Madis Sulev

Madis Sulev
Tartu Observatory

About

16
Publications
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405
Citations

Publications

Publications (16)
Article
Full-text available
To interpret time series of hyperspectral measurements of vegetation canopies, the basic characteristics of the scattering elements forming these canopies—shoots, leaves, or needles—must be known. Unfortunately, data on the seasonal variation of leaf reflectance and transmittance are very scarce. To obtain a ground truth dataset applicable to model...
Chapter
During the last decades, Swedish scientists have studied different aspects of willow forest growth. Some papers on radiation measurements, concerning methods of measurements (Perttu, 1970; Lindroth, Perttu, 1981) and light penetration in willow stand (Eckersten, 1984) have also been published.
Article
A stochastic statistical reconstruction model of gray alder (Alnus incana) was used to describe the architecture of a 5-year-old stand in Tõravere, Estonia. Using the modelled distribution of foliage, crown volume for alder trees was calculated. As the distribution of foliage in alder crowns was very inhomogeneous and leaf area density decreased ra...
Chapter
Regular actinometrical observations in Tartu Actinometric Station started in 1950. Since 1954, it has been regarded as one of the most effectively working actinometric station in the Soviet Union. In 1965, the station was moved, and it is now located at Tõravere, about 20 km southwest from Tartu, on the territory of Tartu Observatory (φ =58°16′, λ...
Article
Full-text available
Upward and downward fluxes of photosynthetically active and broadband solar radiation, and the transmittance of direct solar radiation measured at different heights inside a willow (Salix viminalis) canopy are compared with modeling results. Two approaches are used for modeling the radiation field inside the canopy: solving the radiative transfer e...
Article
In comprehensive studies of radiation climate, remote sensing of the environment, radiation regime of plant canopy, photosynthesis and biomass production, data on direct and diffuse radiation are needed separately for integral and photosynthetically active radiation (PAR). For direct solar PAR, unlike for integral radiation, there exist no global n...
Article
Due to optical processes in the atmosphere the spectral distribution of global, direct solar and diffuse radiation is different and depends on solar elevation, atmosphere transparency etc. Because of various optical properties of phytoelements, the spectral distribution of penetrated and reflected radiation differs from that of incoming radiation....
Article
For characterization of spatial variability of the global photosynthetically active radiation (PAR) Q at different depths in a plant canopy a new statistical treatment has been developed. It is based on the use of the irradiance probability density function (IPDF) which is divided into three parts: IPDF for umbra fuQ, for penumbra fpQ and for sunfl...
Conference Paper
Studies the relationship between optical and geometrical properties of Scots pine (Pinus sylvestris) shoots. For the purpose, measurements of shoot bidirectional reflectance (BDR), bidirectional reflectance distribution function (BRDF) as well as shoot spectral reflectance at different incident and view angles were carried out under laboratory cond...
Book
Full-text available
Theoretical and experimental studies on the stochastic structure of cloud fields and radiation of the earth's atmosphere are reported. A description is given of the array of equipment developed and used to conduct ground and aircraft experimental studies. A survey is made of the measurement methods and the theory of random processes employed in the...
Article
Courvoisier, Schulze andYanishevsky type balancemeters have been compared in field exposure under different weather conditions and in the laboratory. Special attention has been devoted to the selectivity and the temperature regime of the detectors. The installation of the instruments is described and the main results of simultaneous measurements wi...

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