Spectral reflectance and associated photograph of boreal forest understory formation in interior Alaska

Kobayashi, Hideki*; Suzuki, Rikie*; Yang, W.*; Ikawa, Hiroki*; Inoue, Tomoharu*; Nagano, Hirohiko; Kim, Y.*

Polar Data Journal (Internet), 2, p.14 - 29, 2018/11

http://doi.org/10.20575/00000004

The Arctic and boreal regions have been experiencing a rapid warming in the 21st century. It is important to understand the dynamics of boreal forest at the continental scale under the climate and environmental changes. While the role of understory vegetation in boreal forest ecosystems on carbon and nutrient cycling cannot be ignored, they are still one of least understood components in boreal ecosystems. Spectroscopic measurements of vegetation are useful to identify species and their biochemical characteristics. In this data paper, we present spectral reflectances of 44 typical understory formations and five 30-m long transects. The spectral reflectance covers the spectral region of visible, near infrared and shortwave infrared (350-2500 nm). For the transect measurements, we decided the length of transect at 30 m, similar to the scale of one pixel of a Landsat type satellite imagery. The photographs at all positions, where spectral reflectances were obtained, are included to understand the structure and status of each sample. The data set contains six dwarf shrubs (blueberry (), cowberry (), feltleaf willow (), young birch (), young aspen (), and young black spruce ()), two herbaceous (cottongrass () and marsh Labrador tea ()), three mosses (Sphagnum moss, splendid feather moss (), and polytrichum moss ()), and reindeer lichen (). Spectral reflectances from several non-vegetative such as snow, litter, and soil are also included. This spectral and photographic data set can be used for understanding the spectral characteristics of understory formations, designing newly planned spectral observations, and developing and validating the remote sensing methodology of large scale understory monitoring.

Establishment of database for Japan Sea parameters on marine environment and radioactivity (JASPER), 2; Radiocarbon and oceanographic properties

Otosaka, Shigeyoshi; Suzuki, Takashi; Tanaka, Takayuki; Ito, Toshimichi; Kobayashi, Takuya; Kawamura, Hideyuki; Minakawa, Masayuki*; Aramaki, Takafumi*; Senju, Tomoharu*; Togawa, Orihiko

JAEA-Data/Code 2009-020, 27 Pages, 2010/02

JAEA-Data-Code-2009-020.pdf:2.45MB

The database for the Japan Sea parameters on marine environment and radionuclides (JASPER) has been established by the Japan Atomic Energy Agency as a product of the Japan Sea Expeditions. By the previous version of the database, data for representative anthropogenic radionuclides were opened to public. And now, data for radiocarbon and fundamental oceanographic properties (salinity, temperature, dissolved oxygen) including nutrients (silicate, phosphate, nitrate and nitrite) are released as the second volume of the database. In the second volume, 20,398 data records are stored including 2,695 data for temperature, 2,883 data for salinity, 2,109 data for dissolved oxygen, 11,051 data for the nutrients, and 1,660 data for radiocarbon. The database will be a strong tool for the continuous monitoring for contamination by anthropogenic radionuclides, studies on biogeochemical cycle, and development and validation of models for numerical simulations in the sea.

Circulation in the northern Japan Sea studied chiefly with radiocarbon

Aramaki, Takafumi*; Senju, Tomoharu*; Togawa, Orihiko; Otosaka, Shigeyoshi; Suzuki, Takashi; Kitamura, Toshikatsu; Amano, Hikaru; Volkov, Y. N.*

Radiocarbon, 49(2), p.915 - 924, 2007/10

https://doi.org/10.1017/S0033822200042788

no abstracts in English

Benthic front and the Yamato Basin Bottom Water in the Japan Sea

Senju, Tomoharu*; Isoda, Yutaka*; Aramaki, Takafumi*; Otosaka, Shigeyoshi; Fujio, Shinzo*; Yanagimoto, Daigo*; Suzuki, Takashi; Kuma, Kenshi*; Mori, Kosuke*

Journal of Oceanography, 61(6), p.1047 - 1058, 2005/12

https://doi.org/10.1007/s10872-006-0021-2

The detail structure of the Bottom Water in the Japan Sea was revealed by the hydrographic observations. The Yamato Basin Bottom Water (YBBW) exhibits higher temperature, lower dissolved oxygen, and higher nutrients concentrations than those in the Japan Basin Bottom Water (JBBW). Both Bottom Waters meet around the boundary region between the Yamato and the Japan Basins, and form a clear benthic front. It is inferred from the property distributions that the JBBW flowing into the Yamato Basin is trapped by the cyclonic circulation in the basin, and modified to the YBBW in the course of the circulation through the vertical diffusion, geothermal heating and oxygen consumption. The thermal balance of in the YYBW was examined using a box-model. The results show that the effect of geothermal heating has about 70 per-cent of magnitude to the vertical thermal diffusion and both terms cancel the advection term of the cold JBBW from the Japan Basin. The box-model also estimated the averaged residence time for the YBBW was 9.1 years.

Benthic front between the Japan Basin and the Yamato Basin in the Japan Sea

Senju, Tomoharu*; Isoda, Yutaka*; Aramaki, Takafumi; Otosaka, Shigeyoshi; Suzuki, Takashi; Kuma, Kenshi*; Mori, Kosuke*

Proceedings of 12th PAMS/JECSS Workshop, p.3_4_1 - 3_4_4, 2003/11

Abyssal water mass distribution from the Yamato Basin to the Japan Basin in the Japan Sea was observed on the R/V Hakuho-Maru cruise, KH02-3 (October 14-19, 2002). The bottom layer in the Yamato Basin was occupied by the water of higher temperature and lower oxygen compared to that in the Japan Basin. As a result, a benthic front of potential temperature and dissolved oxygen was formed between the Yamato and Japan Basins. Dissolved oxygen and nutrients concentrations show that the bottom water in the Yamato Basin is older than that in the Japan Basin. This indicates the existence of the Yamato Basin Water, which is modified bottom water by the closed circulation in the Yamato Basin. The structure of the benthic front suggests an estuary-like circulation around the mouth of the Yamato Basin; outflow from the Yamato Basin lying on the inflow from the Japan Basin. The highest oxygen water was found on the slope of southern periphery of the Japan Basin. This is considered to be the bottom water from the west transported by the cyclonic circulation in the Japan Basin.

Anthropogenic radionuclides in the Japan Sea; Their distributions and transport processes

Ito, Toshimichi; Aramaki, Takafumi; Kitamura, Toshikatsu; Otosaka, Shigeyoshi; Suzuki, Takashi; Togawa, Orihiko; Kobayashi, Takuya; Senju, Tomoharu*; Chaykovskaya, E. L.*; Karasev, E. V.*; et al.

Journal of Environmental Radioactivity, 68(3), p.249 - 267, 2003/07

https://doi.org/10.1016/S0265-931X(03)00064-X

The anthropogenic radionuclides, Sr, Cs and Pu, in the seawater column of the Japan Sea were measured during 1997-2000. The vertical profiles of radionuclide concentrations showed their typical features; exponential decrease with depth for the Sr and Cs and surface minimum - subsurface maximum for the Pu, and there are no substantial differences between the present study and the previous ones. The area-averaged concentrations and the inventories of radionuclides in the Japan Sea are higher than those in the Northwest Pacific Ocean. In the spatial distributions, high inventory area extends and intrudes from the Japan Basin into the Yamato Basin. It is suggested that radionuclides sink by the vertical transport occurring mainly in the Japan Basin then advect into the Yamato Basin after detouring around the Yamato Rise, and finally, they are accumulated in the deep seawater of the Japan Sea.