Hotaek Park 교수

Arctic river discharge increased over the last several decades, conveying heat and freshwater into the Arctic Ocean and likely affecting regional sea ice and the ocean heat budget. However, until now, there have been only limited assessments of riverine heat impacts. Here, we adopted a synthesis of a pan-Arctic sea ice-ocean model and a land surface model to quantify impacts of river heat on the Arctic sea ice and ocean heat budget. We show that river heat contributed up to 10% of the regional s

This study assessed trends in the variability of soil temperature (T _SOIL ) using spatially averaged observation records from Russian meteorological land stations. The contributions of surface air temperature (SAT) and snow depth (SND) to T _SOIL variation were quantitatively evaluated. Composite time series of these data revealed positive trends during the period of 1921–2011, with accelerated increases since the 1970s. The T _SOIL warming rate over the entire period was faster than the SAT wa

Abstract. This study not only examined the spatiotemporal variations of active-layer thickness (ALT) in permafrost regions during 1948–2006 over the terrestrial Arctic regions experiencing climate changes, but also identified the associated drivers based on observational data and a simulation conducted by a land surface model (CHANGE). The focus on the ALT extends previous studies that have emphasized ground temperatures in permafrost regions. The Ob, Yenisey, Lena, Yukon, and Mackenzie watershe

Abstract A land process model [the coupled hydrological and biogeochemical model (CHANGE)] is used to quantitatively assess changes in the ice phenology, thickness, and volume of terrestrial Arctic rivers from 1979 to 2009. The CHANGE model was coupled with a river routing and discharge model enabling explicit representation of river ice and water temperature dynamics. Model-simulated river ice phenological dates and thickness were generally consistent with in situ river ice data and landscape f

Abstract Mosses strongly affect water and heat fluxes due their high water holding capacity and the provision of insulation. A land surface model (the coupled hydrological and biogeochemical process model, CHANGE) was used to quantitatively assess the influence of moss cover on soil temperature ( T SOIL ), active layer thickness (ALT), and ecosystem carbon balance. The CHANGE model was coupled with a moss process module, enabling the explicit representation of heat, water, and carbon exchange in

[1] A coupled hydrological and biogeochemical model (CHANGE) that evaluates heat, water, and CO2 exchange between the biosphere and atmosphere across a spectrum of various time and space scales is described in this paper. The CHANGE model, which merges important components and functions in Arctic terrestrial ecosystems, is a process model with a self-constrained nature that is based on a complex and nonlinear interplay among hydrological, physiological, biochemical, ecological, and edaphic facto

Abstract Recent years have seen an obvious warming trend in the Arctic. Streamflow and water temperature Tw are important parameters representing the changes of Arctic rivers under climate change. However, few quantitative assessments of changes in river Tw have been conducted at the pan-Arctic scale. To carry out such an assessment, this study used a modeling framework combining a land process model [the coupled hydrological and biogeochemical model (CHANGE)] with models of river discharge Q, i

AbstractA numerical model (LITEM) to evaluate the effect of the litter layer on evaporation was developed and used to estimate evaporation, soil temperature and soil water content. This model includes a sub-model to estimate the resistance of the litter layer to evaporation with its thickness and volumetric water content. The resistance of the litter layer to evaporation increases as volumetric water content of the litter layer decreases and as its thickness increases. Evaporation data in a deci

Abstract Arctic precipitation ( P G ) that occurs as rainfall ( P rain ) or snowfall ( P snow ) depending on the prevailing climatic conditions results in seasonally specific hydrological events. Climate change can affect the P G ‐ and permafrost‐originated water ( P ice ) regimes, resulting in change to ecohydrological processes. However, the relative influences of source waters (i.e., P rain , P snow , and P ice ) on terrestrial hydrological processes have not yet been fully established. Here,

A one‐dimensional, multilayer model that infers the fluxes of heat, water vapor, and CO 2 in a biosphere‐atmosphere system, as well as their sources and sinks, was described and evaluated in a secondary broad‐leaved forest. Coupling of a third‐order closure model allows the model to infer profiles of scalar fluxes, sinks, and sources with the computed velocity statistics. Furthermore, the model combines a leaf water process model and makes it possible to capture the impacts of rainfall events on