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Katata, Genki*; Grote, R.*; Mauder, M.*; Zeeman, M. J.*; Ota, Masakazu
Biogeosciences, 17(4), p.1071 - 1085, 2020/02
Times Cited Count：8 Percentile：50.14(Ecology)Mountain grassland productivity is limited by cold and long winters; thus, rising temperatures and changes in snow cover expected in the future may have large impacts on the grassland yields. To investigate this, we enhanced land surface model (SOLVEG) to account for snow, freeze-thaw events, and grass growth, and the model was applied to the managed grasslands affected by extremely warm winter. The model reproduced temporal variability of observed heat fluxes, soil temperatures and snow depth throughout the 3-year simulation period. High physiological activity during the extremely warm winter led to a CO
uptake of 100 g-C m
, which was, surprisingly, mainly allocated into the below-ground biomass and rarely used for plant growth during spring. This process, which is so far largely unaccounted for in global terrestrial biosphere models, may lead to carbon accumulation in the soil and/or heterotrophic respiration as a response to global warming.
Quansah, E.*; Katata, Genki; Mauder, M.*; Annor, T.*; Amekudzi, L. K.*; Bliefernicht, J.*; Heinzeller, D.*; Balogun, A.*; Kunstmann, H.*
Advances in Meteorology, 2017, p.6258180_1 - 6258180_11, 2017/00
Times Cited Count：3 Percentile：9.47(Meteorology & Atmospheric Sciences)An accurate prediction in the energy partitioning of the net solar radiation into latent and sensible heat fluxes over arid and semiarid regions is one of the challenges in land surface study in weather and climate simulations. Numerical simulations of surface energy and water balances were carried out using a one-dimensional multi-layer atmosphere-SOil-VEGetation (SOLVEG) model for selected days of the dry and rainy seasons over a savanna grassland ecosystem in Sumbrungu in the Upper East region of Ghana. The results for the investigated period between both seasons showed that the model overall reproduced the diurnal changes in the observed net radiation, sensible heat flux, latent heat flux, and ground heat flux. The statistics for the above variables as the correlation coefficient, root mean square error, and normalized standard deviation between the observations and calculations in the dry and wet periods suggest that the model was able to simulate the observed energy fluxes, soil evaporation, and transpiration in savanna grassland ecosystems.
Desai, A. R.*; Wohlfahrt, G.*; Zeeman, M. J.*; Katata, Genki; Eugster, W.*; Montagnani, L.*; Gianelle, D.*; Mauder, M.*; Schmid, H. P.*
Environmental Research Letters, 11(2), p.024013_1 - 024013_9, 2016/02
Times Cited Count：21 Percentile：58.47(Environmental Sciences)Regional ecosystem productivity is highly sensitive to inter-annual climate variability, both within and outside the primary carbon uptake period. However, Earth system models lack sufficient spatial scales and ecosystem processes to resolve how these processes may change in a warming climate. Here, we show, how for the European Alps, mid-latitude Atlantic ocean winter circulation anomalies drive high-altitude summer forest and grassland productivity, through feedbacks among orographic wind circulation patterns, snowfall, winter and spring temperatures, and vegetation activity. Therefore, to understand future global climate change influence to regional ecosystem productivity, Earth systems models need to focus on improvements towards topographic downscaling of changes in regional atmospheric circulation patterns and to lagged responses in vegetation dynamics to non-growing season climate anomalies.
Katata, Genki; Held, A.*; Mauder, M.*
no journal, ,
The leaf wetness was monitored using electrical sensors directly clipped to living leaf surfaces of thin and broad-leaved grasses. The measurements were carried out at the pre-alpine grassland site in Germany from September 20 to November 8, 2013. Numerical simulations of a multi-layer atmosphere-SOiL-VEGetation model (SOLVEG) were carried out for analyzing the data. The model reproduced well the observed leaf wetness, surface fluxes and temperature, and soil temperature and moisture. In rain-free days, a typical diurnal cycle as a decrease and increase during the day- and night-time, respectively, was observed in leaf wetness data. The high wetness level was always monitored under rain, fog, and snowcover conditions. Leaf wetness was also often high in the early morning due to thawing of leaf surface water frozen during a cold night.
Katata, Genki; Mauder, M.*
no journal, ,
An existing multi-layer atmosphere-SOiL-VEGetation model (SOLVEG) developed by the authors was modified to simulate snow and frozen soil processes. The schemes of a multi-layer snow structure for heat and liquid water transports in snow and freeze-thaw processes of soil moisture were incorporated into the model. The performance of the modified model was tested at the pre-alpine grassland site in Germany. The modified model overall reproduced the temporal changes in observations of surface energy fluxes, albedo, snow depth and surface temperature, and soil temperature and moisture. The measured increases of soil water content due to infiltration of melted snow to the soil were simulated by the modified model. The observed large negative sensible and positive latent heat fluxes associated with the typical south foehn, a warm and dry downslope wind of the Alps, were also reproduced in the simulation.
exchange processes at pre-alpine grassland sitesKatata, Genki; Mauder, M.*
no journal, ,
A multi-layer atmosphere-SOiL-VEGetation model (SOLVEG) was modified to simulate snow and frozen soil processes. Heat and liquid water transported within a multi-layer snow structure scheme, and freeze-thaw process of soil water was incorporated into the model. The modified model was applied to pre-alpine grassland sites in TERestrial ENvironmental Observatories (TERENO) networks in Germany. The modified model reproduced the overall temporal changes in observations of momentum, surface energy, and CO fluxes, albedo, physical snow depth and surface temperature, and soil temperature and moisture. Our simulations demonstrated that foehn winds, a southern warm and dry downslope wind of the Alps, strongly enhanced snow melting due to large negative sensible and positive latent heat fluxes. Soon after the snow melted due to foehn winds, CO assimilation immediately occurred even in the middle of winter season.
Desai, A. R.*; Wohlfahrt, G.*; Zeeman, M.*; Katata, Genki; Mauder, M.*; Schmid, H. P.*
no journal, ,
The impact of climate change on regional ecosystem has two important aspects: (1) ecosystems don't respond directly to climate, but indirectly via frequency and occurrence of weather systems, (2) many responses of ecosystems to these weather patterns and extremes are lagged in time. Here, we examine these aspects for northern Alpine grasslands. Long-term flux and phenology observations in Austria and Germany and biophysical models reveal a strong influence of winter air temperature, snowfall, and snowmelt frequency on winter grass mortality and spring grassland carbon uptake. Further, the mode of climate variability that drives winter air temperature and snow depth patterns is primarily the frequency of strong regional southerly Foehn flow. Finally, we demonstrate that much of the interannual variance in Foehn frequency and southerly flow is driven by statistics and climatic trends of 500 hPa pressure patterns in Greenland, part of the Arctic Oscillation.
Katata, Genki; Grote, R.*; Zeeman, M. J.*; Mauder, M.*; Ota, Masakazu; Lu, H.*; Kiese, R.*
no journal, ,
We coupled a multi-layer atmosphere-SOiL-VEGetation model (SOLVEG) with a detail snow scheme and grass growth scheme to investigate snow-free grassland dynamics. We applied the modified SOLVEG to pre-alpine grassland sites in Germany for a year with an exceptional small amount of snowfall. The modified model reproduced temporal changes in observations of surface energy and CO fluxes, soil temperature and moisture, and aboveground biomass. Our simulations and measurements demonstrate that grasses at lower elevation are not dormant and continuously assimilate atmospheric CO even in the middle of winter season. On the other hand, dead leaf biomass increases due to frosts over cold snow-free days. As a result, snow-free wintertime carbon uptake almost balanced with wintertime soil respiration. However, under temperature rise conditions, grass ecosystems act as a strong sink of CO from winter to early spring due to a decrease of frost damages of foliage.
