Kenichi Ueno

この用語が登場している。中国語でも日本語と同 様の意味で云海(yúnhǎi)と表記(発音

長野県菅平高原での15冬季分の積雪断面観測結果に基づき，天候パターンの年々変動が積雪構造に与える影響を明らかにした．2月中旬の積雪深は根雪開始以降の積算降水量と有意な相関を示した．積雪深に占めるざらめ雪層の割合や氷板形成には年々変動が大きく，根雪開始以降の平均気温や積雪上の降雨（ROS）の発生頻度と有意な相関が見られた．アメダスデータから主要な雪層の形成期日を推定すると，氷板やざらめ雪層の発生の多くがROSを伴う低気圧性の降水イベントであった．1991/92年以降の31冬季をサンプルに，12～3月の月単位の気温・降水量・最大積雪深と根雪開始・終了日を変数とし，天候・積雪季節内変化パターンを因子分析により5つ抽出した．3月の気温と根雪終了日の変動傾向を示すパターンは温暖・早期化する変化傾向を示し，1月が高温でROSが多発するパターンは10年程度の周期性を示した．さらに，SNOWPACK積雪モデルを利用して，15冬季の積雪プロファイルをシミュレーションしたうえで観測値と比較した．その結果，モデルはROSの発生日にざらめ雪層を形成し，断面観測によるざらめ率の年々変動も概ね再現する事を示した．

Long-term hourly data records of the Automated Meteorological Data Acquisition System (AMeDAS) with snow depth measurements at three high elevation sites were analyzed in central Japan to assess the decadal scale winter climate variabilities with the effects of observation biases. Year-to-year variations of persistent snow cover periods (PSCPs) did not show a significant shortening trend with the delays of starting the PSCP associated with El Niño in December and forward to the ending of the PSCP with nationwide warming in March. Significant warming trends in the surface air temperature averaged in PSCPs were not identified, and length of the PSCP strongly contributed to the year-to-year variations of monthly averaged winter air temperatures. Long-term variabilities of precipitation records were primarily affected by changing the gauge type and data resolutions. After a simple correction of gauge undercatch by air temperature and wind speed, the amount of precipitation increased by around 20 % at the northern station but only by 3 % in the south due to frequent rain-on-snow events. In the two northern stations, snowfall amounts on the order of around 10 % were estimated to be missing in the precipitation records, where a long-term decreasing trend in occurrences of freezing precipitation was also found. The statistics calculated by AMeDAS data were verified using the data of the Vaisala Present Weather Detector in the Sugadaira Highland.

山岳域の天候変動を特徴付ける雲・霧・強雨や降雪の発現に関する統計的傾向を明らかにした研究例は日本では少ない。本研究では，長野県菅平高原（標高1,320 m）に設置された現在天気計（バイサラ社）で2010年11月から2020年10月にかけ取得したデータを使用し，視程により区分される霧と靄，降水形態，降雨強度の季節変化・日変化の特徴を明らかにした。靄は霧に比べて高頻度で出現し，両者とも夜間に頻度が増加した。霧は春季・秋季に，靄は夏季に頻度が増加した。これに比べて，長野地方気象台（標高418 m）では，靄は寒候期・早朝に増加傾向が見られた。降雪とみぞれは日中に発生頻度が低下した。みぞれの発生はまれで，12月と3月に南岸低気圧・二つ玉低気圧通過時に出現しやすかった。非常にまれであるが，過冷却水滴が集中して観測される期間が存在した。強い降雨の頻度は7-9月，夕方に増加する傾向があり，中程度もしくは弱い降雨の頻度は6月や10月といった梅雨・台風の卓越する時期に増加した。降雪は強度に明瞭な季節・日変化の違いは見られなかったが，強い強度の割合は南岸低気圧や二つ玉低気圧の通過時に増加した。従来の目視による低頻度の観測に代わり，今回示された高時間分解で長期データに基づく特性は，衛星観測や数値実験の検証データとしても有用となると考えられる。

The tendency to form a sea of clouds (SOC) with surface meteorological conditions was observed for 3-year warm periods at the foot of Mt. Yatsugatake by time-lapse camera and meteorological instruments at Fujimi Panorama ski resort, Nagano prefecture. In situ observation revealed large- and small-scale SOCs in the valley. Large-scale SOCs were commonly observed in the early morning, while small-scale SOCs in the eastern valley corresponded with low-level orographic clouds ascending over the slopes of Yatsugatake. An empirical algorithm was developed to detect the occurrence of nocturnal low-level clouds, corresponding to large-scale morning SOCs, using Hiamari-8 images on hourly basis with references to in situ camera observation. SOCs frequently occurred in the large-scale valley or basin in the inland areas in the Japanese Alps region, referred as 12 target areas, and they were infrequent in the coastal areas or high elevations over 2000 m. When we defined days of wide-ranging SOC occurrence, in which SOCs occurred in the half or more of target areas, 67% were associated with a subsidence inversion layer by a synoptic-scale high pressure system. The low-level cloud-top height determined by two camera images at different altitudes almost corresponded with the height of the inversion layer observed by radio-sounding data at Wajima station. We concluded that the synoptic-scale subsidence inversion layer plays an important role in forming large-scale SOCs in the Japanese Alps region in addition to nocturnal radiative cooling conditions.(Publlished in Japanese on Tenki 68, 2021: https://www.metsoc.jp/tenki/year.php)

Nocturnal temperature inversion (NTI) is an important factor characterizing the local climate in mountainous areas. In central Japan, most of the mountain slopes are covered by forests, but the effects of their leaf expansion/fall on the NTI variations in basins have not been clarified. According to a three-year leaf area index (LAI) observation in the mixed forest of the Sugadaira Highland (1320 m a.s.l.), Nagano Prefecture, Japan, we identified weakening of the NTI associated with leaf expansion and strengthening after leaf fall in a small basin. Using digital elevation and land-cover data, we defined the distribution of the deciduous and mixed forests in the catchment area of nocturnal cold air drainage. The estimated timings of leaf expansion/fall at the catchment scale based on the effective cumulative temperature almost coincided with the NTI changes. Micrometeorology observations showed that NTI at the forest floor and downslope winds at the adjacent grassland strengthened during the dormant (leafless) season in the nighttime when the radiative cooling is strong. Calm and clear nights were chosen during the spring dormant season and the summer growing season for 22 and 30 nights, respectively. The heat loss during the cold-air pool development was estimated, and converted to storage heat flux in the forest areas. The storage heat flux was 3.8 W m⁻² more on average in the growing season than the dormant season, and it was less than that of forests estimated in previous studies (several 10 W m⁻²), indicating that an increase in storage heat flux of the forests with leaf expansion could cancel nocturnal radiative cooling and weaken gravity currents at the forest floor.

In Japan, Extratropical cyclone sometimes causes sporadic heavy snow in the coastal cites or heavy rains on snow covers in mountainous areas. Ando and Ueno (2015) identified that heavy precipitation events tend to occur with occluding cyclones. However, three-dimensional structure of precipitation system embedded in the cyclone system are difficult to capture by surface observation network over Japanese archipelago that are composed of complex coastal lines and mountains. This study identified heavy precipitation events during the cold seasons of 2014-2019 by two-day accumulated precipitation data at 137 stations of the Japan Meteorological Agency. The mechanisms for producing heavy precipitation in relation to the structure of an occluding extratropical cyclone were analyzed with the aid of the products of the Dual-frequency Precipitation Radar onboard the Global Precipitation Measurement (GPM) core satellite and trajectory analysis on European Centre for Medium-range Weather Forecasts atmospheric reanalysis data. Upper-ranked events with heavy precipitation were mostly due to extratropical cyclones, and many of them were in mature stages. In the top 50 ranked events, three south-coast cyclones were nominated, and relationships between the development of the mesoscale precipitation system and airstreams were intensively diagnosed. Hourly precipitation changes at stations that recorded heavy precipitation were primary affected by a combination of the warm conveyor belt (WCB), the cold conveyor belt (CCB) and the dry intrusion (DI). Wide-ranging stratiform precipitation in the east of cyclone center was composed of low-level WCB over the CCB and the upper WCB, and convective clouds around the cyclone center was associated with the upper DI over the WCB that provided an extreme precipitation rate at the surface, including formation of a band-shaped precipitation system. The convective cloud activities also contributed to moist air advection over the stationary stratiform precipitation areas recognized as the upper WCB. DPR products also identified deep stratiform precipitation in the cloud-head area behind the cyclone center with mid-level (near-surface) latent heat release (absorption) with increased potential vorticity along the CCB that was made feed-back intensification of the cyclone possible. (This study will be published in GPM special issue of JMSJ)　

This article provides insights from a survey of education programs for sustainable mountain development (ESMD) and comments on the findings from the perspective of United Nations Educational, Scientific and Cultural Organization's.(UNESCO) Education for Sustainable Development (ESD) for 2030 framework. Twenty-eight programs implemented by universities, research institutes, and nonprofit organizations (NPOs) are analyzed in terms of program structure, curriculum, and student needs and trajectories. Three-quarters of the programs are based in Europe and North America, the remainder in Central and East Asia and Australia. The programs fall into 6 categories, ranging from traditional university courses to summer schools, university collaborations, distance education, NPO-run skills-focused schools, and research facilities or observatories. Curriculum development toward ESMD has seen considerable progress, even if single-discipline and single-topic programs continue to be widespread. It has embraced fieldwork to offer learners hands-on experience and, increasingly, to work with local stakeholders in problem-oriented settings. Key elements of the ESD for 2030 framework are found, including concern for transformative learning and critical reflection on the structural causes of unsustainability. However, further research is needed to explore less visible aspects such as nonformal and informal education. Policy advocacy and institutional networking are required to scale up innovative approaches.

Sediment transport activities in periglacial environments are controlled by microclimate conditions (i.e., air and ground temperatures, throughfall), which are highly affected by vegetation cover. Thus, there is the possibility that forest harvesting, the most dramatic change to vegetation cover in mountain areas, may severely impact sediment transport activities in periglacial areas (i.e., soil creep, dry ravel). In this study, we investigated changes in sediment transport activities following forest harvesting in steep artificial forests located in a humid periglacial area of the southern Japanese Alps. In the southern Japanese Alps, rainfall is abundant in summer and autumn, and winter air temperatures frequently rise above and fall below 0^∘. Our monitoring by time lapse cameras revealed that gravitational transport processes (e.g., frost creep and dry ravel) dominate during the freeze–thaw season, while rainfall-induced processes (surface erosion and soil creep) occur during heavy rainfall seasons. Canopy removal by forest harvesting increased the winter diurnal ground surface temperature range from 2.7 to 15.9 ^∘C. Forest harvesting also increased the diurnal range of net radiation and ground temperature, and decreased the duration of snow cover. Such changes in the microclimate conditions altered the type of winter soil creep from frost creep to diurnal needle-ice creep. Winter creep velocity of ground surface sediment in the harvested site (> 2 mm day⁻¹ on the days with frost heave) was significantly higher than that in the non-harvested site (generally < 1 mm day⁻¹). Meanwhile, sediment flux on the hillslopes, as observed by sediment traps, decreased in the harvested site. Branches of harvested trees left on the hillslopes captured sediment moving downslope. In addition, the growth of understories after harvesting possibly reduced surface erosion. Consequently, removal of the forest canopy by forest harvesting directly impacts the microclimate conditions (i.e., diurnal range of ground temperature and net radiation, duration of snow cover) and increases frequency and velocity of periglacial soil creep, while sediment flux on hillslopes is decreased by branches left on the hillslopes and recovery of understories. The impact of forest harvesting on sediment transport activity is seasonally variable in humid periglacial areas, because microclimate conditions relevant to both freeze–thaw processes and precipitation-induced processes control sediment transport.