Current issue: 53(3)

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Silva Fennica 1926-1997
1990-1997
1980-1989
1970-1979
1960-1969
Acta Forestalia Fennica
1953-1968
1933-1952
1913-1932

Articles containing the keyword 'radar'.

Category: Research article

article id 338, category Research article
Andrea Vajda, Ari Venäläinen, Pekka Hänninen, Raimo Sutinen. (2006). Effect of vegetation on snow cover at the northern timberline: a case study in Finnish Lapland. Silva Fennica vol. 40 no. 2 article id 338. https://doi.org/10.14214/sf.338
The presence of permanent snow cover for 200–220 days of the year has a determining role in the energy, hydrological and ecological processes at the climate-driven spruce (Picea abies) timberline in Lapland. Disturbances, such as forest fires or forest harvesting change the vegetation pattern and influence the spatial variation of snow cover. This variability in altered snow conditions (in subarctic Fennoscandia) is still poorly understood. We studied the influence of vegetation on the small-scale spatial variation of snow cover and wind climate in the Tuntsa area that was disturbed by a widespread forest fire in 1960. Radar was applied to measure snow thickness over two vegetation types, the spruce-dominant fire refuge and post-fire treeless tundra. Wind modelling was used to estimate the spatial variation of wind speed and direction. Due to the altered surface roughness and the increased wind velocity, snow drifting was more vigorous on the open tundra, resulting in a 30-cm thinner snow cover and almost half the water equivalent compared to the forest values. The changes in local climate after the fire, particularly in snow cover, may have played an important role in the poor recovery of vegetation: a substantial area is still unforested 40 years after the fire.
  • Vajda, Finnish Meteorogical Institute, Climate and Global Change, P.O. Box 503, FI-00101 Helsinki, Finland ORCID ID:E-mail: andrea.vajda@fmi.fi (email)
  • Venäläinen, Finnish Meteorogical Institute, Climate and Global Change, P.O. Box 503, FI-00101 Helsinki, Finland ORCID ID:E-mail:
  • Hänninen, Geological Survey of Finland, P.O. Box 96, FI-02151 Espoo, Finland ORCID ID:E-mail:
  • Sutinen, Geological Survey of Finland, P.O. Box 77, FI-96101 Rovaniemi, Finland ORCID ID:E-mail:

Category: Article

article id 5156, category Article
Martti Saarilahti. (1982). Tutkaluotaukseen perustuva metsäautotien kantavuuden arvioimismenetelmä. Silva Fennica vol. 16 no. 1 article id 5156. https://doi.org/10.14214/sf.a15071
English title: Predicting the bearing capacity of forest roads using a radar sounding.

Good correlation between radar reflection depth when using a FM-CW radar during winter and bearing capacity measurements during spring breakup was found. Therefore, it might be possible to evaluate the bearing capacity of forest roads using the radar sounding technique.

The PDF includes a summary in Finnish.

  • Saarilahti, ORCID ID:E-mail:
article id 5130, category Article
Martti Saarilahti. (1981). Mikroaaltotutka jään paksuuden mittaukseen. Silva Fennica vol. 15 no. 4 article id 5130. https://doi.org/10.14214/sf.a15187
English title: Radar measurement of ice thickness on ice roads and landing.

Light and economic FM-CW radar has been developed for controlling the bearing capacity of ice roads and landings on ice used for timber transportation and storage of timber in Finland. It was tested on natural ice and ice roads of three lakes in Southern Finland and one location on sea on the southren coast of Finland (a total of 166 observations). Ice thickness varied from 0 to 100 cm. Correlation coefficient between auger and radar measured ice thickness was r=0.99 and absolute error varied from -10 to +7 cm. The quality of ice had no influence, but by improving the interpretation of results, also the quality factors might be detected.

The PDF includes a summary in Finnish.

  • Saarilahti, ORCID ID:E-mail:
article id 7623, category Article
Martti Saarilahti. (1982). Tutkimuksia radioaaltomenetelmien soveltuvuudesta turvemaiden kulkukelpoisuuden arvioimiseen. Acta Forestalia Fennica no. 176 article id 7623. https://doi.org/10.14214/aff.7623
English title: Studies on the possibilities of using radar techniques in detecting the trafficability of peatlands.

The possibilities of using microwave techniques in detecting the trafficability of peatlands is discussed. Three microwave methods were tested. 1) A FM-CW radar using 1.01.8 GHz frequency was used to measure the frost thickness of peat layer. It was possible to follow the variations in snow and frost layer thickness. Total reflected power might indicate the wetness class of the peatland, which is also a trafficability factor. 2) A short-pulse radar with 100 MHz frequency was tested in summer condition. Good profiling of peat layers was obtained, giving basic information for trafficability analysis. 3) A mapping of brightness of temperature of peatlands in summer conditions using a 790 MHz radiometer. The measured brightness temperature was correlated with vegetation cover, thus giving some information of trafficability.

The PDF includes a summary in English.

  • Saarilahti, ORCID ID:E-mail:

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