PRODEM dates are not constant

[mankoff]

ice_discharge/ice_discharge.org

Lines 1687 to 1705 in bb87ab6

	**** PRODEM
	#+BEGIN_SRC bash :exports both :results verbatim
	MSG_OK "dh/dt"
	g.mapset -c PRODEM
	r.mask -r
	f=$(ls ${DATADIR}/PRODEM/PRODEM??.tif | head -n1) # debug
	for f in $(ls ${DATADIR}/PRODEM/PRODEM??.tif); do
	y=20$(echo ${f: -6:2})
	r.in.gdal -r input=${f} output=DEM_${y} band=1
	# r.in.gdal -r input=${f} output=var_${y} band=2
	# r.in.gdal -r input=${f} output=dh_${y} band=3
	# r.in.gdal -r input=${f} output=time_${y} band=4
	# r.univar -g time_2019 # mean = DOI 213 = 01 Aug
	done
	g.region raster=DEM_2019 -pa
	#+END_SRC

Currently PRODEMs are assumed to be tied to the median date (August 1). This should be improved by using the date associated with each pixel. Lining up the dates between the earliest PRODEM and the earlier Khan DEMs should also be done more carefully.