Jankowski, from Indiana, was a commercial artist by day and a serious artist by night. This, of course, isn't accurate because commercial art is serious art. Fine artists want to sell their work just like commercial artists. The divide is not such a vast chasm.
Regardless, in the early 1970s, he moved to Gloucester, Massachusetts and worked full time on his fine art. You may seem other paintings by him that are sort of impressionistic landscapes, many using earthy colors, browns and dark oranges. Apparently his later work became brighter in color.
I confess that I am not 100 percent sure the piece below is BY the artist. You can see more at the gallery site linked above and at the site of the Cape Ann Museum.