Sign up for the daily CJR newsletter . It has been a difficult year for public media. After Congress eliminated more than a billion dollars in federal funding, the Corporation for Public Broadcasting (CPB) shut down , removing support for local stations and the national network that relies on their programming fees. But throughout the turmoil, Frontline , PBS’s flagship documentary series, led by longtime executive producer Raney Aronson-Rath, has remained focused on the ambitious investigative storytelling that has made it a defining force in documentary film. Frontline was launched in 1983 by David Fanning, the only other executive producer in the program’s history. He handed the series over to Aronson-Rath more than three decades later, in 2015. Her role at Boston’s GBH, which produces Frontline , recently expanded to include oversight of two other documentary series, American Experience and Nova .…