80,000 years ground surface temperature history inferred from the temperature–depth log measured in the superdeep hole SG-4 (the Urals, Russia)

2001 ◽  
Vol 29 (3-4) ◽  
pp. 219-230 ◽  
Author(s):  
Dmitry Yu. Demezhko ◽  
Vladislav A. Shchapov
Keyword(s):  
Surface Temperature ◽  
Ground Surface ◽  
Temperature History ◽  
The Urals ◽  
Ground Surface Temperature ◽  
Temperature Depth

scholarly journals Selection of borehole temperature depth profiles for regional climate reconstructions

2007 ◽  
Vol 3 (1) ◽  
pp. 121-163 ◽  
Author(s):  
C. Chouinard ◽  
J.-C. Mareschal
Keyword(s):  
Surface Temperature ◽  
Joint Inversion ◽  
Regional Climate ◽  
Ground Surface ◽  
Temperature History ◽  
Data Set ◽  
Ground Surface Temperature ◽  
Depth Profiles ◽  
Borehole Temperature ◽  
Temperature Depth

Abstract. Borehole temperature depth profiles are commonly used to infer time variations in the ground surface temperature on centennial time scales. We compare different procedures to obtain a regional ground surface temperature history (GSTH) from an ensemble of borehole temperature depth profiles. We address in particular the question of selecting profiles that are not contaminated by non climatic surface perturbations and we compare the joint inversion of all the profiles with the average of individual inversions. We show that the resolution and the stability of the inversion of selected profiles are much improved over those for a complete data set. When profiles have been selected, the average GSTH of individual inversions and the GSTH of the joint inversion are almost identical. This is not observed when the entire data set is inverted: the average of individual inversions is different from the joint inversion. We also show that the joint inversion of very noisy data sets does not improve the resolution but, on the contrary, causes strong instabilities in the inversion. When the profiles that are affected by noise can not be eliminated, averaging of the individual inversions yields the most stable result, but with very poor resolution.

scholarly journals Selection of borehole temperature depth profiles for regional climate reconstructions

2007 ◽  
Vol 3 (2) ◽  
pp. 297-313 ◽  
Author(s):  
C. Chouinard ◽  
J.-C. Mareschal
Keyword(s):  
Surface Temperature ◽  
Joint Inversion ◽  
Regional Climate ◽  
Ground Surface ◽  
Temperature History ◽  
Data Set ◽  
Ground Surface Temperature ◽  
Depth Profiles ◽  
Borehole Temperature ◽  
Temperature Depth

Abstract. Borehole temperature depth profiles are commonly used to infer time variations in the ground surface temperature on centennial time scales. We compare different procedures to obtain a regional ground surface temperature history (GSTH) from an ensemble of borehole temperature depth profiles. We address in particular the question of selecting profiles that are not contaminated by non climatic surface perturbations and we compare the joint inversion of all the profiles with the average of individual inversions. Very few profiles of the Canadian data set meet the selection criteria (e.g. only 13 out of 73 profiles in Manitoba and Saskatchewan were retained). We show that the resolution and the stability of the inversion of selected profiles are much improved over those for a complete data set. When profiles have been selected, the average GSTH of individual inversions and the GSTH of the joint inversion are almost identical. This is not observed when the entire data set is inverted: the average of individual inversions is different from the joint inversion. We also show that the joint inversion of very noisy data sets does not improve the resolution but, on the contrary, causes strong instabilities in the inversion. When the profiles that are affected by noise can not be eliminated, averaging of the individual inversions yields the most stable result, but with very poor resolution.

scholarly journals Ground surface-temperature reconstruction based on data from a deep borehole in permafrost at Janssonhaugen, Svalbard

2000 ◽  
Vol 31 ◽  
pp. 287-294 ◽  
Author(s):  
Ketil Isaksen ◽  
Daniel Vonder Mühll ◽  
Hansueli Gubler ◽  
Thomas Kohl ◽  
Johan Ludvig Sollid
Keyword(s):  
Surface Temperature ◽  
Phase Speed ◽  
Ground Surface ◽  
Temperature Reconstruction ◽  
Geothermal Gradient ◽  
Temperature History ◽  
Deep Borehole ◽  
Near Surface ◽  
Ground Surface Temperature ◽  
Average Value

AbstractAnalyses of the geothermal gradient in permafrost areas constitute a key signal of the ground-surface temperature history. Permafrost temperatures in selected areas are particularly well suited to reconstructing past surface-temperature changes, mainly because there is no thermal disturbance due to circulating groundwater. One year of temperature data from an instrumented 102 m deep borehole in permafrost on Janssonhaugen, Svalbard, is presented. Ground thermal properties are calculated. The average value for the thermal conductivity is 1.85 ±0.05 W m–1 K–1 , and the average value for the thermal diffusivity is 1.1m2 s–1, which gives a phase speed for the annual wave of 5.65 × KT2 m d–1. The depth of zero annual amplitude is 18 m The permafrost thickness is estimated as approximately 220 m. Analysis of the temperatures reveals an increasing temperature gradient with depth. Using a heat-conduction inversion model, a palaeoclimatic reconstruction is presented, showing a warming of the surface temperature over the last 60–80 years. The temperature profile represents a regional signal on Svalbard, which shows an inflection associated with near-surface warming of 1.5 ± 0.5°C in the 20th century.

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