Bonnaventure, Philip
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- ItemAir and surface temperature modelling across a temperate mountain landscape: an investigation of microclimatic influences on surface offsets viewed within the context of epigaeic arthropod thermal habitat(Wiley, 2025) Hassink, Nick; Bonnaventure, Philip; Johnson, Dan L.Development of high-resolution temperature models in mountain environments must include consideration of the influence of complex topography and seasonality on thermal distribution across horizontal and vertical scales. Small-bodied organisms, including arthropods, in montane and alpine ecosystems inhabit environments for which local microclimate and heat transfer is especially important. We developed and applied high-resolution air and surface temperature models for a remote mountain environment using in-situ data for interpolation procedures in ArcGIS Pro. This approach requires recording directional and time-period specific lapse rates to aid in the development of air temperature models. Also examined is the offset between air temperature and surface temperature and to what extent air temperature alone is a reliable indicator of ground-level thermal conditions. We describe an environmentally inclusive surface temperature modelling method that allows for the addition of explanatory layers (landcover, elevation, aspect, slope, and topographic position index) aiding in the interpolation process. These models are used to delineate thermally defined ecological zones and model unique thermal properties of relevance to arthropods across the southern Alberta study area.
- ItemModelling air, ground surface, and permafrost temperature variability across four dissimilar valleys, Yukon, Canada(Canadian Science Publishing, 2024) Garibaldi, Madeleine C.; Bonnaventure, Philip; Noad, Nick C.; Kochtitzky, WillSpatial maps of the air and ground thermal regime were generated for four Yukon valleys. The aim was to model air, ground surface, and ground temperature (at fine spatial resolution) using locally measured inverted surface lapse rates (SLR) to better predict temperature along an elevation gradient. These local models were then compared to a regional permafrost probability model, which utilized differing inversion assumptions, as well as circumpolar and national models generated without considering inversions. Overall, permafrost probability in the regional model matched well with the local models where assumptions of treeline and inverted SLRs held true. When normal SLRs were assumed, permafrost presence was overestimated in each valley. This discrepancy was greatest at high elevations where permafrost was predicted to be the coldest and most widespread. However, the difference between valleys was dependent on surface and subsurface characteristics such as higher snow cover, mature forest, or thick organic layers which show a greater disassociation from the air temperature overall. Appropriate characterization of the SLR is essential for accurate predictions of the ground thermal regime’s spatial distribution and permafrost presence. These models also provide a starting point for better predictions of warming in these valleys and other areas subject to inversions of similar magnitudes.
- ItemModelling permafrost distribution using the temperature at top of permafrost model in the boreal forest environment of Whatì, NT(Canadian Science Publishing, 2024) Vegter, Scott; Bonnaventure, Philip; Daly, Seamus; Kochtitzky, WillCurrent permafrost models in Canadian boreal forests are generally of low spatial resolution as they cover regional or continental scales. This study aims to understand the viability of creating a temperature at the top of permafrost (TTOP) model on a local scale in the boreal wetland environment of Whatì, Northwest Territories from short-term field-collected temperature data. The model utilizes independent variables of vegetation, topographic position index, and elevation, with the dependent variables being ground surface temperature collected from 60 ground temperature nodes and 1.5 m air temperature collected from 10 temperature stations. In doing this, the study investigates the relationship vegetation and disturbance have on ground temperature and permafrost distribution. The model predicts that 31% of the ground is underlain by permafrost, based on a mean annual temperature at TTOP of <0 °C. This model shows an accuracy of 62.5% when compared to cryotic assessment sites (CAS). Most inaccuracies, showing the limitations of the TTOP model, came from peat plateaus that had been burned in the most recent forest fire in 2014. These resulted in out-of-equilibrium permafrost and climatic conditions that TTOP cannot handle well. Commonly, permafrost mapping places Whatì in the extensive discontinuous zone, estimating that between 50% and 90% of the ground is underlain by permafrost. The study shows that a climatically driven TTOP model calibrated with CAS can be used to illustrate ground temperature heterogeneity from short-term data in boreal forest wetland environments. However, this approach likely underestimates permafrost extent and is perhaps not the best-suited modelling choice for near-surface permafrost, which is currently out of equilibrium with the current climate.
- ItemRock glacier inventory and predictive modeling in the Mackenzie Mountains: predicting rock glacier likelihood with a generalized additive model(Canadian Science Publishing, 2024) Thiessen, Rabecca; Bonnaventure, Philip; Lapalme, Caitlin M.Rock glaciers have been the subject of extensive research in recent years due to their potential to serve as indicators of past and present climate conditions and their potential impacts on water resources. Location and descriptive rock glacier data within the Mackenzie Mountains were used to build a rock glacier inventory that will serve as a valuable resource for future research and monitoring efforts. Additionally, this study maps the likelihood of rock glacier presence using extracted variables in a generalized additive model (GAM). The model incorporates attribute data, including potential incoming solar radiation (PISR), topographic position index (TPI), slope, elevation, and lithology as controls for rock glacier development. Topographic data were compiled for three study regions of the Mackenzie Mountains from a 30 m digital elevation model (DEM). The analysis of the GAM showed that the most significant explanatory variables were PISR, elevation, slope, and TPI. The GAM model had an accuracy of 0.87 with a sensitivity of 0.92. This study provides important insights into the controls, distribution, and dynamics of rock glaciers in the Mackenzie Mountains, as well as both the limitations and the potential of statistical models in predicting their occurrence.
- ItemExploring the impact of surface lapse rate change scenarios on mountain permafrost distribution in four dissimilar valleys in Yukon, Canada(Canadian Science Publishing, 2024) Garibaldi, Madeleine C.; Bonnaventure, Philip P.; Noad, NIck C.; Kochtitzky, WillA scenario-based approach was used to test air and ground response to warming with and without changes to inverted surface lapse rates in four Yukon valleys. Generally, climate warming coupled with weakening of temperature inversions resulted in the greatest increase in air temperature at low elevations. However, ground temperatures at high elevations showed the greatest response to warming and variability between scenarios due to increased connectivity between air and ground. Low elevations showed less of a response to warming and permafrost was largely preserved in these locations. Local models also predicted higher permafrost occurrence compared to a regional permafrost probability model, due to the inclusion of differential surface and thermal offsets. Results show that the spatial warming patterns in these mountains may not follow those predicted in other mountain environments following elevation-dependent warming (EDW). As a result, the concept of EDW should be expanded to become more inclusive of a wider range of possible spatial warming distributions. The purpose of this paper is not to provide exact estimations of warming, but rather to provide hypothetical spatial warming patterns, based on logical predictions of changes to temperature inversion strength, which may not directly follow the distribution projected through EDW.