Historical Changes in Seasonal Freeze and Thaw Depths in RussiaOliver W. Frauenfeld, Tingjun Zhang, Roger G. Barry, and David Gilichinsky

SEARCH OSM

Frauenfeld, Zhang, Barry, and Gilichinsky: Historical Changes in Seasonal Freeze and Thaw Depths in Russia SEARCH OSM

242 Russian Stations

Soil Temperature and Freeze/Thaw Depth Soil Temperature Only

Frauenfeld, Zhang, Barry, and Gilichinsky: Historical Changes in Seasonal Freeze and Thaw Depths in Russia SEARCH OSM

Permafrost vs. Seasonally Frozen Ground

Seasonally Frozen Ground Stations Permafrost Stations

Frauenfeld, Zhang, Barry, and Gilichinsky: Historical Changes in Seasonal Freeze and Thaw Depths in Russia SEARCH OSM

Data

For 1930–1990:

• Soil temperature at 9 depths

• Measured freeze/thaw depth

• 0.5° x 0.5° globally gridded air temperature (CRU TS 1.0)

• Freezing and thawing index

• Snow depth from Historical Soviet Daily Snow Depth Data

Frauenfeld, Zhang, Barry, and Gilichinsky: Historical Changes in Seasonal Freeze and Thaw Depths in Russia SEARCH OSM

Interpolation

0.20.40.60.8 1.2 1.6 2.0 2.4 3.2

0.20.40.60.8

1.2

1.6

2.0

2.4

3.2

Measured Values (m)

Inte

rpol

ated

Val

ues (

m)

0.20.40.60.8 1.2 1.6 2.0 2.4 3.2

Measured Values (m)

0.20.40.60.8

1.2

1.6

2.0

2.4

3.2

Inte

rpol

ated

Val

ues (

m)

Interpolated = +1.0 Measured -0.059 Interpolated = +1.0 Measured -0.060

Active Layer Freeze Depth

R = 1.0 R = 1.0

Frauenfeld, Zhang, Barry, and Gilichinsky: Historical Changes in Seasonal Freeze and Thaw Depths in Russia SEARCH OSM

Active Layer Trends

1930 19901978196619541942-0.50

-0.25

0

0.25

0.50

1930 19901978196619541942

30

20

10

0

1930–1990 net change: +0.23 m

1956–1990 net change: +0.20 m

Max

imum

Ann

ual

Dep

th D

epar

ture

(m)

# St

atio

ns

Frauenfeld, Zhang, Barry, and Gilichinsky: Historical Changes in Seasonal Freeze and Thaw Depths in Russia SEARCH OSM

Freeze Depth Trends

1930 19901978196619541942-0.50

-0.25

0

0.25

0.50

1930 19901978196619541942

180

120

60

0

1930–1990 net change: -0.27 m

1956–1990 net change: -0.34 m

Max

imum

Ann

ual

Dep

th D

epar

ture

(m)

# St

atio

ns

Frauenfeld, Zhang, Barry, and Gilichinsky: Historical Changes in Seasonal Freeze and Thaw Depths in Russia SEARCH OSM

Forcing Variables: Active Layer

R = 0.60

R = 0.65

R = 0.65

Correlations Multiple Regression

Active Layer Depth =

+0.32 Tair +0.30 TI +0.52 SD

R = 0.85 (72%)

Trends

4

2

0

-2

-44

2

0

-2

-44

2

0

-2

-4

1930 19901978196619541942

Air Temperature (+0.47)

Thawing Index (+0.34)

Maximum Snow Depth (+0.43)

S t a

n d

a r

d i z

e d

D

e p

a r

t u r

e s

Frauenfeld, Zhang, Barry, and Gilichinsky: Historical Changes in Seasonal Freeze and Thaw Depths in Russia SEARCH OSM

Active Layer Depth =

-0.28 Tair +0.55 FI -0.32 SD

R = 0.90 (80%)

Forcing Variables: Freeze Depth

3210

3210

3210

-1-2

-1-2

-1-2

-3

-3

-31930 19901978196619541942

Air Temperature (+0.42)

Freezing Index

Maximum Snow Depth (+0.59)

R = -0.62

R = 0.79

R = -0.52

Correlations Multiple RegressionTrends

S t a

n d

a r

d i z

e d

D

e p

a r

t u r

e s

Frauenfeld, Zhang, Barry, and Gilichinsky: Historical Changes in Seasonal Freeze and Thaw Depths in Russia SEARCH OSM

Conclusions

• By 1990, active layer depth had increased by at least ~20 cm

• Freeze depth had decreased by over 30 cm by 1990

• Changes in active layer are due to snow cover and air temperature (mean annual and thawing index) forcing.

• Changes in freeze depth are due to air temperature (freezing index and mean annual) and snow cover

• Seasonally frozen ground region of Russia seems more susceptible to climate change than permafrost, although both are being significantly impacted.