This paper https://www.sciencedirect.com/science/article/pii/S1352231017300936 mentions using a 0.5° × 0.5° resolution grid, and I've tried googling to find out what that means in meters but I come across many conflicting answers.

Am I right to say this unit of measurement is called decimal degrees, the value varies depending on where you are on Earth, and for China, this 0.5° × 0.5° in meters is 55.5km x 55.5km?


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You're correct that this UoM is called decimal degrees, and partially correct that the value varies depending where you are on earth.

One degree of latitude is always about the same width. One degree of longitude varies depending on what latitude you're at. The accepted answer to this question explains it well: Calculating longitude length in miles?

The latitude of China ranges from about 18° N to about 53° N (I estimated this by clicking on Google Maps). One degree of Longitude is about 106km wide at 18° N, and about 67 km at 53° N (values provided by this site).

So in China, a 0.5° × 0.5° grid will be (approximately) between

  • 53 km (east-to-west) by 55.5 km (north-to-south)
  • 33.5 km (east-to-west) by 55.5 km (north-to-south)

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