Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
27 Jan 2017
Review status
This discussion paper is a preprint. It has been under review for the journal Hydrology and Earth System Sciences (HESS). The manuscript was not accepted for further review after discussion.
A surface model for water and energy balance in cold regions accounting for vapor diffusion
Enkhbayar Dandar1,2,4, Maarten W. Saaltink2,3, Jesús Carrera1,3, and Buyankhishig Nemer4 1Institute of Environmental Assessment and Water Research (IDAEA), CSIC, c/ Jordi Girona 18-26, Barcelona, 08034, Spain
2GHS, Department of Civil and Environmental Engineering, Universitat Politecnica de Catalunya, UPC, Jordi Girona 1-3, Barcelona, 08034, Spain
3Associated Unit: Hydrogeology Group (UPC-CSIC)
4epartment of Geology and Hydrogeology, School of Geology and Mining Engineering, MUST, Baga Toiruu 46-114, Ulaanbaatar, 14191, Mongolia
Abstract. Computation of recharge in subarctic climate regions is complicated by phase change and permafrost, causing conventional conceptual land surface models to be inaccurate. Actual evaporation tends to fall very low in the Budyko curve and surface runoff tends to be much larger than what would be expected in terms of potential evapotranspiration. We develop a two-compartments water and energy balance model that accounts for freezing and melting and includes vapor diffusion as a water and energy transfer mechanism. It also accounts for the effect of slope orientation on radiation, which may be important for mountain areas. We apply this model to weather data from the Terelj station (Mongolia). We find that direct surface runoff is small and concentrated at the beginning of spring due to snowmelt. Recharge is relatively high and delayed with respect to snowmelt because a portion of it is associated to thawing at depth, which may occur much later. Finally, but most importantly, we find that vapor diffusion plays an important quantitative role in the energy balance and a relevant qualitative role in the water balance. Except for a few large precipitation events, most of the continuous recharge is driven by vapor diffusion fluxes. Large vapor fluxes occur during spring and early summer, when surface temperatures are moderate, but the subsoil remains cold, creating large downwards vapor pressure gradients. Temperature gradients reverse in fall and early winter, but the vapor diffusion fluxes do not, because of the small vapor pressure differences at low temperature. The downwards latent heat flux associated to vapor diffusion is largely compensated by heat conduction, which is much larger than in temperate regions and upwards on average.

Citation: Dandar, E., Saaltink, M. W., Carrera, J., and Nemer, B.: A surface model for water and energy balance in cold regions accounting for vapor diffusion, Hydrol. Earth Syst. Sci. Discuss.,, 2017.
Enkhbayar Dandar et al.
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version      Supplement - Supplement
RC1: 'Review of hess-2016-659', Anonymous Referee #1, 27 Mar 2017 Printer-friendly Version 
AC1: 'Response to comments by referee 1', Enkhbayar Dandar, 23 Apr 2017 Printer-friendly Version 
RC2: 'Review', Anonymous Referee #2, 26 May 2017 Printer-friendly Version 
EC1: 'The authors should respond to referee 2 comments', Hannah Cloke, 31 May 2017 Printer-friendly Version 
Enkhbayar Dandar et al.
Enkhbayar Dandar et al.


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Latest update: 22 Oct 2017
Publications Copernicus
Short summary
This study is motivated by the assessment of water resources in the upper Tuul River Basin (TRB), norther Mongolia. The water and energy balance model accounting for vapor diffusion was developed. Notably, total runoff would be too small, compared to observations, if vapor diffusion is reduced. The downward flux transforms into recharge and it is relevant both in terms of water and energy balances. We conclude that land surface schemes should account for vapor diffusion.
This study is motivated by the assessment of water resources in the upper Tuul River Basin...