add bkg.lfo collection & remove lfo Nx+- collection#719

sdrabenh merged 3 commits intodevelopGEOS-ESM/GEOSgcm_App:developfrom

feature/saraqzhang/addbkglfo2histGEOS-ESM/GEOSgcm_App:feature/saraqzhang/addbkglfo2histCopy head branch name to clipboard