使用全局选项（/ g）时如何使用正则表达式匹配空行？

I'm aware the general question must have been asked many times, but in attempting the suggested solutions I'm getting nowhere. I'd like to match either a new line character without a preceeding > or a new line character on it's own, but I can't seem to get any of the usual suggestions for matching a blank line to work.I'm aware the general question must have been a