Why was robert gray determined to sail up the columbia river

Reasons...

Explanation:

Because it strengthened the United States' claim on its territory and led to the exploration and claim of the Snake River. It also gave the United States control of the Columbia River.

After his return from that expedition, Gray set sail for the northwest coast again on September 28, 1790, reaching his destination in 1792. ... On this journey aboard Columbia Rediviva Gray noticed muddy waters flowing from shore and decided to investigate his belief that it might be the "Great River of the West".

in about winter like late november to january

answer; depression and breathing related sleep disorder(independent);