Area of Great Pacific Garbage Patch 16 times larger than previously estimated

The Great Pacific Garbage Patch is significantly larger than previously estimated, with researchers using 30 vessels and a C-130 Hercules aircraft to catalog over a million pieces of plastic, mostly microplastics. The patch contains more than 79,000 tons of plastic, equivalent to 500 jumbo jets, spread over an area three times the size of France in the North Pacific Ocean. The waste includes plastic bottles, containers, packaging straps, lids, ropes, and fishing nets, which have accumulated over decades.

What methods were used by researchers to catalog the plastic in the Great Pacific Garbage Patch?

What area does the Great Pacific Garbage Patch cover in comparison to France?