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2007-12-11 -- Reprocessed all MOD15A2GFS and MOD15A2PHN products
for years 2000 through 2005 to address the following issues.
MOD15A2GFS (Gap-Filled, smoothed LAI-fPAR):
Summary:
Scaled weights can be outside range of 16 bit integer. This causes
incorrect QC categories to be assigned, which can lead to misclassified
high quality and low quality data.
Details:
After adjustment for second iteration TIMESAT run, small LAI values get
smaller weight and high LAI values get higher weight due to up-fold
weighting scheme. The weight is multiplied by 10000 and saved in short
integer (16-bit) format. The highest possible weight is 4, which is out
of valid range of 16-bit integer after scaling by 10000. Also, pixels
with weights smaller than 0.249 are not classified due to a bug in the
program. The pixels falling into these two situations are marked with
original LAI values in QC layer. Therefore, both high and low quality
data have a chance to slip into MODIS_LAI_FPAR_QC layer with original LAI
values. Four SDS layers are affected: COMPOSED_LAI, COMPOSED_FPAR,
MODIS_LAI_FPAR_QC, COMPOSED_LAI_FPAR_QC.
Solution:
1.Use a weight of 1000 instead of 10000. This avoids the highest weight
out of valid range of 16-bits integer after scaling.
2.Added trap to handle pixels with an adjusted weight between 0.01 to 0.249.
MOD15A2PHE (Phenology derived from Gap-Filled, smoothed LAI-fPAR):
Summary:
Improve temporal resolution of phenology dates from 8 days to 1 day.
Details:
In previous version, the greenup (browndown) date is marked at the
fitted point, which is closest to the time for which the left (right)
edge has increased (decreased) to 10% of the seasonal amplitude measured
from the left (right) minimum level. Therefore, the temporal resolution
of the phenology dates is 8-day.
Solution:
In current version, the greenup (browndown) date is calculate as a
fractional time of an 8-day period by a linear interpolation from
neighbor fitted points before and after 10% of the seasonal amplitude.
The interpolation parameters are calculated from the LAI value at 10%
of the seasonal amplitude and the LAI values from the neighbor fitted
points before and after it.
12 Sep 2007 -- gap-filled, smoothed LAI-FPAR data for years 2001-2005
now available in MODIS-for-NACP data distribution system
01 Jul 2007 -- Add information to QA layers for "not produced" pixels.
-- Fix parameters to allow processing of "border" years (eg 2000) that
do not have a year of seasonal data on either side.
7 Apr 2007 -- Fixed bug in PGE that caused Phenology product SDS to have
data associated with incorrect name. Affects all Phenology products.
20 Mar 2007 -- LAI-FPAR data for years 2001-2005 now available in LAADSWeb
data distribution system
14 Dec 2006 -- LAI data for years 2001-2005 available, all North America tiles
09 Nov 2006 -- refined algorithm. released tiles h11v04, h11v05, h12v04
22 Jun 2006 -- Fixed possible bug in the recently delivered gap-filled LAI product.
It might happen while translating a negative LAI value to an unsigned LAI value.
In the gap filling program, all LAI values from TIMESAT are converted from type
float to type unsigned char (to keep same as MODIS LAI product). Some negative
values which should be rounded to low boundary (0), are translated into a large
unsigned number and are rounded to high boundary (100). Although this did not
appear in 12 Jun 2006 delivery for tile h11v04, it did show up in tests on tile
h12v04. This problem has been fixed, and new tar files were created for tile
h11v04. These are labeled lai*.h11v04.2006-06-22.tar.gz to distinguish from
original delivery.
08 Jun 2006 -- first release of smoothed, gap filled LAI and phenology for tile h11v04.
28 Mar 2006 -- The web server is up and running.
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