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CLIWOC Repurposed

The Climatological Database for the World's Oceans 1750-1850 (CLIWOC) was a project sponsored by the European Union from 2001 through 2003. Meteorological data was extracted from the logbooks of ships, sailing primarily under the flags of Great Britain Spain, The Netherlands, and France. The final report of this project describes the data and the processes undertaken to make it available to the public. The data is included in the final report.

The CLIWOC final report includes some informative graphics, particularly on page 21, that indicate patterns of Atlantic crossings. The intended purpose of this present web site is to explore visualiztions of the CLIWOC data not for their meteorological value, but to illustrate the trade routes of the ships of the four countries. I do regret that ship tonnage is not available since that would make comparisons with some other data sources more meaningful.

As I am grateful to the multi-national CLIWOC project team for all that they did, I would be grateful to people in the mapping and data visualization communites for suggestions and critiques of this web site.

The Nuts and Bolts of This Site

I decided to use the Miller map projection not for any overwhelming reason except that I felt a cylindrical projection would be best for viewing the Atlantic and surrounding land masses. I read the CLIWOC data into NotePad++ where I applied some edits to make the data a bit easier to use. I then read it into an OpenOffice (now LibreOffice) spreadsheet where I applied the Miller transformation (long = lon, lat = 1.25 * ln(tan((pi/4) + 0.4 * phi)) where lon and phi (the latitude) are in radians). I then used R to produce the graphics. Here is the R code and here is the javascript for this site. My code is written to be accessible and easy to follow, even at the cost of being boring. While there are many ways to be more succinct, my primary interest is in sharing. The data as I have cleaned it up and added the Miller projections is here.

Since this is a proof-of-concept I used a simple (i.e. non-Flash) approach to displaying the data. Everything you see is a small, individual plot, transparent against a Miller representation. while there are 553 graphics files, they are small, running between 2 and 13 kilobytes. Being small, they are not a burden even over a slow connection. Generating them takes only a few minutes even on a general-purpose laptop.

Prof. Jean-Paul Rodrigue at the Dept. of Global Studies & Geography, Hofstra Univ., presents a visualization of this data using GIS mappings. He provides very helpful commentary on the interpretation of trade routes. 

There is an animated visualization of ocean currents at planetinaction. The animation may take a while to load.

If There is a Next Step

During data cleanup, I removed many partially null records. These actually have value since some of them show stays in intermediate ports of call. I would like to make use of this information but right now I don't have any great ideas about how to visualize it. Suggestions appreciated but any use will require a great deal of time to review the individual records. I would like to try out a different projection - one that is a "photograph" of the globe, looking down on the Atlantic. That will take some thought.

And Now, On With the Show

You can reach me at info at cassiodorus dot com
Latest mod: November 25, 2014