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Dec
05

Prevailing Ocean Winds

Recently, I have discovered world-wide ocean wind data collected over ten years from the ‘SeaWinds’ scatterometer onboard the ‘QuikSCAT’ satellite on the Internet at Oregon State University: COGOW. The site offers an interactive atlas to view prevailing wind maps and wind roses. For blue-water cruisers, the site is definitely a great source to aid route planning.

In my opinion, usability of the wind atlas at COGOW could be improved. Their service requires flash player, map sizes are relatively small, and there is no way to use the atlas off-line. For these reasons I decided to use their data to generate kml files that can be used with Google Maps and Google Earth (and some other programs).

I have generated kml files for the Atlantic, the Indian, and the Pacific Ocean, one file per month of a year. The files contain prevailing wind arrows at a 2-by-2 degree lon/lat grid. The direction and length of an arrow was obtained by vectorially averaging monthly data over 10 years and over 2-by-2 degree areas (i.e., 32 COGOW data files were averaged for one arrow). The color of an arrow corresponds to the scalar averaged wind speed in knots. In addition, each arrow links to a wind rose image located at COGOW.

The map page here at Pitufa.at incorporates these kml files. Feel free to use this map for your route planning. Any comments are highly appreciated. I also provide them here for download (see below). However, be aware of the disclaimer found in the files and at COGOW. Also useful could be kml files to show other monthly data of pilot charts (such as gale probabilities). Wanna contribute?

Download KMZ File

Download this kmz file (= zipped kml files) to get a world-wide prevailing sea wind atlas which is convenient for off-line usage. You may simply load it into your Google Earth (File > Open…). In your ‘My Places’ panel you will get a list to switch between the months. Displaying them right after loading may take some time. Repeated displaying should work fine.

UPDATE July 5th, 2014: The file no longer worked with newer versions of google earth (6.1 and newer), because of spaces between the coordinate number pairs (!). I uploaded a corrected version which works fine again.

UPDATE Sept. 3rd, 2014: I uploaded a new version that links to windroses in svg format hosted at Pitufa.at.

UPDATE Apr. 12th, 2016: You might have seen that these kml files can be visualized on our Map page. As Google Labs have repeatedly disappointed me by introducing severe bugs in their maps api (which is utilized by our Map page) and showing no commitment to fix those bugs, I wrote an alternative interactive wind atlas and windrose browser that does NOT rely on google maps but is based on OpenLayers.

Christian

6 comments

  1. Kevin says:

    Hi!
    Your prevailing wind .kmz file is a great idea. Unfortunately I can’t get it to work on Google Earth. All that displays when I open it is a red and yellow line around the equator. Am I doing something wrong?
    Thanks,
    Kevin

  2. Danie says:

    Same problem as Kevin, just get a red & yellow bar around the equator

    1. Christian says:

      hi guys,
      thanks for reporting.
      i just double-checked with my own google-earth and the kmz file works nicely. i’m using google-earth version 6.0.3.2197 under linux. i’ll also check whether something happend to the file on the web server.

      1. Kevin says:

        Hi Christian,
        I wasn’t able to figure out any kind of workaround for Google Earth 7.1.2.2041 but I was able to download the older version that you mentioned. The file works flawlessly now. Thanks for putting it together; I really enjoy it!
        Kevin

  3. Maddox says:

    Thanks for writing the alternative browser – Works great with my iPad. The information is a good tool to help plan routes.

    1. Christian says:

      You’re welcome!

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