Correcting Possible Bias

The Philippine case study conducted bias correction by applying a modified quantile scaling technique[1] to each of the four models’ simulation data. This was done to ensure realistic distribution of dry spells for historical period and hopefully more realistic distribution for future periods.

To create a more realistic rainfall distribution, a quantile-quantile bias correction was applied to the rainfall data. Available station data was used to compute the observed rainfall distributions. The number of dry and wet days were adjusted from the model data to match the station data, then the frequency distribution was adjusted to ensure a realistic frequency distribution for the historical period. The adjustment used for the historical period was then applied to the future period, assuming the corrections do not change over time. A final check and adjustment were made to ensure the climate change signal was not altered.

Full details can be found in the case study report.

[1] CSIRO and Bureau of Meteorology. 2015. Climate change in Australia information for Australia’s Natural Resource Management Regions: Technical Report, CSIRO and Bureau of Meteorology, Australia.