This study demonstrated the usefulness of very long-range terrestrial laser scanning(TLS) for analysis of the spatial distribution of a snowpack, to distances up to 3000 m, one of the longest measurement range reporte...This study demonstrated the usefulness of very long-range terrestrial laser scanning(TLS) for analysis of the spatial distribution of a snowpack, to distances up to 3000 m, one of the longest measurement range reported to date. Snow depth data were collected using a terrestrial laser scanner during 11 periods of snow accumulation and melting,over three snow seasons on a Pyrenean hillslopecharacterized by a large elevational gradient, steep slopes, and avalanche occurrence. The maximum and mean absolute snow depth error found was 0.5-0.6 and 0.2-0.3 m respectively, which may result problematic for areas with a shallow snowpack, but it is sufficiently accurate to determine snow distribution patterns in areas characterized by a thick snowpack. The results indicated that in most cases there was temporal consistency in the spatial distribution of thesnowpack, even in different years. The spatial patterns were particularly similar amongst thesurveys conducted during the period dominated by snow accumulation(generally until end of April), or amongst those conducted during the period dominated by melting processes(generally after mid of April or early May). Simple linear correlation analyses for the 11 survey dates, and the application of Random Forests analysis to two days representative of snow accumulation and melting periods indicated the importance of topography to the snow distribution. The results also highlight that elevation and the Topographic Position index(TPI) were the main variables explaining the snow distribution, especially during periods dominated by melting. The intra-and inter-annual spatial consistency of the snowpack distribution suggests that the geomorphological processes linked to presence/absence of snow cover act in a similar way in the long term, and that these spatial patternscan be easily identifiedthrough several years of adequate monitoring.展开更多
This paper reviews the major contributions made by Norwegian scientists to Arctic environmental sciences since the 1880s. The review begins with the first International Polar Year （IPY） in 1882-83. It then considers...This paper reviews the major contributions made by Norwegian scientists to Arctic environmental sciences since the 1880s. The review begins with the first International Polar Year （IPY） in 1882-83. It then considers the 1890s to 1920s with the scientific expeditions focusing on ocean and sea ice conditions of Nansen, Amundsen and H. Sverdrup, and the mapping of the Queen Elizabeth Islands by Otto Sverdrup and colleagues. The period from 1911 to the mid-1920s also witnessed annual expeditions to Svalbard led by Adolf Hoel. The 1930s to 1945 period encompassed the Second International Polar Year when Arctic weather stations were established or maintained. The time interval post-World War II to 2000 witnessed major advances made possible by technical and organizational innovations. The establishment of the Norwegian Polar Institute in 1948 led to extensive research on the glaciers and snow cover in the Svalbard archipelago and to oceanographic and sea ice research in the Barents Sea and Arctic Ocean. Remote sensing methods began to be widely used from the 1980s. The new millennium saw the undertaking of the third IPY and a shift to multinational projects. New fields such as ocean-ice-atmosphere variability became active and there was much attention to high-latitude climate change in the context of global warming.展开更多
1. Overview In June 2021, the 16th Workshop on Antarctic Meteorology and Climate (WAMC) and the 6th Year of Polar Prediction in the Southern Hemisphere (YOPP-SH) Meeting (http://polarmet.osu.edu/WAMC;021/) were held o...1. Overview In June 2021, the 16th Workshop on Antarctic Meteorology and Climate (WAMC) and the 6th Year of Polar Prediction in the Southern Hemisphere (YOPP-SH) Meeting (http://polarmet.osu.edu/WAMC;021/) were held online and hosted by the Polar Meteorology Group at Byrd Polar and Climate Research Center, The Ohio State University, Columbus,Ohio (Fig. 1).展开更多
As the summit of the Antarctic Plateau, Dome A has been received international attentions.In this paper, observational data of an automatic weather station (AWS) at Dome A in 2005–2007 were used to analyze the season...As the summit of the Antarctic Plateau, Dome A has been received international attentions.In this paper, observational data of an automatic weather station (AWS) at Dome A in 2005–2007 were used to analyze the seasonal variations of air temperatures near the ground and snow temperatures within a depth of 10 m. Analyses on the air temperatures show a typical feature of the coreless winter, and strong inversion maintains during the long winter. Accordingly the stratification near the ground is dominated by the near-neutral stable states. Seasonal fluctuations of the snow temperature decrease in amplitude and lag in phase with depth increasing, which leads to distinct seasonal temperature profiles within the depth of 10 m. Measurements show the mean annual air temperature near ground is about 5°C higher than the 10 m firn temperature due to the strong inversion near the ground. However, our estimation of the annual mean of air temperature at the ground based on the boundary layer theory is close to the mean 10 m firn temperature. The lowest air temperature (–82.7°C) currently measured at the Dome A is not the lowest one ever recorded in Antarctica, but the extremely low mean 10 m firn temperature (–58.2°C) indicates very low ground temperature. Given the prominent inversion near the ground, it is expected that Dome A might house the lowest ground temperature on the planet.展开更多
Investigation on spatiotemporal variations of maximum seasonal freeze depth （MSFD） over the Heihe River Basin is of great importance for systematic understanding of regional climate and environmental change, ecologi...Investigation on spatiotemporal variations of maximum seasonal freeze depth （MSFD） over the Heihe River Basin is of great importance for systematic understanding of regional climate and environmental change, ecological-hydrological processes, water resources assessment, construction and resource development. Based on soil and air temperatures at the meteorological stations of the China Meteorological Administration （CMA） over the Heihe River Basin, MSFDs time series are structured into a composite time series over the 1960-2007 period. Evaluating the averaged MSFD time series for 1960 2007 reveals a statistically significant trend of 4.0 cm/decade or a net change of-19.2 cm for the 48-year period over the basin. The MSFD had significantly negative correlation with mean annual air temperature （MAAT）, winter air temperature, mean annual ground surface temperature （MAGST）, degree days of thawing for the air （DDTa） as well as for the surface （DDTs）, and degree days of freezing for the surface （DDFs）. While there was significantly positive correlation between DDF,. and MSFD time series, MSFD was deeper and changed greatly in the Heihe River source area. It was shallower in the east-central basin and gradually deepened in other sections of the basin. The MSFD distribution pattern in 2003-2005 is consistent with that of averaged degree days of freezing for air （DDFa） in 1960-2007. However, the maximum of MSFD may not be accurate, because there is no long term observation data in the deep seasonally frozen ground regions near the lower boundary of permafrost. With increasing elevation, averaged DDFa increased at a rate of 51.6 ℃-day/100m, therefore, the MSFG and the date reaching MSFG became deeper and later, respectively.展开更多
Changes in ground surface thermal regimes play a vital role in surface and subsurface hydrology, ecosystem diversity and productivity, and global thermal, water and carbon budgets as well as climate change. Estimating...Changes in ground surface thermal regimes play a vital role in surface and subsurface hydrology, ecosystem diversity and productivity, and global thermal, water and carbon budgets as well as climate change. Estimating spring, summer, autumn and winter air temperatures and mean annual air temperature（MAAT） from 1960 through 2008 over the Heihe River Basin reveals a statistically significant trend of 0.31 °C/decade, 0.28 °C/decade, 0.37 °C/decade, 0.50 °C/decade, and 0.37 °C /decade, respectively. The averaged time series of mean annual ground surface temperature（MAGST） and maximum annual ground surface temperature（MaxAGST） for 1972–2006 over the basin indicates a statistically significant trend of 0.58 °C/decade and 1.27 °C/decade, respectively. The minimum annual ground surface temperature（MinAGST） in the same period remains unchanged as a whole. Estimating surface freezing/thawing index as well as the ratio of freezing index to thawing index（RFT） in the period between 1959 and 2006 over the basin indicates a statistically significant trend of-42.5 °C-day/decade, 85.4 °C-day/decade and-0.018/decade, respectively.展开更多
Although we live in an era of unprecedented quantities and access to data,deriving actionable information from raw data is a hard problem.Earth observation systems(EOS)have experienced rapid growth and uptake in recen...Although we live in an era of unprecedented quantities and access to data,deriving actionable information from raw data is a hard problem.Earth observation systems(EOS)have experienced rapid growth and uptake in recent decades,and the rate at which we obtain remotely sensed images is increasing.While significant effort and attention has been devoted to designing systems that deliver analytics ready imagery faster,less attention has been devoted to developing analytical frameworks that enable EOS to be seamlessly integrated with other data for quantitative analysis.Discrete global grid systems(DGGS)have been proposed as one potential solution that addresses the challenge of geospatial data integration and interoperability.Here,we propose the systematic extension of EASE-Grid in order to provide DGGS-like characteristics for EOS data sets.We describe the extensions as well as present implementation as an application programming interface(API),which forms part of the University of Minnesota’s GEMS(Genetic x Environment x Management x Socioeconomic)Informatics Center’s API portfolio.展开更多
Ground-based measurements are essential for understanding alpine glacier dynamics,especially in remote regions where in-situ measurements are extremely limited.Prom 1 May to 22 July 2005（the spring-summer period）,an...Ground-based measurements are essential for understanding alpine glacier dynamics,especially in remote regions where in-situ measurements are extremely limited.Prom 1 May to 22 July 2005（the spring-summer period）,and from 2 October 2007 to 20 January 2008（the autumn-winter period）,surface radiation as well as meteorological variables were measured over the accumulation zone on the East Rongbuk Glacier of Mt. Qomolangma/Everest at an elevation of 6560 m a.s.l.by using an automatic weather station（AWS）.The results show that surface meteorological and radiative characteristics were controlled by two major synoptic circulation regimes：the southwesterly Indian monsoon regime in summer and the westerlies in winter.At the AWS site on the East Rongbuk Glacier,north or northwest winds prevailed with high wind speed（up to 35 m s^（-1） in January） in winter while south or southeast winds predominated after the onset of the southwesterly Indian monsoon with relatively low wind speed in summer.Intensity of incoming shortwave radiation was extremely high due to the high elevation,multiple reflections between the snow/ice surface and clouds,and the high reflective surrounding surface.These factors also caused the observed 10-min mean solar radiation fluxes around local noon to be frequently higher than the solar constant from May to July 2005.The mean surface albedo ranged from 0.72 during the spring-summer period to 0.69 during the autumn-winter period. The atmospheric incoming longwave radiation was greatly affected by the cloud condition and atmospheric moisture content.The overall impact of clouds on the net all-wave radiation balance was negative in the Mt. Qomolangma region.The daily mean net all-wave radiation was positive during the entire spring-summer period and mostly positive during the autumn-winter period except for a few overcast days.On monthly basis,the net all-wave radiation was always positive.展开更多
基金CGL2014-52599-P “Estudio del manto de nieve enla montana espanola y su respuesta a la variabilidad y cambio climatico” funded by the Spanish Ministry of Economy and CompetitivenessEl glaciar de Monte Perdido: estudio de su dinámica actual y procesos criosféricos asociados como indicadores de procesos de cambio global” (MAGRAMA 844/2013).
文摘This study demonstrated the usefulness of very long-range terrestrial laser scanning(TLS) for analysis of the spatial distribution of a snowpack, to distances up to 3000 m, one of the longest measurement range reported to date. Snow depth data were collected using a terrestrial laser scanner during 11 periods of snow accumulation and melting,over three snow seasons on a Pyrenean hillslopecharacterized by a large elevational gradient, steep slopes, and avalanche occurrence. The maximum and mean absolute snow depth error found was 0.5-0.6 and 0.2-0.3 m respectively, which may result problematic for areas with a shallow snowpack, but it is sufficiently accurate to determine snow distribution patterns in areas characterized by a thick snowpack. The results indicated that in most cases there was temporal consistency in the spatial distribution of thesnowpack, even in different years. The spatial patterns were particularly similar amongst thesurveys conducted during the period dominated by snow accumulation(generally until end of April), or amongst those conducted during the period dominated by melting processes(generally after mid of April or early May). Simple linear correlation analyses for the 11 survey dates, and the application of Random Forests analysis to two days representative of snow accumulation and melting periods indicated the importance of topography to the snow distribution. The results also highlight that elevation and the Topographic Position index(TPI) were the main variables explaining the snow distribution, especially during periods dominated by melting. The intra-and inter-annual spatial consistency of the snowpack distribution suggests that the geomorphological processes linked to presence/absence of snow cover act in a similar way in the long term, and that these spatial patternscan be easily identifiedthrough several years of adequate monitoring.
文摘This paper reviews the major contributions made by Norwegian scientists to Arctic environmental sciences since the 1880s. The review begins with the first International Polar Year （IPY） in 1882-83. It then considers the 1890s to 1920s with the scientific expeditions focusing on ocean and sea ice conditions of Nansen, Amundsen and H. Sverdrup, and the mapping of the Queen Elizabeth Islands by Otto Sverdrup and colleagues. The period from 1911 to the mid-1920s also witnessed annual expeditions to Svalbard led by Adolf Hoel. The 1930s to 1945 period encompassed the Second International Polar Year when Arctic weather stations were established or maintained. The time interval post-World War II to 2000 witnessed major advances made possible by technical and organizational innovations. The establishment of the Norwegian Polar Institute in 1948 led to extensive research on the glaciers and snow cover in the Svalbard archipelago and to oceanographic and sea ice research in the Barents Sea and Arctic Ocean. Remote sensing methods began to be widely used from the 1980s. The new millennium saw the undertaking of the third IPY and a shift to multinational projects. New fields such as ocean-ice-atmosphere variability became active and there was much attention to high-latitude climate change in the context of global warming.
基金the International Association of Meteorology and Atmospheric Science(IAMAS)/International Commission on Polar Meteorology(ICPM)Scientific Committee on Antarctic Research(SCAR)+2 种基金the World Meteorological Organization(WMO)for supporting these workshopsFinancial Support from the Office of Polar ProgramsNational Science Foundation(Grant No.NSF 1823135,1924730,192473,and 1951603)。
文摘1. Overview In June 2021, the 16th Workshop on Antarctic Meteorology and Climate (WAMC) and the 6th Year of Polar Prediction in the Southern Hemisphere (YOPP-SH) Meeting (http://polarmet.osu.edu/WAMC;021/) were held online and hosted by the Polar Meteorology Group at Byrd Polar and Climate Research Center, The Ohio State University, Columbus,Ohio (Fig. 1).
基金supported by the National Science & Technology Pillar Program (Grant No. 2006BAC 06B05)Treasury Special Program of China (Grant No. GYHY200706005)+1 种基金the National Natural Science Foundation of China (Grant No.40921003)the International S&T Cooperation Project of the Ministry of Science and Technology of China (Grant No.2009DFA21430)
文摘As the summit of the Antarctic Plateau, Dome A has been received international attentions.In this paper, observational data of an automatic weather station (AWS) at Dome A in 2005–2007 were used to analyze the seasonal variations of air temperatures near the ground and snow temperatures within a depth of 10 m. Analyses on the air temperatures show a typical feature of the coreless winter, and strong inversion maintains during the long winter. Accordingly the stratification near the ground is dominated by the near-neutral stable states. Seasonal fluctuations of the snow temperature decrease in amplitude and lag in phase with depth increasing, which leads to distinct seasonal temperature profiles within the depth of 10 m. Measurements show the mean annual air temperature near ground is about 5°C higher than the 10 m firn temperature due to the strong inversion near the ground. However, our estimation of the annual mean of air temperature at the ground based on the boundary layer theory is close to the mean 10 m firn temperature. The lowest air temperature (–82.7°C) currently measured at the Dome A is not the lowest one ever recorded in Antarctica, but the extremely low mean 10 m firn temperature (–58.2°C) indicates very low ground temperature. Given the prominent inversion near the ground, it is expected that Dome A might house the lowest ground temperature on the planet.
基金supported by the Global Change Research Program of China (No. 2010CB951402)the Natural Science Foundation of China (Nos. 91025013, 91325202)+1 种基金the State Key Laboratory of Frozen Soil Engineering (No. SKLFSE-ZY-06), CAS, Chinathe Major Research Plan of the Natural Science Foundation of China (No. 2013CBA01802)
文摘Investigation on spatiotemporal variations of maximum seasonal freeze depth （MSFD） over the Heihe River Basin is of great importance for systematic understanding of regional climate and environmental change, ecological-hydrological processes, water resources assessment, construction and resource development. Based on soil and air temperatures at the meteorological stations of the China Meteorological Administration （CMA） over the Heihe River Basin, MSFDs time series are structured into a composite time series over the 1960-2007 period. Evaluating the averaged MSFD time series for 1960 2007 reveals a statistically significant trend of 4.0 cm/decade or a net change of-19.2 cm for the 48-year period over the basin. The MSFD had significantly negative correlation with mean annual air temperature （MAAT）, winter air temperature, mean annual ground surface temperature （MAGST）, degree days of thawing for the air （DDTa） as well as for the surface （DDTs）, and degree days of freezing for the surface （DDFs）. While there was significantly positive correlation between DDF,. and MSFD time series, MSFD was deeper and changed greatly in the Heihe River source area. It was shallower in the east-central basin and gradually deepened in other sections of the basin. The MSFD distribution pattern in 2003-2005 is consistent with that of averaged degree days of freezing for air （DDFa） in 1960-2007. However, the maximum of MSFD may not be accurate, because there is no long term observation data in the deep seasonally frozen ground regions near the lower boundary of permafrost. With increasing elevation, averaged DDFa increased at a rate of 51.6 ℃-day/100m, therefore, the MSFG and the date reaching MSFG became deeper and later, respectively.
基金supported by the Chinese Academy of Sciences Key Research Program (No. KZZD-EW-13)the Natural Science Foundation of China (Nos. 91025013, 91325202)+1 种基金the State Key Laboratory of Frozen Soil Engineering (No. SKLFSE-ZY-06), CASthe Major Research Plan of the National Natural Science Foundation of China (No. 2013CBA01802)
文摘Changes in ground surface thermal regimes play a vital role in surface and subsurface hydrology, ecosystem diversity and productivity, and global thermal, water and carbon budgets as well as climate change. Estimating spring, summer, autumn and winter air temperatures and mean annual air temperature（MAAT） from 1960 through 2008 over the Heihe River Basin reveals a statistically significant trend of 0.31 °C/decade, 0.28 °C/decade, 0.37 °C/decade, 0.50 °C/decade, and 0.37 °C /decade, respectively. The averaged time series of mean annual ground surface temperature（MAGST） and maximum annual ground surface temperature（MaxAGST） for 1972–2006 over the basin indicates a statistically significant trend of 0.58 °C/decade and 1.27 °C/decade, respectively. The minimum annual ground surface temperature（MinAGST） in the same period remains unchanged as a whole. Estimating surface freezing/thawing index as well as the ratio of freezing index to thawing index（RFT） in the period between 1959 and 2006 over the basin indicates a statistically significant trend of-42.5 °C-day/decade, 85.4 °C-day/decade and-0.018/decade, respectively.
文摘Although we live in an era of unprecedented quantities and access to data,deriving actionable information from raw data is a hard problem.Earth observation systems(EOS)have experienced rapid growth and uptake in recent decades,and the rate at which we obtain remotely sensed images is increasing.While significant effort and attention has been devoted to designing systems that deliver analytics ready imagery faster,less attention has been devoted to developing analytical frameworks that enable EOS to be seamlessly integrated with other data for quantitative analysis.Discrete global grid systems(DGGS)have been proposed as one potential solution that addresses the challenge of geospatial data integration and interoperability.Here,we propose the systematic extension of EASE-Grid in order to provide DGGS-like characteristics for EOS data sets.We describe the extensions as well as present implementation as an application programming interface(API),which forms part of the University of Minnesota’s GEMS(Genetic x Environment x Management x Socioeconomic)Informatics Center’s API portfolio.
基金Supported by the National Basic Research Program of China(2007CB411503)the Knowledge Innovation Program of the Chinese Academy of Sciences(KZCX3-SW-344/339)+2 种基金the International Arctic Research Center,University of Alaska Fairbanks, through the U.S.NSF cooperative agreement(OPP-0327664) to Tingjun Zhangthe National Natural Science Foundation of China (40501015/40401054)the China Meteorological Administration Special Research Project(GYHY(QX)2007-6-18)
文摘Ground-based measurements are essential for understanding alpine glacier dynamics,especially in remote regions where in-situ measurements are extremely limited.Prom 1 May to 22 July 2005（the spring-summer period）,and from 2 October 2007 to 20 January 2008（the autumn-winter period）,surface radiation as well as meteorological variables were measured over the accumulation zone on the East Rongbuk Glacier of Mt. Qomolangma/Everest at an elevation of 6560 m a.s.l.by using an automatic weather station（AWS）.The results show that surface meteorological and radiative characteristics were controlled by two major synoptic circulation regimes：the southwesterly Indian monsoon regime in summer and the westerlies in winter.At the AWS site on the East Rongbuk Glacier,north or northwest winds prevailed with high wind speed（up to 35 m s^（-1） in January） in winter while south or southeast winds predominated after the onset of the southwesterly Indian monsoon with relatively low wind speed in summer.Intensity of incoming shortwave radiation was extremely high due to the high elevation,multiple reflections between the snow/ice surface and clouds,and the high reflective surrounding surface.These factors also caused the observed 10-min mean solar radiation fluxes around local noon to be frequently higher than the solar constant from May to July 2005.The mean surface albedo ranged from 0.72 during the spring-summer period to 0.69 during the autumn-winter period. The atmospheric incoming longwave radiation was greatly affected by the cloud condition and atmospheric moisture content.The overall impact of clouds on the net all-wave radiation balance was negative in the Mt. Qomolangma region.The daily mean net all-wave radiation was positive during the entire spring-summer period and mostly positive during the autumn-winter period except for a few overcast days.On monthly basis,the net all-wave radiation was always positive.
