Fine Structure of High-Energy Pulses from a Stimulated Brillouin Scattering-Assisted Q-Switch Tm-Doped Fiber Laser

peer reviewedWe have demonstrated a simple all-fiber thulium (Tm) laser Q-switched by stimulated Brillouin scattering (SBS). The maximum output pulse energy was 80 μJ. This allowed us to generate a broadband spectrum directly at the laser outputs. For the first time, we measured the fine structure of the output pulses with a resolution of less than 100 ps. It was found that the SBS Q-switched laser is capable of generating bunches of picosecond pulses. The effect of modulation instability on the pulse decay is discussed. The potential application of the investigated laser radiation for producing destructive effects on soft biological tissues has been demonstrated

Моделирование распределения водного эквивалента снежного покрова в тундре с использованием ГИС и данных полевой снегомерной съёмки

An approach for snow water equivalent (SWE) modelling in tundra environments has been developed for the test area on the Yamal peninsula. Detailed mapping of snow cover is very important for tundra areas under continuous permafrost conditions, because the snow cover affects the active layer thickness (ALT) and the ground temperature, acting as a heat-insulating agent. The information concerning snow cover with specific regime of accumulation can support studies of ground temperature distribution and other permafrost related aspects. Рассматривается методика моделирования водного эквивалента снежного покрова, основанная на статистической обработке данных полевой снегомерной съёмки и геоинформационном анализе различных параметров: рельефа, направления ветра, кустарниковой растительности. Установлено, что особенности рельефа в значительной степени влияют на перераспределение снежного покрова. Так, на вогнутых участках толщина снега увеличивается, а на выпуклых – уменьшается, поэтому индекс кривизны поверхности служит эффективным параметром при моделировании толщины снежного покрова на том или ином участке. Между толщиной снежного покрова и индексом кривизны поверхности установлена высокая степень корреляции (R = −0,83). Учёт перераспределения снега ветром очень важен для региона исследования. Чтобы объяснить основные закономерности этого процесса, мы применили механизм введения поправок при индексировании наветренных и подветренных склонов. Для классификации поверхности использована растровая модель экспозиции склонов, построенная на основе цифровой модели рельефа (ЦМР). В соответствии с господствующим направлением ветра положительные значения поправок присваивались подветренным склонам, а отрицательные – наветренным. Установлено, что кустарниковая растительность служит «ловушкой» для перевеваемого ветром снега, однако высота растительности не определяет его толщину, поскольку толщина снега может быть и больше, и меньше высоты стеблей, и зависит она от других факторов.

Geodatabase and WebGIS project for long-term permafrost monitoring at the Vaskiny Dachi Research Station, Yamal, Russia

The research station Vaskiny Dachi (VD) in central Yamal, Western Siberia was established in 1988. Continuous monitoring of the permafrost state is conducted since 25 years, which allows collecting a large amount of data related to permafrost state and environment of this region. To store and visualise the geospatial data, containing our knowledge of the research area and research topic, we created a geodatabase (GDB) to operatively process different types of geospatial data. The produced GDB contains so far 11 vector feature datasets and raster data in the same coordinate system. The vector data represent: 1) bathymetry; 2) social-economic objects; 3) field data; 4) geomorphology; 5) hydrography; 6) landscapes; 7) permafrost; 8) snow; 9) topography; 10) vegetation; 11) long-term measurement grids and transects (Circumpolar Active Layer Monitoring (CALM) transect, CALM measurement grid). All these feature datasets contain 60 feature classes of spatial data in total. Some of the geodata layers are directly linked to data bases of field data. The raster data contain 37 layers, including a digital ele vation model with derivatives, a map of snow distribution for the key site, ba thymetric maps and other maps of different scale. Moreover, the key area is a site for international research projects and the ongoing exchange of the data is supported by the VD GDB. Geographical Information System (GIS) allows collecting, storing and processing geospatial data from different sources in a wide range of types and formats. WebGIS platforms allow displaying the geospatial data for different users, giving the impression of the general pro cesses on the certain geographic area. Also, we use the WebGIS service to publish the data and to make it available for the larger community. This paper is an overview on the permafrost studies at the VD research station, the GDB for permafrost monitoring as well as the established Yamal WebGIS project

Строение и формирование ледогрунтовых жил второй озёрно-аллювиальной террасы на севере Гыдана в позднем неоплейстоцене–голоцене

The syngenetic ice and ice-ground composite veins in khasyrey (alas) and interalas plateaus were studied on the second lake-alluvial terrace located in the North of the Gydan Peninsula near the village of Gyda. On the basis of the radiocarbon dating, the time of formation of deposits containing veins from was established – from 16 640 to 854 BP. The peat deposits are mainly represented by the following species: Carex sp., Eriophorum  sp., Betula nana, Equisetum  sp., Calamagrostis  sp., Vaccinium vitis-idaea, Drepanocladus  sp., Empetrum sp., Vaccinium uliginosum, Rubus arcticus, Petasites sp. It is established that the polygonal-veined ice of khasyrey and interalas plateaus, except for vertical-striped «clean» ice, contain areas with vertical wavy streaks of ice-ground. Ice of elementary veins and segregation ice were revealed in the composition of veins according to structural and textural features in polarized light. Elementary ice veins compose «clean» ice sections of veins and segregation ice which are their ice-ground sections. Elementary veins are indicative of the predominance of the process of frost cracking during the formation of polygonal-vein ices. The presence of inclusions of ice-ground in the structure of veins points is evidence of a manifestation of local thermokarst processes under the growth of polygonal-vein ice. Ice-ground veins were formed by repeated thawing of the initial ice veins. The formation of ice-ground veins during syngenetic freezing of sediments of the second lake-alluvial terrace is related to uneven manifestation of thermokarst in different facies situations and and climate changes at the Early Pleistocene and Holocene.Изучены сингенетические ледяные и ледогрунтовые жилы, а также сезонно- и мёрзлые отложения на севере Гыданского полуострова. Включение сегрегационного льда в состав полигонально-жильного проходило в период сингенетического промерзания осадков второй террасы на севере Гыдана в динамичной озёрно-аллювиальной обстановке и связано с неравномерным проявлением термокарста во второй половине сартанского периода и в голоцене

GIS- and field data based modeling of snow water equivalent in shrub tundra

An approach for snow water equivalent (SWE) modelling in tundra environments has been developed for the test area on the Yamal peninsula. Detailed mapping of snow cover is very important for tundra areas under continuous permafrost conditions, because the snow cover affects the active layer thickness (ALT) and the ground temperature, acting as a heat-insulating agent. The information concerning snow cover with specific regime of accumulation can support studies of ground temperature distribution and other permafrost related aspects

Geodatabase and WebGIS project for long-term permafrost monitoring at the Vaskiny Dachi Research Station, Yamal, Russia

The research station Vaskiny Dachi (VD) in central Yamal, Western Siberia was established in 1988. Continuous monitoring of the permafrost state is conducted since 25 years, which allows collecting a large amount of data related to permafrost state and environment of this region. To store and visualise the geospatial data, containing our knowledge of the research area and research topic, we created a geodatabase (GDB) to operatively process different types of geospatial data. The produced GDB contains so far 11 vector feature datasets and raster data in the same coordinate system. The vector data represent: 1) bathymetry; 2) social-economic objects; 3) field data; 4) geomorphology; 5) hydrography; 6) landscapes; 7) permafrost; 8) snow; 9) topography; 10) vegetation; 11) long-term measurement grids and transects (Circumpolar Active Layer Monitoring (CALM) transect, CALM measurement grid). All these feature datasets contain 60 feature classes of spatial data in total. Some of the geodata layers are directly linked to data bases of field data. The raster data contain 37 layers, including a digital ele vation model with derivatives, a map of snow distribution for the key site, ba thymetric maps and other maps of different scale. Moreover, the key area is a site for international research projects and the ongoing exchange of the data is supported by the VD GDB. Geographical Information System (GIS) allows collecting, storing and processing geospatial data from different sources in a wide range of types and formats. WebGIS platforms allow displaying the geospatial data for different users, giving the impression of the general pro cesses on the certain geographic area. Also, we use the WebGIS service to publish the data and to make it available for the larger community. This paper is an overview on the permafrost studies at the VD research station, the GDB for permafrost monitoring as well as the established Yamal WebGIS project

Geodatabase and WebGIS project for long-term permafrost monitoring at the Vaskiny Dachi Research Station, Yamal, Russia

The research station Vaskiny Dachi (VD) in central Yamal, Western Siberia was established in 1988. Continuous monitoring of the permafrost state is conducted since 25 years, which allows collecting a large amount of data related to permafrost state and environment of this region. To store and visualise the geospatial data, containing our knowledge of the research area and research topic, we created a geodatabase (GDB) to operatively process different types of geospatial data. The produced GDB contains so far 11 vector feature datasets and raster data in the same coordinate system. The vector data represent: 1) bathymetry; 2) social-economic objects; 3) field data; 4) geomorphology; 5) hydrography; 6) landscapes; 7) permafrost; 8) snow; 9) topography; 10) vegetation; 11) long-term measurement grids and transects (Circumpolar Active Layer Monitoring (CALM) transect, CALM measurement grid). All these feature datasets contain 60 feature classes of spatial data in total. Some of the geodata layers are directly linked to data bases of field data. The raster data contain 37 layers, including a digital ele vation model with derivatives, a map of snow distribution for the key site, ba thymetric maps and other maps of different scale. Moreover, the key area is a site for international research projects and the ongoing exchange of the data is supported by the VD GDB. Geographical Information System (GIS) allows collecting, storing and processing geospatial data from different sources in a wide range of types and formats. WebGIS platforms allow displaying the geospatial data for different users, giving the impression of the general pro cesses on the certain geographic area. Also, we use the WebGIS service to publish the data and to make it available for the larger community. This paper is an overview on the permafrost studies at the VD research station, the GDB for permafrost monitoring as well as the established Yamal WebGIS project

Structure and formation of ice-ground veins of the second lake-alluvial terrace in the North of Gydan in the late Neopleistocene–Holocene

The syngenetic ice and ice-ground composite veins in khasyrey (alas) and interalas plateaus were studied on the second lake-alluvial terrace located in the North of the Gydan Peninsula near the village of Gyda. On the basis of the radiocarbon dating, the time of formation of deposits containing veins from was established – from 16 640 to 854 BP. The peat deposits are mainly represented by the following species: Carex sp., Eriophorum  sp., Betula nana, Equisetum  sp., Calamagrostis  sp., Vaccinium vitis-idaea, Drepanocladus  sp., Empetrum sp., Vaccinium uliginosum, Rubus arcticus, Petasites sp. It is established that the polygonal-veined ice of khasyrey and interalas plateaus, except for vertical-striped «clean» ice, contain areas with vertical wavy streaks of ice-ground. Ice of elementary veins and segregation ice were revealed in the composition of veins according to structural and textural features in polarized light. Elementary ice veins compose «clean» ice sections of veins and segregation ice which are their ice-ground sections. Elementary veins are indicative of the predominance of the process of frost cracking during the formation of polygonal-vein ices. The presence of inclusions of ice-ground in the structure of veins points is evidence of a manifestation of local thermokarst processes under the growth of polygonal-vein ice. Ice-ground veins were formed by repeated thawing of the initial ice veins. The formation of ice-ground veins during syngenetic freezing of sediments of the second lake-alluvial terrace is related to uneven manifestation of thermokarst in different facies situations and and climate changes at the Early Pleistocene and Holocene