Niño Index Phase Analysis (NIPA) readaptation

Readaptation of the Niño Index Phase Analysis (NIPA) module initially developed by Zimmerman et al. (2016) and then readapted by Giuliani et al. (2019). The present version has been modified to work also for subseasonal lead-times. NIPA is a framework that searches for links between Global and Local variables exploiting the phases of climate indices