Detecting Arctic Change Using the Koppen Climate Classification

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Detecting Arctic Change Using the Koppen Climate
Classification
Satellite NDVI

• Muyin Wang1
• James E. Overland2
• 1 JISAO/UW,
• 2 PMEL/NOAA, Seattle, WA

Photos from the Ayiyak River (Alaska) show an
increase in shrubs. Sturm et al., 2001, Nature
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The Koppen Classification
Data
NCEP/NCAR reanalysis 2.5x2.5 1948-2002
Kalnay, et al, 1996
CRU/UA TS2.0 0.5x0.5 1901-2000
Mitchell, et al, 2003
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Vegetation Distribution based on Koppen
Classification
Tundra
NCEP
Frost
Boreal
1978
1998
Temperate
CRU
1950
1998
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Calculated Vegetation Distribution Based on CRU/
NCEP
106 km2
Tundra
106 km2
Boreal
Temperate
106 km2
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Satellite Normalized Differences Vegetation Index
(NDVI) is calculated from the visible (VIS) and
near-infrared (NIR) light reflected by vegetation
in the AVHRR channels.
The value increases from 0.1 to 0.9 for
progressively increasing amounts of green
vegetation.
Global monthly NDVI data set is provided by NASA
on 1x1o resolution from July 1981 to September
2001.
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Distribution of vegetation type based on Koppen
classification
The summer NDVI climatology
The lost tundra areas
The change in NDVI from 1980s to 90s
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CONCLUSIONS

• The potential impact of vegetation changes to
  feedbacks on the climate system is enormous
  because of their large land area and multiyear
  memory of the vegetation cover in the Arctic
  region.
• The Koppen classification based on SAT agrees
  well with satellite NDVI. Both indicate a
  significant decrease in the tundra area in the
  past 20 years about 1 million km2 lost.
• A similar decreasing trend was seen in the early
  1900s, but with smooth slope.

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The Area of Tundra Group Based on CRU SAT And the
Averaged NASA NDVI for 50-90oN
Correlation -0.70
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Anomalies of Vegetation Group for Sub-regions
Scandinavia
Siberia
N.W. America
N.E. America
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THE LOST TUNDRA AREA Max - Min
CRU 1950 1998
NCEP 1978 -1998
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Anomalies of Tundra Boreal for sub-regions in
Arctic
10oW 120oE
106 km2
Scandinavia
Siberia
120oE 170oW
106 km2
170oW 80oW
106 km2
N.W. America
N.E. America
80oW 40oW
106 km2
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