A comparative study of geothermal and meteorological records of climate change in Kamchatka |
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| Authors: | V Čermák J Šafanda L Bodri M Yamano E Gordeev |
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| Institution: | (1) Geophys. Inst. Acad. Sci. Czech Republic, Boční II/1401, 141 31 Prague 4, Czech Republic;(2) Res. Group Geophys. Env. Phys., Hung. Acad. Sci., 1117 Budapest, Hungary;(3) Earthquake Res. Inst., Univ. Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan;(4) Geophysical Service RAS, Petropavlovsk Kamchatski, 683006, Russia |
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| Abstract: | To reconstruct the recent climate history in Kamchatka, a series of repeated precise temperature logs were performed in a
number of boreholes located in a broad east-west strip (between 52 and 54°N) in the central part of Kamchatka west of Petropavlovsk-Kamchatski.
Within three years more than 30 temperature logs were performed in 10 holes (one up to six logs per hole) to the depth of
up to 400 metres. Measured temperature gradients varied in a broad interval 0 to 60 mK/m and in some holes a sizeable variation
in the subsurface temperatures due to advective heat transport by underground water was observed. Measured data were compared
with older temperature profiles obtained in the early eighties by Sugrobov and Yanovsky (1993). Even when older data are of
poorer precision (accuracy of about 0.1 K), they presented valuable information of the subsurface temperature conditions existing
20–25 years ago. Borehole observations and the inverted ground surface temperature histories (GSTHs) used for the paleoclimate
reconstruction were complemented with a detailed survey of meteorological data. Namely, the long-term surface air temperature
(SAT) and precipitation records from Petropavlovsk station (in operation since 1890) were used together with similar data
from a number of local subsidiary meteo-stations operating in Central Kamchatka since 1950. Regardless of extreme complexity
of the local meteorological/climate conditions, diversity of borehole sites and calibration of measuring devices used during
the whole campaign, the results of the climate reconstruction supported a general warming of about 1 K characteristic for
the 20th century, which followed an inexpressive cooler period typical for the most of the 19th century. In the last three
to four decades the warming rate has been locally increasing up to 0.02 K/year. It was also shown that the snow cover played
a dominant role in the penetration of the climate “signal” to depth and could considerably smooth down the subsurface response
to the changes occurred on the surface. |
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| Keywords: | borehole temperatures temperature logs climate change recent warming |
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