1,721,024 research outputs found
Rock Glaciers in the Patagonian Andes: An Inventory for the Monte San Lorenzo (Cerro Cochrane) Massif, 47° S
Full text linkAlthough rock glaciers in the Central and Desert Andes of Argentina and Chile have been previously studied in detail, much less attention has been paid to the occurrence of these permafrost forms in Patagonia. Recently, however, the establishment of the Argentinean Glacier Inventory program, which intends to inventory and monitor all ice masses along the Argentinean Andes, has started a large amount of new geocryological research. The project is designed to provide reliable and worldwide comparable results, supported by well established technical procedures and background information. Presented here is the first rock glacier inventory of the Monte San Lorenzo (Cerro Cochrane) region in the southern Patagonian Andes. A total of 130 intact (9.86 km2) and 47 fossil (1.45 km2) landforms were inventoried using two 2.5 m resolution ALOS Panchromatic Remote-sensing Instruments for Stereo Mapping images. Since the Argentinean federal initiative described above legally protects all rock glaciers in the country as water reserves, and due to the little scientific knowledge concerning rock glaciers in the vast majority of the Patagonian Andes, this inventory provides an important basis for political decision-making and opens further geocryological research avenues for the Patagonian region in general.Fil: Falaschi, Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Tadono, Takeo. Japan Aerospace Exploration Agency; JapónFil: Masiokas, Mariano Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin
ALOS-derived glacier and rock glacier inventory of the Volcán Domuyo region (~36° S), southernmost Central Andes, Argentina
Full text linkIn this study we use optical ALOS AVNIR-2 and PRISM satellite images to map and inventory glaciers as well as active, inactive and fossil rock glaciers in the Volcán Domuyo region (36°16' S-36°54' S), located in the northwestern tip of the Neuquén Province in Argentina. The area is termed "Transition Cordillera" since it lies between the southernmost reaches of the Central Andes and the Patagonian Andes. We inventoried a total of 106 glaciers, covering an area of ~25.4 km2, and 173 intact rock glaciers (~11.3 km2) in the year 2009. Using a 1990 Landsat scene from this area, we estimated a retreat rate of 26% reduction (~1.4% per year) of the glacier covered area between 1990 and 2009. The minimum elevation of the front talus of active rock glaciers indicates that the lower limit of discontinuous mountain permafrost in the region is located around 2800 m a.s.l. The results here provide new information about the current extent and recent behavior of glaciers and the spatial distribution of mountain permafrost in this poorly known region of the southern Andes. The lack of complete, long climate records in the area precludes detailed analyses of the recent response of glaciers to climate variability. However, regional warming trends and a recent reduction in winter precipitation may have contributed to the observed recent glacier wastage in the Domuyo region.Fil: Falaschi, Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Masiokas, Mariano Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Tadono, Takeo. Japan Aerospace Exploration Agency; JapónFil: Couvreux, Fleur. Météo-France; Franci
Rock glacier inventory of the Valles Calchaquíes Region (~ 25°S), Salta, Argentina, derived from ALOS data
Full text linkRock glaciers near the Andean mountains of central and northwestern Argentina provide an important supply of water for agriculture, but data on their number, size, geographic distribution and altitudinal range are poorly known. Here, we provide the first detailed rock glacier inventory of the Valles Calchaquíes region of Salta, Argentina, based on 2.5 m x 2.5 m resolution Advanced Land Observing Satellite PRISM (Panchromatic Remote-sensing Instruments for Stereo Mapping) satellite images. Rock glacier outlines were manually digitised and a total of 488 were identified, which cover a total area of c. 59 km2. The lower limits of intact and fossil rock glaciers are at c. 4300 m asl and 4100 m asl, respectively. Because rock glaciers are protected by law in Argentina, the inventory provides an important basis for political decision-making about water resources and for further periglacial and environmental studies in this region.Fil: Falaschi, Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Científico Tecnológico Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Castro, Mariano Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Científico Tecnológico Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Masiokas, Mariano Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Científico Tecnológico Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Tadono, Takeo. Japan Aerospace Exploration Agency; JapónFil: Ahumada, Ana Lia. Fundación Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
TIFF images of rock glacier surface velocities for Valley Calchaquíes region, Salta Province, Argentina
No full textFor the Valles Calchaquíes region, Northwestern Argentina, we derived rock glacier surface velocities (in unit m/a) from multi-temporal aerial and satellite imagery using a feature tracking approch. The data covers three epochs (EPs), EP1 from 1968 to 2009, EP2 from 2009/2010 to 2020, EP3 from 2020 to 2023. Given the variable availablility of aerial and satellite images, the spatial coverage is not the same for all three EPs and the limit of detection is spatially variable. For our analysis, we used rock glacier outlines as published by the Inventario Nacional de Glaciares of Argentina (https://www.glaciaresargentinos.gob.ar/; polygon data can be downloaded there) that have a minimum area of 0.02 km². We provide seperate data sets, one per epoch containing all derived average rock glacier velocities (unit m/a), and one only containing rock glacier velocities that exceed the limit of detection (unit m/a) of our analysis (see publication for details). While the data containing all derived average velocities is intended to document where feature tracking was performed, the data containing rock glacier velocities exceeding the limit of detection shall be used for analysis
Rock glacier surface velocities for Valley Calchaquíes region, Salta Province, Argentina
No full textFor the Valles Calchaquíes region, Northwestern Argentina, we derived rock glacier surface velocities (in unit m/a) from multi-temporal aerial and satellite imagery using a feature tracking approch. The data covers three epochs (EPs), EP1 from 1968 to 2009, EP2 from 2009/2010 to 2020, EP3 from 2020 to 2023. Given the variable availablility of aerial and satellite images, the spatial coverage is not the same for all three EPs and the limit of detection is spatially variable. For our analysis, we used rock glacier outlines as published by the Inventario Nacional de Glaciares of Argentina (https://www.glaciaresargentinos.gob.ar/; polygon data can be downloaded there) that have a minimum area of 0.02 km². The data table provides information on the location of the rock glaciers investigated in our study, as well as mean surface velocities (in unit m/a) exceeding the limit of detection (in unit m/a) for each landform and epoch investigated
ALOS-2/PALSAR-2 Calibration, Validation, Science and Applications
Full text linkTwelve edited original papers on the latest and state-of-art results of topics ranging from calibration, validation, and science to a wide range of applications using ALOS-2/PALSAR-2. We hope you will find them useful for your future research
Characteristics of Glacier Lakes in the Ladakh Range, Western Indian Himalayas
No full text日本の陸域観測技術衛星「だいち」(ALOS)に搭載された PRISMとAVNIR-2の光学センサによって2007-2010年に撮影された高分解能衛星画像を用いて, インド北西部のラダーク山脈にある195の氷河湖(0.0001km[2]以上)を確認した. そのうち0.001-0.05km[2]の氷河湖数が93%を占めており, 小規模な氷河湖が分布する地域である. 最大の氷河湖(0.25km[2])はラダーク山脈南東部の北側斜面に位置する. 主要な氷河湖のタイプはモレーンダム湖である. ラダーク山脈の氷河湖の最低位高度は, 山脈の北西端(4860m)と南東端(5560m)で大きく異なる. 1962年-1980年に撮影された米国軍事偵察衛星Corona KH-4A, KH-4B, Hexagon KH-9の衛星写真, その後のJERS-1(衛星)/OPS(センサ名), SPOT4, Landsat7/ETM+, Terra/ASTER, ALOS/PRISM, ALOS/AVNIR-2の衛星画像の分析により, ラダーク山脈北西部のドムカル谷流域に分布する13の氷河湖の多くは1960年代以降に出現したことがわかった. ドムカル谷最大の氷河湖No.3は, 1965-2000年に0.0012km[2]/年, 2000-2010年に0.0033km[2]/年で拡大を続けており, 2000年以降の拡大速度は大きい. ドムカル谷上流のタベイ・ルンパ谷の氷河前面には, 2011年に新たに出現した氷河湖No.13を確認した. この氷河湖は2010年10月28日の衛星画像ではまだ存在していないが, 2011年の6～8月のわずか2カ月間で面積0.0398km2, 体積528, 000m3, 最大水深28mまで発達した. この氷河湖はドムカル谷で2番目に大きく, 現地調査や継続したモニタリングが必要である.Using high-resolution optical imageries taken between 2007 and 2010 by the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) and the Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2) onboard the Advanced Land Observing Satellite (ALOS), 195 glacier lakes (>0.0001 km2) were investigated in the Ladakh Range, northwestern India. 93% of 195 glacier lakes are of sizes between 0.05 and 0.001 km2, small glacier lakes are distributed in this range. The largest glacier lake (0.25 km2) is located in the southeastern part of the Ladakh Range, and Lake types are mostly moraine dammed lake. The lowest elevations of the glacier lakes differ greatly between northwestern (4, 860 m) and southeastern (5, 560 m) parts of the Ladakh Range. Corona KH-4A (8 October 1965), Corona KH-4B (28 September 1971), Hexagon KH-9, JERS-1/OPS, SPOT4, Landsat7/ETM+, Landsat5/TM, Terra/ASTER and ALOS/PRISM, ALOS/AVNIR-2 satellite imageries show that most of 13 glacier lakes in the Domkhar Valley have developed since the 1960s. Only 3 of the 13 glacier lakes have continued to expand since the 1960s, and their expansion rates have increased markedly since 2000. In upstream from the main Domkhar Valley, we confirmed a new glacier lake in front of a glacier in the Tabei Lungpa Valley. The lake did not exist on 28 October 2010, but then appeared suddenly over a span of about 2months. The area of the lake increased from 0.0072 km2 on 08 June 2011 (Terra/ASTER) to 0.0398 km2 on 3 August 2011 (Landsat5/TM). The estimated volume of the glacier lake is 528, 000 m3 and its maximum depth is 28 m using a Digital Elevation Model (DEM) from ALOS/PRISM. This lake is the second-largest glacier lake in the Domkhar Valley
Current State of the Glacier Lakes and Related Outburst Floods in the Domkhar Valley, Ladakh Range, Indian Himalayas
No full textインド北西部のジャンム・カシミール州のラダーク山脈, ドムカル(Domkhar)谷上流に分布する氷河湖の現状を衛星画像解析と2010年6月と9月の現地調査から明らかにした. また, 2009年3, 8月, 2010年8-9月にも過去の氷河湖決壊洪水の発生時期やその被害に関する情報収集を現地でおこなった. Domkhar 谷上流部には, 32の小規模なクリーンタイプの氷河(氷河表面がデブリで覆われていない氷河; 0.008km2-1.2km2)とモレーンで堰き止められた11の氷河湖(0.003km2-0.096km2)が存在する. これら氷河の面積は1994-2009 年の約15年間で約3%消失した. 11の氷河湖の拡大履歴をみると, 3つの氷河湖は1980年以降拡大を続けており, 他の3 つは急激に面積を減少させ, 残りはほとんど変化していない. Domkhar 谷で最大の氷河湖(0.096km2)の拡大速度は, 0.0013km2/year(1980-2000年)と0.0033km2/year(2000-2010年)であり, 2000年以降拡大速度が大きくなっている. Domkhar 谷で5 つの氷河湖を現地調査した結果, 最大水深40mほどの氷河湖が2つあり, 湖水量は約1, 112, 000m3 と427, 000m3 であった. Domkhar谷における過去の氷河湖決壊洪水を衛星画像解析により調べたところ, 2000年以降に小規模な決壊が4回生じていた. Gongpa-Rangchong 谷の下流域に広がる土石流堆積物は, 2003年に生じた氷河湖決壊洪水によるものであった. 調査した5つの氷河湖の面積と水量の関係式から, 2003年に決壊した氷河湖(0.005km2)の水量を見積ったところ, 小規模な氷河湖(16, 900m3)による決壊であることがわかった. この氷河湖決壊洪水は小規模であったが, 下流域に土石流堆積物を堆積させ, Domkhar谷で木製の橋, 水車小屋, 畑などを破壊した. この氷河湖の決壊要因は, 氷河湖を堰きとめるアイスコアードモレーン内部に発達したアイストンネルの開通によるものであった. Gongpa-Rangchong 谷の上流部にある氷河湖(427, 000m3)では, 湖を堰き止めるモレーン内部に発達するアイストンネルを確認した.We studied glacier lakes in the Domkhar Valley of the Ladakh Range (Indian Himalayas), state of Jammu and Kashmir, northwestern India, based on satellite images and a field survey undertaken in June and September 2010. Information about glacier lake outburst floods (GLOFs) in the past and their damages was collected by interviews for local people in March and August 2009 and August-September in 2010. 32 small (0.008km[2]–1.2km[2]) glaciers and 11 glacier lakes (0.002–0.096km[2]) were found in the valley. The glaciers shrank by 3% in total area from 1994 to 2009. Three of the glacier lakes have expanded since 1980, three glacier lakes shrank rapidly in the 2000s, and five glacier lakes have remained unchanged in its areal extent. The largest glacier lake (0.096km[2]) in the Domkhar Valley had expansions rate of 0.0013km[2]/year in 1980–2000 and 0.0033km[2]/year in 2000–2010; the expansion rate was higher after 2000. Of the five glacier lakes studied, two glacier lakes with maximum depths of ~40m had water volumes of ~1, 112, 000m[3] and ~427, 000m[3]. An investigation of GLOFs in the Domkhar Valley using satellite imagery showed that four small GLOFs occurred since 2000. Fresh debris-flow deposits in the Gongpa-Rangchong Valley have been caused by a small GLOF in 2003. Although the estimated volume (~16, 900m[3]) of the lake was small, wooden bridges, fields, and water mills in the villages of Domkhar Valley were damaged. This GLOF occurred when an ice tunnel opened within the ice-cored moraine damming the lake. We observed that icetunnel drainage from a glacier lake (water volume ~427, 000m[3]) in the Gongpa-Rangchong Valley seem to develop at present
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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