Historical Changes in Seasonal Freeze and Thaw Depths in Russia Oliver W. Frauenfeld, Tingjun Zhang,...
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Transcript of Historical Changes in Seasonal Freeze and Thaw Depths in Russia Oliver W. Frauenfeld, Tingjun Zhang,...
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.