Hi I am doing precipitation bias correction for a hydrologic model where the rainfall data was obtained from a gridded precipitation dataset.  For the bias analysis, I am using the monthly linear scaling and separating the wet season and dry season by using  the closest met station and a gridded rainfall data at a point.   However, I do have a few questions that are listed below:

1.  What is the maximum distance between the met station and the station that is used in the watershed that you can use for the bias correction. a) flat terrain b) mountainous terrain

The next few questions are where the met station is not close to the rainfall point, 

2.  When performing comparison with one met station, and the distance is not relatively close, how do you account for the spatial variation in rainfall from multiple stations.

3. When you are comparing the average precipitation values using the linear scaling, how do you account for the precipitation lapse rate (mountainous terrain).

4.  If you are using average monthly values over thirty years, could you use WorldClim data since the data is located at a point and that would account for spatial variation.

Thanks,

Shaffiq