Description and operation of the different processes

Before any message-based processing, start the posttroll nameserver:

$ cd /path/to/posttroll/bin
$ ./nameserver

This script handles the connections between different message publishers and subscribers.


Trollstalker is a script that monitors the arrival of given files in the specified directories. When such a file is detected, a pytroll message is sent on the network to notify other interested processes.

An example configuration file for trollstalker is provided in trollduction/examples/trollstalker.ini_template:

# This config is used in Trollstalker.


# posttroll message topic that provides information on new files
# This could follow the pytroll standard: 

# input directory that trollstalker watches

# filepattern of the input files for trollstalker
# uses the trollsift syntax:

# instrument names for mpop

# logging config for trollstalker. Comment out to log to console instead.

# logging level, if stalker_log_config is not set above. Possible values are:

# inotify events that trigger trollstalker to send messages

# port to send the posttroll messages to, optional so use "0" to take a random
# free port.

Of course, other sections can be added to the file for other files to be watched.

In order to start trollstalker:

$ cd trollduction/bin/
$ ./ -c ../examples/trollstalker.ini -C noaa_hrpt

Now you can test if the messaging works by copying a data file to your input directory. Trollstalker should send a message, and depending on the configuration, also print the message on the terminal. If there’s no message, check the configuration files that the input directory and file pattern are set correctly.


l2processor is the process that reads satellite data and generates composites
from it. It is triggered by messages fullfilling a given topic, reads the data file, resamples the data to given areas and generates image composites.

Before starting to configure l2processor, make sure that your mpop has been setup correctly (mpop.cfg, areas.def, satellite definitions). l2processor relies heavily on mpop.

To configure l2process, the user needs to supply at least a configuration files and a product list. The product list format is explained below.

An example configuration file for l2processor is provided in trollduction/examples/l2processor_config.ini_template:

# This config is used in l2processor

# the topics in the messages to listen to.
# the instruments we want to process
# the list of products we want to generate for this type of data
# the log config file

Start l2processor by:

$ cd trollduction/bin/
$ ./ -c ../examples/master_config.ini -C noaa_hrpt

Product configuration file format

The product list configuration file is an xml file that contains information about the desired output of l2processor. An example file is provided in trollduction/examples/product_config_hrpt.xml_template:

<?xml version="1.0" encoding='utf-8'?>
<?xml-stylesheet type="text/xsl" href="prodlist2.xsl"?>

<!-- This config is used by Trollduction.-->

  <!-- common default values -->

  <!-- aliases: substitutions to make in the filenames. E.g. replace in "platform_name" items. -->
    <platform_name src="Metop-A" dst="metop02" />
    <platform_name src="Metop-B" dst="metop01" />
    <platform_name src="NOAA-15" dst="noaa15" />
    <platform_name src="NOAA-18" dst="noaa18" />
    <platform_name src="NOAA-19" dst="noaa19" />
    <platform_name src="EOS-Terra" dst="terra" />
    <platform_name src="EOS-Aqua" dst="aqua" />
    <platform_name src="Suomi-NPP" dst="npp" />

  <!-- variables: substitution to make in the xlm attributes. E.g. replate "output_dir" items matching with real path -->
    <output_dir id="path0">/san1/sir</output_dir>
    <output_dir id="path3">/san1/pps/www/latest</output_dir>
    <output_dir id="path4">/san1/pps/www/ash</output_dir>
    <overlay id="black">#000000</overlay>
    <overlay id="white">#ffffff</overlay>

  <!-- variables section with attribute. E.g. if the "MODE" environment variable is defined to "offline", the items should take these values instead. This takes of course precedence over the standart "variables" section. -->
  <variables MODE="offline">
    <output_dir id="path0">/local_disk/data/out/sir</output_dir>
    <output_dir id="path1">/local_disk/data/out/sir</output_dir>
    <output_dir id="path2">/local_disk/data/out/rgb</output_dir>
    <output_dir id="path3">/local_disk/data/out/rgb</output_dir>
    <output_dir id="path4">/local_disk/data/out/rgb</output_dir>

  <!-- areas to group together for processing -->
    <group id="africa">afhorn,mali</group>
    <group id="asia">afghanistan</group>
    <group id="eport">eport</group>
    <group id="highres" unload="True" resolution="250">baws250</group>

    <!-- dump to netcdf -->
    <!-- calibrated, satellite projection -->
      <file format="netcdf4">{time:%Y%m%d_%H%M}_{platform}{satnumber}.nc</file>

    <area id="eurol" name="Europe_large">
      <!-- Generate the product only if sun is above the horizon at the
           defined longitude/latitude -->
      <product id="overview" name="overview" output_dir="path0" sunzen_day_maximum="90" sunzen_lonlat="25, 60">
        <file output_dir="tmp">{time:%Y%m%d_%H%M}_{platform_name}_{areaname}_{productname}.png</file>

      <!-- Generate only if the Sun is below the horizon -->
      <product id="night_overview" name="night_overview" sunzen_night_minimum="90" sunzen_lonlat="25, 60">
        <file format="png">{time:%Y%m%d_%H%M}_{platform_name}_{areaname}_{productname}.png</file>

      <!-- Generate also thumbnails -->
      <product id="natural" name="dnc" output_dir="path1" thumbnail_size="640x640" thumbnail_name="{platform_name}_{start_time:%Y%m%d_%H%M}_{orbit_number:05d}_{areaname}_dnc_thumbnail.png" sunzen_day_maximum="90" sunzen_lonlat="25, 60">

      <!-- add overlay using pycoast configuration "black.cfg"-->
      <product id="green_snow" name="green_snow" output_dir="path3" overlay="/usr/local/etc/pytroll/black_overlay.cfg" sunzen_day_maximum="90" sunzen_lonlat="25, 60">


    <!-- another area -->
    <area id="euron1" name="North europe, 1km/pixel">
      <product id="red_snow" name="red_snow" sunzen_day_maximum="90" sunzen_lonlat="25, 60">
        <file format="png">{time:%Y%m%d_%H%M}_{platform_name}_{areaname}_{productname}.png</file>

      <product id="cloudtop" name="cloudtop">
        <file format="png">{time:%Y%m%d_%H%M}_{platform_name}_{areaname}_{productname}.png</file>

      <product id="night_fog" name="night_fog" sunzen_night_minimum="90" sunzen_lonlat="25, 60">


The first part, <common>, can be used to give default values that are used, if not overridden, by all the <product> definitions.

The second part is <aliases> and contains the substitutions to perform in the file patterns (from src to dst)

The third part is <variables> which holds the substitutions for the tag attributes. Adding an attribute to <variables> checks if the corresponding environment variable is set to the given value, and uses these substitutions if it does.

The fourth part is the <groups> defining the area to group for processing. This means for example that the data will be loaded for the whole group (cutting at the area definition boundaries if supported). Setting th unload attribute to “true” provokes the unloading of the data before and after processing the group.

The next part is the <product_list> which contains the list of products and areas to work on.

The next layer of the product configuration is the <area>, which holds the following attributes:

  • name — replaces the {areaname} tag in the file name template
  • id — the name of the area/projection definition given in mpop areas.def file

The following layer is the <product> details to be produced in the area. The <product> section is given for each product. These values override the defaults given (if any) in the <common> section.

Required attributes within <product>:

  • id — name of the function (from mpop.image) that produces the product

  • name — user-defined name for the composite, this will replace the {productname} tag in the file name pattern

  • overlay — the color of the overlay to put on the image, in hex hash

    (e.g. #ffffff for white) or alternatively the path to the overlay configuration file to pass to pycoast.

  • thumbnail_size and thumbnail_name — the size and filename of the thumbnail to produce. The thumbnail will be written in the same directory as the image.

  • sunzen_day_maximum — Sun zenith angle, can be used to limit the product to be generated only during sufficient lighting

  • sunzen_night_minimum — Sun zenith angle, can be used to limit the product to be generated only during sufficient darkness

  • sunzen_lonlat — comma-ceperated longitude and latitude values that can be used to define the location where Sun zenith angle values are checked. Only effective if either sunzen_day_maximum or sunzen_night_minimum is given.

  • sunzen_xy_loc — comma-ceperated x- and y-pixel coordinates that can be used to define the location where Sun zenith angle values are checked. Only effective if either sunzen_day_maximum or sunzen_night_minimum is given. Faster option for sunzen_lonlat, but needs to be determined separately for each area.

The final layer is the <file> tag which holds information of the file to be saved. It can have the following attributes:

  • output_dir — the destination directory
  • format — the file format to use. This is optional, but if the file format cannot be easily guessed from the file extension, it’s good to write it here.
  • The text of this <file> item is the filename pattern to use.

Data dumps

An alternative to the <product> tag is the <dump> tag that saves the resampled data to the given filename (pattern). It can also be inserted at the previous layer to do a data dump of the unprojected data.


Watches files or messages and gathers satellite granules in “collections”, sending then the collection of files in a message for further processing.

To be written


Receive and translates scisys ground-station message to pytroll messages.

To be written


Run aapp

To be written


Run pps

To be written


Run viirs l0 -> l1 processor

To be written


Run modis l0 -> l1 processor

To be written