I'm looking for a way to quantify the uncertainty associated with GRACE equivalent water thickness measurements for a specific region. The region I'm working with has an area of about 11,500 km^2, which I know is quite small of an area to be using GRACE data for, but it is currently my only option. It is also my understanding that errors and uncertainties are larger at small spatial scales, compared to larger scales.
Is it possible to quantify what the associated uncertainties in this case might be? I'm using the average of the JPL and CSR monthly EWT values as is suggested in this article: https://grace.jpl.nasa.gov/data/choosing-a-solution/
Any help is appriciated. Thank you.