Satellite Observations to Monitor Subarctic Rain-On-Snow Events

Rain-on-snow (ROS) events have been the focus of numerous studies in the past five years. Their characteristics(frequency, extent, and duration) represent a new and relevant climate indicator. However, monitoring ROS occurrences remotely using satellite observations is deemed challenging. The ROS events can be sporadic, of very different intensities, and the outcome of the rain water uncertain (either it freezes in the snow cover or runs off). Using passive and active microwave remote sensing observations, our study proposes new approaches to monitor the occurrence of ROS events.Specifically, we utilize observations from Advanced Microwave Scanning Radiometer 2 (AMSR2), and Global Precipitation Measurements (GPM) Microwave Imager (GMI), and GPM Dual-frequency Precipitation Radar (DPR). We compare our ROS detection against weather stations and recently published algorithms using a different set of microwave frequencies

Increasing the Adaptive Capacity of Indigenous People to Environmental Change: The Potential Use of an Innovative, Web-Based, Collaborative-Geomatics Informatics Tool to Reduce the Degree of Exposure of First Nations Cree to Hazardous Travel Routes

The arctic and subarctic regions of Canada are experiencing amplified climate change impacts, which are disproportionately impacting Canadian indigenous populations’ ability to safely travel on land to acquire resources. Less predictable and more dangerous travel conditions are impacting not only the health and safety of individuals but also the traditional lifestyles that are vital to the cultural well-being of these indigenous communities. The University of Waterloo’s Computer Systems Group has developed a novel decision-support tool termed “Collaborative-Geomatics.” This web-based informatics tool can allow for the community to monitor, in real-time, the safety of travel routes. Using handheld GPS tracking systems, the utility of the geomatics system to present real-time travel conditions was carried out in a Canadian First Nations community, located along the Western James Bay coast. The results of this study showed that the collaborative-geomatics tool offers the potential to monitor and store information on the safety of travel routes, helping to promote adaptive capacity and aid in knowledge transfer within arctic and subarctic indigenous communities

Precipitation in the Alaska central Arctic

Thesis (Ph.D.) University of Alaska Fairbanks, 2015Environmental change currently stimulates much of the interest in high-latitude hydrologic studies, as northern areas are expected to be strongly impacted by warming. This thesis consists of a comprehensive assessment of solid and liquid precipitation throughout the Alaska Central Arctic. The founding hypothesis are: (1) the spatial distribution of snow and warm season precipitation are linearly related to elevation, (2) annual precipitation inputs are dominated by warm season precipitation when potential moisture sources are ice free, and (3) moisture responsible for snow-producing storms is primarily advected through atmospheric circulation. To verify the validity of the hypothesis, the temporal variability and spatial distribution of snow and warm season precipitation were extensively measured. Snowpack patterns were established using over 1000 snow surveys from end-of-winter field campaigns. The snowpack distribution patterns were similar from year to year and relatively independent of elevation, with roughly an average of 100 mm of snow water equivalent (SWE) from the Arctic Coast to the Brooks Range divide. For the same 1500 m change in elevation, warm season precipitation has a large orographic change, which increases more than 240 mm. Warm season precipitation was evaluated using 31 meteorological stations and although a strong spatial distribution was found, no discernible long-term trends were identified in the somewhat limited 29 year data set. The accumulation of end-of-winter SWE and warm season precipitation measurements were combined to evaluate the distribution of annual precipitation. Annual precipitation varies temporally and spatially over the Alaska Central Arctic. At high elevations, 70% of the annual precipitation is liquid, while at low elevations, liquid precipitation only represents 40% of the annual budget and end-of winter SWE becomes the dominate precipitation contributor. Moisture responsible for snow-producing storms was found to originate from different sources depending on the time of year and ice cover conditions. North originating moisture is three times more likely to occur during the fall when sea ice is thin, or nonexistent. Mid-winter moisture was found to advect into the Arctic from the south. The timing and travel pathways of snowfall events were determined using an atmospheric model (HYSPLIT) and supplemental surface analysis charts

Shallow soil moisture - ground thaw interactions and controls

Soil moisture and ground thaw state are both indicative of a hillslope’s ability to transfer water. In cold regions in particular, it is widely known that the wetness of surface soils and depth of ground thaw are important for runoff generation, but the diversity of interactions between surface soil moisture and ground thaw themselves has not been studied. To fill this knowledge gap, detailed shallow soil moisture and thaw depth surveys were conducted along systematic grids at the Baker Creek Basin, Northwest Territories. Multiple hillslopes were studied to determine how the interactions differed along a spectrum of topological, typological and topographic situations (T³ template). Results did not show a simple relationship between soil moisture and ground thaw as was expected. Instead, correlation was a function of wetness such that the correlation between soil moisture and ground thaw improved with site wetness. To understand why differences in soil moisture and ground thaw state arose, water and energy fluxes were examined for these subarctic study sites to discern the key processes controlling the patterns observed. Results showed that the key control in variable soil moisture and frost table interactions among the sites was the presence of surface water. At the peatland and wetland sites, accumulated water in depressions and flow paths maintained soil moisture for a longer duration than at the hummock tops. These wet areas were often locations of deepest thaw depth due to the transfer of latent heat accompanying lateral surface runoff. Although the peatland and wetland sites had large inundation extents, modified Péclet numbers indicated that the relative influence of external and internal hydrological processes at each site were different. Continuous inflow from an upstream lake into the wetland site caused advective and conductive thermal energies to be of equal importance to ground thaw. The absence of continuous surface flow at the peatland and valley sites led to the dominance of conductive thermal energy over advective energy for ground thaw. A quantitative explanation for the shallow soil moisture-ground thaw patterns was provided by linking hydrological processes and hillslope storage capacity with the calculated water and energy fluxes as well as the modified Péclet number. These results suggest that the T³ template and the modified Péclet number could be very useful parameters for differentiating landscape components in modeling soil moisture and frost table heterogeneity in cold regions

Passive microwave derived snowmelt timing: significance, spatial and temporal variability, and potential applications

Snow accumulation and melt are dynamic features of the cryosphere indicative of a changing climate. Spring melt and refreeze timing are of particular importance due to the influence on subsequent hydrological and ecological processes, including peak runoff and green-up. To investigate the spatial and temporal variability of melt timing across a sub-arctic region (the Yukon River Basin (YRB), Alaska/Canada) dominated by snow and lacking substantial ground instrumentation, passive microwave remote sensing was utilized to provide daily brightness temperatures (Tb) regardless of clouds and darkness. Algorithms to derive the timing of melt onset and the end of melt-refreeze, a critical transition period where the snowpack melts during the day and refreezes at night, were based on thresholds for Tb and diurnal amplitude variations (day and night difference). Tb data from the Special Sensor Microwave Imager (1988 to 2011) was used for analyzing YRB terrestrial snowmelt timing and for characterizing melt regime patterns for icefields in Alaska and Patagonia. Tb data from the Advanced Microwave Scanning Radiometer for EOS (2003 to 2010) was used for determining the occurrence of early melt events (before melt onset) associated with fog or rain on snow, for investigating the correlation between melt timing and forest fires, and for driving a flux-based snowmelt runoff model. From the SSM/I analysis: the melt-refreeze period lengthened for the majority of the YRB with later end of melt-refreeze and earlier melt onset; and positive Tb anomalies were found in recent years from glacier melt dynamics. From the AMSR-E analysis: early melt events throughout the YRB were most often associated with warm air intrusions and reflect a consistent spatial distribution; years and areas of earlier melt onset and refreeze had more forest fire occurrences suggesting melt timing\u27s effects extend to later seasons; and satellite derived melt timing served as an effective input for model simulation of discharge in remote, ungauged snow-dominated basins. The melt detection methodology and results present a new perspective on the changing cryosphere, provide an understanding of melt\u27s influence on other earth system processes, and develop a baseline from which to assess and evaluate future change. The temporal and spatial variability conveyed through the regional context of this research may be useful to communities in climate change adaptation planning

Impacts of a Changing Climate and Land Use on Reindeer Pastoralism: Indigenous Knowledge and Remote Sensing

The Arctic is home to many indigenous peoples, including those who depend on reindeer herding for their livelihood, in one of the harshest environments in the world. For the largely nomadic peoples, reindeer not only form a substantial part of the Arctic food base and economy, but they are also culturally important, shaping their way of life, mythologies, festivals and ceremonies. Reindeer pastoralism or husbandry has been practiced by numerous peoples all across Eurasia for thousands of years and involves moving herds of reindeer, which are very docile animals, from pasture to pasture depending on the season. Thus, herders must adapt on a daily basis to find optimal conditions for their herds according to the constantly changing conditions. Climate change and variability plus rapid development are increasingly creating major changes in the physical environment, ecology, and cultures of these indigenous reindeer herder communities in the North, and climate changes are occurring significantly faster in the Arctic than the rest of the globe, with correspondingly dramatic impacts (Oskal, 2008). In response to these changes, Eurasian reindeer herders have created the EALAT project, a comprehensive new initiative to study these impacts and to develop local adaptation strategies based upon their traditional knowledge of the land and its uses - in targeted partnership with the science and remote sensing community - involving extensive collaborations and coproduction of knowledge to minimize the impacts of the various changes. This chapter provides background on climate and development challenges to reindeer husbandry across the Arctic and an overview of the EALAT initiative, with an emphasis on indigenous knowledge, remote sensing, Geographic Information Systems (GIS), and other scientific data to 'co-produce' datasets for use by herders for improved decision-making and herd management. It also provides a description of the EALAT monitoring data integration and sharing system and portal being developed for reindeer pastoralism. In addition, the chapter provides some preliminary results from the EALAT Project, including some early remote sensing research results

The missing pieces for better future predictions in subarctic ecosystems: a Torneträsk case study

Arctic and subarctic ecosystems are experiencing substantial changes in hydrology, vegetation, permafrost conditions, and carbon cycling, in response to climatic change and other anthropogenic drivers, and these changes are likely to continue over this century. The total magnitude of these changes results from multiple interactions among these drivers. Field measurements can address the overall responses to different changing drivers, but are less capable of quantifying the interactions among them. Currently, a comprehensive assessment of the drivers of ecosystem changes, and the magnitude of their direct and indirect impacts on subarctic ecosystems, is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years, and is one of the most studied sites in the Arctic. In this study, we summarize and rank the drivers of ecosystem change in the Torneträsk area, and propose research priorities identified, by expert assessment, to improve predictions of ecosystem changes. The research priorities identified include understanding impacts on ecosystems brought on by altered frequency and intensity of winter warming events, evapotranspiration rates, rainfall, duration of snow cover and lake-ice, changed soil moisture, and droughts. This case study can help us understand the ongoing ecosystem changes occurring in the Torneträsk area, and contribute to improve predictions of future ecosystem changes at a larger scale. This understanding will provide the basis for the future mitigation and adaptation plans needed in a changing climate

Response of ice cover on shallow lakes of the North Slope of Alaska to contemporary climate conditions (1950–2011): radar remote-sensing and numerical modeling data analysis

Air temperature and winter precipitation changes over the last five decades have impacted the timing, duration, and thickness of the ice cover on Arctic lakes as shown by recent studies. In the case of shallow tundra lakes, many of which are less than 3 m deep, warmer climate conditions could result in thinner ice covers and consequently, in a smaller fraction of lakes freezing to their bed in winter. However, these changes have not yet been comprehensively documented. The analysis of a 20 yr time series of European remote sensing satellite ERS-1/2 synthetic aperture radar (SAR) data and a numerical lake ice model were employed to determine the response of ice cover (thickness, freezing to the bed, and phenology) on shallow lakes of the North Slope of Alaska (NSA) to climate conditions over the last six decades. Given the large area covered by these lakes, changes in the regional climate and weather are related to regime shifts in the ice cover of the lakes. Analysis of available SAR data from 1991 to 2011, from a sub-region of the NSA near Barrow, shows a reduction in the fraction of lakes that freeze to the bed in late winter. This finding is in good agreement with the decrease in ice thickness simulated with the Canadian Lake Ice Model (CLIMo), a lower fraction of lakes frozen to the bed corresponding to a thinner ice cover. Observed changes of the ice cover show a trend toward increasing floating ice fractions from 1991 to 2011, with the greatest change occurring in April, when the grounded ice fraction declined by 22% (α = 0.01). Model results indicate a trend toward thinner ice covers by 18–22 cm (no-snow and 53% snow depth scenarios, α = 0.01) during the 1991–2011 period and by 21–38 cm (α = 0.001) from 1950 to 2011. The longer trend analysis (1950–2011) also shows a decrease in the ice cover duration by ~24 days consequent to later freeze-up dates by 5.9 days (α = 0.1) and earlier break-up dates by 17.7–18.6 days (α = 0.001)

Development and application of hydrological and limnological monitoring in lake-rich landscapes of Canada’s subarctic National Parks

Arctic and subarctic environments are being adversely influenced by human-caused climate change across our entire planet. Canada’s northern freshwater ecosystems are influenced by a variety of environmental stressors and are particularly sensitive to climate change, since small shifts in climate have the potential to substantially alter their hydrological, limnological, and biogeochemical conditions. Some other indirect effects on northern freshwater landscapes are the expansion of vegetation as well as changes in wildlife and waterfowl populations and distribution. It is, therefore, critical to understand the observed and predicted influences of climate change and other environmental stressors on these northern freshwater environments dominant in arctic and subarctic landscapes, since they are considered productive northern “oases” and provide important habitat for wildlife and natural resources for indigenous communities. Concerns have been increasing regarding climate change, rapidly changing lake levels, and the associated effects on aquatic ecological integrity within two of Canada’s northern lake-rich national parks, Vuntut National Park (VNP), Yukon Territory, and Wapusk National Park (WNP), Manitoba. To address these issues, Park-led monitoring programs have been established to track status and trends of lake hydrological conditions using water isotopes, yet there remains a need to translate these data into a format that can be used by Parks Canada for their reporting requirements. Here, a novel water isotope-based lake hydrological monitoring program is applied that directly encompasses Parks Canada’s long-term monitoring protocols and provides a sensitive way to detect hydrological change. Lake category (VNP - ‘snowmelt-dominated’, ‘rainfall-dominated’, or intermediate and WNP - coastal fen, interior peat plateau, or boreal spruce forest) and season-specific (spring, summer, fall) water isotope-based hydrological thresholds were used to establish the condition (‘good’, ‘fair’, ‘poor’) of Parks Canada’s hydrological ‘Ecological Integrity Measure’ for lakes within these two northern parks. Variability in the condition of VNP monitoring lakes exists between lake category (‘rainfall-dominated’, ‘snowmelt-dominated’, intermediate) as well as by season (spring, fall) from 2007 to 2015. However, rainfall-dominated lakes show the most variability in lake condition, spanning from lakes that fall entirely within the ‘good’ condition to lakes that are almost entirely in ‘fair’ to ‘poor’ conditions. In WNP, variability in lake condition exists between lake category (coastal fen, boreal spruce forest, interior peat plateau) and season (spring, summer, fall) from 2010 to 2013. However, during the spring and summer of 2014 and the entire ice-free season of 2015, these lakes improved to ‘fair’ or ‘good’ conditions, reflecting an increase in the precipitation/evaporation ratio. This research and monitoring-program development has bridged the gap between research science and Parks Canada monitoring by providing protocols and technical support to establish an effective long-term lake hydrological monitoring program for sensitive northern freshwater environments. During the past ~40 years, WNP has experienced a rapid increase in Lesser Snow Goose (LSG) population and a corresponding expansion in the LSG-disturbed geographic region. This has raised concerns about environmental effects of their activities on WNP’s aquatic ecosystems. Previous studies have found that using standard limnological measurements (e.g., specific conductivity) combined with carbon isotope variables (δ13CDIC, δ13CPHYTOPOM, Δ13CDIC-PHYTOPOM) is informative and effectively captures differences in limnological and carbon behaviour in LSG-disturbed ponds compared to unaffected ponds. This research compiles mid-summer limnological and carbon isotope data from 45 lakes during 2015 and 2016, which span a LSG disturbance gradient (undisturbed, actively-disturbed, severely-disturbed) across a portion of WNP. In 2015, higher mid-summer values of specific conductivity, pH, TP, TKN, DIC, DOC, and δ13CPHYTOPOM paired with lower mid-summer values of δ13CDIC and Δ13CDIC-PHYTOPOM values were characteristic of severely-disturbed ponds when compared to undisturbed and actively-disturbed ponds. Results from 2016 indicate a clear LSG disturbance gradient with increasing values of specific conductivity, pH, TP, TKN, DIC, DOC, and δ13CPHYTOPOM paired with decreasing values of δ13CDIC and Δ13CDIC-PHYTOPOM, as LSG disturbance increased from undisturbed to actively-disturbed to severely-disturbed ponds. Reduced sensitivity to LSG disturbance during 2015 can be attributed to substantial rainfall that occurred during the month of July prior to and during sampling. These limnological trends can be explained by an array of processes including chemically-enhanced CO2 invasion, elevated catchment runoff of nutrients, carbon and ions, as well as enhanced aquatic productivity, which increasingly influenced the nutrient and carbon balance of ponds along a LSG disturbance gradient. A numerical synthesis of the data identified established (by La Perouse Bay), active (the landscape to the north and northwest of Thompson Point), and emerging (the inland area in the southern portion of the study region) areas of LSG disturbance. Continued monitoring of LSG disturbance within WNP is critical to understand how freshwater environments in WNP will respond to historical, active, and new LSG disturbance. The analyses and interpretations presented in this research will serve as a useful tool for Parks Canada staff to monitor aquatic ecosystem trends and status as LSG population and migration patterns continue to evolve. Monitoring and anticipating lake hydrological and limnological change is challenging in the north due to its remoteness and the sensitivity of shallow lakes and ponds to multiple environmental stressors. Often, due to the lack of alignment and effective communication of research priorities between southern researchers and northern agencies, the short duration of funding, as well as the high turnover rates of staff and graduate students, the science and training necessary to create the foundations for agency-led monitoring is not always feasible. However, by means of substantial efforts to augment relations with Parks Canada staff, a long-term lake monitoring program within Wapusk National Park (the ‘Hydroecology Monitoring Program’) was successfully established in 2015. These efforts included instilling the significance of our research to Park’s staff and the local community of Churchill, providing the necessary training and knowledge transfer, as well as offering ongoing assistance and guidance. This monitoring program has been developed in a format that aligns with Parks Canada’s mandate, can be utilized for their reporting requirements, and is designed to focus on two major threats to aquatic ecosystems: 1) Pond Water Dynamics/Lake Hydrology monitoring and 2) Goose Aquatic Impact monitoring. Several key contributions transformed this research science into action and application. These include operationalizing agency-led monitoring (e.g., creation of training schematics and standard operating procedures), communicating monitoring results with science practitioners (e.g., scientific reports and open-access data), and communicating research with the general public (e.g., news articles, public presentations, and the Expedition Churchill interactive platform). In summary, research presented here is a contribution to the new research paradigm in northern Canada, where collaborative, interdisciplinary, and community-driven research reflects northern priorities and leads to action