Time Series Manager

This page comprises a short definition of Time Series in the context of the SNAP Time Series Tool, and describes how such Time Series are created and edited using the Time Series Manager tool.

Time Series

Within the Time Series Tool, a time series is specified by several source products and variables. Every product comprising remote-sensing bands may be used as source product of a time series. However, products need to share at least one remote-sensing band in order to create a meaningful time series. A time series comprises several bands of the same variable, for example, 4 bands of TSM_mean, each originating from a different source product.

Time Series Manager Tool

The Time Series Manager, opened by a click on ts-manager-button , allows to manage time series in a broad sense. In short, it allows the user to

create a time series
import in-situ data
map band names
edit a time series' time frame
view a time series
export a time series

Screenshot 1 shows the time series manager in its initial state.

Screenshot 1 - Time Series Manager in initial state

The point of entry is the Time Series Wizard, which is started by clicking on new-button . It allows the user to specify source products in three different ways: either a directory is scanned for products or a directory is scanned together with its sub-directories, or single products may be chosen (see Screenshot 2).

Screenshot 2 - Defining Time Series source products

If all specified products are on the same grid and have the same bounds, the following step is skipped. If not, the products need to be reprojected for the time series. Reprojection is done by specifying an already projected reference product and using its CRS and its bounds. Therefore, these reference products needs to intersect the products which shall appear in the time series. See Screenshot 3 for the wizard's reprojection page.

Screenshot 3 - Reprojecting time series source products

In the next step, the wizard allows to specify the variables the time series shall contain. The list of possible variables is derived from the products which have been chosen in the previous step. This step is displayed in Screenshot 4.

Screenshot 4 - Specifying the variables

After that, the user may assign the time series a name and finish the wizard. See Screenshot 5.

Screenshot 5 - Setting the name and finishing the wizard

After the wizard is finished, the Time Series Manager now looks as displayed in Screenshot 6.

Screenshot 6 - The Time Series Manager

General Information

On the upper left, there are provided some general information about the time series, such as the start and end time, the CRS and the dimensions. In the upper middle, the variables from the bands may be selected and de-selected. Only selected variables are featured in the time series, thus, if a variable becomes de-selected, it is instantly excluded from the time series.
On the upper right, in-situ variables may be added or removed. The lower panel displays the product sources and allows the user to add or remove products of the time series.

Buttons at the right side

On the panel's right, there are a number of buttons which become active after creating the time series.

Import in-situ data

The insitu-button -button allows the user to load in-situ data from a CSV-file. The columns within that file need to be tab (char='\t') separated.
See listing 1 for an exemplary in-situ source file.

Name	Lon	Lat	Time	Fo	CHL
AMRU2	7.8333	54.6667	2010-01-23 01:21	19.9	0.46
DTEND	4	55.5	2010-01-25 18:35	16.9	0.39
DTEND	4	55.5	2010-01-25 19:35	16.8	0.41

Listing 1 - An exemplary in-situ source file

The import mechanism automatically detects columns for station name, latitude, longitude, and time. All other columns are interpreted as measurement parameter.
Note that all valid column names are case insensitive.

Column	valid names
Latitude	"lat", "latitude", "northing"
Longitude	"lon", "long", "longitude", "easting"
Time	"time", "date"
Station name	"name", "station", "label"

Names Association

On click on the namesAssociation-button -Button, the names association dialog (see Screenshot 7) opens.

Screenshot 7 - Names Association

That dialog allows the user to create a mapping between satellite and in-situ data. This is needed if the names in the satellite products are different from the names within the in-situ data, but shall be handled equally. The first step is to create a new alias name (in the example 'algal_2') and then choose from the list of band names and the list of in-situ variable names the names which are to be grouped within that alias. Multiple list entries from a single list may be chosen by holding the Ctrl-button while clicking.

The edit-time-span-button -button allows to edit the valid time span of the time series. The respective dialog is shown in Screenshot 8. Products whose time bounds do not fit into the time span specified in the tool are excluded from the time series.

Screenshot 8 - Edit time span

The view-button -button allows the user to show one of the selected variables in the Product Scene View.