There appears to be an increase in variability between CRU TS 1.0 and CRU TS 2.0. Why?
Without examining the grid-boxes concerned, this is impossible to answer definitively. However, the following remarks may be of some help. Any such increase in variability is often noted in a less-well-observed region of the world. Small additional numbers of stations becoming available in the underlying database (on which the interpolations are based) may result in a substantial increase in apparent variability. For example, in CRU TS 1.0 the only time-series information might be provided by a station at a distance of 200 km. Because of the large distance involved, this station might only allow a weak inter-annual variability in precipitation in the region of interest. However, if an extra station at a distance of only 20km was added to the database before CRU TS 2.0 was calculated, the apparent inter-annual variability might become much stronger. If this explanation seems relevant, the information on time-series analysis might also be of interest. That page addresses trends, but the
