I could not find the original source of this hi-res scan.

More info...

I saw the image on Gurney Journey’ blog post (with more images): Miyazaki: Digging into the Subconscious which links these sources (links to amazon):

More info:
Miyazaki on Wikipedia
Miyazaki Quotes
Books about Miyazaki’s Philosophy and Art:
Starting Point, Essays and Memoirs by Miyazaki, 1979-1996
The Art of Spirited Away
The Art of Princess Mononoke
The Art of My Neighbor Totoro: A Film by Hayao Miyazaki
Films:
Hayao Miyazaki Collection: Box Set of 11 Movies (Blu-Ray)
Hayao Miyazaki & Studio Ghibli DVD Collection

Then I found the hi-res version using reverse image search (Yandex found the posted version):