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Measurement of snow— water equivalent using airborne gamma-ray spectrometry
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MEASUREMENT OF SNOW---WATER EQUIVALENT GAMMA-RAY SPECTROMETRY
MARKKU
PELTONIEMI,
Geophysics Departmenl. I .i ( Finland)
JOUKO
VIRONMAKI
Geological
Survey
and MARTTI
of Finland,
USING AIRBORNE
KORHONEN
Kivimiehentie
1, SF-02150
Espoo
During the winter 1976-77, three airborne spectrometer surveys were flown in southern Finland. Total radioactivity and potassium count rates were used to calculate snow- .water equivalents on four snow profiles, 0.6 -1.5 km in length. The airborne results were compared with ground data from the same profiles. The linear absorption coefficients of air and water, and the reference count rates were determined from the first, pre-snow flight results. An average snow- water equivalent of 143 mm from total, and 166 mm from potassium count rates was calculated from the results of the second flight, compared to 143 mm calculated from ground measurements. Results from the third flight gave the averages 53 mm, 52 mm and 44 mm, respectively. The standard deviation for all total count rate results was 9 mm, for the potassium results 12 mm, and for the ground results 4 mm on the average. Soil moisture corrections were not applied.
EXAMPLES OF RESISTIVITY MEASUREMENTS BURDEN AND BEDROCK STRUCTURES
TEUVO
IN STUDYING
OVER-
PERNU
Department
of Geophysics,
llniversity
of Ouiu, Linnanmaa,
SF-901 00 Oulu 10 (Finland)
Resistivity measurments at various sites in Finland show great variations in resistivity values, especially for overburden materials (from 2 Rm to 100000 R m). In studying overburden structures and materials multilevel resistivity profilings together with complementary soundings using a half-Schlumberger electrode array are most preferable. A series of shallow soundings exemplifies studies on an esker formation. Normal Schlumberger soundings are suitable for the delineation of slowly dipping conductive or nonconductive beds to the depths of several hundred meters. Complementary profilings are, however, often needed. An example of resistivity profiling in separating vertical structures of a schist belt is compared with VLF-R and AMT-measurements.
MEASUREMENT OF SNOW---WATER EQUIVALENT GAMMA-RAY SPECTROMETRY
MARKKU
PELTONIEMI,
Geophysics Departmenl. I .i ( Finland)
JOUKO
VIRONMAKI
Geological
Survey
and MARTTI
of Finland,
USING AIRBORNE
KORHONEN
Kivimiehentie
1, SF-02150
Espoo
During the winter 1976-77, three airborne spectrometer surveys were flown in southern Finland. Total radioactivity and potassium count rates were used to calculate snow- .water equivalents on four snow profiles, 0.6 -1.5 km in length. The airborne results were compared with ground data from the same profiles. The linear absorption coefficients of air and water, and the reference count rates were determined from the first, pre-snow flight results. An average snow- water equivalent of 143 mm from total, and 166 mm from potassium count rates was calculated from the results of the second flight, compared to 143 mm calculated from ground measurements. Results from the third flight gave the averages 53 mm, 52 mm and 44 mm, respectively. The standard deviation for all total count rate results was 9 mm, for the potassium results 12 mm, and for the ground results 4 mm on the average. Soil moisture corrections were not applied.
EXAMPLES OF RESISTIVITY MEASUREMENTS BURDEN AND BEDROCK STRUCTURES
TEUVO
IN STUDYING
OVER-
PERNU
Department
of Geophysics,
llniversity
of Ouiu, Linnanmaa,
SF-901 00 Oulu 10 (Finland)
Resistivity measurments at various sites in Finland show great variations in resistivity values, especially for overburden materials (from 2 Rm to 100000 R m). In studying overburden structures and materials multilevel resistivity profilings together with complementary soundings using a half-Schlumberger electrode array are most preferable. A series of shallow soundings exemplifies studies on an esker formation. Normal Schlumberger soundings are suitable for the delineation of slowly dipping conductive or nonconductive beds to the depths of several hundred meters. Complementary profilings are, however, often needed. An example of resistivity profiling in separating vertical structures of a schist belt is compared with VLF-R and AMT-measurements.