Department of Atmospheric Physics Chronicle

The list of people who work/have worked at the Department of Atmospheric Physics is listed here

Updated on June 9, 2008. 
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Diaries of meteorological observations in the archives of the observatory start from 1st January 1808. Such names as Th. Clausen and Carl Laurenti are mentioned, look at the Virtual Museum of Tartu Observatory.

First lasting meteorological observations in Tartu were set by J.J.F.W. Parrot in 1821-1834. 
Continuous observations were initiated by L.F. Kämtz who came to Tartu in 1841. 
At the same time with Kämtz, meteorological observations were made by J.H. Mädler.



Systematical meteorological observations at Tartu University were initiated by A.J. von Oettingen. He founded the Meteorological observatory (Metobs) and acted as its long-term director. He also organised a set of meteorological stations (appr. 300) in the Baltics and convened their work.

The directors of Metobs were 
A.J. von Oettingen, from 1865 to 1875 and from 1891 to 1893, 
J.K. Weihrauch, from 1875 to 1891, 
B.B. Golitsõn 1893, 
B.I. Sreznevski, from 1894 to 1918, 
Alfred Lothar Wegener in 1918 during the German occupation, 
G.K. Koch, from 1918 to 1925.

Metobs purchased an actinometer (Hvolson type) and the actinometric observations started under the direction of B.I. Sreznevski.

The Callendar solar radiation recorder was installed. The instrument was used to record the solar radiation from 1911 to 1915 and for some time in 1926.

Kaarel Kirde defended his doctoral thesis in Hamburg in 1921, in 1925 he became the docent of geophysics and meteorology at Tartu University and the professor in 1930. He was the director of Metobs until 1944.

J. Letzmann defended the doctoral thesis on the kinematics of whirlwinds.

Metobs purchased the Ångström compensation pyrheliometer. The instrument was used for the measurements of direct solar radiation on cloudless days in the Metobs house at Liivi 4, Tartu up to the Second World War. The instrument was destroyed in September 1944.

Aarne Kärsna defended his doctoral thesis "The system of unimodal distribution curves of Lexis series with the examples in climatology' under the supervision of K. Kirde.

1941 Metobs is reorganised into Tartu Geophysical Observatory of the Hydrometeorological Service of ESSR. K. Kirde became the director of the Geophysical Observatory and the professor of geophysics of Tartu University.

K. Kirde departed to Germany. In 1941 A. Kärsna was deported to Siberia, J. Letzmann left in 1939. The work in Metobs was continued by younger staff H. Liidemaa and H. Mürk.


Institute of Physics, Mathematics and Mechanics

1 January 1947 
The Institute of Physics, Mathematics and Mechanics at the Academy of Sciences was founded. Mathematician, professor Arnold Humal was named the director of the institute. Located in two cities, the institute was mainly based on the astronomical and meteorological observatories of Tartu University. The sector of physics and geophysics was lead by Anatoli Mitt, H. Liidemaa was the senior and A. Ohu the junior research associate, this was the whole staff of the geophysical observatory. The topics of the geophysical observatory were: 
- meteorological and climatological observations, 
- microclimatological studies, 
- actinometrical measurements, 
- seismometrical measurements.

The Institute of Physics, Mathematics and Mechanics was concentrated to Tartu. Aksel Kipper became a new director of the institute. The sector of physics and geophysics was lead by H. Liidemaa, its staff increased up to 15 persons. Supported by H. Liidemaa, E. Medvedjev founded an actinometric station, which was opened on 1 January 1950.

Juhan Ross became the head of actinometric station. The actinometric station was transferred out of Tartu, to Räni. The scheduled observations were initiated, they lasted until 1960.


Institute of Physics and Astronomy (IPA)

9 October 1952 
The former Institute of Physics, Mathematics and Mechanics was named the Institute of Physics and Astronomy.

In the development plan of the geophysical observatory of IPA the following research topics were fixed: Estonian climate (especially microclimate), actinometry, agroclimate, theoretical studies in meteorology and actinometry. 
J. Ross started his measurements of radiation in plant canopies on a field of rye.

H. Tooming began the studies of radiation in vegetation by measurements in a maize field.

An All-Union actinometric conference was held in Tartu. 
Juhan Ross defended his candidate dissertation entitled 'Measurement problems of the shortwave radiation of ground surface'. 
Valdur Tiit initiated the observations of noctilucent clouds, Herbert Niilisk was also related to the activity. The observations began in summer in Tallinn (Ch. Villmann et al.) and Tartu (Ü. Veltmann, T. Kala). Both the actinometric and noctilucent cloud measurements formed a part of the program of international geophysical year.

16 October 1958 - the actinometric station was reorganised into the laboratory of atmospheric physics, J. Ross was named the head of the laboratory. 
From 12 to 14 December an All-Union scientific meeting on noctilucent clouds was held in Tartu.

Heino Tooming defended his candidate thesis 'Reflection and absorption of solar radiation in plant canopies'. 
Olev Avaste defended the candidate thesis entitled 'The shortwave radiation field of cloudless sky', supervisor K.S. Shifrin. 
From 16 to 19 May 1961 the Seventh All-Union meeting on noctilucent clouds organised by IPA was held in Tallinn.

Helgi Niilisk defended her candidate thesis 'Atmospheric thermal radiation', supervised by Prof. K. Ya. Kondratyev. 
Herbert Niilisk elaborated an instrument to measure the spectral irradiance and a photometric rod for measuring sunflecks in vegetation.

On 29 April 1963 the main building of the observatory in Tõravere was inaugurated. 
Charles Willmann defended the candidate thesis 'Physical nature of noctilucent clouds'. 
Charles Willmann was named the vice-director of the institute. 
The building of the new actinometric station in Tõravere started. 
An extensive field campaign of phytoactinometry was organised in Jõgeva. Among the participants, in addition to the groups from Tartu, were groups from Moscow (Institute of Geography, Institute of Plant Physiology) and Leningrad (Main Geophysical Observatory). 
J. Ross formulated the radiative transfer equation for plant canopies. 
H. Moldau elaborated the spectrogoniometer for measuring the scattering phase function of plant leaves.

A new international center for the data analysis of noctilucent clouds was opened in Tõravere. 
The field campaign of phytoactinometry took place in Moldova. Among the participants were 6 associates from IPA and 11 students of Tartu University. 
A. Laisk designed the device for measuring the leaf inclination and orientation.

The actinometric station was moved from Tartu to Tõravere. 
From 10 May 1965 to 25 August 1965 the field campaign was held in Tadjikistan with 21 participants from Estonia. Groups of phytometric measurements in corn and cotton, actinometry, spectral actinometry, statistical actinometry and photosynthesis participated. 
Ülo Mullamaa defended the candidate thesis 'The atlas of optical properties of waving sea surface', supervisor Prof. G.V. Rosenberg. 
Jüri Reemann defended his candidate thesis 'The instrumental integration of radiation in actinometry', supervisor J. Ross. 
Herbert Niilisk defended the candidate thesis 'The spectral radiation regime of some crops in the region of photosynthetically active radiation', supervisor L.B. Krasilschikov. 
Ilmar Undla defended the candidate thesis 'The regularities in the variability of sums of solar radiation', supervisor M.I. Budyko. 
Agu Laisk defended his candidate thesis 'Experimental study of shortwave radiation in plant canopies', supervisor B.I. Styro. 
A. Laisk elaborated an optical instrument to measure the fraction of gaps in plant canopies that was later named by Dr. E. Lemon as 'mouse'. 
J. Ross and T. Nilson published the concept of the G-function.

A working group of noctilucent clouds lead by Ch. Willmann was established. 
Madis Sulev defended his candidate thesis 'The instrumentation and methods for measurements of ground surface radiation balance', supervisor J.D. Janishevski. 
Viivi Põldmaa-Russak defended the candidate thesis 'The twilight method in atmospheric remote sensing', supervisors J.D. Janishevski and Prof. G.V. Rosenberg. 
Heino Moldau defended his candidate thesis 'Scattering properties of plant leaves', supervisor I.A. Shulgin. 
Herbert Niilisk was named the vice-director of IPA. 
From 15 to 18 March 1966 an international symposium 'Noctilucent clouds as indicators of processes in the higher atmosphere' was held. 
H. Tooming formulated his principle of maximum productivity of plant stands. 
J. Ross published his work on quantitative growth functions of plants.

Agu Laisk designed the statistical analyser and measured the statistical distribution of radiation fluxes in some crops. 
Juhan Ross and Tiit Nilson found the exact solution of the radiative transfer problem for the plant canopy with horizontal Lambertian leaves.

Uno Veismann defended the candidate thesis 'A photometer based on twin telescopes to measure the brightness of stars', supervisor N.F. Kuprevitch. 
Tiit Nilson defended his candidate thesis 'Mathematical modeling of radiation regime of plant stands', supervisor J. Ross.

Vello Ross defended his candidate thesis 'The phytometric studies of geometrical structure and growth of some agricultural crops', supervisor J. Ross. 
The IBP/PP technical meeting was held in Trebon, Czechoslovakia and the second part in Moscow. H. Tooming was the only representative from IPA who was able to participate in the first part in Trebon, although J. Ross, A. Laisk and T. Nilson were also among the invited speakers. 
T. Nilson derived the plant canopy gap fraction formulas considering the clumping and regularity effects in the spatial dispersion of foliage. 
Margaret Anderson presented the 'Cosmos' fish-eye lens to the group of phytoactinometry.

Sirje Keevallik defended her candidate thesis 'Radiative transfer in statistically inhomogeneous turbid media', supervisor J. Ross. 
Väino Unt was named the vice-director of IPA.

Juhan Ross defended his doctoral thesis 'Plant canopy optical properties in relation to its geometrical structure and photosynthesis.' 
Lauri Luud was named the vice-director of IPA. 
Measurement campaigns of plant and canopy structure and radiation transmission into the plant canopies were done during the years 1970-1973 in the agricultural fields at Kuremaa and forests site of Voore (Institute of Zoology and Botany). Participants V. Ross, T. Nilson, A. Aho, A. Koppel, O. Kull, J. Saks, E. Pastak, S. Vaher. Among other instruments the inclined point quadrat instrument, A. Laisk's mouse and hemispheric canopy photography were used.

Olev Avaste defended his doctoral thesis 'Shortwave radiation field in the Earth atmosphere.' 
Heino Tooming defended his doctoral thesis 'Radiation regime and productivity of plant cover.' 
Vello Oja defended his candidate thesis 'Experimental investigation of leaf photosynthesis by means of CO2 balance.'


Institute of Astrophysics and Atmospheric Physics (IAAP)

The Institute of Astrophysics and Atmospheric Physics located in Tõravere was established on 1 October 1973 as a part of the former IPA. 
Kalju Eerme defended his candidate thesis 'Photoelectric photometry from outside the atmosphere,' supervisor A. Sapar. 
M. Sulev elaborated the 4-channel teleradiometer TSFM-4M for reflectance measurements of ground surface from aircraft.

The working group of noctilucent clouds was reorganised into the laboratory of spatial research lead by Ch. Villmann. 
Väino Unt became the director of IAAP. 
Ülo Mullamaa defended his doctoral thesis 'The optics of stochastically inhomogeneous structures.' 
Ain Kallis defended his candidate thesis 'The effect of solar radiation on the productivity, growth and efficiency of vegetation on different latitudes,' supervisor H. Tooming. 
Olavi Kärner defended his candidate thesis 'Investigation of temporal variability of cloudiness and global radiation,' supervisors K.S. Shifrin and O. Avaste. 
The sea expedition TROPEX-74 on the Russian vessel 'Academician Korolev' to study the structure of cloud fields on tropical seas. Participants from IAAP: Ü. Mullamaa, H. Niilisk, A. Kuusk, M.Tiisler and O. Kurm. Duration 8 months and route: Vladivostok - Rabaul - Panama - Havanna - Dakar - Las Palmas - Havanna - Panama - Rabaul - Vladivostok. 
T. Nilson participated in the international seminar 'Heat and mass transfer in the biosphere. Transfer processes in the plant environment' held in Dubrovnik, Yugoslavia.

Agu Laisk defended his doctoral thesis 'The kinetics of photosynthesis and photorespiration of leaves'. 
Märt Rahi defended his candidate thesis 'Study of leaf water supply in relation to photosynthesis and respiration'. 
Gidrometeoizdat in Leningrad issued Juhan Ross' monograph 'The radiation regime and architecture of plant canopies'. 
J. Reemann elaborated his infrared thermometer for the aircraft measurements. 
Airborne measurements of directional distribution and spatial variability of reflectance of agricultural fields and forests started under the supervision of J. Ross. The main instruments used were the four-channel radiometer TSFM-4M (M. Sulev) and infrared thermometer (J. Reemann). The aircraft and helicopter measurement campaigns lasted to the end of 1980-s. The instrumentation was elaborated by M. Sulev, J. Reemann, A. Aho, A. Kuusk. J. Ojaste together with the Special designing bureau of Estonian Academy of Sciences. In the measurements T. Nilson, K. Ross, J. Anton, A. Aho, M. Kirikal, V. Aplei, J. Kõdar, A. Kuusk, A. Savikhin, E. Meikas, U. Peterson, P. Pajusalu participated.

The workgroup lead by Ch. Villmann together with four cosmonauts was awarded the Soviet Estonian science prize for the results in the investigations of noctilucent clouds. 
Hanno Ohvril defended his candidate degree with the thesis 'The correlation analysis between the field of cumulus clouds and radiation field', supervisor Ü. Mullamaa. 
T. Nilson published the theoretical treatment of gap fraction and its statistics in non-homogeneous plant canopies. Among others, the new types of gap fraction formulas for forest canopies were derived, and possibilities to quantitatively describe the crown-level hot-spot phenomenon and estimation of leaf area index by means of inversion of the measured gap fraction data were given.

V. Põldmaa, H. Ohvril, A. Kurvits and Ü. Kährik took part in the sea expedition on the vessel 'Academician Vernadski' on the Atlantic ocean.

The laboratory of space radiometry was formed lead by Uno Veismann. 
Andres Kuusk defended his candidate thesis 'The structure of cloud fields and radiation regime of the ground surface', supervisor Ü. Mullamaa. 
An extensive field campaign in Tamme at lake Võrtsjärv with the participants from IAAP, Institute of Zoology and Botany and geography department of Tartu University. Measurements of surface irradiance and reflectance, soil temperature and water regimes and of surface energy balance was carried out. 
A joint field campaign between the University of Helsinki, Karelian Forest Institute and IAAP was held in Karelia. Relations between the radiation regime and stand structure in a pine forest were studied. From IAAP J. Ross, T. Nilson, A. Aho and K. Ross participated.

Teofilus Tõnnisson defended his candidate thesis 'The energetic graduation of remote sensing radiometers of the near infrared region', supervisor U. Veismann. 
Rein Rõõm defended his candidate thesis 'Radiative transfer in planetary atmospheres considering anisotropic scattering', supervisor O. Avaste. 
11th All-Union Symposium in Actinometry was organised by IAAP in Tallinn. 24 presentations were given by the researchers from IAAP. 
J. Ross and V.A. Kanevski suggested the Monte-Carlo method to study the radiation field of a spruce tree. A. Kuusk elaborated a theoretical treatment to describe the hot-spot phenomenon of the plant canopy modelled as a plate medium. 
A. Aho and M. Sulev elaborated the four-channel hand-held radiometer to measure the reflectance factors of plant canopies and soil. Since then the instrument has been in use in the reflectance and transmittance measurements in the agricultural fields and forests during an extended period.

A joint project named 'Eco-physiology of trees and exchange of mass and energy in the forests of taiga zone' between the Soviet Academy of Sciences and Finnish Academy was carried out during1981-1985 (project no 12). The participants from the Soviet side were the Forest Institute of the Karelian Branch of Soviet Academy of Sciences and IAAP, from the Finnish side the Forest faculty of the University of Helsinki. From IAAP the project sub-leader was Juhan Ross and secretary Tiit Nilson. Field measurements and workshops were carried out in Finland and Karelia. 
From 1986-1990 the project was continued under a new name 'Bio-production processes of pine forests'. 
Dr. W. Junk Publishers issued the English version of the book by J. Ross 'The Radiation Regime and Architecture of Plant Stands'. 
Matti Pehk defended his candidate thesis 'Determination of energetic characteristics of normal K- and M-giant stars in the infrared spectral region', supervisor L. Luud. 

The chair of geophysics was opened at Tartu University, Olev Avaste was elected the head of the chair. 
Ülo Mullamaa defended his doctoral thesis 'The radiation field modulated by natural inhomogeneous structures'. 
A. Laisk and V. Oja were awarded a state premium based on the investigations of kinetics of carbon metabolism. 

Aleksandr Marshak defended his candidate thesis 'On the speed of convergence of the solution of radiative transfer equation with the discrete ordinate method', supervisor G. Vainikko.

From 1983-1987 measurements of the seasonal course of reflectance of cereal crops by means of the Aho-Sulev four-channel field radiometer were carried out in Tamme (Lenin state farm) and Erika, near Tartu (T. Nilson, J. Anton, V. Aplei, K. Ross, J. Kõdar, N. Danziger).

From 17 to 20 August 1984 an international seminar on noctilucent clouds was held in Tallinn. 
From 21 to 28 August 1984 the 9th International Cloud Conference was held in Tallinn. 

Tõnu Viik was named the director of IAAP. 
The new laboratory of biophysics was formed lead by Agu Laisk. 
Heino Moldau defended his doctoral thesis 'Auto-regulation of plant production process during water deficit'. 
Juri Knjazikhin defended his candidate thesis 'Discrete ordinate method and the linear algebraic model', supervisor G. Vainikko. 
The laboratory of spatial radiometry introduced a certified measuring and calibrating set 'Specter'. 
T. Nilson and A. Kuusk published their first approximate analytical canopy reflectance model. 
A. Kuusk published his canopy hot-spot model.

U. Peterson started the measurements of seasonal and successional reflectance on clearcut communities by means of the Aho-Sulev four-channel field spectro-radiometer.

First foreign scientists (Thomas Herbert from Miami University, USA; Le Van Lieu from Vietnam) were allowed to work at IAAP in Tõravere for extensive time periods.

Space research and spatial radiometry laboratories were joined into the space research laboratory lead by Uno Veismann. 
Juhan Ross was elected an academician of All Union Agricultural Academy.

Juhan Ross was given the honour doctor degree of University of Joensuu, Finland. 
Tiit Nilson worked 3 months at the University of Joensuu. 
Rein Rõõm was named the vice-director of IAAP.

The international field campaign TARTEX-90 was held in Tõravere, the surface energy balance components and boundary layer turbulence characteristics were measured. Among the participants there were scientists from IAAP, Main Meteorological observatory of German Democratic Republic, Atmospheric Institute of Chech and Slovak Republic, Atmospheric Physics Institute from Moscow. 
T. Nilson published his first forest reflectance model.

Andres Kuusk defended his doctoral thesis 'Opposition effect in the reflection from plant canopies'. 
Tiit Nilson defended his doctoral thesis 'Radiative transfer in nonhomogeneous plant canopies'. 
Helgi Arst defended her doctoral thesis 'Radiation characteristics of the atmosphere and sea as the information sources of natural environment'. 
As main research topics optical monitoring of ground surface (development of vegetation reflectance models, use of satellite information, successional changes in forest reflectance), studies of atmospheric aerosol from the satellites by means of the teleradiometer FAZA, studies of global cloudiness and of Estonian radiation climate. 
Springer issued the monograph edited by R.B. Myneni and J. Ross 'Photon-Vegetation Interactions. Applications in Optical Remote Sensing and Plant Ecology.' Among others the contributions by J. Ross, A. Kuusk, T. Nilson, A. Marshak and Y. Knyazikhin were included. 
T. Nilson worked 1.5 months in Universities of Wisconsin and Miami and in NASA Goddard and Ames, USA. 
A. Kuusk worked a month at the New York State University in Binghamton (USA).

On 25 March 1992 Charles Willmann passed away. 
The group of biophysics was transferred to Tartu University, Agu Laisk was elected the professor of plant physiology. 
Joint chairs of Tartu University and IAAP of biogeophysics and dynamic meteorology were formed, T. Nilson and R. Rõõm were elected the professors of the respective joint chairs. 
Viivi Russak defended her PhD thesis 'The solar radiation at Tõravere'. 
Urmas Peterson defended his MS thesis 'The seasonal and successional dynamics of reflectance in forest clear-cut communities in Estonia'. 
From 3 to 8 August 1992 the international radiation symposium IRS'92 was organised in Tallinn.

Juhan Ross was elected an academician of the Estonian Academy of Sciences. 
The actinometric station in Tõravere was included into the list of candidates to the world BRNS (Basic Radiation Network Stations). 
Urmas Peterson defended his PhD thesis 'The reflectance factor dynamics of Estonian forest communities'. 
The measurements of atmospheric ozone layer thickness were initiated in Tõravere. 
J. Ross and M. Sulev measured the scattering phase function of coniferous shoots by means of a specially designed laboratory goniometer. 
An energy forest was planted in Tõravere as a result of a joint Swedish-Estonian project. 
U. Peterson and T. Nilson published the paper on the successional reflectance trajectories in northern temperate forests.

From 28 February to 2 March 1994 an international conference 'Energy forest - growing and exploitation' was held as organised by IAAP and Institute of Zoology and Botany, Tartu. 
T. Nilson, A. Kuusk and U. Peterson measured radiation variables in Mediterranean oak forests near Montpellier, France. The Aho-Sulev 4-channel field radiometer KFM-4 was supplied with a data logger CR-10. 
A new set of instruments was elaborated for the radiation measurements in the energy forest. 
Regular measurements of ozone layer started. 
Meelis Mölder became a doctoral student at Uppsala University. 
From November 1994 to March 1995 A. Kuusk worked at the Goddard Space flight Center, USA. 
A. Kuusk published his multispectral canopy reflectance model MSRM.


Tartu Observatory (TO)

On 21 September1995 IAAP was renamed to Tartu Observatory. 
On 1995-1996 field measurements of plant canopy radiation regime were carried out in Järvselja, Estonia, Uppsala and Umeå, Sweden and Montpellier, France (T. Nilson, A. Kuusk, J. Anniste, J. Praks). 
A. Kuusk worked 6 months in INRA Grignon and Avignon, France.

T. Nilson, J. Anniste ja M. Lang linked the forest reflectance model to forestry databases. 
J. Ross, T. Nilson and A. Kuusk participated in a remote sensing conference in Beijing. A. Kuusk worked two weeks with the Institute of Geography in Beijing.

During 1997-2002 the group of vegetation remote sensing (lead by T. Nilson) participated in the Swedish remote sensing project named RESE (Remote Sensing for the Environment) financed by the Swedish MISTRA fund.

The joint chairs of Tartu University and TO ceased to exist. The atmospheric physics department (lead by Rein Rõõm) contained the following groups 
- ground surface energetics 
- remote sensing of vegetation 
- dynamical meteorology 
- climatology and actinometrical monitoring. 
The measurements of erythemal UV (ultraviolet) radiation were initiated in Tõravere. 
A plant canopy analyser LAI-2000 and CCD-camera ST-8 were purchased. Based on the latter, A. Kuusk elaborated a 2-band hemispheric-view radiometer for the detailed study of the radiation field within plant canopies. 
A new certified etalon lamp was purchased by laboratory of radiometry. 
The atlas of satellite images of Estonia 'Estonia as seen from the space' by U. Peterson, R. Aunap and J. Eilart was issued. 
From the state budget the research projects are financed: 
- Radiation regime of the atmosphere and ground surface and optical monitoring of Estonian environment (principal investigator J. Ross); 
- Climate forming factors and dynamic weather forecast for Estonia ((principal investigator R. Rõõm). 
U. Peterson started his analysis of Estonian land-use and land-use change by means of satellite images. 
Non-hydrostatic HIRLAM version was elaborated in the workgroup of dynamical meteorology. 
A. Kuusk published his work on the determination of vegetation parameters on large areas from a Landsat TM image by means of inversion of a reflectance model.

Laurits Leedjärv became the director of TO. 
Beginning from January, the actinometric station belongs to BSRN. 
A. Kuusk became a member of the editorial board of the journal "Agricultural and Forest Meteorology" and the field editor of the journal "Agronomie". J. Ross has been a member of the editorial board of "Agricultural and Forest Meteorology" for several years already. 
Measurements of high angular resolution radiation field by means of an imaging radiometer based on the CCD-camera ST-8 started.

Tiit Nilson was named a principal investigator of the research project 'Radiation regime of the atmosphere and ground surface and optical monitoring of Estonian environment'. 
Matti Mõttus defended the MS thesis 'Statistical description of direct solar radiation in willow coppice', supervisors J. Ross and T. Nilson. 
International evaluation of remote sensing and surface energetics workgroups, both the groups were given 'good' by the ecology expert teams from UK and Finland. 
A. Kuusk, M. Lang and U. Peterson measured radiation regime in experimental forests in Flakaliden (Sweden) and production forests in Ruokolahti (Finland). 
On the forest test site of the international VALERI project in Järvselja measurements with the plant canopy analysers LAI-2000 were made together with the colleagues from Toulouse M. Leroy and C. Lelong. Similar measurements were repeated in years 2001-2005.

The workgroup of dynamic meteorology was transferred to the Environmental institute of Tartu University. Rein Rõõm was elected the professor of meteorology. 
Scientific centers of excellence were formed in Estonia. The workgroup of vegetation remote sensing was included into the Center of Excellence of Basic and applied ecology (leader Prof. Olevi Kull, Institute of botany and ecology, Tartu University). 
Mait Lang defended his MS thesis "Forest reflectance model as an interface between satellite images and forestry databases", supervisor T. Nilson. 
The measurements of leaf area and canopy cover were carried out on the VALERI test site in Järvselja. 
Understorey vegetation reflectance spectra in the range 400-2500 nm were measured by means of a GER-2600 spectrometer borrowed from Stockholm University. The spectral library is available on the web site 
A part of the willow coppice in Tõravere was replaced by alder plantation.

On 21 June 2002 Juhan Ross died. 
The structure of atmospheric physics department was changed, T. Nilson was named the leader of the department. Two groups were formed 
- Vegetation remote sensing lead by T. Nilson 
- Atmospheric sensing lead by U. Veismann. 
New target financed project 'Optical remote sensing of environment in Estonia and Baltic region' was started, principal investigator T. Nilson. 
Sirje Keevallik left to the Institute of Sea Systems at the Tallinn Technical University. 
A NASA sunphotometer CIMEL-318, belonging to the AERONET system was installed in Tõravere (O. Kärner being the principal investigator and M. Sulev taking care of the technical performance of the instrument).

The 'Handbook of Estonian solar radiation climate' was issued compiled by Viivi Russak and Ain Kallis, edited by Heino Tooming. 
On 11 April 2003 the seminar 'Ch. Villmann 80' was held in Tõravere. 
On 3 June 2003 the first Estonian remote sensing seminar with 50 participants was held in Tõravere, organized by Tiit Nilson. 
The working group of atmospheric sensing purchased a fiber optical spectrometer AvaSpec-256, working in the interval 240-440 nm. 
T. Nilson, A. Kuusk, M. Lang and T. Lükk published in Ambio a summary paper on forest reflectance modeling based on the research made within the Swedish RESE project.

Matti Mõttus defended his PhD thesis 'Shortwave radiation field in willow coppice' supervisors J. Ross and T. Nilson. 
After her post-doc period in Uppsala, Anu Reinart joined the vegetation remote sensing group. Remote sensing of inner water bodies and of coastal seas were her main research topics. 
On 25 September 2004 our long term co-worker Rutt Koppel passed away. 
Oleg Okulov joined the vegetation remote sensing group as a post-doc for two years. 
With the funding help by Center of excellence of basic and applied ecology, a spectrometer FieldSpec Pro (350-1050 nm) was purchased. 
Tiit Nilson and Andres Kuusk gave the lecture course 'Physical models in remote sensing' for master and doctoral students in Tikkurila, Finland. The course was organized by the Finnish forest research institute. 
A. Kuusk and T. Nilson participated with their forest reflectance model FRT in the international comparison of reflectance models.

Andres Kuusk took the department leader position and the principal investigator post of the target financed project 'Optical remote sensing of environment in Estonia and Baltic region'. 
The fourth book in the Universe-series 'The Universe in light and rain' compiled by Uno Veismann and Rein Veskimäe was issued. The authors were from Tartu Observatory, environmental and geography institutes of Tartu University, Estonian Meteorological and Hydrological Institute, Estonian Sea Institute, etc. 
On 10 July 2005 the European Space Agency experimental satellite Proba measured with the imaging spectrometer CHRIS the VALERI program test site in Järvselja. The region of 14x14 km was measured in 18 bands (from 438 to 1035 nm) with the 17-m pixel size from 3 different view directions. 
Two canopy reflectance models (two-layer homogeneous and forest reflectance model) participated in the 3rd phase of the international comparison of radiative transfer models. 
Matti Mõttus took a post-doc position at the University of Helsinki. 
On 11 October 2005 the second Estonian remote sensing seminar was held in Tõravere, organized by A. Reinart.

Kersti Püssa defended her PhD theses "Forest edges on medium resolution Landsat Thematic Mapper images', supervisors J. Liira (Tartu university) and U. Peterson. 
The infrared camera ThermaCAM SC-3000 was purchased together with the Center of excellence of basic and applied ecology. 
Reflectance spectra of forests at Järvselja test site were measured with an airborne 256-channel spectrometer designed by J. Kuusk.

Tiit Nilson was given the honour doctor degree of University of Helsinki, Finland. 




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Liidemaa, H., 1992. Tartu Ülikooli Meteoroloogia Observatooriumi rajamine ja meteoroloogia areng Eestis aastail 1865-1918. Teaduse ajaloo lehekülgi Eestist, VIII, Valgus, Tallinn, lk. 63-79. (In Estonian). 
Mürk, H., 1992. Meteoroloogia- ja klimatoloogiaalasest uurimistööst Eestis 1920-1940. Teaduse ajaloo lehekülgi Eestist, VIII, Valgus, Tallinn, lk. 80-98. (In Estonian). 
Palm, I., 1992. Meteoroloogia õpetamisest Tartu ülikoolis aastail 1919-1940. Teaduse ajaloo lehekülgi Eestist, VIII, Valgus, Tallinn, lk. 99-122. (In Estonian). 
Annual reports of Tartu Observatory 1991.. 
Photo collection of the library of Tartu University, 
Teaduse ajaloo lehekülgi Eestist, VIII, Valgus, Tallinn, lk. 99-122. (In Estonian). 
Siilivask, K. (Koostaja), 1982. Tartu Ülikooli ajalugu. II, 1798-1918. Eesti Raamat, Tallinn. (In Estonian). 
Tooming, H., 2001. Ilm ja inimesed, Teaduste Akadeemia kirjastus, Tallinn. (In Estonian). 
Tähetorni kalendrid. (In Estonian). 

Kalju Eerme 
Ain Kallis 
Andres Kuusk 
Tiit Nilson 
Viivi Russak 
Madis Sulev