The solid light blue line indicates 2009 relative to 2005, 2007 and 2008. (searcharcticscience.org)
Light blue lines over the black reiterate the figure; two shapes — resembling a «t» and a «y» — on each side disrupt the gray monochrome ground. (michaelwerner.com)
Black vertical stripes are flanked by blue and violet creating an optical central horizontal light blue line — I think. (patternsthatconnext.wordpress.com)