This package provides access to a number of mission databases and indices
(geomagnetic and solar wind parameters). The original data sets have been
rewritten to the CDF-format using
ISTP/IACG
and Cluster guidelines, and when
possible, have been modified to include
physical quantities such as fluxes. Magnetic coordinates have in most cases
been (re)-calculated using the UNILIB library.
Databases available now are indicated in green or blue on a clickable gif.
Databases indicated in red will be added in the future.
To start a query,
click on the green time bar for geomagnetic indices/Solar wind data or a blue
time bar or the satellite name for a selected mission.
The sections below describe the inputs that are to be provided on these forms
by the user in order to perform a data set query.
The user has to specify the start and end dates and times for searching the
database.
The query start and stop times are reset to the first and last valid data
points in the original query interval.
For instance, if the user specifies 01 Jun
1995 0h 0m 0s and 31 Jul 1995 23h 59m 59s for start and stop date for a query
in the Meteosat data base, the
resulting period will span the range 01 Jun 1995 00:00:00.000 - 30 Jun 1995
23:33:06.767 because no data is available during July 1995.
Time resolution:
The behaviour of the query depends on the selection made above. The database
is first queried for all matching records, which are not necessarily evenly
spread. The maximum number of transmitted points is restricted to 2500.
If the "Maximum resolution" was chosen and if the query results in less than
2500 points, all of them are included in the result
file and plots. If, on the other
hand, the query results in more than 2500 points, a reduction scheme is applied.
The methodology for the reduction scheme is as follows:
The resulting period
is divided into 2500 intervals of equal duration. The valid points in each
interval are then reduced to one single value. How this value is calculated,
depends on the selected reduction scheme for that
variable. The numbers of matching points before and after reduction are reported
in the Report file.
If a fixed interval was chosen as time resolution, a test is made to see if
this will result in more or less than 2500 records. If there are less than 2500
records, the reduction is made with the user specified resolution. If more than
2500 records would be produced, the automatic reduction scheme
is used and the user is warned that the time resolution has been
modified.
Pressing the button brings up the page
with the available variables for this data set.
Form 2: Variable selection
Select variables to retrieve
The variables to be included in the query can be selected with the menus:
from the list of variables.
The list of available variables depends on the selected mission. The next
list gives the available data sets and provides links to a detailed
description of each data set.
The options Mean, Minimum and Maximum define the reduction scheme, if
applicable,
for the selected variable:
- Mean: The arithmetic mean of the valid data points within each interval
is calculated.
Note: If a longitude is chosen as variable, the vector mean is calculated;
i.e. the mean of longitudes 1 and 359 is 0, while the arithmetic mean is 180.
- Minimum: The minimum value of the valid data points within each interval
is used.
- Maximum: The maximum value of the valid data points within each interval
is used.
The averaged values are written to the results
file.
Statistics of the reduction for each variable are included in the
results file.
Remarks
For selecting individual channels from multidimensional variables, the user
has to indicate both the reduction scheme and click the appropriate for the channel
The button brings up a new page with
other available data for the same time period.
Form 3: Available data sets
The table here lists the data sets which have other data for the same time
period. The possible values for the status of these data sets are:
- Primary data set (blue background): This indicates that this data sets is considered as
being the main for this query. Constraints can be implied on variables from
this data set. This data set cannot be removed during the current query (see
actions below).
- Not selected (red background): No variables from this data set have been added to the
current query.
- Selected (green background): Variables from this data set are included in the current query.
For each of the listed data sets, three possible actions are available in the
third column. Only the actions that make sense are available as hyperlinks.
These actions are:
- Select (only for <status> = 'Not selected'): Add variables from this
data set to the current query. The link brings up the page with the available
variables for this data set.
- Edit the selection (for <status> = 'Primary data set' or 'Selected'):
Add or delete variables, or change the reduction scheme for variables from this data set.
- Remove the selection (only for <status> = 'Selected'): Remove all
variables from this data set in the current query.
Constraints
The next section of the table lists the status and actions of constraints to
apply on the query. Constraints can only be applied to the variables of the
primary data set or to the selected indices. The status is 'Active', i.e.
constraints will be applied, or 'Inactive', i.e. no application of constraints.
The possible actions are the same as with the data sets.
Note: When the status of the constraints is 'Active', and the
INDICES data set is selected or edit, the status will automatically
change to 'Inactive', in order to preserve consistency between selected
variables and applied constraints.
The button starts the execution of
the query and brings up the first results page.
Form 4: Defining constraints
This page allows the user to set a number of constraints on the retrieved
data. The constraints add limitations (minimum and/or maximum valid values) on
one or more queried parameters. For
instance, when setting the constraint on local time to be between 08 h and 20 h
while querying for fluxes, only the fluxes observed during local time
between 08 h and 20 h will be included in the results file.
The possible constraints can be divided into three groups:
Geocentric position
Depending on the database being queried, the retrieved data can be limited by
means of the following parameters:
- Longitude
- Latitude
- Altitude
- Local time
Depending on the available parameters for the selected mission, this list
can be restricted. For instance, for the Meteosat mission, no detailed
information about altitude and latitude is available, and these parameters are
considered to be constant. Obviously, in this case, no restrictions can be made
on the range.
The longitude, latitude and altitude are given in a geodetic coordinate
system.
As longitude and local time are defined modulo 360 degrees and modulo 24 h
respectively, it is allowed to specify a maximum
that is less than the minimum. If the restriction to apply is e.g. only local
time from 10 PM till 6 AM, then set the minimum to 22 and the maximum to 6.
The valid
range for each value depends on the selected mission.
Magnetic coordinates
Limitations can be imposed on the magnetic coordinates
(B,L). The
valid range for the values depends on the selected mission.
Indices
The geomagnetic indices and solar wind data which were selected on the indices
page can be restricted to the range of interest.
Form 5: Outputs part 1
Tables
The database query produces the files listed in the table below.
A description of the format of the
files can be brought up by clicking on their description in the table.
On the results page of the database query, a file can be viewed (in a new
window) by clicking on its
description. It can then be downloaded from the new window to the user's
computer with the "File" menu of the browser (some browsers allow direct
downloading by clicking with the right hand mouse button, for instance).
List of output files generated by the database query
| File name | Description |
|---|
SPENVIS.DBP | Report file |
SPENVIS.DBR | Query results |
The output of the database query consists of two files: the report file
SPENVIS.DBP, and the query results file SPENVIS.DBR.
The report file SPENVIS.DBP is a printable file containing the
input parameters, and summary tables. It contains the actual
time interval of the query, the number of matching records, whether or not
data reduction was applied, and if
so, the number of matching records before the reduction.
The results file SPENVIS.DBR contains the actual matching records,
restricted to a total number of 2500. For each record, the selected variables
and statistics of the data reduction are included.
Graphics
This section displays the plot files already generated, or the message No
files found when no plots have been generated yet.
Generate new graphics
Two types of plots have been implemented.
The user can plot one variable of the
query as function of an other variable. The plot will result in a scatter plot
with plus signs as symbol, and without tracing lines between the data plots.
Options for the plot can be given in the next input page.
The second plot type will plot a number of variables as function of time in
different panels (stacked plot). On this page, all selected variables are
listed in a table, and the user can indicate in which panel of the plot he
wants this variable. panel 0 means no plot at all (default), panel 1 the top
panel, panel 10 the bottom panel. A maximum of 10 stacked panels can be plotted
. The size of the panels
depends on the selected number and the selected format. When a PS-file is
selected, the plot fits on a A4-page. Panels that are not used are simply skipped,
and take no place on the resulting plot, i.e. giving as input:
- <var1> --> panel 1
- <var2> --> panel 2
and
- <var1> --> panel 3
- <var2> --> panel 7
without using other panels will result in exactly the same plot.
More than one variable can be plotted in the same panel, as long as they are
one-dimensional. Plotting a spectrogram (indicated with (all channels) in the
variable list) with another variable will result in an error. When selecting
the same panel for more than one variable, the user should be aware of the
resulting ranges. It makes e.g. no sense to plot the plasma temperature
(variable from the indices data set) and geomagnetic field strength on the same
panel!
Plotting options can be entered in the next input page,
which is obtained by pressing the
button.
The button brings the user back to the
available data sets input form where data sets and/or
variables can be added or removed from the query. This button does not allow to
change the time period or the primary data set. In order to change these
parameters, use the
in the menu bar at the top of the page.
Form 6: Plotting options
This form gives the available plot options for the plots selected on the previous form.
Scatter plot
This table lists the selected variables for the x (horizontal) and y (vertical)
axes of the scatter plot.