How I use Digital Atmosphere
Fred van den Bosch / February 2007



This paper describes how I use Digital Atmosphere. First I tell how I started with the program and my two main ideas about the use: automating the whole process and integrating it with weather satellite images. I give some hints about automating the whole process, followed by an introduction about weather satellites. I show the different types of satellites and explain how to use them as background image in Digital Atmosphere.

New sources of information are maps and images from the Deutsche Wetterdienst.

To manage all that information I developed POVIM. I explain what I did to structure my system and to view all the maps and images. Finally I give an impression of my system and I present some future plans and wishes.



1. Introduction

For many years I am receiving weather satellites. About 25 years ago it was only possible to receive some polar satellites. Today there are a couple of polar satellites, 5 geostationary satellites and you also have the possibility to receive images from internet.

A couple of years ago I also started with Digital Atmosphere. Rather soon I wanted to automate the whole process. This to make it easy for myself: all maps that are needed are ready to view. It started with some easy scripts and rather quick I had a lot, also helped by the forum where other users published some nice scripts. For some time DA made every hour a couple of maps, fully automated. But I wanted more.

The next idea was to integrate DA with the weather satellite images. My final goal was to have not only the basic maps, but also images with weather information on it, all fully automated. Of course the interactive working with DA is always possible to see specific situations that are not automated. In the following paragraphs I describe what I have done to realize it.



2. Automating Digital Atmosphere

First I started to make some structure in different parts. I made two new folders:
  • maps - In this folder I store all the different maps I have made. I have maps for background images, color-fill and lines. Here I have added the type (lines etc.) to the filename.
  • scripts - I made some subfolders for the different type of scripts: import, export, fill, line, overlay and test for not-yet-finished scripts.

    Next step was to make a couple of scripts for hourly running. I did that by combining a couple of small “basic” scripts into one “main” script. See also my wishes at the end of the paper. This “main” script was entered into the DA-scheduler. Downloading from the internet and making maps are –in my case- separate scripts. A lot of scripts can be found on the DA2 forum. But it’s nicer to make your own scripts. I have written an article [1] for GEO, the Group for Earth Observation, where I explain into detail how to make and test scripts. Back issues are still available via their website [2].



    3. Integrating Digital Atmosphere and weather satellite images

    After the scripts produced their hourly maps it was time for the next challenge: making the weather satellites images to a background for the weather maps. Before I describe how this can be done I first will give some general information about satellites. There are two types of weather satellites, polar and geostationary.



    3.1. Polar satellites. Polar satellites are flying around the earth on a height of about 840 km. They are sending their signals on 137 MHz. With a cheap receiver [3] and simple antenna receiving their signals is relatively simple. The photo shows my mobile station during a holiday in Vietnam. At the moment there are 4 satellites that you can receive a couple of times a day. There are several programs for decoding the signals: Wxtoimg [4], SatSignal [5] and APTDecoder [6]. The last program is freeware. Personally I use Wxtoimg and sometimes APTDecoder.



    The photo shows a composite image from a couple of passes with Vietnam in the middle. The images from polar satellites can be used as a background. Disadvantage is that they are not sent on a fixed time every day. That’s why they less suitable to use as the images from the geostationary satellites. Nevertheless it’s possible and not so difficult. Here is an abstract of an article I wrote for the GEO Quarterly [7] that explains how to use them.


    3.1.1. Initial.

  • Wxtoimg - Set in the following parameters: latitude, longitude, north, south, west, east, scale. Choose values that will give the image you want. Remove the mark by “disable map overlay”, choose in for “Orthographic” and generate the image. Write down the size in pixels (they will appear on the bottom of the screen, just before showing the image), choose [Image/White background] and save the image as BMP.

  • Digital Atmosphere - Generate a map. Use for latitude and longitude the same values as in Wxtoimg. Use for scale a size that generates more or less the same map as Wxtoimg. It is not so important at this moment. Give width en height the values from Wxtoimg. Generate the map and if it’s ok, save it with [Map/Save map] as BMP.

    3.1.2. Fine-tuning. Repeat the next steps until both maps fits exactly.
    1. Choose icon “load map” and read the Wxtoimg image.
    2. Choose . This option will project the DA-map over the image and will surely not fit. Now we must try to make the DA-map fit. This is done by making changes in .
    3. Latitude. This will move the map in vertical direction.
    4. Longitude. This will move the map in horizontal direction.
    5. Scale for resizing the map.
    6. Make small changes in the steps 3, 4 and 5. After DA will generate a new map.
    7. Continue with step 1.
    It can happen that meridians do not fit exactly onto each other. Then you can rotate the image in Wxtoimg by changing the “reference longitude”.

    3.1.3. Finishing. Save the DA-map for the last time. This must be done because every lay-out has its own base map and parameter-files. Always open this corresponding map before loading a picture with a different layout from Wxtoimg. The dimensions of the map can be changed by modifying the “width” in the parameter of Wxtoimg. Give width en height in DA the same values as in Wxtoimg.

    3.2. Geostationary satellites

    Geostationary satellites are on a fixed point in the sky. At the moment there are several satellites active. The most important for the amateur are Meteosat 8, GOES-11, GOES-12 and MTSAT-1R. Meteosat covers Europe and Africa, GOES covers America and MTSAT Asia. There are 2 ways to receive them: via an antenna and via internet. There are also differences between America and Europe.

    3.2.1. Europe. In Europe it is possible to receive the signals via an 80 cm. dish. A receiving program is needed and you must register at Eumetsat [8]. Beside that some programs are needed to handle the received files and convert them into images. Suitable are the programs of David Taylor [5] and Rob Alblas (freeware) [9]. Via David Taylor’s GeoSatSignal it is possible to make images that can be used as background for Digital Atmosphere.


    This is an example of an image with added fleet code. The left part of the chart is white because that’s the border of what the satellite can see. I left it because I want to see the isobars etc. there. The procedure to make the image fit in Digital Atmosphere is the same as described in 3.1.

    3.2.2. America. It is possible to receive signals via C-band. I don’t have experience in this field but it is possible to view if you are within the footprint for all EUMETCast services [10]. You are lucky if you are in the footprint for the C-band Africa service, because this has more services than the American service.

    3.2.3. Internet. The only MSG data you can download via the internet is the low resolution (LRIT) data. Disadvantage is that it’s only Europe. You will not need the user key or receiving software for this. You must only register with Eumetsat to get a username/password to access their site. I don’t have experience with downloading LRIT either.



    4. Weather maps

    Since September 2006 it is possible to receive maps, synops and weather satellite images from the Deutsche Wetterdienst (DWDSAT) for free. This information is received by satellite, but can also be downloaded from internet. I must emphasize that this is mainly information about Europe.

    Most used maps will be the ones that start with fx401. A big help to know what the maps are, is the Products Catalogue. It can be downloaded from the site of the Deutsche Wetter Dienst http://www.dwd.de/en/Technik/Kommunikation/dwdsat/prodkat.htm It’s a good idea to print it for a quick lookup. On the same site you can find a comprehensive explanation under “Explanations to the product catalogue”.

    There are files beginning with “sat”. These are satellite images and can be viewed with a photo viewer or with “DWDSAT HRPT Viewer”, a program of David Taylor [5]. This program can also read files with the extension .BZ2. Files, beginning with “grb” can be read with “GribViewer”, also from David Taylor [5]. This all can be a good addition to Digital Atmosphere.






    5. POVIM: Managing all images and maps

    5.1. Introduction

    The primary reason for the development of POVIM is simple: my system was starting to get into a bit of a mess. I had a lot of different satellite images and Digital Atmosphere maps. I continually had to search where specific files had been stored. Designing a logical structure for my whole system solved that problem [12]. Of course Digital Atmosphere fits smoothly in this structure.

    It was also difficult to view same maps/images in time. Designing and building a specific viewer did the trick.

    First I will explain something about POVIM. Then I will show how the Product- and Presentation Manager are performing and how this can be a great advantage for Digital Atmosphere maps.

    5.2. POVIM in general

    I made a presentation at the GEO 2005 Symposium [2] under the above title. POVIM is a framework for Product Oriented Video, Images and Maps. It provides the functional design for:
  • the automation of computer programs
  • a separate reception PC
  • a master folder containing a hierarchy of sub-folders
  • a convention of systematic filenames throughout
  • everything in a logical and consistent structure.

    5.3. POVIM Product Manager

    During the above step I decided to use the term “products”. A product can be an image, a video or a map. In fact everything is a product. Every product has unique attributes like name, folder, type (image, map etc.). So products are for instance: a surface map with fleet codes, a map with temperatures, a map with plots, an image of a certain area or a video of a certain area.

    To view all products I first used a simple photo viewer. But I wanted more functionality. So I decided to develop my own viewer: POVIM Product Manager (PM). POVIM PM integrates all the separate programs. POVIM PM consists of 2 parts: the Product Manager and the Presentation Manager and offers the following possibilities.







    5.3.1. Product Manager.
  • create your own products and where they are stored
  • structure products into maximal 3 levels
  • every level can be defined to your own choice
  • combine same type of products into groups e.g. Oceans, Hurricanes, Europe etc.
  • a product can be ; generated: there is already an image ; to-generate: make the image during presenting ; a group: a couple generated / to-generate
  • make files with basic information
  • define all the programs you use for weather satellites and weather watching.

    5.3.2. Presentation Manager.
  • selecting up to 20 products from a list of products
  • present them in thumbnails
  • synchronized scrolling in steps of 5, 15 and 60 minutes
  • call your favourite photo viewer to see the images on full screen
  • use all the options of your photo viewer like zoom, scroll and print
  • choose a different date and time
  • display generated images or generate the image "on the flow"
  • present details for every image (if in the database)
  • display the latest received image in case it does not has a periodicity of 15 minutes
  • display images (jpg, bmp) video (avi, mpeg) and maps(jpg, bmp) from e.g. Digital Atmosphere
  • start satellite- or weather program or go to a specific internet site. In this way you can e.g. start Digital Atmosphere directly to show a specific situation or visit sites for lightning and radar. The radar sites are mainly for the European users.
  • directly start the photo viewer to see the content of all the folders in thumbnails ; this is of course depending on the options your viewer provides.




    5.4. POVIM and Digital Atmosphere

    One of the main advantages of POVIM is that you can define the different DA-maps as products. Then you can view a couple of products at the same time and scroll them in time to view the development of certain phenomena. On the above figure you see the main screen with some selected products. Clicking on a map starts the photo viewer to show the map/image on full-screen. The DWDSAT maps can also be added as products.

    5.5. RotateDWDSAT

    Some DWDSAT maps are 45 degr. rotated. This is a separate program I made to rotate them and convert them to jpg. The converting has two reasons:
  • to know what files are converted
  • jpg’s are easier to use in Visual Basic programs.
  • By doing this you can directly view the received maps in their “normal” presentation.

    5.6. Downloads from my website

    All programs I mentioned here (and some others) can be downloaded from my website [12] for free. You will find a more comprehensive description on my website.



    6. System

    Personally I use 3 computers for running the above described programs:
  • Receiving (running 24/7) On this pc I receive the weather satellites and make basic images of the signals.
  • Processing (running 24/7) This system runs all scheduled programs ; Making color images of the basic satellite images ; Making Digital Atmosphere maps: lines, color filled and with satellite backgrounds ; Running my weather station
  • Main system (running when necessary) Here runs POVIM. From here I can go to the other two systems to get my images and maps. Of course such an extended system is not a must. Even with just one pc you can receive or download satellite images and combine them.



    7. Future

    Currently everything is working fine. But of course there are some wishes and plans to improve the system.

    7.1. Plans

    I have a lot of plans for improving a lot of things. Two of the most important are:
  • Better website In the near future I want to add some more charts to my website. This will be a combination of “normal” charts and charts with a satellite image as background. Also some cloud movies will be added.
  • POVIM Presentation Manager I want to try to make it easier to add new products to the program.

    7.2. Wishes

    The wishes are most for Digital Atmosphere in combination with the automation of the processes. My main target is to make Digital Atmosphere as easy, user-friendly and most of all as automated as possible. So in my opinion the following will be a big improvement:
  • Default folders The use of default folders in preferences for scripts, maps etc. The advantage is that you can place the folders on a place where it is easy to add them to the daily (automated) backup. Also when you want to use a script or a map you directly are in that folder.
  • Using scripts in menu Things would be much easier when it’s possible to call a script from a menu option. You don’t have to add a lot of lines to the menu for using a complicated function but you can make a script. This is more structured then directly calling a script.
  • Calling scripts I like to have a function where you can call another script file: 
    CALL, filename

    where filename is a valid script name. In this way you can make and test small scripts, give them a useful name and if they are OK add them easily to the existing script. This will give much more structure and flexibility to the scripting.



    8. References

  • [1] Using scripts in Digital Atmosphere, Fred van den Bosch, GEO Quarterly, September 2005
  • [2] Group for Earth Observation, http://www.geo-web.org.uk/index.html
  • [3] R2FX receiver, http://www.df2fq.de/produkte/r2fx.html
  • [4] WXtoImg, http://www.wxtoimg.com
  • [5] SatSignal, David Taylor, http://www.satsignal.net
  • [6] APTDecoder, http://www.ptast.com/apt/decoder/index.html
  • [7] Using Wxtoimg images in Digital Atmosphere, Fred van den Bosch, GEO Quarterly, May 2004
  • [8] Eumetsat, http://www.eumetsat.int/Home/index.htm
  • [9] Xrit2pic, Rob Alblas, http://www.alblas.demon.nl/wsat/
  • [10] Footprint Eumetcast services, http://www.eumetsat.int/Home/Main/What_We_Do/EUMETCast/index.htm?l=en
  • [11] DWDSAT, http://www.dwd.de/en/Technik/Kommunikation/dwdsat/
  • [12] POVIM, Fred van den Bosch, http://www.fredvandenbosch.nl