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Permafrost plays an important role in numerous environmental processes at high latitudes and in high mountain areas. The identification of mountain permafrost, particularly in the discontinuous permafrost regions, is challenging due to limited data availability and the high spatial variability of controlling factors. This study focuses on mountain permafrost in a data-scarce environment of northern Mongolia, at the interface between the boreal forest and the dry steppe mid-latitudes. In this region, the ground temperature has been increasing continuously since 2011 and has a high spatial variability due to the distribution of incoming solar radiation, as well as seasonal snow and vegetation cover. We analyzed the effect of these controlling factors to understand the climate--permafrost relationship based on in situ observations. Furthermore, mean ground surface temperature (MGST) was calculated at 30-m resolution to predict permafrost distribution. The calculated MGST, with a root mean square error of ±1.4°C, shows permafrost occurrence on north-facing slopes and at higher elevations and absence on south-facing slopes. Borehole temperature data indicate a serious wildfire-induced permafrost degradation in the region; therefore, special attention should be paid to further investigations on ecosystem resilience and climate change mitigation in this region. [ABSTRACT FROM AUTHOR]

Mongolia is not only a water-scarce but also a data-scarce country with regard to environmental information. At the same time, regional effects of global climate change, major land use changes, a booming mining sector, and growing cities with insufficient and decaying water and wastewater infrastructures result in an increasingly unsustainable exploitation and contamination of ground and surface water resources putting at risk both aquatic ecosystems and human health. For the mesoscale (≈15,000 km²) model region of the Kharaa River Basin (KRB), we investigated (1) the current state of aquatic ecosystems, water availability and quality; (2) past and expected future trends in these fields and their drivers; (3) water governance structures and their recent reforms; and (4) technical and non-technical interventions as potential components of an integrated water resources management (IWRM). By now, the KRB is recognized as one of the most intensively studied river basins of the country, and considered a model region for science-based water resources management by the Mongolian government which recently adopted the IWRM concept in its National Water Program. Based on the scientific results and practical experiences from a six-year project in the KRB, the potentials and limitations of IWRM implementation under the conditions of data-scarcity are discussed. [ABSTRACT FROM AUTHOR]

Soil moisture has widely been identified as a key factor for vegetation distribution in semi-arid areas. In the forest-steppe ecotone of the Khentii Mountains in northern Mongolia, soil moisture is directly controlled by exposition, slope, the presence or absence of permafrost, and vegetation cover. This study investigates the distribution of soil moisture and highlights the effects of a recent wildfire on this fragile ecosystem. Steep southerly exposed slopes are permafrost free and covered with steppe vegetation. Here, relatively warm and dry soils prevail, and high drying rates were observed following precipitation events during the summer period. The less inclined northerly exposed slopes are covered with taiga and feature relatively cold and wet soils overlying permafrost. Following a wildfire, the mean thickness of the organic surface layer drastically decreased from 0.15 m in the pristine taiga to 0.03 m in a heavily burned forest. As vegetation removal directly reduced evapotranspiration, soils in the burned forest were significantly the wettest and soil drying was less pronounced. Simultaneously, permafrost degradation was enhanced due to a significant increase in soil temperature. Thus, the conversion of forest areas to steppe after wildfires appears to be a long-term and possibly irreversible process during the ongoing climatic trend. [ABSTRACT FROM AUTHOR]

High topographic heterogeneity and complex mechanisms between the atmosphere and the ground create unique hydro-climatic processes over mountainous regions. Based on in situ observations, we present the spatial variability of ground surface temperature (GST) in the Khentii Mountains of northern Mongolia, which is situated at the southern fringe of the Eurasian permafrost zone. Changes in the hydrothermal regime of the active layer were investigated in association with changing climate and wildfire effects. The results reveal that the GST tends to increase continuously since 2011 in both thawing and freezing seasons, and varies significantly within a short horizontal distance, particularly during the thawing season. Extreme weather events, such as drought and heavy snowfall, amplify the increase in the ground temperature and deepen the seasonal thawing depth. The fire-induced loss in organic layer resulted in a greater heat penetration deeper into the ground and unbalanced the moisture distribution. Overall, the thawing depth is greater by >1.7 m under severely burned forest, compared to unburned forest. Given that about 30% of the boreal forest was affected by wildfire in the study area, the ground thermal regime changed considerably. The findings suggest that the combination of regional temperature rise and more frequent extreme weather and wildfire events in the region triggers permafrost degradation and alters the hydrothermal regime in the future. [ABSTRACT FROM AUTHOR]

Livestock production is a socioeconomic linchpin in Mongolia and is affected by large-scale livestock die-offs. Colloquially known as dzuds, these die-offs are driven by anomalous climatic events, including extreme cold temperatures, extended snow cover duration (SCD) and drought. As average temperatures across Mongolia have increased at roughly twice the global rate, we hypothesized that increasing cold season surface melt including soil freeze/thaw (FT), snowmelt, and icing events associated with regional warming have become increasingly important drivers of dzud events as they can reduce pasture productivity and inhibit access to grazing. Here, we use daily brightness temperature (Tb) observations to identify anomalous surface melt and icing events across Mongolia from 2003–2016 and their contribution to dzuds relative to other climatic drivers, including winter temperatures, SCD, and drought. We find a positive relationship between surface melt and icing events and livestock mortality during the fall in southern Mongolia and during the spring in the central and western regions. Further, anomalous seasonal surface melt and icing events explain 17–34% of the total variance in annual livestock mortality, with cold temperatures as the leading contributor of dzuds (20–37%). Summer drought showed the greatest explanatory power (43%) but overall had less statistically significant relationships relative to winter temperatures. Our results indicate that surface melt and icing events will become an increasingly important driver of dzuds as annual temperatures and livestock populations are projected to increase in Mongolia. [ABSTRACT FROM AUTHOR]

Knowledge of the snow cover dynamics in mountains of the semi-arid regions on Earth is essential for an improved understanding of the hydrological regime and for human water supply in a water scarce environment. In the semi-arid Sugnugur headwater catchment (in the Khentii Mountains, northern Mongolia), a spatial analysis of seasonal snow cover duration (SCD) was achieved on a 30 m grid by integrating the spatial resolution of Landsat-7, Landsat-8 and Sentinel-2A images with the daily temporal resolution of MODIS snow products (2000-2017). Validation was achieved using in situ measurements from winter field campaigns and spatially distributed surface temperature recordings. We found a mean increase of SCD with altitude at approximately +6 days/100m. However, no altitude-dependent changes in snow depth could be observed during the field campaigns. The southern exposed valley slopes are either snow free or covered by intermittent snow throughout the winter months due to high sublimation rates and prevailing wind. The estimated mean SCD ranges from 124 in the lower parts of the catchment to 226 days on the mountain peaks, with a mean underestimation of 12-13 days. Snow onset and melt dates exhibited large inter-annual variability, but no significant trend in the seasonal SCD was evident. Our method supports the better quantification of snow melt rates and thus water availability in this semi-arid environment. It can be applied to high-resolution snow mapping in similar mountainous regions. [ABSTRACT FROM AUTHOR]