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Introduction
Sea Ice Index
Monthly Sea Ice Images
Daily Sea Ice Images
Browse & Compare Images
Archived
Data & Images
Image
Derivation
Interpretation
Resources
Soil Temperature
Alaska
Russia
Snow Cover
Snow Off Day
Greenness
SINDVI
Nascence
Peak
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Greenness: Peak NDVI
Peak NDVI is the maximum value that occurs between the Spring and Fall
equinox. If that value does not exceed 0.3, the Peak NDVI is flagged
as missing for that pixel, and mapped to a grey color.
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Average Peak NDVI The
mean peak value obtained over the period 1982 - 2001. From the
Pathfinder data set. |
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Current Peak NDVI Peak
NDVI for the last growing season. From the MODIS data set. See Continuing
the time series with MODIS data for discussion of differences
with Pathfinder data. |
Peak NDVI Anomalies (Relative to 1982-2001 Mean)
Peak NDVI Anomaly, First Five Years
Pathfinder Data Minus Mean
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Peak NDVI Anomaly, Last Five Years
Pathfinder Data Minus Mean
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Notes: The images above reflect a circumpolar rise
in peak NDVI. Compared with nascence and SINDVI, there is less spatial
and temporal variability. One reason may be that peak NDVI is not as
sensitive an indicator. Peak NDVI may approach saturation, because as
vegetation density goes up, absorption of visible and IR radiation approaches
a maximum beyond which increases in vegetation density no longer register
in NDVI. See Continuing the time
series with MODIS data for discussion of why more recent MODIS data
are not used.
Peak NDVI, Average
Regional Values |
Peak NDVI Anomaly,
Average Regional Values |
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Notes: Time series of peak NDVI values (left) and anomalies
from the 1982-2001 mean (right) for 100 km areas of Russia, Canada, and
Alaska show a general upward trend in peak NDVI that, like that of SINDVI,
is fairly well correlated from place to place. The downward spike at
all locations in 1992 reflects the residual effect of the 1991 Mt. Pinatubo
volcanic eruption. (Smaller SINDVI values in 1992-1994 remained in many
NDVI data sets even after attempts to correct for Pinatubo's effects
on AVHRR-derived NDVI, and primary production may have been reduced as
a result of increases in stratospheric aerosols, according to Stow et
al., 2003).
Peak NDVI, North Slope
Subregions |
Peak NDVI Anomalies,
North Slope Subregions |
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Notes: The North Slope, Alaska, region was divided
into subsections based on literature suggesting a different greening
response for coastal versus inland tundra (see Discussion).
The peak NDVI for coastal tundra is lower than that for inland higher
elevation tundra but anomalies in peak value are quite similar.
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