& swfluxfile, swfluxstartdate, swfluxperiod,
_RL swfluxstartdate
& swfluxperiod, swfluxstartdate,
swfluxstartdate = 0.
call CAL_TOSECONDS ( difftime, swfluxstartdate ,mythid )
swfluxstartdate = modelstart + swfluxstartdate
& swfluxstartdate