Hironori Yabuki

Water and Energy Exchanges at Forests and a Grassland in Eastern Siberia Evaluated Using a One-Dimensional Land Surface Model

Water and energy exchanges are evaluated for two larch forests, one pine forest, and one grassland area in eastern Siberia near Yakutsk using a one-dimensional land surface model. Diurnal and seasonal variations of fluxes are simulated reasonably with general stomatal parameters at all sites. In the grassland site, the Bowen ratio is 0.2 in midsummer; it is smaller than that in forest sites (about 1). Sensitivity tests indicate that leaf area should be given accurately along with total plant area index including stem and branch areas. If both plant and leaf areas are given, the outline of seasonal heat balance can be simulated using the same stomatal parameters for forests and grassland sites with the model. In the larch site on the left bank of the Lena River, although input precipitation varies widely from 82 to 236 mm year to year from 1998 through 2000, calculated total evapotranspiration varies only within a range of 50 mm around 238 mm in the larch site. Understory evapotranspiration contributes 37%‐44% to total evapotranspiration; interception is 15%‐21% of precipitation. Evapotranspiration normalized by potential evaporation is 0.37 for larch sites almost independent of year; for grassland it is 0.52. At some sites, evapotranspiration in the warm season exceeds precipitation, thereby implying either a warm-season depletion of water storage in the soil column (most likely melted water from the thawing of the soil) or a horizontal transport of subsurface melt water from neighboring areas, or both.

Nonuniform Distribution of Tundra Snow Cover in Eastern Siberia

Abstract Characteristics of snow cover in a small watershed in Arctic tundra near Tiksi, eastern Siberia, were studied by observation and model simulation. First, helicopter observation, snow survey on three traverse lines, and trigonometric survey of snowdrift were carried out at the end of the winters of 1999 and 2000 to estimate the amount and distribution of snow. The observed locations of snowdrifts in the two years were mostly the same. The area of the snowdrift, including shallow snowdrifts, was larger in the year of high winter precipitation than in the year of low winter precipitation. The snowdrifts were formed on the riverbed and lee sides of cols rather than on steep leeward-facing slopes. Second, snow distribution was simulated using a snow distribution model. The results of simulated snow distribution at the end of winter agreed well with the results of the observations. The results of the simulations showed that approximately 40% of winter precipitation was sublimated. The simulations also ...

Glacial lake inventory of Bhutan using ALOS data: methods and preliminary results

Abstarct The Advanced Land Observing Satellite (ALOS) is relatively new. Its optical sensors are capable of making high-resolution digital surface models (DSMs). For the first time, the task of constructing a regional-scale inventory of glacial lakes based on ALOS data has been undertaken. This study presents the data-processing methods and the results of validation and analysis on the ALOS-based glacial lake inventory of Bhutan in the Himalaya. The analysis based on GPS measurements taken at Metatshota lake in the Mangde Chu sub-basin, one of the glacial lakes assessed as presenting a potential flood danger, shows a validation estimate of 9.5 m for the location of the ALOS-based polygon, with a root mean square of 11.7 m. A comparison with digitized data from the International Centre for Integrated Mountain Development (ICIMOD) shows that positioning and evaluation of terrain changes can be significantly improved using ALOS data. Preliminary analysis of the glacial lakes in four sub-basins, Mo Chu, Pho Chu, Mangde Chu and Dangme Chu, reveals that the frequency distribution of lake sizes biases towards smaller lakes. Glacial lakes 0.01–0.05km2 in area account for ~55% of the total number and occupy 13% of the total area. Together our results demonstrate the usefulness of high-resolution ALOS data with accurate DSMs for studying glacial lakes. High priority must be given to continuously improving and updating the glacial lake inventory with high-resolution satellite data.

APPLICATION AND METADATA FORMAT OF THE CRYOSPHERE DATA ARCHIVE PARTNERSHIP (CrDAP)

An international data archive is critical for understanding the climate system dynamics of the cryosphere. Currently, no such system exists though data collection and integration efforts are ongoing. The Cryosphere Data Archive Partnership (CrDAP) is developing an open system for storing cryospheric observation data and metadata. First stage data handling in CrDAP focused on integrating point observational and photographic data. The metadata structure of CrDAP was extended based on ISO 19115, which is a geographic information metadata standard of the International Organization for Standardization (ISO).