Saroma-ko Lagoon, located on the Okhotsk Sea coast of Hokkaido, is seasonally covered by flat, homogeneous, easily accessible and safe sea ice. As such, it proves a very useful experimental site for the study of sea ice processes, the inter-comparison of methods, the testing of equipment, and the training of researchers new to the Polar regions. In this contribution, we describe a physical, chemical, and ecosystem survey at Saroma-ko Lagoon, conducted over February 23-28, 2019 under the auspices of the SLOPE2019 (Saroma-ko Lagoon Observations for sea ice Physico-chemistry and Ecosystems 2019) program. Sea ice cores were collected to examine temperature, salinity, oxygen isotopic ratio, thin sections, and chemical and biological parameters such as carbonate chemistry, CH4, nutrients, chlorophyll a concentrations, and ice algae community assemblage. Broadband and spectral irradiance measurements were carried out above/under the sea ice, and different sensors were inter-compared at close positions and environments. Equipment such as spectrometers, air-sea ice CO2/CH4 flux chamber, and under-ice turbulent heat flux systems were tested for future Arctic and Antarctic expeditions. Finally, an artificial pool was dug into the sea ice to understand the effect of snow particles on ice growth and to compare the gas exchange process over sea ice with an ice-free water surface. Our SLOPE2019 field campaign activities provided useful information for inter-comparison work and future sea ice research in the polar oceans.
Glacier lake outburst floods (GLOF) at Laguna de los Témpanos, a glacier-dammed side lake of Glaciar Steffen, Hielo Patagónico Norte, were documented for a period between December 1974 and February 2020. With manual interpretation of 150 remote sensing images of aerial surveys, vertical aerial photographs, Landsat MSS, TM, ETM and OLI, ALOS, and ASTER images, 19 GLOFs were captured/inferred by focusing on icebergs and water levels, except two periods in the 1980s and the 1990s for which no image was available. This translates to the occurrence of the GLOF on average once ca. every 14 months. Many GLOFs occurred in late summer to early fall, with a few in late spring: but one GLOF was inferred to have occurred in wintertime. The causes of GLOFs were supposed to be heavy rainfalls, probably accompanied with rapid snow/ice melting by warm air temperatures, judging from the general weather condition over the laguna area. The latest two GLOFs (2016 & 2017) were very large, enough to have completely exposed the lake floor in the middle section. The GLOF of 2017 (Mar. 31) was registered in a hydrograph set up at Lower Río Huemules. After this GLOF, the water level has become stable with a more or less continuous outlet stream along the glacier sidewall and there has been no GLOF to date. So probably the prospect of another GLOF has considerably diminished by now. As Glaciar Steffen receded about 6km during this study period, the glacier has thinned accordingly, to which the water level adjusted with three distinctive relatively stable states while fluctuating frequently.
The load created by snow greatly affects forest trees; however, almost no studies have reported on the mechanical stress in tree trunks due to snow under field conditions. In this study, we monitored trunk bending stresses using strain gauges during the snowfall season at two sites, Tadami and Kaneyama, both in a cool-temperate forest in Japan. Measurements were made of the various sizes and trunk shapes of beech trees at Tadami, and of beech trees and Japanese cedars at Kaneyama. Young’s modulus and bending strength were also measured. At Tadami, beech trees with substantially curved trunks often bent down to the ground surface soon after snowfall started. The strain no longer increased once a tree had lodged; however, individuals with larger diameters had stresses exceeding the proportional limit stress. By contrast, among beech trees with erect trunks, those with larger diameters had smaller maximum strain and estimated stress values. These results imply that in areas greatly affected by snow, beech trees struggle both to remain erect and to grow to diameters of 10cm or more. At Kaneyama, large strain values exceeding 1% were observed in trees with a diameter at breast height ≤7cm, all of which were cedars. Among trees of the same diameter, strain values were lower in beech trees than in cedars, and Young’s modulus was three times larger for beech trees. These results indicate that it is more difficult to grow erect cedars compared to erect beech trees in regions with deep snow.