Simulating pan‐Arctic runoff with a macro‐scale terrestrial water balance model

A terrestrial hydrological model, developed to simulate the high‐latitude water cycle, is described, along with comparisons with observed data across the pan‐Arctic drainage basin. Gridded fields of plant rooting depth, soil characteristics (texture, organic content), vegetation, and daily time series of precipitation and air temperature provide the primary inputs used to derive simulated runoff at a grid resolution of 25 km across the pan‐Arctic. The pan‐Arctic water balance model (P/WBM) includes a simple scheme for simulating daily changes in soil frozen and liquid water amounts, with the thaw–freeze model (TFM) driven by air temperature, modelled soil moisture content, and physiographic data. Climate time series (precipitation and air temperature) are from the National Centers for Environmental Prediction (NCEP) reanalysis project for the period 1980–2001. P/WBM‐generated maximum summer active‐layer thickness estimates differ from a set of observed data by an average of 12 cm at 27 sites in Alaska, with many of the differences within the variability (1σ) seen in field samples. Simulated long‐term annual runoffs are in the range 100 to 400 mm year^?1. The highest runoffs are found across northeastern Canada, southern Alaska, and Norway, and lower estimates are noted along the highest latitudes of the terrestrial Arctic in North America and Asia. Good agreement exists between simulated and observed long‐term seasonal (winter, spring, summer–fall) runoff to the ten Arctic sea basins (r = 0·84). Model water budgets are most sensitive to changes in precipitation and air temperature, whereas less affect is noted when other model parameters are altered. Increasing daily precipitation by 25% amplifies annual runoff by 50 to 80% for the largest Arctic drainage basins. Ignoring soil ice by eliminating the TFM sub‐model leads to runoffs that are 7 to 27% lower than the control run. The results of these model sensitivity experiments, along with other uncertainties in both observed validation data and model inputs, emphasize the need to develop improved spatial data sets of key geophysical quantities (particularly climate time series) to estimate terrestrial Arctic hydrological budgets better. Copyright © 2003 John Wiley & Sons, Ltd.     

Soluble species in aerosols collected on the route of the Second Chinese National Arctic Research Expedition

Aerosol samples are collected on the route of the Second Chinese NationalArctic Research Expedition from July 15 to September 28,2003.The concentration ofwater soluble ions(Na~+,NH_4~+,Ca~(2+),Cl~-,MSA,SO_4~(2-)and so on)are ana-lyzed.By correlation analysis,the ions can be divided into three groups:(1)Na~+,Mg~(2+),K~+,Ca~(2+),Cl~-,SO_4~(2-),mainly from sea salt;(2)NH_4~+,NO_3~-,markedlyfrom coastal regions of the continents;(3)Acetate,MSA,C_2O_4~(2-),from othersources.Marine aerosols are the dominant origin,Cl~- and Na~+ are the most domi-nant anion and cation,respectively and these two ions(Na~++Cl~-)account for 55.6% of the total aerosol loading.The mean equivalence ratio of NH_4~+/SO_4~(2-)is 0.45,we suggest that ammonium and sulfate exist mainly as NH_4HSO_4.The concentrationof NO_3~- shows three different patterns on the route of expedition:Japan Sea with me-dian value of 15.2 neq·m~(-3);Sea of Okhostk and Bering Sea of 1.8 neq·m~(-3)andArctic Ocean of 0.4 neq·m~(-3).Bering Sea is a high MSA area.Through the com-parison of the concentration of main water soluble ions between the First and SecondChinese National Arctic Research Expedition,the variation matches each other.     

Recent occurrence of large jökulhlaups at Lake Tuborg,Ellesmere Island,Nunavut

The varved sediment record from glacially-fed Lake Tuborg, Ellesmere Island, Nunavut, shows that only three large jökulhlaups have occurred there in the last millennium: 2003, 1993, and 1960. Detailed analyses of sediment microstructure and particle size, combined with in-situ hydrometeorological and limnological process studies, allowed jökulhlaup facies identification and discrimination from deposits from other processes. Deposits from large jökulhlaups are anomalously thick, typically lack internal structure, have sharp bases, and fine upwards. The ice-dammed lake above Lake Tuborg (the source of the jökulhlaups) likely changed its drainage style in 1960, from ice-dam overtopping to ice-dam flotation and glacial tunnel enlargement by melt widening, which allowed the lake to drain completely and catastrophically. Complete drainage of ice-dammed lakes by ice-dam flotation is rare in the region is due to the pervasiveness of cold-based ice. Twentieth century warming is likely responsible for some combination of dam thinning, lake expansion and deepening, and changing the thermal regime at the base of the dam. Anomalously thick individual varves were periodically deposited beginning in the nineteenth century, and their thickness increased with time. This likely reflects a combination of increased ice dam overtopping, subaqueous slope failures, sediment availability and rising air temperature. The varve record presented here significantly correlates with a previous, shorter record from Lake Tuborg. However, generally weak correlations are found between the new varve time series, regional records of air temperature, and glacial melt from ice cores on the Agassiz Ice Cap. It is hypothesized that on short timescales, sedimentation at the coring location reflects a complex and varying integration of multiple hydroclimatic, geomorphic and limnologic influences.     

Community collaboration and climate change research in the Canadian Arctic

Research on climate change impacts, vulnerability and adaptation, particularly projects aiming to contribute to practical adaptation initiatives, requires active involvement and collaboration with community members and local, regional and national organizations that use this research for policy-making. Arctic communities are already experiencing and adapting to environmental and socio-cultural changes, and researchers have a practical and ethical responsibility to engage with communities that are the focus of the research. This paper draws on the experiences of researchers working with communities across the Canadian Arctic, together with the expertise of Inuit organizations, Northern research institutes and community partners, to outline key considerations for effectively engaging Arctic communities in collaborative research. These considerations include: initiating early and ongoing communication with communities, and regional and national contacts; involving communities in research design and development; facilitating opportunities for local employment; and disseminating research findings. Examples of each consideration are drawn from climate change research conducted with communities in the Canadian Arctic.     

论北极原住民的人口结构与社会问题——以加拿大为例

本文探讨近十几年来加拿大北极北极原住民人口的快速增长以及人口结构年轻化现象．由此而来的一系列社会问题的产生,尤其是年轻男性高的自杀率更应引起全世界人民的关注．这给原住民社会的发展造成了极大的障碍。我们在关注北极丰富的自然资源、环境问题以及军事安全问题,不应该忽视祖祖辈辈生活中这土地上的原住民当下所面临的各种社会问题。     

Definition and analysis of the circulation indices of polar vortex at 10 hPa in the Northern Hemisphere

A set of circulation indices are defined and calculated to characterize monthly mean polar vortex at 10 hPa geopotential height chart in the Northern Hemisphere,including area-(S),intensity-(P) and center position (λc,φc)-indices by use of 1948-2007 NCEP/NCAR 10 hPa monthly height data.These indices series are used to investigate the seasonal variation and interannual anomaly of polar vortex,along with the relations with global warming,ozone anomaly and Arctic Oscillation (AO).The results show that (1) there is anticyclonic (cyclonic) from Jun.to Aug.(from Sep.to Mar.).The change of spring circulation pattern is slower than that of autumn.(2) S can be replaced by P due to the interannual synchronal variations of the intensity and area for polar vortex.The interannual (interdecadal) variations of P are significant in Jan.(Jul.).(3) The anomalies of system center position in Jan.are more evident than that in Jul.(4) The variations of mean temperature at mid-stratosphere in the vicinity of pole zone in Jan.are different from that in Jul.,but they are synchronal with the corresponding P and not significant correlation with the trend of global warming.However,the relationship between P and total O3 in Jul.are obvious.(5) There is so notable correlation between P and AO that P can represent AO.