detecting arctic change using the koppen climate classification

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Detecting Arctic Change Using the Koppen Climate Classification. & Satellite NDVI. Muyin Wang 1 James E. Overland 2 1 JISAO/UW, 2 PMEL/NOAA, Seattle, WA. Photos from the Ayiyak River (Alaska) show an increase in shrubs . Sturm et al., 2001 , Nature. The Koppen Classification. Data. - PowerPoint PPT Presentation

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Page 1: Detecting Arctic Change Using the Koppen Climate Classification
Page 2: Detecting Arctic Change Using the Koppen Climate Classification

Detecting Arctic Change Using the Koppen Climate

Classification

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

& Satellite NDVI

Page 3: Detecting Arctic Change Using the Koppen Climate Classification

The Koppen Classification

Temperate D T>= 10oC for 4 or more months

Boreal E T>= 10oC for 1-3 months

PolarTundra Ft 0oC <= T <10oC in summer

Perpetual Frost

Fi T < 0oC in summerData

NCEP/NCAR reanalysis 2.5x2.5 1948-2002

CRU/UA TS2.0 0.5x0.5 1901-2000Mitchell, et al, 2003

Kalnay, et al, 1996

Page 4: Detecting Arctic Change Using the Koppen Climate Classification

TundraFrostBoreal

Temperate

Vegetation Distribution based on Koppen Classification

NCEP

CRU

1978

1950

1998

1998

Page 5: Detecting Arctic Change Using the Koppen Climate Classification

Calculated Vegetation Distribution Based on CRU/

Tundra

Boreal

Temperate

NCEP10

6 km

2

106 k

m2

106 k

m2

Page 6: Detecting Arctic Change Using the Koppen Climate Classification

Satellite Normalized Differences Vegetation Index (NDVI) is calculated from the visible (VIS) and near-infrared (NIR) light reflected by vegetation in the AVHRR channels.

NIR – VISNIR + VIS

NDVI =

Global monthly NDVI data set is provided by NASA on 1x1o resolution from July 1981 to September 2001.

The value increases from 0.1 to 0.9 for progressively increasing amounts of green vegetation.

Page 7: Detecting Arctic Change Using the Koppen Climate Classification

1.0

0.8

0.6

0.4

0.2

0.0

Distribution of vegetation type based on Koppen classification

The lost tundra areas

The summer NDVI climatology

The change in NDVI from 1980s to 90s

Page 8: Detecting Arctic Change Using the Koppen Climate Classification

CONCLUSIONSThe 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.

Page 9: Detecting Arctic Change Using the Koppen Climate Classification

The Area of Tundra Group Based on CRU SATAnd the Averaged NASA NDVI for 50-90oN

Correlation Correlation = = -0.70-0.70

Page 10: Detecting Arctic Change Using the Koppen Climate Classification

Scandinavia

Siberia

N.W. America

N.E. America

Tundra Boreal + Temperate

Anomalies of Vegetation Group for Sub-regions

Page 11: Detecting Arctic Change Using the Koppen Climate Classification

THE LOST TUNDRA AREA: Max - Min

CRU: 1950 – 1998 NCEP: 1978 -1998

Page 12: Detecting Arctic Change Using the Koppen Climate Classification
Page 13: Detecting Arctic Change Using the Koppen Climate Classification

Anomalies of Tundra & Boreal for sub-regions in Arctic

Scandinavia

Siberia

N.W. America

N.E. America

Tundra Boreal

106 k

m2

106 k

m2

106 k

m2

106 k

m2

10oW ~120oE

120oE ~170oW

170oW ~80oW

80oW ~40oW

Page 14: Detecting Arctic Change Using the Koppen Climate Classification