs.
Little work has been done with these tapes at the Data Center. The
information below is therefore incomplete.

7.1.1 Operational RAFS Analyses and Forecasts

Form: digital
Size:
Volume:

These are the Regional Area Forecast System analyses and forecasts
prepared at NMC operationally every six hours. The analyses are on the
LFM grid and include all significant and mandatory levels. The data
that had arrived by the cutoff time are also included.


7.1.2 Operational Aviation Run Analyses and Forecasts

Form: digital
Size:
Volume:

These are the aviation analyses and forecasts prepared at NMC
operationally every six hours.


 7.1.3 Global Data Assimilation System Analyses and Forecasts

Form: digital
Size:
Volume:

These are the GDAS analyses and forecasts prepared at NMC
operationally every twelve hours.


7.1.4 Final Observation Data

Form: digital
Size:
Volume:

These are the final observation data, including all operational data
that arrived past the cutoff times, but within 24 hours of real-time.


 7.1.5 PREPOA NMC Preprocessed Data

Form: digital
Size:
Volume:

These are the processed data used in the NMC operational analyses,
including DMSP soundings.


 7.2 ERICA Compact Disc

Form: digital
Size: 650 Mbytes
Volume: 1 CD ROM disc

The ERICA CD ROM will contain the most popular ERICA data sets; its
release in April, 1990, will allow us to use it as the principal data
distribution to researchers interested in ERICA data, although the
data will also be available on various magnetic media on request.

The CD will use the ISO 9660 format, the international CD ROM standard
for data. It will be accessible from both personal computers (Apple
and IBM), and workstations.

Data Sets on the ERICA CD ROM are listed below, along with the numbers
of the sections in which they are described in this Guide. The sizes
of the data sets are conservative estimates; actual size are somewhat
smaller.

Aircraft data:
        Compressed P3 Flight Level Data (2.1.1) 120 Mbytes
        Compressed NCAR Flight Level Data (2.2.1) 43 Mbytes
        PIREPS from PROFS, ACARS (2.3.2) 7 Mbytes

Sounding data:
        Master Sounding Files (3.1.1) 135 Mbytes
        Soundings Extracted from Flight Level Data (3.3.4) 10 Mbytes

Satellite data:
        Compressed 14km SST Analyses (5.8.1) 5 Mbytes
        Compressed 50km SST Analyses (5.8.1) 3 Mbytes

Boundary Layer data:
        EDC Reformatted NCDC Surface Hourly Airways (6.3.1) 123 Mbytes
        EDC Reformatted DATSAV Surface Data (6.3.4) 120 Mbytes
        Canadian Surface Hourly (6.3.7) 28 Mbytes
        NS Mesonet Data (6.3.6) 15 Mbytes
        EDC Combined TD-1129 Format Data (6.5.3) 15 Mbytes
        EDC Combined Buoy and C-MAN Data (6.5.8) 9 Mbytes

Documentation and Access Software 10 Mbytes

Text of ERICA Data Users Guide 1 Mbyte

NCAR Terrain Data
        North American Elevation (30-sec grid) 10 Mbytes
        East US Land Use (1/4 x 1/6 degree) 2 Mbytes

TOTAL: 656 Mbytes

Documentation and Access Software:
        Each data set will have accompanying documentation on the CD.
Not all of our documentation is digitized, so a collection of paper
documents (probably about 100 pages) will accompany each CD.

FORTRAN 77 source code for access subroutines will be provided on the
CD.  Each set will have a subroutine which the researcher may
incorporate into his or her own programs. The subroutines will access
the data in as uniform a fashion as is possible, considering the
differences in sets. At some later date a more complete software
package may be prepared at the Data Center which will tie together all
of these subroutines into a unified data access system.

We intend to release another GALE CD ROM, and perhaps other ERICA CD
ROMs devoted to data sets that are too large to fit on this one (e.g.
P3 radar data, digital satellite imagery). Cliff Mass of the
University of Washington also releases various data on CDs (e.g. NMC
Grid Point Data).

In terms of dollars per byte, CD ROMs compare very favorably with
magnetic tape, even with the one-time cost of buying a CD ROM drive
(less than $1000). In terms of convenience, both for the researcher
and the Data Center, CD ROMs provide a significant advantage. Finally,
the ERICA CD ROM will make all of the most requested data available to
researchers using only a microcomputer.