How do I identify consecutive positive values in an array?

I have a seismic section in the form an array that's a 4809x3874 double (I've taken a screenshot of a portion for context). I want to identify the top horizon (the thick green band) which, in the array, is multiple (9-12) rows of consecutive positive values in a single column. How can I identify these consecutive rows of positive values thereby identifying the top reflector?