Many studies have been conducted on air pollution in Ulaanbaatar city. However, most have focused on the sources of pollutants and their characteristics and distribution. Although the location of the city subjects it to unavoidable natural conditions where air pollution accumulates during the cold season, nature-based solutions have not yet been considered in the projects implemented to mitigate air pollution levels. Therefore, this study aims to determine the combined influence of geography and atmospheric factors on cold season air pollution. The spatiotemporal variations in the variables were investigated using meteorological observation data from 1991 to 2020 in the different land-use areas. Then, atmospheric stagnation conditions and air pollution potential parameters were estimated from daily radiosonde data. Subsequently, the temporal variations in air pollutants were studied and correlated with estimates of the above parameters. In the Ulaanbaatar depression, the stable cold air lake (colder than −13.5 °C), windless (34–66% of all observations), and poor turbulent mixing conditions were formed under the near-surface temperature inversion layer in the cold season. Moreover, due to the mountain topography, the winds toward the city center from all sides cause polluted air to accumulate in the city center for long periods. Air pollution potential was categorized as very high and high (<4000 m²·s⁻¹), in the city in winter, indicating the worst air quality. Thus, further urban planning policy should consider these nature factors.

This study evaluates the spatial suitability of land for nomadic pastoralism across two distinct seasonal periods: winter–spring and summer–autumn. Nomadic pastoralism is a cornerstone of Mongolia’s rural livelihood system, but its sustainability is increasingly challenged by pasture degradation, climatic variability, and socio-economic pressures. Since pasture quality and accessibility fluctuate significantly between seasons, identifying suitable grazing areas is critical for ensuring both ecological resilience and herder well-being. To capture these dynamics, seven environmental and socio-economic factors were selected for each season and analyzed using a geographic information system (GIS)–based multi-criteria decision analysis (MCDA). Factor selection followed the methodological guidelines for pasture suitability assessment issued by the Agency of Land Administration and Management, Geodesy and Cartography (ALAMGaC), while additional determinants reflecting herder mobility and traditional grazing practices were incorporated to refine the evaluation framework. The results reveal distinct seasonal contrasts. During the winter–spring season, 11.26% of the study area was identified as unsuitable for grazing, 18.02% as less suitable, 46.37% as moderately suitable, and 24.35% as highly suitable. In contrast, summer–autumn conditions produced a less favorable distribution, with 23.83% unsuitable, 30.66% less suitable, 30.22% moderately suitable, and only 15.29% highly suitable. These differences emphasize the influence of climatic and ecological seasonality on pasture productivity and herding strategies. The findings suggest that sustainable pasture management requires not only an understanding of spatial heterogeneity but also season-specific planning. Such an approach can provide valuable insights for policymakers, land managers, and local herding communities seeking to maintain the viability of nomadic pastoral systems under changing environmental and socio-economic conditions.