Hi All-
I've been trying to deal with fields like Total Accumulated Precip in
the GFS model which is on mixed intervals of accumulation. For example,
the 3hr forecast is a 3 hr accumulation and the 6hr forecast is a 6 hour
accumulation, 9hr fcst is 3 hr, 12h fcst is 6 hr, etc. There are also
fields like Longwave radiation (OLR) which is on mixed averaging
intervals. Similar to the precip, but it's an average, not an
accumulation. I've written a little Jython routine to "unmix" the
intervals which I thought I'd share. You pass in the grid, the
accumulation interval you want to unmix (default 6hr) and whether it's
an accumulation (1) or an average (0). Please share any improvements
you might make with the community:
def unmixIntervals(grid,cumTime=6,accum=True):
from ucar.visad.data import CalendarDateTime as cdt
from java.util import TimeZone as tz
ugrid = grid.clone()
timeSet = GridUtil.getTimeSet(grid)
timeArray = cdt.timeSetToArray(timeSet)
for time in range(len(timeArray)):
if (time > 0):
prevhour =
int(timeArray[time-1].formattedString("HH",tz.getTimeZone("GMT")))
nowhour =
int(timeArray[time].formattedString("HH",tz.getTimeZone("GMT")))
if (nowhour%cumTime == 0 and prevhour%cumTime != 0):
if (accum):
tsgrid = sub(grid.getSample(time),grid.getSample(time-1))
else:
tsgrid = sub(2*grid.getSample(time),grid.getSample(time-1))
ugrid.setSample(time,tsgrid)
return ugrid
Enjoy!
Don
--
Don Murray
NOAA/ESRL/PSD and CU-CIRES
303-497-3596
http://www.esrl.noaa.gov/psd/people/don.murray/
