Institute of Geophysics of the CAS, v. v. i.

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Field stations

Department of Geothermics - Field Stations

    The department of Geothermics makes use of  experimental geothermal data, obtained, among other,  in boreholes at three localities at the territory of the Czech republic. These boreholes were drilled by the Geophysical Institute and  are up to 150 meters deep. Each of the localities  is equipped with automated registration of temperature and other parameters. All but the Sporilov GFU-1 stations are using registration boxes, produced by Ing.Fiedler Electronic for Ecology Company, Ceske Budejovice, Czech Republic. The Sporilov station is on-line connected to a desktop computer.

  

Kocelovice   (49° 28' 02" N,  13° 50' 18" E,  518 m a.s.l.)

    The station is situated at the territory of  the meteorological station, belonging to the Czech Hydrometeorological Institute and was put in operation in 1998.
 The borehole is 40 meters deep, cased by a plastic tube of 120 mm diameter.  Thermistor sensors are fixed in an inner tube, 28 mm in diameter, filled with water up to the surface, in depths of 0.02, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.75, 1, 1.5, 2, 2.5, 3, 4, 5, 7.5, 10, 15, 20, 25, 30, 35, 40 meters. Air temperature is measured at 0.2, 1 and 2 meters. In addition to temperature measurements, level of underground water, precipitations,  snowcover thickness, wind speed and direction, solar radiation and air moisture are also registred. Between the two tubes there is space enough to enable inserting  a portable temperature probe. The rate of registration is preselectable in a wide range of time, an appropriate rate is once in an hour. Because of limited memory of the registration unit, accumulated data are to be transfered into a notebook (serial line RS-232) no later than four times in a year. A wireless transfer to the GFU network is under preparation.

 Measuring stationControlling unit
  

Spořilov    (50° 02' 27" N,  14° 28' 39" E,  274 m a.s.l.)

     The station GFU-1 is located at the grounds of the Geophysical Institute and has been operating since 1994. There are two boreholes close to each other at this station, 140 meters and 40 meters deep, drilled in Ordovican sediments with an uppermost layer of loam. The former is designed for measuring the temperature profile by means of a portable probe hanging on a cable. The latter is equipped with thermistor sensors in fixed levels: 0,  0.05, 0.1, 0.2,  0.5, 0.75, 1, 1.5, 2, 2.5, 3, 4, 5, 7.5, 10, 15, 20, 25, 30, 35, 40 meters. Air temperature is monitored in 1 meter and 2 meters heights. This station accommodates also a solar radiation meter and precipitation monitor. Registration of  data is controlled by an on-line computer. Temperature data from the depths 0.75 m and deeper are stored 7 times a day, the air temperatures and soil temperatures up to 0.5 m as well as the solar radiation  are stored every half an hour. The precipitation monitor has its own recorder.

For correct interpretation of the last climatic changes, based on inversion of the temperature profile of deep boreholes, relationship between the soil and surface air temperatures must be taken in account. Therefore an experimental field for continuous monitoring of the surface heat transfer was put into operation in June 2002. It is located  some 150 meters apart of GFU-1.    A set of models of surface conditions, each model being 150 cm in diameter and 60 cm deep, incorporates grassy and barren clayey soil, sand and asphalt. Each model incorporates registration of underground temperature in 5 levels, the air temperature in 2 levels, soil moisture, solar radiation both direct and reflected. Wind speed, precipitations and snow layer complete the set of data observed.  The obtained time-temperature series are used for speculation on soil and air temperature coupling, comparison of temperatures under different surfaces and determination of changes of diffusivity in individual materials caused by soil moisture changes.
     The site is permanently monitored by a camera designed to see the surface state, especiall the snow layer. All the measured data are transmitted to the the server of GFU.

Svojšice   (49° 14' 39" N,  13° 27' 06" E,  585 m a.s.l.)

   The borehole is 150 meters deep, drilled in the year 2000 in the neighbourhood of a house for study of possibility and efficiency of heating by a heat pump. The experiment should proove ability of the Earth's upermost layer to accumulate heat produced in a solar collector in summer in  order to make use of it for heating in winter. 16 temperature sensors are fixed in five depth levels inside and outside the inner casing, at the inlets and outlets of the water pipes next to the borehole and next to the heat exchanger. Separately  also the temperature of  heating water and air temperature in the house is measured. Registration of water flow through the pipelines as well as electric power consumption complete the system.
 Assuming the maximum efficiency of the solar panel be 70%, the 1.5 m2 surface can produce a heating power of 1 to 10 kWh/day, depending on season and weather. The experiment should demonstrate that in summer this heat can be stored in the Earth (blue tubes) to be recalled in winter (red tubes). The accumulated heat will be converted into heating energy by means of a heat pump (green tubes). According to the producer of the heat pump (MYTOS Ltd., Pavel Myslil, Prague, Czech Republic) the heating power is about three times higher then  the heat pump motor consumption.