Pre joining (‒j)

To increase long-term variances, segments can be pre-joined. Instead of joining two 10 day segments, the segments are pre-joined into 20 day segments by joining two segments that come from the same year. This can be achieved with the -j options, which specifies how many 10-day segments to pre-join. A value of 2 will create 20-day segments.

wxgen sim -db db.nc -n 21 -t 365 -o j2.nc -j 2

Example

Pre-joining increases the variance at longer timescales:

wxgen sim -db db_agg.nc -n 1000 -t 365 -o j1.nc -j 1
wxgen sim -db db_agg.nc -n 1000 -t 365 -o j2.nc -j 2
wxgen verif j1.nc j2.nc -m variance -xlog