On the appropriate definition of soil profile configuration and initial conditions for land surface–hydrology models in cold regions

Abstract

Abstract. Arctic and subarctic regions are amongst the most susceptible regions on Earth to global warming and climate change. Understanding and predicting the impact of climate change in these regions require a proper process representation of the interactions between climate, carbon cycle, and hydrology in Earth system models. This study focuses on land surface models (LSMs) that represent the lower boundary condition of general circulation models (GCMs) and regional climate models (RCMs), which simulate climate change evolution at the global and regional scales, respectively. LSMs typically utilize a standard soil configuration with a depth of no more than 4 m, whereas for cold, permafrost regions, field experiments show that attention to deep soil profiles is needed to understand and close the water and energy balances, which are tightly coupled through the phase change. To address this gap, we design and run a series of model experiments with a one-dimensional LSM, called CLASS (Canadian Land Surface Scheme), as embedded in the MESH (Modélisation Environmentale Communautaire – Surface and Hydrology) modelling system, to (1) characterize the effect of soil profile depth under different climate conditions and in the presence of parameter uncertainty; (2) assess the effect of including or excluding the geothermal flux in the LSM at the bottom of the soil column; and (3) develop a methodology for temperature profile initialization in permafrost regions, where the system has an extended memory, by the use of paleo-records and bootstrapping. Our study area is in Norman Wells, Northwest Territories of Canada, where measurements of soil temperature profiles and historical reconstructed climate data are available. Our results demonstrate a dominant role for parameter uncertainty, that is often neglected in LSMs. Considering such high sensitivity to parameter values and dependency on the climate condition, we show that a minimum depth of 20 m is essential to adequately represent the temperature dynamics. We further show that our proposed initialization procedure is effective and robust to uncertainty in paleo-climate reconstructions and that more than 300 years of reconstructed climate time series are needed for proper model initialization.

Representation and improved parameterization of reservoir operation in hydrological and land-surface models

“…Future research work may include (1) examining the applicability of the DZTR model for regions with severely limited data by examining the utility of other data sources such as those derived from satellite-based observations (Savtchenko et al, 2004;Garambois and Monnier, 2015;Gao et al, 2012) and using the area-volume relationship approximated by regular geometric shapes (e.g., Yigzaw et al, 2018) and (2) examining direct one-way and/or two-way coupling of WMMs with CMs and LSMs for developing a seamless coupled framework for the simulation of naturally engineered watershed systems.…”

“…Inflows to and releases from a reservoir can be approximated by stream-flow stations located upstream and downstream of the reservoir, respectively. Further, satellite missions such as MODIS (Savtchenko et al, 2004) and satellite radar altimetry provide information on lake and reservoir surface area dynamics and reservoir water elevation for some large reservoirs. The combination of MODIS and satellite radar altimetry allows deriving storage-area-depth relationships (Gao et al, 2012;Andreadis et al, 2007;Zhang et al, 2014;Yoon and Beighley, 2015).…”

Representation of Water Management in Hydrological and Land Surface Models

“…MESH is Environment and Climate Change Canada's Land Hydrlogy-Land Surface Modelling System (Pietroniro et al, 2007) and has been widely used in different parts of Canada (Davison et al, 2016;Haghnegahdar et al, 2017;Yassin et al, 2017;Sapriza-Azuri et al, 2018;Berry et al, 2017). MESH is a grid-based modelling system composed of three components: (1) the Canadian Land Surface Scheme (CLASS) (Verseghy, 1991;Verseghy et al, 1993), (2) lateral movement of surface (overland) runoff and sub-surface water (interflow) to the channel system within a grid cell and 3hydrological routing using WATROUT from the WATFLOOD hydrological model (Kouwen et al, 1993).…”

Permafrost variability over the Northern Hemisphere based on the MERRA-2 reanalysis

“…We employed the strategy of Schaefer et al (2015) to handle the uncertainty propagation, i.e. adding in quadrature the uncertainty components from each scale/level involved (see Supplement for a detailed description).…”

“…Existing remote sensing ALT products have been retrieved from groundbased ground-penetrating radar (GPR) (A. Jafarov et al, 2017), airborne polarimetric synthetic aperture radar (SAR), and spaceborne interferometric SAR (Liu et al, 2012;Li et al, 2015;Schaefer et al, 2015). These ALT products are available at the landscape scale and can complement our modelling analysis.…”