Daniel F. Nadeau

• Ph.D.
• Full professor at Université Laval

Proglacial valleys of the St. Elias Mountains in western Canada are major sources of historical mineral dust emissions, as evidenced through loess records, yet no estimates of contemporary emissions exist for this region. In these landscapes, dust emissions occur at the interface of glaciofluvial and aeolian processes, not only subject to large sea...

Small thermokarst lakes, formed by the thawing of ice-rich permafrost, are significant sources of greenhouse gases (GHG). Most estimates of emissions rely solely on daily measurements, which may bias annual flux calculations. In this study, we combined GHG flux measurements from two intensive summer campaigns with nearly two years of continuous tem...

This study presents a probabilistic model that partitions the precipitation phase based on hourly measurements from a network of radar-based disdrometers in eastern Canada. The network consists of 27 meteorological stations located in a boreal climate for the years 2020–2023. Precipitation phase observations showed a 2 m air temperature interval be...

Proglacial valleys are important historical and contemporary sources of mineral dust emissions. These dust sources are situated within a complex mountainous terrain, which induce a series of superimposed meteorological phenomena. This paper assesses the forcing mechanisms of high wind speed (HWS) events in the dust storm–prone A’ą¨y Chu (Slims Rive...

High latitude regions, including the circumpolar boreal biome, are experiencing important changes in the availability of usable surface water because of climate change. In this context, an adequate representation of the land-atmosphere interaction is critical to ensure optimal management of current and future water resources, forest management, and...

In the boreal forest of eastern Canada, winter temperatures are projected to increase substantially by 2100. This region is also expected to receive less solid precipitation, resulting in a reduction in snow cover thickness and duration. These changes are likely to affect hydrological processes such as snowmelt, the soil thermal regime, and snow me...

Rain-on-snow events can cause severe flooding in snow-dominated regions. These are expected to become more frequent in the future as climate change shifts the precipitation from snowfall to rainfall. However, little is known about how winter rainfall interacts with an evergreen canopy and affects the underlying snowpack. In this study, we document...

At high latitudes, lake-atmosphere interactions are disrupted for several months of the year by the presence of an ice cover. By isolating the water column from the atmosphere, ice, typically topped by snow, drastically alters albedo, surface roughness, and heat exchanges relative to the open water period, with major climatic, ecological, and hydro...

Ice Control Structures (ICS) are a solution to mitigate ice jams that cause major flooding events in communities located near riverbanks. The design of these structures remains empirical due to the difficulty of obtaining reliable data on ice forces in the field. In this study, ice forces were estimated using structural deformation of the Sartigan...

Ice Control Structures (ICS) are a solution to mitigate ice jams that cause major flooding events in communities located near riverbanks. The design of these structures remains empirical due to the difficulty of obtaining reliable data on ice forces in the field. In this study, ice forces were estimated using structural deformation of the Sartigan...

This study presents a probabilistic model that partitions the precipitation phase based on hourly measurements from a network of radar-based disdrometers in eastern Canada. The network consists of 27 meteorological stations located in a boreal climate for the years 2020–2023. Precipitation phase observations showed a 2-m air temperature interval be...

As the vegetation in the Arctic changes, tundra ecosystems along the southern border of the Arctic are becoming greener and gradually giving way to boreal ecosystems. This change is affecting local populations, wildlife, energy exchange processes between environmental compartments, and the carbon cycle. To understand the progression and the implica...

The hydrological processes of cascading hydroelectric reservoirs differ from those of lakes, due to the importance of the inflows and outflows that vary with energy demand. These heat and water advection terms are rarely considered in water body energy balance analyses even though reservoirs are common man-made infrastructures, especially in North...

Rain-on-snow events can cause severe flooding in snow–dominated regions. These are expected to become more frequent in the future as climate change shifts the precipitation from snowfall to rainfall. However, little is known about how winter rainfall interacts with an evergreen canopy and affects the underlying snowpack. In this study, we document...

In the boreal forest, winter temperatures are projected to increase substantially by 2100, resulting in a reduction in snow cover thickness and duration. These changes are likely to affect hydrological processes such as snowmelt, the soil thermal regime, and snow metamorphism. The exact impact of future changes is difficult to pinpoint in the borea...

The proglacial valleys of western Canada and southeast Alaska accommodate seasonal dust sources, constrained by the mountainous terrain and originating from notably high rates of glacial erosion and sediment production within the St. Elias Mountains. Despite a long history of frequent and intense dust storms, insight into the mesoscale dynamics dri...

The proglacial valleys of western Canada and southeast Alaska accommodate seasonal dust sources, constrained by the mountainous terrain and originating from notably high rates of glacial erosion and sediment production within the St. Elias Mountains. One historical measurement campaign precedes the contemporary investigation of dust emissions in th...

As the vegetation in the Arctic changes, tundra ecosystems along the southern border of the Arctic are becoming greener and gradually giving way to boreal ecosystems. This change is affecting local populations, wildlife, energy exchange processes between environmental compartments, and the carbon cycle. To understand the progression and the implica...

We report a tunable all-fiber laser emitting a maximum output power of 2.55 W around 3240 nm. The fiber laser cavity based on a fluoride fiber doped with dysprosium ions yields an efficiency of 42% according to the in-band launched pump power at 2825 nm. Due to a custom piezoelectric fiber Bragg grating (FBG) package, mechanical strains applied to...

The thermal regime of hydroelectric reservoirs differs from that of lakes, as it is influenced not only by natural inflows and outflows of energy, but also by management rules through regulated downstream constraints and more importantly the electric demand through turbine flows. These advection terms are rarely assessed for hydroelectric reservoir...

This dataset presents snow temperature profiles from nine different boreal forest sites in eastern Canada collected over two consecutive winters, 2016-17 and 2017-18. The dataset includes snowpack temperature profiles, snow depth, air temperature, and soil temperature. In addition, the two flux towers provided us with the additional heat and water...

Accurately modeling the interactions between inland water bodies and the atmosphere in meteorological and climate models is crucial, given the marked differences with surrounding landmasses. Modeling surface heat fluxes remains a challenge because direct observations available for validation are rare, especially at high latitudes. This study presen...

Water bodies such as lakes and reservoirs affect the regional climate by acting as heat sinks and sources through the evaporation of substantial quantities of water over several months of the year. Unfortunately, energy exchange observations between deep reservoirs and the atmosphere remain rare in northeastern North America, which has one of the h...

The proglacial valleys of western Canada and southeast Alaska accommodate seasonal dust sources, constrained by the mountainous terrain and originating from notably high rates of glacial erosion and sediment production within the St. Elias Mountains. One historical measurement campaign precedes the contemporary investigation of dust emissions in th...

Arctic‐boreal landscapes are experiencing profound warming, along with changes in ecosystem moisture status and disturbance from fire. This region is of global importance in terms of carbon feedbacks to climate, yet the sign (sink or source) and magnitude of the Arctic‐boreal carbon budget within recent years remains highly uncertain. Here, we prov...

We report a tunable all-fiber laser emitting a maximum output power of 2.55 W around 3240 nm with a tuning range of 1.5 nm used on field as an illumination source for active imaging of methane and water vapor.

Water bodies such as lakes and reservoirs affect the regional climate by acting as heat sinks and sources through the evaporation of substantial quantities of water over several months of the year. Unfortunately, energy exchange observations between inland water bodies and the atmosphere remain rare in northeastern North America, which has one of t...

Observations of turbulent heat fluxes over inland water bodies are scarce despite being critical to adequate lake parametrization for numerical weather forecast and climate models. Scintillometry has allowed for the regional (~ km²) estimation of turbulent heat fluxes, but few studies have assessed its performance over water. We compare scintillome...

The forest–tundra ecotone is a large circumpolar transition zone between the Arctic tundra and the boreal forest, where snow properties are spatially variable due to changing vegetation. The extent of this biome through all circumpolar regions influences the climate. In the forest–tundra ecotone near Umiujaq in northeastern Canada (56∘33′31′′ N, 76...

The boreal forest covers a significant portion of the Northern Hemisphere and is snow‐covered for over half of the year. Understanding the interactions between the forest canopy and snow is essential in hydrological, meteorological, and climate modeling. However, this is challenging because the density of a forest can range from closed canopies to...

The forest-tundra ecotone is a large circumpolar transition zone between the Arctic tundra and the boreal forest, where snow properties are spatially variable due to changing vegetation. The extent of this biome through all circumpolar regions influences the climate. In the forest-tundra ecotone near Umiujaq in northeastern Canada (56°33'N, 76°28'W...

Arctic landscapes are covered in snow for at least 6 months of the year. The energy balance of the snow cover plays a key role in these environments, influencing the surface albedo, the thermal regime of the permafrost, and other factors. Our goal is to quantify all major heat fluxes above, within, and below a low-Arctic snowpack at a shrub tundra...

Cold content (CC) is an internal energy state within a snowpack and is defined by the energy deficit required to attain isothermal snowmelt temperature (0 ∘C). Cold content for a given snowpack thus plays a critical role because it affects both the timing and the rate of snowmelt. Measuring cold content is a labour-intensive task as it requires ext...

Rising temperatures in the southern Arctic region are leading to shrub expansion and permafrost degradation. The objective of this study is to analyze the surface energy budget (SEB) of a subarctic shrub tundra site that is subject to these changes, on the east coast of Hudson Bay in eastern Canada. We focus on the turbulent heat fluxes, as they ha...

Arctic landscapes are covered in snow for at least six months of the year. The energy balance of the snow cover plays a key role in these environments, influencing the surface albedo, the thermal regime of the permafrost, and other factors. Our goal is to quantify all major heat fluxes above, within, and below a low Arctic snowpack at a shrub tundr...

Hydrological models used for reservoir management typically lack an accurate representation of open-water evaporation and must be run in a scarce data context. This study aims to identify an accurate means to estimate reservoir evaporation with simple meteorological inputs during the open-water season, using long-term eddy covariance observations f...

One of the roles of Land Surface Models (LSMs) is to partition evapotranspiration (E) into overstory transpiration (E_T), understory evapotranspiration (E_G), and wet canopy evaporation (E_C). Unfortunately, only a handful of studies have evaluated the performance of LSMs with E partitioning. Unlike dry canopies which are dominated by transpiration...

The maximum entropy production (MEP) approach has been little used to simulate evaporation in forests and its sensitivity to input variables has never beenyet to be systematically evaluated. This study addresses these shortcomings. First, we show that the MEP model performed well in simulating evaporation during the snow-free periods at six sites i...

This study evaluates the simulation of water balance components at half-hourly time steps from the Canadian Land Surface Scheme (CLASS) when driven by a 500-year stochastic meteorological data set produced by the Advanced WEather GENerator (AWE-GEN) at two boreal sites with contrasting water availability. The CLASS was driven by ERA5 reanalysis dat...

The Soil, Vegetation, and Snow (SVS) land surface model was recently developed at Environment and Climate Change Canada (ECCC) for operational numerical weather prediction and hydrological forecasting. This study examined the performance of the snow scheme in the SVS model over multiple years at ten well-instrumented sites from the Earth System Mod...

Cold content (CC) is an internal energy state within a snowpack and is defined by the energy deficit required to attain isothermal snowmelt temperature (0 °C). For any snowpack, fulfilling the cold content deficit is a pre-requisite before the onset of the snowmelt. Cold content for a given snowpack thus plays a critical role because it affects bot...

Snowmelt contributes a significant fraction of groundwater recharge in snow-dominated regions, making its accurate quantification crucial for sustainable water resources management. While several components of the hydrological cycle can be measured directly, catchment-scale recharge can only be quantified indirectly. Stable water isotopes are often...

Snow cover plays a key role in the water and energy budgets over cold regions. Understanding and parameterizing water and heat exchange over snow surfaces in hydrologic models remains a major challenge. An innovative approach based on the theory of maximum entropy production (MEP) was developed for modeling energy budgets for snow‐covered surfaces....

This dataset is supporting information to: Schilling et al. (2021): Quantifying groundwater recharge dynamics and unsaturated zone processes in snow‐dominated catchments via on‐site dissolved gas analysis. Water Resour. Res., e2020WR028479, DOI: 10.1029/2020WR028479 The data was used to develop a novel tracer method for the quantification of groun...

Evaporation of intercepted rain by a canopy is an important component of evapotranspiration, particularly in the humid boreal forest, which is subject to frequent precipitation and where conifers have a large surface water storage capacity. Unfortunately, our knowledge of interception processes for this type of environment is limited by the many ch...

Following a period of rapid geomorphological upheaval, induced by glacial retreat, the Ä’äy Chù (Slims River) valley has demonstrated an increase in the frequency and magnitude of dust emission beyond historical activity, marking this site as ideal to explore the dynamics of aeolian erosion from a high-latitude, inland dust source. The propensity a...

This paper examines the morning transition period of the atmospheric boundary layer for convective summer days over steep topography. An experimental transect composed of two turbulence towers was installed in summer 2010 on a steep, west-facing slope of Val Ferret, in the Swiss Alps. The analysis focuses on valley-scale processes as well as near-s...

Over the past decades, researchers have made significant progress toward a fundamental understanding of the budgets of turbulence variables over flat and homogeneous terrain, and only more recently over complex terrain. However, temperature variance budgets, which are parameterized in most meteorological models, are still poorly understood even und...

Peatlands and forests cover large areas of the boreal biome and are critical for global climate regulation. They also regulate regional climate through heat and water vapour exchange with the atmosphere. Understanding how land-atmosphere interactions in peatlands differ from forests may therefore be crucial for modelling boreal climate system dynam...

Temperature-index (TI) models are commonly used to simulate the volume and occurrence of meltwater in snow-fed catchments. TI models have varying levels of complexity but are all based on air temperature observations. The quality and availability of data that drive these models affect their predictive ability, particularly given that they are frequ...

The response of evapotranspiration (ET) to warming is of critical importance to the water and carbon cycle of the boreal biome, a mosaic of land cover types dominated by forests and peatlands. The effect of warming-induced vapour pressure deficit (VPD) increases on boreal ET remains poorly understood because peatlands are not specifically represent...

The Canadian Land Surface Scheme (CLASS) has been applied over the years in coupled and uncoupled (offline) modes at local, regional, and global scale using various forcing data sets. In this study, CLASS is applied at a local scale in the offline configuration to evaluate its performance when driven by the ERA5 reanalysis. Simulated surface energy...

In snow‐fed catchments, it is crucial to monitor and model the snow water equivalent (SWE), particularly when simulating the melt water runoff. SWE distribution can, however, be highly heterogeneous, particularly in forested environments. Within these locations, scant studies have explored the spatiotemporal variability in SWE in relation with vege...

The recently developed Soil, Vegetation, and Snow (SVS) land surface model is being progressively implemented at Environment and Climate Change Canada (ECCC) for operational numerical weather and hydrological predictions. The objective of this study is to evaluate the ability of SVS, in offline point-scale mode and under snow-free conditions, to si...

Two-wavelength scintillometer systems can provide much needed measurements of area-averaged sensible and latent heat fluxes. However, these devices rarely have been deployed on canopy-covered complex terrain, and never in the circumpolar boreal biome, where large-scale fluxes are essential to hydroclimate modellers. We present a comparison of fluxe...

Humid boreal forests are unique environments characterized by a cold climate, abundant precipitation, and high evapotranspiration. Transpiration (ET), as a component of evapotranspiration (E), behaves differently under wet and dry canopy conditions, yet very few studies have focused on the dynamics of transpiration to evapotranspiration ratio (ET/E...

A set of 28 simulations from five regional climate models are used in this study to assess the Great Lakes’ water supply from 1953 to 2100 following emissions scenarios RCP4.5 and 8.5 with a focus on bi-weekly changes in the means and extremes of hydrological variables. Models are first evaluated by comparing annual cycles of precipitation, runoff,...

The boreal forest will be strongly affected by climate change and in turn, these vast ecosystems may significantly impact global climatology and hydrology due to their exchanges of carbon and water with the atmosphere. It is now crucial to understand the intricate relationships between precipitation and evapotranspiration in these environments, par...

Total terrestrial evaporation, also referred to as evapotranspiration, is a key process for understanding the hydrological impacts of climate change given that warmer surface temperatures translate into an increase in the atmospheric evaporative demand. To simulate this flux, many hydrological models rely on the concept of potential evaporation (PE...

Natural wetlands constitute the largest and most uncertain source of methane (CH4) to the atmosphere and a large fraction of them are found in the northern latitudes. These emissions are typically estimated using process (“bottom-up”) or inversion (“top-down”) models. However, estimates from these two types of models are not independent of each oth...

Hydrological projections under future climate change have been shown to be sensitive to the formulation of evapotranspiration. Many hydrological models still rely on empirical formulations of this flux, and hence do not take into account the surface energy budget. On the other hand, land surface schemes, which are used within the climate models to...

Natural wetlands constitute the largest and most uncertain source of methane (CH4) to the atmosphere and a large fraction of them are in the northern latitudes. These emissions are typically estimated using process (bottom-up) or inversion (top-down) models, yet the two are not independent of each other since the top-down estimates rely on the a pr...

Total terrestrial evaporation is a key process to understand the hydrological impacts of climate change given that warmer surface temperatures translate into an increase in the atmospheric evaporative demand. To simulate this flux, many hydrological models rely on the concept of potential evaporation (PET) although large differences have been obser...

Forest canopies act as permeable barriers between the atmosphere and the ground, reflecting and absorbing solar radiation. In the boreal forest, the large number of gaps and heterogeneities further complicates these processes. Several studies have adequately measured and modeled the transmittance of solar radiation through forest canopies in wester...

Boreal forest covers a third of Canada surface and accounts for 75% of all its forests. Over this type of environment, most of the previous measurements of surface-atmosphere water and energy fluxes are obtained with the eddy covariance method. While being very reliable, the method has a local scale footprint of a few hectares. This can be problema...

Boreal forest covers roughly 14% of the earth emerged surface and consists of a third or all the forests in the world. There are many studies on the surface-atmosphere exchanges of water and energy for this type of environment. However, most of the previous experiments use the eddy covariance method to measure these fluxes. The method, while being...

The maximum entropy production (MEP) model based on nonequilibrium thermodynamics and the theory of Bayesian probabilities was recently developed to model land surface fluxes, including soil evaporation and vegetation transpiration. This model requires few input data and ensures the closure of the surface energy balance. This study aims to test the...

Traditionnellement, les modèles hydrologiques opérationnels n'imposent pas de contrainte de conservation d'énergie à la surface. Lorsque soumis à un réchauffement climatique, ils ont tendance à surestimer l'évapotranspiration et se révèlent alors de piètres outils de simulation des ressources hydriques à long terme. Pour s’attaquer à cette problém...

Located in northern Quebec, Canada, eight hydroelectric reservoirs of a 9782-km² maximal area cover 6.4% of the La Grande watershed. This study investigates the changes brought by the impoundment of these reservoirs on seasonal climate and precipitation recycling. Two 30-year climate simulations, corresponding to pre- and post-impoundment condition...

Located in northern Quebec, Canada, eight hydroelectric reservoirs of a 9782-km2 maximal area cover 6.4% of the La Grande watershed. This study investigates the changes brought by the impoundment of these reservoirs on seasonal climate and precipitation recycling. Two 30-year climate simulations, corresponding to pre- and post-impoundment condition...

To address certain limitations with their current operational model, Environment and Climate Change Canada recently developed the Soil, Vegetation, and Snow (SVS) land surface model and the representation of subsurface hydrological processes was targeted as an area for improvement. The objective of this study is to evaluate the ability of HydroSVS,...

Boreal forest covers roughly 10% of the earth emerged surface, making it one of the world most common type of landscape. There is a large number of studies on the land- atmosphere exchanges of water and energy for this type of forested surfaces. However, few were located in complex terrain, and to the best of our knowledge, none have looked at cont...

La forêt boréale est le type d’environnement le plus commun au Canada, occupant environ 30% du territoire. Pour mieux exploiter cette forêt et le potentiel hydroélectrique de ses rivières, il est nécessaire de mesurer, comprendre et modéliser les processus physiques affectant son hydrologie et son climat. Ces dernières caractéristiques sont particu...

Peatlands occupy around 13% of the land cover of Canada, and thus play a key role in the water balance at high latitudes. They are well known for having substantial water loss due to evapotranspiration. Since measurements of evapotranspiration are scarce over these environments, hydrologists generally rely on models of varying complexity to evaluat...

Data collected during a multi-year, wind-resource assessment over a multiland use coastal environment in Belize are used to study the development and decay of wind and turbulence through the morning and evening transitions. Observations were made on three tall masts, forming an inland transect of approximately 5 km. The wind distribution is found t...

This study assesses the performance of QUIC-URB, a fast-response urban flow model, and QESRadiant, a ray tracing radiation transfer model. Both models are components of the QUIC EnvSim 3D urban micro-scale model, which aims to simulate meteorological variables at high spatiotemporal resolution (~1min, ~1m) in urban settings. The evaluation was perf...

Solar irradiance is the largest driver of land-surface exchanges of energy, water and trace gases. Its absorption by a forest canopy generates considerable sensible and latent heat fluxes as well as tree temperature changes. A fraction of the irradiance gets transmitted through the canopy and powers another layer of energy fluxes which can reach su...

La prévision du risque hydrologique s’appuie sur la modélisation pour dresser le portrait du cycle de l’eau au Québec dans un climat futur changeant. Une lacune importante des modèles hydrologiques actuels est leurs formulations pour estimer l’évapotranspiration, qui ne sont pas pourvues d’une contrainte de conservation de l’énergie à la surface. T...

Data collected over an arid shallow slope (2–4°) during the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) Program are used to study the katabatic structure and onset of katabatic flow through the evening transition. An unprecedented suite of instrumentation, including a transect of five turbulence towers with 29 sonic anemomete...

We present a valley fog case study in which radiation fog is modulated by topographic effects using data obtained from a field campaign conducted in Heber Valley, Utah from January 7–February 1, 2015, as part of the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) program. We use data collected on January 9, 2015 to gain insight i...

The boreal forest is one of the most common types of landscape in the world, covering roughly 10% or the earth’s emerged surface. There are a large number of studies on the exchanges of water and energy between the atmosphere and forested surfaces, but very little have focused on the influence of topography on evapotranspiration (ET). Many physical...

Climate change is expected to increase air and water temperatures, as well as the severity and occurence of heavy rainstorms. By 2090, the average number of days of ice cover over the Great Lakes are expected to decrease significantly. These conditions favor an increase in lake evaporation, and, therefore, a decrease in Great Lakes water levels. In...