Visit the Map Room
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.
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
The Nuts and Bolts of This
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
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
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.
You can reach me at info at cassiodorus dot com
Latest mod: November 25, 2014