SOI Data Sets
The browsers provided for selecting and exporting data from the SOI
Data Storage and Distribution System (DSDS) need to make multiple queries
to the database, depending on the particular datasets selected.
It may take a while for the first search page to come up.
This is not a problem with your internet connection!
After that, the queries should be very fast until you make your final
selection. Because most of the data archive is off-line, delays
in actual data export can be up to a day or more, depending on
the number of other pending requests. You will be informed by mail at
the time your request is logged and again when it has been satisfied (or
when it has failed for some reason).
Data Requests by Source
Available under conditions of the
SOI data policy
- Data derived from observations with the MDI instrument on SOHO in space.
- Quick-look data derived from observations with the MDI instrument on SOHO
in space as captured in near-real time from the Experiment Operations Facility
- Data derived from ground-based (test) observations with the MDI flight
- Data derived from (test) observations with the MDI simulator.
- Ancillary data from the SOHO spacecraft.
- Quick-look data processed into Datasets corresponding to Campaign Sequences.
Available under conditions set by the
- Data from the upgraded Global Oscillations Network Group
- Data from the Taiwan Oscillations Network
- Mt Wilson MOF
- Data from the Mt. Wilson 60-ft tower MOF instrument
- Data derived from observations with the High-L Helioseismometer at
Kitt Peak National Observatory
- Data derived from observations with the High-L Helioseismometer
operating at the South Pole
- Data derived from observations with the Low-L instrument operated
by the High Altitude Observatory
- Simulations by Stein
- Simulations of solar hydrodynamic convection on supergranulation scales
(48 Mm wide by 20 Mm deep)
Data Requests by Dataset Name
(if you know the exact SOI dataset names of the data you want)
SOI data sets are available for export via the following mechanisms
(click for explanations):
Details of the required information for each export mechanism are
provided in the export help page
and on the export request forms themselves.
Please note that many SOI datasets are large. Data storage
requirements will be posted prior to final submission of your request.
Organization of SOI Data
Data sets contained in the Solar Oscillations Investigation (SOI) master
database fall into three classes:
This document is a brief overview of the entire contents of the SSSC database
and is intended to help people get started in using the database. If you
already know the name or attributes of the data series you are interested in,
you may use a form provided to query the database directly.
Be aware, however, that for historical
reasons the dataset names available for user queries are not necessarily
the same as the identifiers used internally in the database.
(No description of the actual names in use in the database, including
entitities other than scientific data, is available.)
- Scientific data from the Michelson Doppler Imager (MDI) on board SOHO,
and data products derived from the analysis of these data.
Distribution of these datasets is governed by the
SOI data policy.
Briefly, the data policy is that:
Since the beginning of the SOHO extended mission (1998), all
data are available for unrestricted use
from the time of their availability at the SSSC.
- Instrumental test and calibration data derived from ground tests of
MDI and the simulator instrument. These data are not likely to be
useful for scientific analysis, but they are available as is
for any purposes without restriction.
- Imported data sets from other instruments and observatories obtained
by the SOI project for comparative studies, project development, and
independent analysis. These data are only available for redistribution
under the applicable restrictions or requirements imposed by their original
Types of SSSC Data
Datasets are described in the SSSC database by Program, Processing Level
and Series Name. A dataset described by a unique combination of these
attributes (which consist of both a name and a sequence number)
is a set of data files with a common organization together with
any ancillary data files providing information about the whole collection.
A dataset can physically occupy a single directory in a disc file system.
The SSSC Database
There are two database tables with information about SOI data. One, the
dataset table, contains a line for each unique data series, i.e.,
each unique combination of Program name (and number), Level name (and number),
and Series name (and number). The other provides information about a subset
of these data series specified by some (not all) unique combinations of
the names, ignoring different numbers. The second database contains the
information needed by certain analysis modules to gather together multiple
datasets from a data series, so entries in it are only required for those
data series whose component sets are to be collected this way.
Datasets are organized by program according to the instrumental origin of
the original observational data. (When high-level analyzed data are based
on datasets from multiple original programs, as for example with correlative
or comparative studies, they will be cross-referenced from each program.
So far there is no such case.) The program determines the data rights and,
in the case of MDI data, the likely scientific utility of the derived
datasets. Separate pages describe the organization of the datasets
within each program, and the associated data rights.
Data products are organized within the SOI project according to
their level of processing as follows:
Descriptions of the different levels of processing as applied specifically
to SOI data are given elsewhere
(SOI Data Availability).
- Instrumental data in their original format.
As a rule, raw data are not suitable for direct analysis.
- Raw data which have been converted to the format of
a standard external storage protocol, usually FITS files.
Level-0 data are preumed uncalibrated and stored in instrument units.
- Level-1 (Calibrated)
- Level-0 data which have been calibrated
into physical units of the observable and time and location
of the observation. Level-1 data are intended to be suitable for
science data analysis and may be the final data product for some
- Collections of Level-1 data which have been assembled together with
certain descriptive and ancillary data products (files) for use
in SOI pipeline processing.
Level-1.5 data products are stored as self-contained sets
of files using standard storage protocols such as FITS and CDF,
along with easily readable text information in straight ASCII
- Level-1 data which have been somehow reorganized by e.g.
projection, smoothing, sampling, filtering, transforms, etc.
Examples of Level-2 data products
are spherical harmonic amplitude time series and frequencies of
solar oscillation modes for various intervals of time.
- When data are initially acquired at Level-2
(this is sometimes the case for imported data products)
it may be necessary to assemble them for use in further SOI
pipeline processing with the same kinds of descriptive and
ancillary data products (files) as with the Level-1.5 data.
Level names take the following forms:
- lev0, lev0i (the i denotes imported data)
- lev1, lev1i
- lev2, lev2i, lev2[i]_XXX,
where XXX is a descriptive identifier for the type of reorganization
involved in the Level-2 processing, e.g.:
- avg, averaged (smoothed) data
- bin, binned data
- fx, Fourier-transformed
- map, mapped (projected) data
- shc, spherical harmonic coefficients
- smpl, sampled data
- track, tracked data (mapped and collected in space-time data cubes)
- lev2.5, lev2.5_xxx
There is no consistency to data series names except occasionally within
individual programs and levels. Data within the mdi program at
the raw level are named with reference to the originating telemetry
the level-0 level they are named by the relevant Data Product
Code (DPC), a hexadecimal representation of a 32-bit pattern. (A
Data Product Decoder is available here for
interpreting the meaning of individual DPC's.)
Series names at level-1 and higher may or may not be more meaningful.
The main data selection page for each program should contain a description
of the associated series names.
Oracle Forms for Querying the SOI Database
Page last revised
Thursday, 14-Sep-2006 16:00:35 PDT
Please address comments and questions to Rick Bogart, SOI Data Scientist