Figure 7: Visited confluences (top) and light pollution (bottom) created by the U.s. national oceanic and atmospheric administration.

Figure 7 discovers an astonishing correlation: the upper part of the figure shows each of the world’s confluence visits as a square. The brightness of the pixels is according to the number of revisits. The bottom picture is based on totally different data, showing the earth by night in a composed picture from NASA. Central Europe, the USA, Japan are clearly the brightest regions in both pictures, whereas central Africa, the Brazilian jungle, Greenland and Antarctica both times are represented by dark spots. Only for some touristy regions such as New Zealand and the Western USA confluencing activities are ahead of the emitted light in the region. Apparently, key factors such as Gross National Product (GNP) and population density seem to be the main drivers for both, light emission and confluence visiting.

Figure 8: land based confluence points by degree latitude. negative values represent the southern hemisphere. the fraction of visited confluences is drawn in black.

Figure 8 presents the distribution of confluences by latitude. Antarctica causes all intersections at latitude 78°S or further to the South Pole to fall on land. But almost none of these Antarctic confluences have been visited. Figure 9 focuses on the percentage of finalisation, showing that for latitudes between 40°S and 30°S almost all confluences have been visited by some Australian, South African and Argentinean enthusiasts. At the equator as well as close to the poles, finding integer degree intersections seems to be rather difficult due to remote jungles, swampy tundra and ice. The two main peaks in Figure 9 indicate that temperate zones are preferable regions for confluencing.

The reported accuracies of locating confluences are driven by two key factors: the minimal distance at the nearest point and the GPS accuracy. Initial positional accuracies had been around 10-30m, but after removal of selective availability in May 2000 accuracies improved to 5-10m. Nowadays with the help of augmentation systems accuracies of 1-5m are typical. In the year 2012, assuming availability of 35 Beidou Navigation Satellites, 18 GLONASS satellites, 30 Galileo satellites and an improved GPS, positional accuracies of less than a meter can be expected. With 107 satellites in the sky, positional service will cover deep canyons and forests. Even today a fix position solution is oftentimes possible for confluences that are located in forests or valleys but accuracies are low due to shading of satellites.

Figure 9: percentage of land based confluence points that have been visited. 100% means that all confluences for particular latitudes have been completed and the project goal is being fulfilled.