borehole data and climate reconstruction in korea
DESCRIPTION
BOREHOLE DATA AND CLIMATE RECONSTRUCTION IN KOREA Yasukuni OKUBO 1 , Hyoung-Chan KIM 2 , Youhei UCHIDA 3 , Shusaku GOTO 4 and Jan SAFANDA 5 1 Geological Survey of Japan, AIST, [email protected] 2 Korea Institute of Geoscience and Mineral Resources, [email protected] - PowerPoint PPT PresentationTRANSCRIPT
BOREHOLE DATA AND CLIMATE RECONSTRUCTION IN KOREA
Yasukuni OKUBO1, Hyoung-Chan KIM2, Youhei UCHIDA3, Shusaku GOTO4
and Jan SAFANDA5 1 Geological Survey of Japan, AIST, [email protected]
2 Korea Institute of Geoscience and Mineral Resources, [email protected] Geological Survey of Japan, AIST, [email protected]
4Aso Volcanological Laboratory, Kyoto University, [email protected] Institute of Czech Republic, [email protected]
This is a global perspective of surface temperature change over the last five centuries, averaged from 863 individual reconstructions.
Heat flow densities on the geological map of Korea (GSJ and KIGAM, 2002).
Examples of measurements
Deep enoughOld enough Not over-flowing
Important Litho. T-dif.
Hydrodynamic free
Location of boreholes(●) and meteoric stations(▲). 128127 129 130 13112639
38
37
36
35
34
33 126 127 128 129 130 13133
34
35
36
37
38
39
SeoulGapyung
Ulsan
0 50 100 150 200
Synoptic station
Borehole
km
0
100
200
300
400
500
600
700
800
900
1000
Dep
th(m
)
Seoul, KOREA (02000002)
Temperature(oC)
1 0 1 5 2 0 2 5 3 0 3 5 4 0
Long. 127.0249639Lat. 37.488575
Cry
stal
lin
e ro
ck
Temperature – depth data of Seoul
0
100
200
300
400
500
600
700
800
900
1000
Dep
th(m
)
Gapyung, KOREA (03560010)
Temperature(oC)
1 0 1 5 2 0 2 5 3 0 3 5 4 0
Long. 127.5118889Lat. 37.7549111
Temperature – depth data of GapyungS
edim
enta
ry r
ock
0
100
200
300
400
500
600
700
800
900
1000
Dep
th(m
)
Ulsan, KOREA (05220003)
Temperature(oC)
1 0 1 5 2 0 2 5 3 0 3 5 4 0
Long. 129.2846944Lat. 35.4115278
Temperature – depth data of Ulsan S
edim
enta
ry r
ock
Inversion
T (z,t i;T0,Ti ,G , ) T0 G z Ti erfcz
2 ti
erfc
z
2 t i1
i
ti is time stepTi is temperature difference between ti - tI +1 G is geothermal gradient
Unknown parameters in the inversion are T0 , Ti , G, k , which are independent of depth.
The time step is fixed to be 5 years in this case.
(T - T0 ) / (Ts - T0 ) = erfc [ z / ( 2 ( k t ) 1/2 ) ]
Reconstructed surface temperature and Reconstructed borehole temperature
in Seoul
>150 m
90-140 m
1700-1800AD
mid-20th
<90 m
Red curve indicates the reconstructed surface temperature.Two blue lines show the range of standard deviation 1.Black fluctuating lines denote observed surface temperatures.
Reconstructed surface temperature and Reconstructed borehole temperature
in Gapyung
50-200 m
mid-20th
<80 m
Reconstructed surface temperature and Reconstructed borehole temperature
in Ulsan
110-320 m
50-110 m
Till 1900AD
mid-20th
DISCUSSION 1
Surface temperature increase over the last 50 years.
Result of Seoul could reflect urbanization.
Hydrodynamic perturbation disturbs a conductive and steady state thermal regime at the shallow depth.
New data acquisition near the meteoric station to confirm the amplitude of temperature increase is necessary.
DISCUSSION 2
Unknown thermal diffusivity sometimes produces a misinterpretation.
CONCLUSIONS 1
Korea is a vacant area for the surface temperature reconstruction from borehole data.
The observed temperature data often include the hydrodynamic perturbation.
Reconstructed GST series are concordant with the observed GST.
The result in Seoul could reflect urbanization effect.
To confirm these results, new data acquisition and reconstruction are necessary.
CONCLUSIONS 2
Surface T increases over the last 50 years.