FAQ

How are monthly station to gridded data bias ratios calculated?

The following steps describes the default method to the gridwxcomp.calc_bias_ratios.calc_bias_ratios function (i.e., the method kwarg = ‘long_term_mean’) for all variables except temperature:

1. Pair up daily station data with corresponding gridded data.

2. For each month on record, select those that have at least 10 (default threshold) days of paired data.

3. Group all daily data by month, e.g. all dates that lie in the month of July.

4. Take the mean of the grouped station data and divide by the mean of the grouped gridded data.

   • For temperature data the difference is calculated as opposed to station:gridded ratios. In other words step 4. becomes: mean of grouped station minus the mean of grouped gridded data.

See also

For more information on this calculation and the other options see the Step 3: Calculate monthly, seasonal, and annual station:gridded biases and statistics section in the tutorial.